2000-#1

ShopTalkSand by the Numbers:Follow these tips to properly prepare wood and fiberglasssurfaces for painting or varnishing. By Wayne Redditt

Sailboat RiggingReplacing orSupplementing Keel Bolts:Checking keel bolts should bepart of a routine inspection.Here’s how to identify problemsand repair damaged keel bolts. By Nick Bailey

ElectronicsElectrical Troubleshooting:A multimeter is the quintessentialtool to detect DC and AC electrical faults and to measurevoltage, current and resistance. By Larry Douglas

Powerboat RiggingKeel Protector: Easy-to-install,just peel n’stick this ultra-toughkeel “bumper.”

Good BoatkeepingCustomized handrails add adecorative touch and protectsolar panels from side impact.By David & Zora Aiken

COLUMNS

KEEPING DRY BELOW DECKSIs your boat’s existing bilge pump system adequate? Here’s the lowdown on pump types, flow rates, installation options and other information you need to evaluate and plan an upgrade. By Nick Bailey

NOT ALL CLAMPS ARE EQUALHose clamps vary greatly in quality and construction. What you may think is an "all-stainless" clamp could sink your boat.

Step-by-Step Bilge Pump Replacement

FITTING OUT TIPS AND TRICKS

THE WEAK LEAKLeaking fuel tanks are becoming a common and serious problem in older boats. Here’s the latest info on tank materials, step-by-step tank repair methods, replacement options and installation tips. By Nick Bailey

WATER COOLING SYSTEMSEverything you need to know about raw-water and closed cooling systems — components, corrosion protection, pressure testing for leaks and blockages, and converting to a closed cooling system. By Robert Hess

TROUBLESHOOTING STARTING SYSTEMSEngine won’t start? This step-by-step diagnostic guide will get your engine running again. By Robert Hess

ENGINE TEMP CONTROLA faulty thermostat causes an engine to overheat or to operate too cold, either condition resulting in costly damage. Here’s how to test, remove and replace your engine’s thermostat. By Robert Hess

Departments

Q&A Talkback

TECHNICAL HELPLINETech Tips

U P G R A D E

M A I N T E N A N C E

D I Y M E C H A N I C

See page 28 for details

Q+Talkback AExhaust ReworkQ: I have just acquired a convertedtrawler with a dry exhaust vented upand out through the roof. I would liketo redirect it throughthe transom, butfor somereason,all tran-som-out

exhausts seem tobe wet. The engineis cooled by aclosed-circuit cool-ing system and Idon't want tochange it. Are thereproblems with lead-ing a dry exhaustout through the tran-

som, apartfrom puttingin a goose-

neck and lots of sound-noise insula-tion? Jack Creswick, Melbourne, Australia

A: The advantage of a dry exhaustsystem is that it eliminates problemsrelated to engine-cooling water orseawater backing up into exhaustmanifolds. According to the expertsat Soundown, from the water injec-tion elbow on the engine, you wouldattach the exhaust hose to an axialwaterdrop silencer. This silencer sep-arates the engine-cooling water andcooled exhaust gases and dischargesthem separately. You have three dis-charge options: discharge the waterout the bottom of the boat via abelow-waterline thru-hull and routethe exhaust gases to an above-water-

line thru-hull on the transom; orrecombine the water and dischargeas a traditional wet exhaust; or usethe boat's existing stack and send thewater and exhaust gas up the stackin a traditional configuration. Somelarger yachts have a valve to selecteither up-the-stack discharge or thru-

transom.This sys-

tem iseasilydesigned

into a newboat, but is limited in a rebuilt due toexisting piping runs, bulkheads, etc.Where the engine is mounted belowthe waterline, you will have to dis-charge into a standard waterliftwhich connects to a waterdropsilencer, then discharge the waterand gas separately as per the aboveoptions, similar to a generator appli-cation.— Jan Mundy

Wax 3, Buff 1Q: I am looking for recommenda-tions on restoring my boat’s fiber-glass. I have tried a few restorersand waxes but they don’t last. Ron McMillan, "Mary-Mac" Ottawa,Ont.

A: Unfortunately, once the polishingstarts it never ends. The longest last-ing shine is the one on a factory-newboat. After gelcoat has been buffed,it requires constant attention to keepthat showroom look. It’s possible theproducts you’ve been using don’t lastbecause of application intervals. It’snot unusual to wax a boat two orthree times a season in northern cli-mates, more often in southern areas.You should only have to buff once aseason, usually before launching inthe spring. 3M makes a great fiber-

glass buffing compound that I highlyrecommend. Others are Meguiars orAquaBuff. Follow up with a brand-name wax formulated for fiberglass. — Wayne Redditt

Freshwater Flush Q: My S2 9.2A sailboat has aportable self-contained head and Iintend replacing same with a Raritanor Par. I already have a holdingtank. Can I flush the new head frommy freshwater system? If so, should Itap into the line before or after thepump? Brian Lee, St. Catharines, Ont.

A: Forget trying to use your potablewater system to supply freshwater toyour toilet unless you plan to discon-nect it from your sink faucets. Thisapproach is unsanitary becausemost marine toilets, other thanSealand Vacuflush units, share acommon pump, piston and valvebody for both sewage and flushwater. Other than some dinky flap-per valves there is nothing to preventnasty pathogens from swimmingback upstream to your drinkingwater while the system is idle. If youdon’t want to install a thru-hull it maybe practical to tee into an overboardsink drain below the waterline as asource of flush water. However, toprevent siphoning back into the boatbe ready to install an anti-siphonvented loop in the flush waterlinebetween the bowl and the headpump. — Nick Bailey

Plug-WittedQ:: I just bought my first boat, a 15-footer with a 15hp outboard andhave a dumb question. Does thedrain plug insert from inside the boator outside? Johnny Nixon, Vinton, Ohio

Q+A

A: It's better to askthen be sunk. You'd besurprised at the numberof boats that sink everyyear because someoneforgot the plug or did-n’t know. Install theplug from the outsideand screw in tight.Apply some waterproof grease to the rubber housing soit removes easily after every haulout. Replace plug whenthreads or housing wears, and carry at least two spares.— Jan Mundy

What’s Missing? Q: We purchased a 1976 7.2m (24') SeaRayWeekender last summer and the 255hp MerCruiser startsand runs fine for an hour or so, then starts missing, firstat higher rpms, later even at 1,000 to 1,500, while welimp home at 10 mph. Anything faster and the engineoccasionally backfires through the carb. Symptoms alsoappear when we run the engine for 20 minutes, shut itdown for a lunch stop, then restart to come home. Wehave changed plugs, coil, primary wire from ignition tocoil, complete carb overhaul, water filter separator,points and condenser, and added Bardol to the oil andgas tanks. When we bought the boat it had an upscaledistributor in it, new plug wires, platinum plugs, and anew coil, as if the previous owner had also been chasingthis demon.Hugh Enns, Blind Bay, B.C.

A: It only takes three things to make an engine workproperly: fuel, spark and compression. One of thesethree is giving you difficulty. A good mechanical diagno-

sis is the first step. Do a compression test to establish thatthe mechanical part of the engine is working correctly.Compression or mechanical problems don’t tend to beintermittent, so the fault is likely voltage related or fuel.Attach a vacuum gauge to the inlet fuel supply line — thevalue should not be above 5cm (2") of vacuum. Anengine that misfires through the carburetor indicates thatit’s lean on fuel, overadvanced timing or overheatingcaused by sticking intake valves. A weak voltage or igni-tion system where all fuel doesn’t get burned probablyalso causes backfiring. Your engine’s breaker-point igni-tion must have 8 to 10 volts at the coil with the enginerunning. Make sure the coil is an external resistor-typecoil. Did you replace the supply wire with a regular wireor a resistor wire? Your engine’s alternator puts out 14volts. The resistor wire steps this down to 10 volts at thecoil. If the coil receives more voltage, it overheats andburns out points. If it’s only receiving 6 volts, the coilwon’t overheat, it just performs poorly. If after all yourdiagnosing, your engine still runs poorly, I suggest youtake it to a certified marine mechanic. TIP: When diagnos-ing engine trouble, if you install new components with noeffect, return the original components, otherwise you can’tsource the cause of the problem.— Steve Auger, Mercury Marine

Better to Cover Than Go BareQ: I just purchased a ‘97 Four Winns that has never seenbottom paint and plan to keep it in a marina on theDelaware River. Are there any alternatives to bottompaint? I have been told my only other option is to haul outevery two weeks and pressure wash it. David Buddendorff, Croydon, Penn.

A: Since gelcoat is porous, you need to apply some typeof "sealer." Fouling tends to fill the pores of the gelcoat,making cleaning difficult, even with an acid cleaner (i.e.MaryKate On/Off), and yellows the hull. You could applya clear bottom wax, followed by frequent power wash-ings. We have tried various waxes specially formulatedfor underwater applications (i.e. Easy On, Super Slick)but have not yet found one that eliminates fouling anddoesn't require either weekly cleaning or cleaning with anacid wash if left for longer periods before cleaning. Testareas include the Hudson River (brackish water) and fresh-water. Unless you get an endorsement from your localmarine store or a fellow boater, I don't recommend usinga bottom wax. There are epoxy coatings available (i.e.VC Underwater Epoxy) but these don't have any antifoul-ing properties and the boat would need hauling everyweek or two for cleaning, a task made easier with prod-ucts containing Teflon. Unfortunately, there aren't otherviable solutions that work that we are aware of.— Jan Mundy

Prep for Barrier CoatQ: My boat’s bottom paint is thick due to yearlyrenewal. This spring I would like to sand the bottom andapply a barrier coat, then reapply new anti-foulingpaint. Must all the old finish be removed? Chuck Bentley, Rensselaer, N.Y.

A: To apply a barrier coat all of the old antifouling mustbe removed. There are various methods to do this: havethe boat sand- or baking-soda blasted; have it powerpeeled (i.e. The Peeler); apply a chemical peel such asPeel Away; grind (not recommended); or sand heavilywith 60-grit paper to make the antifouling more porous,then apply a paint remover (i.e. Interstrip 299E). Afterthe paint has been removed sand the bottom with 80-gritpaper, and then wipe down with fiberglass solvent wash(i.e. Interlux 202). Apply your barrier coat according tothe manufacturer’s instructions, then apply the anti-foulingpaint. — Jan Mundy

Heads UpQ: I’m in the process of restoring a ‘79 Montego 19.Recently I saw some sailboats with pop-up companion-way tops, adding about 25.4cm (10") of headroom. Itlooks like a good idea. Any suggestions for making a

Need help with a problem? Unableto find information on products ordo-it-yourself projects?

DIY TALKBACK is a special reader servicethat makes available to you the resourcesof marine industry experts on topics suchas boat repair, engines, trailers, electricity,plumbing, electronics, sails, maintenanceand more.

Cost is FREE to DIY subscribers.

Send your questions to:TALKBACK via mail or E-mail. Include yourname, subscriber ID number (if known), boatname and home port in all correspondence.Non-subscribers must include payment.

MAIL:P.O. Box 22473 Alexandria, VA 22304

E-MAIL: info@diy-boat.com

TECHN

ICAL HELPLIN

E

new fiberglass top? Also, do you rec-ommend using a router or Dremeltool with a spiral bit, rather than asaw, to cut the glass?D. Leary, Quantico, Virginia

A: If you intend to remove the exist-ing cabin top and make a new onethat hinges upward, I would have torecommend against that. The cabintop is a very important structural partof the boat and this sort of changemay create dangerous conditions ofweakness in the structure. The com-panionway hatch could be made topivot upwards, instead of sliding inthe rails, to allow standing headroomunder the hatch. It's useful at dock-side, but probably not so solid whileunderway. For cutting fiberglass, arouter with a down spiral bit worksfine. You would be at it a long timewith a Dremel tool, as they are sim-ply not powerful enough for cuttingfiberglass. Make sure that there areno embedded hardware parts beforeusing the router.— Wayne Redditt

Gelcoat StreakingQ:: 10.2m (34') Silverton has someyellowish streaks while other partsare either white or off-white. Arethere products to restore the hull toan all-white color? Kevin Gallagher, "Millie," BelmontHarbor, Chicago, Ill.

A: Your hull likely has what is knownas alkaline streaking. Someone, atsometime, used an alkaline cleaner(i.e. Fantastik, Castrol Super Clean)which was allowed to dry. Thecleaner attacking the gelcoat causesthe streaking. Some alkaline cleanershave great cleaning power but mustbe rinsed thoroughly and neverallowed to dry. There is no cure,aside from painting. — Jan Mundy

Q+A

STAKES FOR STRAKES: Lowes (a large building supply chain in theU.S.) sells 19mm- (3/4"-) squaretomato stakes made of teak or otherweather-resistant look-alike wood.After two years of garden use, thewood shows no signs of decay andhas a silvery gray surface with agolden hue underneath. Perfect forsmall cockpit grates, eyebrows (ifscarfed together) and lots of othersmall projects, or laminate sometogether for bigger jobs. A bundlecosts about US$4.Brian Gilbert, “Atricilla,”Charleston, S.C.

A COSTLY MEAL: We’re not surewhy, but some muskrats enjoy a tastymeal of rubber. A pinhole morsel ina shift cable bellow can sink a boatin hours. Raisethe outdrive outof the water andturn to starboardto help to repeland prevent acci-dental sinking. OMC drives builtbefore 1985 have a rubber-typetransom gasket, an especially easydinner target.For theseengines,OMC makesa rodentguard, a bigchunk of plastic with the center cutout for the outdrive.Warren Mills, owner GannonNarrows Marina, Peterborough, Ont.

E-COMMUNICATIONS: Whenyou need to stay in touch whilecruising, buy a Sharp TM-120(US$119), a new portable pocketcomputer with an acoustic coupler.Dial a toll-free number to send andreceive e-mails and faxes from any

phone, wired or wireless. No needto carry a laptop, acquire anInternet server or seek out librariesor Internet cafés. Long distancecharges apply only when callingfrom outside the U.S. David Burns, aboard “Kari II,” viae-mail.

FILTERING FUEL AT THE PUMP:Marina fuel tanks are often a sourceof water and dirt. Instead of pump-ing fuel directly into the tank, pumpit into a large funnel fitted with afine screen in the bottom andinserted into the fuel intake hose.

PARTS ORGANIZERS: Use inex-pensive plastic drawer organizers,preferably with see-through lids, forstashing fasteners, nav gear and amyriad of small parts accumulatedonboard. Available in a variety ofsizes andshapes,some fitsnuglyunder deck-heads orshelves. For units with opaque tops,instant glue a sample onto eachdrawer for easy identification.

FILTER GUARD: Some engineshave the oil filter located behind thefan belt. Should the belt loosen, itcould hole the filter. In order to pre-vent this, slip a hose clamp aroundthe filter where the belt lines up withthe filter.

EMERGENCY VENT PLUGS:Most boats are fitted with deckvents but few of these are sealed.Under extreme conditions, boardingseas could wash away the vents,leaving 7.6cm (3") or larger holesin the deck. Constructed similar to

tapered seacock plugs, fashionthem from cedar or pine, beginningwith a diameter that is slightlylarger than the maximum openingof the vent and with an overalllength of about 30.5cm (12"). Forconstruction details, see DIY 1995-#1 issue, page 21.

REST PEACEFULLY: To quiet noisyinternal mast halyards, cables andwires, slide lengths of foam insula-tion, the kind used for wrappingpipes, up the mast.

GLUE ADVICE: No boatbuildershould be without Gorilla Glue (LutzFile and Tool, Cincinnati, Ohio). Itfoams up and crystallizes in place,making for a super-strong bond,even when joints aren’t perfect. Doug Barnard, “Fiesta Bimbo,”Agoura, Calif.

MARKING SCOPE: To estimatehow much anchor line to let out,insert pieces of polyester cord ortape through the line at your normalanchoring lengths. Laying theanchor line along the deck frombow to stern and back gives anaccurate measure of total length.Wayne Rezendes, “Makai,”Honolulu, Hawaii

Tech Tips welcomes contributionsfrom readers. If you have a boat-tested tip you’d like to share,send complete information alongwith your name, boat name andhome port to: DIY Tech Tips

P.O. Box 22473Alexandria, VA 22304

Or E-mail to info@diy-boat.com.

Tech Tips ✓

ShopTalk

By Wayne Redditt

Virtually every surface finishing jobbegins with surface preparation.For simple tasks such as waxing, agood cleaning may be all that’srequired. For painting or varnishingthough, more thorough preparationis always in order.

Almost all paint or varnish (film)applications demand abrading ofthe surface prior to applying thefilm. There are many typesof abrasives (sandpaper is abit of a misnomer) andplenty of methods of usingthem.

Abrasive particle size isdesignated by number. Alow number indicates acoarser material that is moreaggressive and leavesdeeper, wider scratches. Thissystem applies to most abra-sives. (Specialized systemsusing micron designationshave the reverse numberingof common abrasives.) Formost purposes, I use 80(coarsest), 120, 240, and 320(finest), normally garnet for every-day use, Adalox for sanding epoxyresin.

When removing old paintdown to the substrate, don’t startwith abrasives. Use only heat guns,chemical strippers and scraperswhen removing paint that is flakingoff or has large open splits thatsoon will flake off. Don’t removesolid-adhering paint — it has agreat bond to what is underneath,

so why start from scratch. Surface prep on boats usually

involves four categories: a barewood surface; a wood surface thathas paint adhering to it; a bare gel-coat surface; and a painted fiber-glass surface.

When hand-finishing a barewood surface, start with 80 grit ona sanding block to remove anyhigh spots. Anything coarser than

this will probably remove morematerial than desired. If you areflattening (fairing) a surface, sandat an angle to the grain to removethe material quicker. Sand out thecross scratches with 120 grit, mov-ing the block in the grain directionof the wood. Don’t sand past 120grit for woods like mahogany, teak,oak or ash. When power-sandingwith an orbital or double-actionorbital sander, you have less con-cern about the grain direction,

although it’s not advisable to movean orbital rapidly across the grainas it will scratch deeply. Handsanding is actually more aggressivethan power sanding; powersanders leave a shallower scratchmark than similar grit done byhand.

If your project requires paintingover bare gelcoat, use a fiberglassgelcoat cleaner prior to sanding.

This will remove all traces ofmold-release agents, waxesand other surface contami-nants that won’t be removedby sanding. Sanding the sur-face without removing thesecompounds will surely resultin poor paint adhesion later.Read the can labels beforeproceeding and sand onlyto the grit recommended.

Treatment for wood orfiberglass surfaces that havepaint adhering well is simi-lar. The object is to lightlyabrade the paint surface toprovide mechanical as well

as chemical adhesion from the newpaint. The idea of mechanicaladhesion is derived from the beliefthat the liquid film flows into the tinyscratches created from sanding andlocks in tightly upon drying. Thismeans that you don’t want to createa shiny or burnished surface whensanding. Consequently, you mustuse the coarsest grit that will ade-quately be covered by the new film.Some professionals never sand withanything finer than 240 grit before

SAND BY THE NUMBERS Follow these tips to properly prepare wood and fiberglass surfaces forpainting or varnishing.

Tools of the trade.

painting. It depends on the “hide” that the paint sys-tem will deliver. Always consult instructions on thecan’s label or contact the supplier. If it specifies 320grit, then that’s as light as you should go.

Newer abrasion systems incorporate special ingre-dients on the paper’s surface to help shed dust. Thesenon-loading type abrasive papers mean that dustwon’t clog up your paper after the first stroke. Wetsanding with wet-dry paper is still a viable alternativeto the no-clog types.

Immediately prior to painting, use a tack rag toremove all dust. Dust will ruin all of the hard work youwent through to create the “tooth” on the surface andthe film won’t stick. Completely unfold the tack rag,bundle it up into a loose ball, then lightly dust the sur-faces to bepainted.Turn therag overoften.Don’t pressthe tackrag hardonto thesurface, itmay trans-fer contam-inants thatwill causepaint fail-ure later.

About the author:Wayne Redditt teaches boatbuilding, repairand restoration at Georgian College’s Marine Technology-Recreation course in Orillia, Ont.

Easy paper changes, 3M Hookit sanding pad and discs use ahook-and-loop attachment system and are available in mostany grit.

Used specially for detailed finishing, 3M flexi-ble sanding sponges in five grits from mediumto microfine can be used either wet or dry.

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Upgrade

By Nick Bailey

Despite the fact that most boatsare fitted with one or morebilge pumps, sinkings are

common nonetheless. I’m alwaysamazed how many boats are only acorroded fuse or dead battery awayfrom sinking. Even more amazing isthe blind faith boat owners have inwhat is often a very fragile andinadequate pump system. Manypumps are hard pressed to keep aboat afloat at the dock, let alone inthe event of an emergency under-way. A properly installed and main-tained bilge pump system is yoursecond line of defense against sink-ing, behind a watertight hull, and sodeserves your earnest attention andresources.

Types of Pumps Most bilge pumps are either centrifu-gal (submersible) or positive dis-placement (non-submersible) type.Both types can run dry for sustainedperiods without damage, unlike aflexible impeller pump which over-heats and comes apart almost imme-diately if run dry.

Centrifugal pumps (commonsubmersible pump) have a curvedsolid impeller designed to slingwater entering from the center axisof the pump housing into an outletpipe mounted tangential to the housing. A centrifugal pump moveswater by momentum alone and asno suction is created it won’t selfprime. Many have a detachable

base plate, fastened by screws inthe bilge and the pump motorassembly snaps or twist locks intothe base plate. Slots incorporated inthe motor or base plate housingserve as a debris screen to keep theimpeller from fouling. A dischargehose leads to a thru-hull above thewaterline. It’s a very simple plumb-ing installation in concept but onethat is subject to a variety of prob-lems — connecting a dischargehose often cuts actual pump perfor-mance down to half (or less) ofrated capacity (see “PumpPerformance”).

Positive displacement pumps usea reciprocating flexible diaphragmor piston to force water out of thepump on the down stroke and suckwater into the pump on the upstroke.The pump inlet and outlet have aone way flapper or duckbill valve toensure that fluid can only go in thedesired direction on each stroke.Due to the suction created, pumpsare self priming and often mountedremote from the bilge with onlyintake hose and bilge strainer, auseful feature for boats with a bilgesump too narrow or inaccessible tofit a submersible pump, or in shal-low bilges where bilge water levelmust be kept to a minimum.

The weakness of diaphragmpumps is their limited capacity. Evenelectric diaphragm pumps don’t getmuch above 1,200 gallons per hour(gph), a capacity otherwiseexpressed as 20 gallons per minute

(gpm). This isdue to the inefficiency of their one-gush-at-a-time reciprocating action.Most manually actuated bilgepumps are the diaphragm type (i.e.Edson, Bosworth, Henderson,Whale) with rated capacities from 5to 30 gpm. As all diaphragm pumpsare easily crippled by debris lodg-ing in one-way valves, a bilge pick-up strainer or in-line filter mustalways be installed.

Pump PerformanceFor all pumps, manufacturers pro-vide the rated capacity and flowrate data. Nominal ratings arebased on “open flow” conditions;for example, the pump is operatingin a bucket with no hose attached.This nominal “maximum flow” ratingdoes not even remotely indicate howa pump will perform in a typicalinstallation.

The hydraulic head pressure thepump must overcome to push waterthrough the hose and up to the discharge thru-hull governs realisticpump performance. Two factors con-tribute to head pressure: static head— vertical distance from the pumpto the discharge thru-hull — anddynamic head, which is the totalfrictional resistance within the dis-charge plumbing, usually expressedas an equivalent to feet of statichead. Adding static head to thedynamic head gives the total headpressure (also expressed in feet) thatthe pump must overcome. Pump

KEEPING DRY BELOW DECKSIs your boat’s existing bilge pump system adequate? Here’s the lowdown on pump types, flow rates, installationoptions and other information you need to evaluate andplan an upgrade.

manufacturers usually provide infor-mation regarding the maximumallowable head height and a graphof flow versus head height (Figure1).

Another important capacity fac-tor is whether full voltage is avail-able to power the pump. Open flowrating is usually based on pump per-formance with a 13.6-volt DCpower supply. (This represents thevoltage available while the engine isrunning and alternator is charging.)In actual usage, this voltage is rarelyavailable at the pump. The enginemay not be running, wiring may betoo small in gauge for the length ofrun, there may be corroded connec-tions or the batteries may not befully charged. All these conspire toreduce available voltage and thepump’s actual performance. It’s pos-sible to theoretically calculate whatflow rate can be expected in agiven installation, but as a rule ofthumb assume a 50% reduction inflow rate for a normal installation,and even worse for an installationwith high head pressure. Since sub-mersible bilge pumps won’t lift waterbeyond a 1.8m to 3m (6' to 10')head, it’s important to check thepump’s performance specificationsin relation to the requirements ofyour particular installation.

How Big a Bilge Pump?There are no mandatory pump sizerequirements for plea-sure craft from theU.S. Coast Guard oreven any recommen-dations from theAmerican Boat andYacht Council (ABYC).The American Bureauof Shipping (ABS) rec-ommends that vesselsunder 19.5m (65') beequipped with a 24gpm and a 12 gpmpump totaling 36gpm (or 2,160 gph).If we assume this rec-

ommendation is for actual pumpperformance, then this spec calls fora pumping capacity of 5,000 gphor larger, depending on how restric-tive the installation.

Without detailed small craft rec-ommendations your pump choicelargely depends on whether youview it as a convenience to dewaterthe bilge from minor leaks or as amajor safety system designed tokeep the boat afloat in the event ofa critical failure such as a brokenthru-hull or ruptured shaft log.According to a graph (Figure 2)adapted from the “Navy Salvor’sHandbook” by Nigel Calder andpublished in Professional BoatBuilder No. 57, a 25mm (1") hole30cm (1') below waterline lets in1,200 gph, a flow rate which looksmanageable. A 50mm (2") hole at

the same depth floods at the rate of79 gpm or 4,760 gph, a situationequivalent to the failure of a largethru-hull and a flow rate thatexceeds the rated capacity of anybilge pump.

The largest popular submersiblepumps on the market range from4,000 to 8,000 rated gph andrequire 5cm or 7.6cm (2" or 3") dis-charge hoses. Assuming the typical50% of rated performance, even the8,000-gph unit won’t keep up witha 5cm (2") hole. Nonetheless, if asystem is to be considered adequatefor anything other than routinedewatering, it should be able tocope with the most likely failure, ifnot the very worst case emergency.

System PlanningBefore upgrading an existing pumpsystem, it’s necessary to evaluate

0

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15

160150140130120110100908070605040302010

HE

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FLOWRATE (gpm)

3/4" outlet

1" outlet

1.5" outlet

Depth Diameter of of Hole Hull Opening

1" 1.5" 2" 2.5" 3" 3.5" 4” 6”

1' 20 44 79 123 177 241 314 707

2' 28 62 111 174 250 340 444 1,000

3' 34 77 136 213 306 417 544 1,124

4' 39 88 157 245 353 481 628 1,414

5' 44 99 176 274 395 538 702 1,581

6' 48 108 192 301 433 589 770 1,731

Figure 1

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SAMPLE SUBMERSIBLE PUMP PERFORMANCE

Figure 2 - FLOODING RATES (gpm)

Upgrade

your boat’s layout. The first questionis whether the boat is divided intoseparate compartments that, if notwatertight, can at least retain waterup to a damaging level. Each sepa-rate compartment should have itsown bilge pump sized to handle thelikely source of leak in that compart-ment (see “Pump by the Numbers”on page 16).

A 7.5m (25') cabin cruiser, forexample, typically has the enginecompartment separated from thecabin by a watertight bulkhead. Inthe cabin, there may be a 12mm(1/2") head intake and two 25mm(1") sink drains. A single 2,500 gphshould be adequate to handle onebroken thru-hull assuming two won’tbreak simultaneously. In the enginecompartment the most common

worst case scenario is a rupturedwater intake or exhaust hose alsoequivalent to a 25mm (1") flow rateof 1,200 gph, so a second 2,500gph unit should suffice, provided theexhaust outlet stays above water.

A smaller open or cuddy cabin23-footer is at risk of beingswamped in a big sea, or even in aheavy rain. Although cockpits areself draining, a lot of water still getsin through engine hatch covers andneed the largest possible pumps tohandle the flow.

If your boat doesn’t have sepa-rate compartments or large limberholes draining into a common bilge,two pumps on separate circuitsshould still be considered the mini-mum to provide back up in case apump fails or clogs. At least one ofthe pumps should be of high capac-ity to deal with a worst case leak.

Sailboats often have a very nar-row or shallow bilge that cannotaccommodate a larger submersible

WATER- PROOF WARE

When you have a very wetboat and need to keep connec-tions dry and corrosion free, usea watertight plastic containerand terminal strip. A similar con-cept to the watertight fuse boxdescribed in “DIY Projects,”1999-#1 issue, put the terminalstrip loose in the box, pull wiresthrough a single hole punched inthe bottom, attach ring connec-tors to wires and connect themto the terminal strip, mount thebox to any convenient nearbyvertical surface and snap on thelid. Make sure the hole in thebox faces down so rising ordripping water can’t get in.

— Jan Mundy

TIPS

pump. A small submersible electricpump or typical standard-equippedmanual diaphragm bilge pump,although fine for routine dewatering,is not adequate for emergency use.Any boat that is configured in away that prevents the installation ofa properly sized electric pump is agood candidate for a standby emer-gency-only bilge pump system (seebelow).

Larger boats have more equip-ment, more and larger thru-hulls thattend to be situated deeper in thewater. This increased depthincreases hydraulic head pressurebehind a leak and resulting rate offlooding.

Emergency-Only PumpsFor small boats, an Edson self-con-tained, portable pump kit fits in acockpit locker and is quick-to-assem-ble when needed. A viable strategyfor an effective emergency-onlypump for larger boats would be astandby high-capacity, engine-drivenpump (pricey) or a large submersibleelectric pump (more affordableupgrade) mounted in the lowestavailable space in, or near, thebilge.

Rubber-impeller style engine-dri-ven pumps from Jabsco are capableof self priming and are engaged by

either a level-actuated manual clutchor by a remote switch actuated elec-tric clutch (Figure 3, C). The largestversion has a rating of 5,000 gph atfull speed (2,200 rpm) and a conser-vative capacity rating at 3m (10') ofhead. Intended for higher horse-

power engines (30 plus), engine-dri-ven units obviously require you tobecome aware of the leak before theengine drowns, so some kind ofhigh-water alarm would be useful(i.e. Bilge Sentry, Ultra PumpswitchSenior). Like any impeller pump, if

Figure 3

A: Manual diaphragm pump (i.e. Edson)with inline strainer keeps debris fromclogging the pump.

B: Submersible bilge pump with separatefloat switch, on-off-manual switch andoptional red light (and/or audible alarm)operation indicator.

C: High-capacity engine-driven clutchpump has manual on-off lever (or elec-tric) and includes bilge strainer.

A CBDA

VID

AIKE

N

Clutch pump unit

Pump

Pump switch

Alarm (opt.)On/Off/Auto Switch

BIlgestrainer

Manual pump

TYPICAL PUMP INSTALLATIONS

the engine-driven pump runs dry itwill quickly smoke the rubberimpeller, but by then you have pre-sumably stopped the leak. If youwant to get fancy on electric clutchversions, install a vacuum-sensingswitch that detects when the pumpsucks air and disengages the clutch.

Installation GuidelinesManual bilge pumps (i.e. Edson) arerobust, simple devices and seldomfail. Electric bilge pumps are alsorobust and simple but reliability isanother matter entirely. When anelectric bilge pump fails, it’s rarelythe fault of the pump but more likelyto be a result of poor installation ormaintenance: faulty wiring, aclogged pump inlet, and a stuck orbroken float switch. (See page 22for complete installation details).

Positioning: A submersible pumpmust be firmly fastened in the deep-est part of the bilge. If access to theideal spot is difficult, or you arereluctant to drive screws into thehull, mount the pump on an alu-minum L-shaped bracket and fastenthis to anything convenient andsolid, like a stringer or rib. If youare planning to mount two pumps, itmakes sense to have one larger thanthe other and mounted higher up(Figure 4). The smaller pump(lower power consumption) wouldbe your every day pump and thelarger reserve, back-up pump usedwhen the other fails, or the rate offlooding exceeds the smaller unit’scapacity.

With planing powerboats, thelowest point while underway maybe different from the lowest point atrest. You may want a pump at eachlocation, particularly if there are sep-arate compartments.

Upgrade Figure 4

A: Both pumps on same circuit; B: Backup pump on separate circuit.

PUMP BY THE NUMBERSOwner of Galleon Jewelers and avid sportsfisherman, Captain RichardProvenzano may be considered somewhat eccentric when it comes tostaying afloat. Moored in Sebastian, Fla., his 11m (36') Hatteras hasweathered numerous hurricanes, floods and the like which he largelyattributes to having seven pumps onboard. Starting at the bow are twoin the forward stateroom, one 1,200 gph unit in the bilge and one 800gph high-water pump mounted 15cm (6") higher that attaches to thedrain sump from the shower. “When I’m shy on fuel, the boat’s bowheavy in the slip,” says Provenzano, “and if the lower pump fails, theboat won’t fill with water.” Mounted in the engine compartment are two2,000-gph pumps under each engine. In the bilge below the compan-ionway beside the Racor filters is a Lovett pump. “This one is the mainpump.” Another two 1,500 gph pumps reside in the stern bilge. Thisgives a total pumping capacity of about 11,000 gph. “It’s a lot ofpumps, but leaks happen.”— Jan Mundy

PRIMARY AND BACKUP PUMP INSTALLATIONS

3-way Switch

Secondary pumpand switch

Primary pumpand switch

Alarm (optional)

Secondary pumpand switch

3-way Switch

A

B

Primary pumpand switch

Primary pump and switch

Plumbing: Most hose sold for bilgepump use is light plastic corrugatedstuff [Ed: Specs, standards and rec-ommended options for marine hoseappears in DIY 2000-#2 issue.]Corrugations have the advantage ofmaking the hose flexible enough toturn tight corners without kinking, butthey also contribute a significantamount of resistance to water flowadding to the dynamic head pressurethe pump must overcome. Eachbend, elbow and hose length itselfcontributes to resistance. So, to mini-mize adverse head pressure the hoseroute should theoretically be as shortas possible, rise as little as possible,have few bends and have no corru-gations. The discharge thru-hull mustalso be a safe distance above thewaterline to avoid back siphoning.

Back Siphoning and CheckValves: Some systems may have thebilge pump discharge installed belowthe waterline with a check valve toprevent back siphoning. If you dothis, your boat will sink — it’s not amatter of if, just when. Every checkvalve eventually gets a bit of debrislodged in the flapper and when it nolonger seals the boat sinks.

Sailboats have particular diffi-culty finding a good above waterline

Upgrade

location for the discharge simplybecause when heeled over in a stiffbreeze the waterline on the leewardside may be up on deck somewhere.Conversely, an outlet on the wind-ward side may now be 3.6m (12')straight up from the pump (Figure5). On one tack the pump wants toback siphon and sink the boat, onthe other tack the head pressure is sogreat it may not pump any water atall. There are three solutions: reefsails to reduce heel; lead the dis-charge hose to the center of the tran-

1.Unlike submersible pumps that continuously cycle on and off, Rule Mate pumpshave an integral float switch that turns the pump on only when water level rises. 2.Conventional float switch. 3.A high-water alarm triggered by an electrode providesearly warning to irregular bilge water levels. 4. Ultra Pumpswitch has an non-jammingenclosed float and magnetic switch; Senior model features a high-water alarm 5.A"smart" bilge switch, the Bilge Buddy shuts off the pump switch when it senses petro-leum products in the bilge; 6. Compact and quickly assembled when needed, Edsonone gallon-one stroke portable pump kit includes carrying board and quick-connectcouplings. 7.A manual override switch or a three-position on off auto switch lets youmanually pump out the dregs and override a stuck float switch.

SYSTEM COMPONENTS

PUMP CYCLE METERAbout 10 years ago, Rockland, Mass., marine sur-

veyor David McKie installed a bilge pump "minutemeter" on hisboat. Developed by a local inventor, the analog meter mounted inlinewith the float switch and registered pump-operating time in minutes, sim-ilar to an engine hourmeter. Recording meter readings before leavingthe boat and upon returning gave McKie an accurate audit of pumprun-time. We’re not aware of any off-the-shelf products available, but ifyou’re handy with electronics, it’s a simple device to make. — Jan Mundy

TIPS

1

2

3

4

5

6

7

NOT ALL CLAMPS ARE EQUALHose clamps vary greatly in qualityand construction. What you may thinkis an "all-stainless" clamp could sinkyour boat. By Jan Mundy

Replacing a failed submersible pump in one of our6.6m (22') test boats prompted an investigation intohose clamps.

You’ll note in the photo (below) the badly cor-roded clamps connecting hoses to below-waterlinethru-hulls not equipped with seacocks. Like mostboaters, we hadn’t examined the clamps until theneed arose. Besides saltwater (this is a freshwater-used boat), cleaners and chemicals in bilge watercan and do accelerate corrosion of isome metals.Clamp failure in the bilgecan sink a boat; clampfailure on a fuel line canbe fatal.

Close inspection offive brands, four obtainedfrom marine stores and one removed from our testboat, netted surprising results. Many clamps sold arenot all 100% corrosion-proof stainless-steel construc-tion. Stamped on every clamp screw was "AllStainless," yet the clamps in our test boat had badlyrusted screws and corroded bands underneath thescrew housings.

Although clamps may be labeled all-stainless,there are different grades of stainless; clamps arecommonly made of 304, 316 or 400. Series 302,304 and 305 stainless, commonly referred to as 18-8, are non-magnetic, but freely succumb to crevicecorrosion. More expensive is non-magnetic 316, alower carbon, higher nickel andchrome content stainless whichmakes it more corrosion resis-tance. Type 400 stainless ismagnetic and corrodesrapidly in the marine environ-ment.

Our magnetic testfound three clamps withmagnetic screws andhousings, which meansthey are highly corro-sive. Two clamps,AWAB and Ideal All316 SS held no attrac-tion.

Our tests prove that boaters once again must beaware of what they’re buying, and when it comes to pur-chasing clamps, look for either AWAB or equivalent "All316 Stainless" clamps. You’ll pay more, but it’s unlikelyyou’ll have to replace them. When in doubt, carry a bigmagnet.

Lastly, contrary to popularbelief, tighter is not better. Use themanufacturers recommended tighten-ing torque, typically 45 to 55 inch-pounds, or secure as tight as possi-ble with a screwdriver. Using aratchet or socket wrench overtight-ens clamps and damages hoses.

Two hose clamps (left andcenter) with magnetic,potentially corrosive screwpins and housings stamped"All-Stainless" purchasedfrom a local marine store,and clamp (right) removedfrom test boat. Perforatedbands encourage crevicecorrosion and are prone tocracking.

Only two of five"all-stainless"clamps passed themagnet test:AWABand Ideal All 316 SS.

Details of a premium hose clamp: all-316 non-metallic, non-corrosive stainless; solid non-perforated band prevents metalfatigue and breakage, and uniform clamping force; stampedband threads on outside offer high clamping force; smoothband inside with no perforations and rolled edges preventhose damage; pin housing designed to maintain circular shape.

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BILGE PUMP SENTINEL

Easy to add to an existing system, this simple alarm sounds every time the bilgepump cycles.

By Paul Shard

This may be the most important upgrade you add toyour boat — an alarm that sounds when your auto-matic bilge pump cycles. Water flow from a leakingstuffing box or parted hose-clamp can quickly over-come a pump, a plight that can continue undetected,as the boat sinks lower in the water. Numerous caseshave been reported of boaters opening the hatch,stepping down into the cabin into a foot of water.With hundreds of gallons sloshing in the bilge, itbecomes very difficult to find the source of the leak.

The solution is to install an audible bilge alarm.Any water in the bilge is detected immediately. Thealarm should be audible both in the cabin and ondeck, even when the engine’s running (alternatively,consider more than one alarm). If you already havean electric pump with a separate float switch, analarm is added easily. If you don’t have an auto-matic pump with float switch, it may be a good timeto install one.

To connect an alarm to an existing bilge pumpswitch, purchase a 12-volt DC alarm from a marineor electronics supply store. Models with indicatorlight and buzzer are usually mounted in a panel.Buzzer-only units can be mounted anywhere withinhearing range. A location near the bilge pumpswitch simplifies wiring. Wire the alarm’s hot (posi-tive) lead to the terminal on the back of the bilgeswitch that manually turns on the pump (Figure 3,B). This terminal also has power to it when the floatswitch turns on the pump. Connect the other wire toa negative bus bar. Now test the system: switch thebilge pump to manual or lift the float switch to acti-vate the pump. Every time the float switch turns onthe pump, the alarm also sounds.

Some boats have “intelligent” bilge pumps withintegral float switch in the same housing. Some mod-els (Rule Mate) are wired with a manual override. Ifnot so equipped, the easiest option is to add a sepa-rate float switch and alarm. Mount the float switchabove the existing automatic switch so the alarmsounds when water rises above normal. One alterna-tive, if you have room in the bilge, is to install asmaller second pump with an alarm (as described

above) but mounted lower in the bilge. Now thispump sounds the alarm when it detects water; theoriginal pump becomes a backup.

Boat motion may occasionally activate the switchthen turn on the pump and alarm, though no water isactually pumped overboard. On a rough day, thisgets annoying. Commonly caused by a poorlydesigned float switch or improper mounting, raisethe switch slightly higher than the pump. If this does-n’t resolve the problem, consider a switch with alarger vertical distance between the trigger points,such as the Ultra Pumpswitch, Groco Bilge PumpControl Kit or other ones that compensate for back-flow without activating the switch.

Installed on our 37-footer, “Two-Step,” this alarmsystem has been problem-free for 10 years and35,000 miles of international cruising. On four occa-sions it alerted us to potentially dangerous problems.One time the dripless shaft seal had jammed withdebris when we put the motor in gear and waterwas pouring in. It was easy to fix since the waterlevel was still very low in the bilge and I could seethe spray leaking out the seal. Occasionally thealarm activates in the middle of the night, usuallyafter a heavy rain. Personally I don’t mind hearing itcycle on for a few seconds, then go off again. It’swhen it comes on and stays on I take action.Altogether, it’s the cheapest stay-afloat insurance wehave on board.

About the author: Paul Shard and his wife and busi-ness partner, Sheryl, are the authors of “Sail Away!A Guide to Outfitting and Provisioning for Cruising”published by Pelagic Press. You can follow theiradventures at www.searoom.com.

LOSS COVERAGEIf your boat should sink are you

insured? A loss due to “unknown” causes willlikely be covered by the insurance company.Should a survey prove that the sinking was dueto lack of maintenance or negligence, it’s possi-ble your claim might not be covered. Checkyour policy now for “exclusions” ere you need tofile a claim. — Jan Mundy

TIPS

Figure 5

Static head varies in sailboats whenheeled and siphoning potential variesdepending on the tack.

DAVI

D AI

KEN

clamps (see “Not all Clamps areEqual” on page 19).

Batteries: Most submersible pumpsdraw about 6 amps of 12-volt DCcurrent for every 1,500 gph ofcapacity. If your boat has a 90-ampbattery at 80% charge (which isoptimistic) you could theoretically runa 3,000 gph pump (or two 1,500-gph units) for three hours before youuse up half the available juice. Theother half of the battery’s charge willbe available at lower and lower volt-ages, so pumping efficiency will falloff rapidly.

If you have the motor running orplugged into shorepower with thebattery charger going, batterycapacity is not a problem. If you areadrift with a disabled engine andtaking on water, a good bilge pumpsystem doesn’t mean much if yourbatteries can’t supply the neededpower until rescued. There are onlytwo kinds of marine batteries; crank-ing batteries or deep cycle batteries,

som, if you have access; lead thehose up to the deck head and installa siphon break or riser loop.Hopefully, the hose is now above theheeled waterline and the extra headpressure on the other tack won’t crip-ple the pump. Never install checkvalves for the reasons mentionedabove.

Powerboat manufacturers ofteninstall the bilge pump outlet a fewinches above the waterline to avoidannoying sounds of water splashing.Beware of crowded cockpit partieswhere excessive weight can sub-merge thru-hulls. To avoid a backsiphon, the discharge hose should berouted through a riser loop. Riserheight is a compromise betweenavoiding a back siphon and decreas-ing pump performance. A 46cm(18") riser ought to be about right.

If you hate the thought of drillinganother hole in the hull for a thru-hull,it’s possible to tee the discharge intoexisting above-waterline outlets (i.e.cockpit scuppers or sink drains) aslong as the hose rises high above thewaterline and includes a riser loop. Ifin doubt, do not attempt.

Finally, make sure all hoses can’tkink, are well supported and are alldouble clamped with non-corrosive

which cost two to three times asmuch but last five times as long.Don’t skimp on batteries if you wantyour pumps to keep your boat afloatin an emergency.

Wiring: Bilge pumps are probablythe only electrical item that shouldremain powered even when themain switch is turned off. Wiredirectly to the battery terminal ormore neatly to the battery connec-tion post(s) on the back of the mainswitch.

Pump performance suffers a lotfrom small voltage drops due to linelosses, so when specifying wiresizes, ABYC 3% voltage loss tablesshould be used (refer to “WiringHandbook,” DIY 1998-#4 issue). Forexample: a pump draws 15 ampsand you need 9m (30') of conductorto power it, the tables specify 8gauge AWG wire to keep voltagelosses within 3%.

Making durable connections tothe float switch and pump is always

(Continued from page 18)

BILGE PUMPREPLACEMENTBy Jan Mundy

Boatbuilders often mount bilge pumpsin inaccessible areas deep in thebilge, usually before the deck is inplace, unmindful of replacement orservicing. Particularly in small power-boats, replacement demands crawl-ing through a small hatch, oftenworking blind. (Use a mirror for arearview look if you’re adept at work-ing backwards.)

Submersible bilge pumps typi-cally run for nine years before failureand less for leaky boats where thepump regularly cycles or dry boats,where lack of use causes corrosion orgrit, sand or salt build-up. Failurealso occurs when water gets into thepump through wires or shaft seal —the pump fills with water then goesthrough several freeze-thaw cycles.

This was the case with a Mayfairpump in one of DIY’s test boats whenit failed to run after 10 years of nor-mal use in freshwater. Replacement isan easy one-hour job, after removingthe old unit, drying the bilge andsealing the original mounting holes.

1 If you’re lucky, the original pumphas a detachable base, so removingmounting screws is easy. The Mayfairunit didn’t; removal meant danglingin a narrow stern locker, gropingwith hands, trying to locate threePhillips-head screws. For bilge work,an extra-long handled screwdrivercomes in handy. Note the corrodedhose clamps in the photo (above).

2 Since pumps rarely have the samefootprint, the next step is to seal theoriginal mounting holes with 3MPremium filler, 3M 4200 (I prefer theFast Cure) 5200 or equivalent brand.Be sure holes are dry before filling.While you’re down there, inspect thehull for other openings in the hull andproperly seal. I found a few extraholes drilled by the manufacturer,none were sealed. (The very first itemon your to-do list after purchasing aboat, either new or used, should beto rebed every piece of hardware,caulk voids, holes, etc.)

3 Placement of pump and switch iscritical. Even when replacing, it’s bestto double-check the location. Positionthe pump base (strainer) so the noz-zle aligns with the discharge hoseand locking tabs line up with thepump body. The float switch shouldmount at least 6mm (1/4”) above the

a problem in an area that is oftenwet, particularly in saltwater.Corrosion at these connections is themost common cause of pump fail-ure. Corrosion increases electricalresistance, which in turn can causea connection to overheat or break.

Bilge pump wires and connec-tions must be watertight, preferablycrimp-on connections with self-adhe-sive, heat-shrink terminals. No wirenuts (Marette plugs) or tape.Specialty UL-approved multi-strandBoat Cable (or BC) is available forbilge pumps (two or three color-coded conductors 18 to 14 AWGwith water-resistant jacket). All con-nections should be above the maxi-mum bilge water level or as high aspossible, fastened securely andaway from float switches, controlcables, shafts, etc.

Fuses: Corroded fuses and fuseholders are the next most commonreason pumps won’t go when theyought to. Because of this weak link,

some surveyors even disagree withABYC recommendations that a fuseor breaker should protect this circuit,like all others. Submersible pumpscan overheat and even melt butrarely catch fire. The big dangerhere is a short circuit in wiring to thepump causing a fire. To minimizethat possibility and preserve circuitprotection keep any in-line fuses outof the bilge and in the closest avail-able location with quick access.Check and clean terminals often,and replace fuses every yearregardless.

Automatic Pump SwitchesGenerically known as float switches,there are many different kinds avail-able. All of them can malfunctionand frequently do, most likely fromoily, hairy, slimy debris-filled sludgethat inhabits most bilges. Switchesbecome so badly fouled that theyclog or stick. If stuck in down posi-tion, the boat might sink. If stuck in

the up position, your pump runs onand on until it eventually burns outor flattens your battery — then theboat sinks.

The first step in keeping the floatswitch and pump alive is to keepyour bilge clean and free of debris.Maybe it’s time to add a drip panunder the engine [Ed: refer to DIYProjects, 1996-#4 for how to buildone] or a separate graywater sumpfor the shower. Don’t pump fuel —or oil-mixed bilge brew overboard.It pollutes and is illegal in manyareas with fines up to US$5,000.

If the bilge sump is narrow andlong enough to allow a few inchesof water to surge back and forth itcan beat relentlessly on an exposedfloat switch until the hinge or wiresbreak. If your boat has this sort oflayout you need a switch housed ina protective cover (which unfortu-nately can foul up) or install a cheapbaffle to protect the switch. Installingthe switch near a bulkhead with thehinge facing the surge will also help

strainer so it’snot automati-cally runningall the time.Rule pumpscome with anadapter thatconnects the

switch to the pump base and posi-tions the switch at the proper height.Pumps are prewired and include fas-teners; you’ll need to supply sealantand heat-shrink connectors.

4 Carefully drill a pilot hole in thehull for the pump base, liberallycaulk around the hole, then fastenbase with supplied screws. Don’t drillthrough!Nevermountbasedirectlyon a

cored hull — a leaking fastener canquickly delaminate cores below thewaterline. Instead, install a hard-wood (teak or mahogany) backingblock, then attach base to block.

5 Connect the hose, double clamp(if enough clearance on hose barb)and install the pump switch.

6 You have an option of wiring thepump for man-ual or auto-matic opera-tion. Since thisboat alreadyhad an auto-matic-manual pump control, westripped the lead ends, connectednegative and positive ends to theoriginal wires leading from the paneland battery, routing the wires high,just underneath the deckhead. Endswere crimped together using adhe-

sive-lined,heat-shrinkconnectors. Ifyou don’thave any,seal the con-nectors with

sealant. Note: positive lead frombilge pumps should connect directlyto the positive battery post so as notto accidentally disconnect with themaster switch. Also, all pumps mustbe fused and with the proper sizefuse or a pump may overheat andblow a circuit. The original pumpinstallation included an in-line 6-ampfuse, the new Rule pump required a9-amp fuse.

7 Not included but recommended isa protective float switch cover. Forextra reliability, add a second switchmounted slightly higher. Better yet,add a second pump.

protect it. Wiring inside a switch not rated to carry thesame amperage as the pump draws, will overheat, caus-ing premature failure due to fatigue or corrosion.

In a sailboat the float switch must be on the samefore-aft axis as the pump, otherwise it won’t operate inthe same depth of water when the boat heels. Thiscauses the pump to run dry on one tack, yet not triggerthe pump when needed.

Although a switch will work installed on a pump’seither positive or negative feed, don’t install it on thenegative side. This leaves the pump energized at alltimes. In saltwater there is a high risk of stray currentleaks to ground. Any current leak from the pump willdestroy it and possibly any metal thru-hull, which pro-vides a path to ground. Proper bonding of thru-hulls willdelay but may not prevent damage from stray currentgalvanic protection. [Ed: DC bonding systems and corro-sion will be covered in upcoming issues.]

Make sure the float switch is set up to shut down thepump long before it begins to suck air, otherwise it willeither never shut off reliably or water remaining in thehose will drain down and re-trigger the switch, settingup an endless cycle. You may need to choose a switchwith a larger vertical distance between the trigger pointsfor on and off (see “Bilge Pump Sentinel” on page 20).

Some panel switches have a provision to show anindicator light when the pump is activated; you may oth-

Upgrade

erwise be unaware that the pump isworking. Another useful gadgetavailable is a cycle counter so youcan gauge typical daily or weeklypump use and look for any suddenjumps in pump activity that mayindicate a packing gland beginningto leak or a bad plank seam.

Another potentially useful acces-sory is a high-water alarm, such asa separate unit that’s triggered by asecondary float switch or by thebackup pump. If you are away, ahigh-water audio alarm or flashinglight can also alert your docksideneighbors or marina staff that yourboat is in trouble. [Ed: Considerupgrading to one of the newer,high-tech switches, such as the elec-tronic "smart" Bilge Buddy or mag-netic Ultra Pumpswitch. These self-

contained, non-jamming switchescost as much as $100 more thana standard "cheap" float switch— buy the best you can afford.]

ConclusionThere is no fail-safe bilge pumpsystem that will keep you afloat inall circumstances. It’s important tounderstand the capabilities andlimitations of your own systemand never take it for granted,especially any automatic system.While underway, there is no sub-stitute for regular manual checksof bilges as part of normal watchkeeping. When at a mooring, noautomatic system can ever substi-tute for weekly visits to your boatjust to make sure it’s afloat.

About the author: Nick Bailey isservice manager of Bristol Marinein Mississauga, Ont., and an avidThunderbird-class racer.

EMERGENCY AUX PUMP

A raw-water cooled inboardengine is easily converted todouble as an emergency bilgepump. Installation requires threevalves, a couple tee fittings andhose connections. You’ll findcomplete how-to instructions andconfiguration options in"Modifying Raw-water CoolingSystems," article in DIY 1997-#3 issue, now available in PDFformat in DIY ONLINE athttp://secure.the-wire.com/diy-boat/reprints.html. — Jan Mundy

TIPS

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when the next bolt goes. Variousfamous ocean racers, ”Drum,” “Villede Paris” and many others, nodoubt, designed a little closer to thelimit than your average familycruiser, have publicly demonstratedsailing without a keel. I don’t recom-mend it.

There is no way to positively

S a i l b o a tRigging

DIY boat owner 2000- #1 (888) 658-BOAT 25

By Nick BaileyOther than running aground, will youever need to replace a keel bolt? Ifyou keep your boat in freshwater,you aren’t likely to have any prob-lems for a very long time. Saltwaterboats are another matter.

Consider these examples fromBristol Marine’s service files: a 12-year-old racer-cruiser from a top-rated manufacturer was hauled outfor some minor keel fairing. Theowner also requested, as part of rou-tine maintenance, that the keel boltsbe tightened. Fifteen minutes into thejob the technician returned andunceremoniously dropped a fractured25mm- (1"-) diameter stainless steelstud on my desk. Under very gentletorque the bolt had snapped off deepinside the hull. Quick inspection con-firmed that only 10% of the fractureface was freshly broken metal, theother 90% was badly corroded andhad been for some time. A phonecall to the owner confirmed that theboat had spent most of its life in salt-water.

On another occasion, a 15-year-old trailerable boat was in forreplacement of the fractured originalvermiculite and resin filler in the keelsump. Upon removing the old filler toexpose the bolts, we discoveredsome of the supposedly stainlessbolts were partly cut through due tocorrosion, but only where buried inthe cracked and soggy filler. Theexposed portion still looked nice andshiny. The boat had recently arrivedfrom a saltwater location.

What happened here? In bothexamples, a process known as

REPLACING OR SUPPLEMENTING KEEL BOLTS

crevice corrosion destroyed the stain-less-steel keel bolts.

What Lurks UnseenWhat makes crevice corrosion partic-ularly nasty is that it only occurs inhidden and inaccessible locations,typically where keel bolts are buriedin the hull. Small amounts of saltwa-ter seep into contact with the bolts,stagnate and become de-oxy-genated. Lack of oxygen in contactwith metal bolts is where troublebegins. Stainless steel stays shinyand “stainless” under normal circum-stances because it contains chromiumwhich forms a tough protective oxidewhen exposed to air and well oxy-genated water. Remove oxygen andthe protective oxide coating breaksdown, exposing metal to the water.Saltwater provides the electrolyterequired to set up a miniature gal-vanic cell, either on the surface caus-ing pitting corrosion or inside amicroscopic crack or crevice, causingthe dreaded crevice corrosion. Aslong as stainless steel remains wet oreven damp, corrosion proceedsunchecked, eating away at themetal. Crevice corrosion is surpris-ingly common in older salt-waterboats and tends to be worse in tropi-cal waters due to lower oxygen con-tent, higher salinity and the greaterreactivity that warm temperaturesprovide.

Identifying ProblemsMost keel fastening systems aredesigned with a conservative safetyfactor and you can get away withone broken bolt. Real trouble begins

Checking keel bolts should be part of a routineinspection. Here’s how to identify problems andrepair damaged keel bolts.

Integral studs cast into keel.

Easy access, windows cast or cut intokeel and filled with fairing putty havenuts and washers at bottom end.

Holes drilled and tapped into keel forthreaded bolts have nuts and oversizewashers or backing plates (preferred) onthe top end.

Figure 1

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(888) 658-BOAT DIY boat owner 2000- #1

identify bolt condition without either removing the keel orindividual bolts. A broken or badly weakened boltalways becomes obvious when retorquing. It pops looseor turns indefinitely without tightening. Check with themanufacturer or your local yard to confirm the recom-mended maximum torque, but keep in mind that any22mm (7/8") or larger diameter bolt requires tremendousleverage to the point where it’s exceedingly difficult toover-torque.

Another place to watch is the keel-hull joint. Anythingmuch larger than a hairline crack here can be a sign oftrouble or at least may indicate it’s time to tighten thebolts. This is best checked while the boat hangs in theslings. Once the boat is cradled and hull weight rests onthe keel, any cracks tend to close up again. These signsmay identify a broken bolt, but the only method todirectly confirm if corrosion has begun an attack on thebolts is to expose them.

Repair StrategiesBolt configuration and ballast type largely dictate how tofix bolts that are severed or deeply pitted by corrosion.

Keels with integral studs (Figure 1) are the worstcase and the most common keel fastening method. Theonly practical option is to drop the keel (see “Droppingand Refitting a Keel” on page 28) and, if there is enoughroom in the keel sump, install a supplementary (or sister)bolt. This is done in one of two ways. Using an oxyacety-lene torch, cut a window in the keel to access a nut (simi-

External flange recessed or faired into hull has flat head boltswith nuts and oversize washers or backing plates on top.

Full keel with external ballast converts to internal by adding afiberglass laminate overlay.

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Figure 5

FrontView

KeelHull

lar to Figure 2), then drill a hole down from above for athreaded rod or bolt. This method works best on leadkeels. Alternatively, drill and tap the keel for a new sisterfastener. This works best on cast iron. It may be possibleto salvage the stud by threading on a heavy sleeve tobridge the damaged area and reinforce the bolt. Thisoften requires excavating around the stud at the top of thekeel to expose enough good threads to give any hope ofsuccess. It may also present difficulties refitting the keeldue to the larger hole required in the hull. Most profes-sional yards would do this sort of repair only on a “noguarantees” basis as the sleeve will not be as strong asthe original bolt.

If you are faced with drilling or tapping large diame-ter holes, you will need to rent the appropriate powertools. However, the keel may need to be cradled andtransported to a machine shop capable of handling largescale boring and cutting. Neither lead nor cast iron areeasy materials to work with: lead jams and binds tools,cast iron is just very hard and brittle.

Keel bolt configurations as shown in Figure 2, 3and 4 can theoretically be removed, inspected andreplaced. Because this is done one at a time, it may bepractical to do this without dropping the keel. Haul outand cradling are still recommended to minimize thechance of disturbing the keel-hull bond. Aggressivelycaulk new bolts with a polyurethane or polysulphidesealant on reinstallation. Boats with keel windows(Figure 2) or external flanges (Figure 4) have the boltend hidden by fairing filler and may require lots of grind-ing and chiseling to expose the end. Broken bolts aremore difficult to extract but can be knocked out of theexternal flange with a driving pin or, in the case of thewindow keel, driven down then cut off one piece at atime with a hacksaw. (Are we having fun yet?) An extrac-tor tool designed for broken studs (i.e. Easyout) may alsowork with smaller bolts.

A broken tapped bolt (Figure 3) is very difficult toremove particularly in cast-iron keels. The bolt is likelyseized into place by corrosion. You may have to drill itout and retap the hole. I envision some difficulty getting

the drill press down the compan-ionway so this one may alsorequire keel removal andmachine shop work as in keelswith integral studs (Figure 1).

For fiberglass boats withlow-profile full keel configura-tions (Figure 5), it doesn’t mat-ter how the keel is fastenedbecause the repair approach iscompletely different. It may bemore practical to laminate sev-eral layers of fiberglass to

Typical top-end installa-tion with backing plateand washer.

or two onto the existing hull. As isnormal practice, make sure the hullsurface receiving the overlappinglaminates is ground to bare glassand is clean and dry. If you are unfa-miliar with glass lay up procedures,hire a professional.About the author: Nick Bailey is ser-vice manager of Bristol Marine inMississauga, Ont.

encase the keel and bond it to whatbecomes, in essence, a new part ofthe hull. This converts the boat fromexternal ballast to internal. Many tra-ditional full-keel glass boats are builtthis way and neatly sidestep thewhole keel bolt corrosion issue.

Laminate thickness of the newkeel should match the original hullthickness and overlap at least a foot

DROPPING ANDREFITTING A KEEL

1 Haul out and cradle. Put a jackunder the keel to ease it down later orelse use screw jacks on the cradlepads to raise the boat. For boatslonger than 8.1m (27') or when thecradle is unsuitable, book a Traveliftor crane. You may need to devise away to separate the keel and hull.

2 Rent or borrow tools. You’ll needextra deep sockets, a heavy drive bar,extra long lever arm (a pipe will do)and a long extension to reach into thebilge. You may also need a variety ofwedges and a sledge hammer plusglass tools for grinding, filling, fairingetc. Professional yards rarely lendtools.

3 Undo keel nuts. Use a threadlubricant to help prevent stainless-on-stainless galling (binding and seizing).

4 If needed, grind away fillers orfiberglass to expose the keel-hull joint.

5 Lift the boat (or drop the keel) sothat the full weight of the keel is sus-pended by 6mm (1/4") or so, thentake a break.

6 If the keel doesn’t drop on itsown (most won’t), carefully drivewedges in between the keel and thehull at the joint. Lift the keel or lowerthe hull and repeat until 5cm to 7.6cm(2" to 3") of bolts are exposed.

7 Inspect bolts carefully to assessany corrosion damage.

8 To remove the keel, install bracesto support the keel in an upright posi-

tion. Lift the boat, or lower the keel therest of the way.

9 Proceed with the bolt repair orreplacement as required.

!º Clean mating surfaces on keeland hull with a mini grinder.

!¡ Reposition keel under hull andmate bolts to holes in hull.

!™ Apply thick bead of sealantaround each bolt and hole only —don’t cover mating surfaces withsealant as its flexibility makes the keelwiggle too much.

!£ Mix up epoxy resin thickenedwith cabosil and chopped fiber to athick paste. Apply liberally to top ofkeel.

!¢ Immediately join keel and hulltogether and torque into place using astaggered tightening pattern. Recradleif needed.

!∞ Before epoxy fully cures, removeexcess that has squeezed out. Makesure air temps are warm enough forepoxy to cure, otherwise set up heatlamps.

!§ Fill and fair the repair area,repaint and launch. Check for leaks. Ifit leaks, see Step 1. If not, go sailingin heavy air. Check again for leaks.

Fin Keel dropped for rebedding.

Electronics

By Larry Douglas

There are few worse environments forelectricity than a boat. Combinebroad temperature ranges, vibration,moisture and salt spray and electricalproblems are a common enigma formost boaters. When it happens, youneed to be prepared with the knowl-edge and proper tools to solve theproblem. Perhaps the most commonand most important tool for electricaltroubleshooting is the portable multi-meter, also referred to as a voltmeteror VOM for an analog unit, or DMMfor a digital one.

Multimeters come in many sizes,prices and types. All measure volt-age, current and resistance; somemodels also measure inductance, fre-quency and/or capacitance. Thoughmore costly, my preference is a digi-tal unit. Those who have used analogmultimeters (VOM) will find that theincreased accuracy, repeatability andruggedness of the modern DMM,although more expensive, makesthem a better choice for marine use.A suitable DMM for boat use shouldmeasure common AC and DC volt-ages, DC current up to 10 amps andresistance from less than one ohm toover 10,000 ohms. It should displayat least three full digits plus a leading"1" and be accurate to 1% or better.Some DMM units are auto ranging,which means once you select a func-tion, the meter adjusts the decimalpoint based upon the measuredvalue. This makes them slightly easier

to use but adds to the price. You canspend less than US$20 or more thanUS$170 on a portable DMM and,as with most other tools, you getwhat you pay for. Pick a name-brandmeter that gives you the features youlike. If you choose a meter from thelow end of the price scale, you mightwant to buy two. The second unit willcome in handy when you drop thefirst one. Also purchase a spare setof leads with probes. They will prob-ably wear out long before the meterneeds replacement and a brokenlead results in an erroneous readingor worse, fools you into thinking thepower is off when it’s not.

Measuring BasicsEverytime you turn on your multime-ter, form the habit of moving the dialto the "X1 ohms" scale and touchingthe two probes together. The displayshould move from indicating an opencircuit to nearly 0 ohms. This confirmsthat the meter and probes work andis an important safety check. Nowselect the appropriate measurementtype (AC voltage, DC voltage, resis-tance) and the range, except autoranging meters. The following infor-mation is not intended to replace themanual that accompanies your meter.Now place the red and black probesacross (in parallel with) the circuit tomake the voltage or resistance mea-surement.

Current (amps) measurementsare not made in exactly the same

ELECTRICAL TROUBLESHOOTING

A multimeter is the quintessential tool to detectDC and AC electrical faults and to measure voltage, current and resistance.

Always ensure selector switch is in thecorrect position and the red (hot or"+") and black ("COM" or "–") leadends are in the proper input jacksbefore taking a measurement.

Check meter operation before everyuse: move the selector dial to the X1ohms scale and touch the probe endstogether. If you get a reading otherthan "0," the battery or fuse needsreplacing or the leads or meter aredefective.

Selector switch on "DC voltage" scalechecks battery voltage (no loads).

Marine Equipment InstallationsHere’s how to choose, install and operate equip-ment for your boat includ-ing: air conditioning and heating systems, audio systems, bow thrusters, davits, lightning protec-tion, propane systems,

refrigeration, windlasses and more.

Fiberglass Boat RepairHow to survey, repair and prevent cosmetic and structural damage in fiberglass hulls, decks and transoms. Includes the step-by-step repair

of minor cracks and gouges, large holes, water-soaked decks, delaminated hulls and proper installation of hardware.

Nautical NecessitiesFrom cleaning to fuel filter-ing to waterproofing charts, you’ll find ideas and inspi-ration in this compilation of tips to do-it-yourself boat maintenance, repair and

troubleshooting. Divided into 20 categories to make look up easy.

Better Boats More than 200 do-it-yourself projects. Practical solutions to deck and cockpit refitting, inte-rior renovations, rigging upgrades, space-saving

equipment storage, safety add-ons and other nifty items to customize your boat.

Sailboat RiggingA practical guide to deck layouts, equipment repairs, performance upgrades, rig tuning, sail controls and steering systems.

Building With Starboard22 Projects and Fabrication Techniques: The ideal choice for replacing wood compo-nents onboard – won’t delaminate, rot or splinter and requires no paint.

Plumbing 101A boat owner’s guide to the inspection, mainte-nance, repair, trouble-shooting and upgrading of onboard plumbing systems.

DIY MechanicGasoline and diesel engine service. How to maintain, troubleshoot and repair outboard engines, stern-drives and diesel inboards.

AC/DC Electrical SystemsA guide to expanding, upgrading, surveying and troublshooting your boat’s AC and DC electrical system. All articles follow ABYC Standards.

Painting & RefinishingThe complete guide to painting and refinishing hulls, topsides and decks with marine coatings.

Launch & Haulout How to prepare your boat for spring launch and win-ter storage. Includes lay-up checklists, maintenance and lubrication guides, engine servicing, haulout guidelines, easy-to-build storage covers and more.

Technical CD-ROM Library for Boat Owners

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To order call 1-888-658-BOAT or Shop Online at www.diy-boat.com

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Electronics Connection

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ing, and troubleshooting marine electronics for most any layout or equipment and budget in a step-by-step approach. $19.95

Powerboat RiggingFrom gauges to propellers to steer-ing systems, here’s everything you need to know to maintain and repair your boat and trailer, improve boat handling and perfor-

mance, and find solutions to common servicing problems.

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TROUBLESHOOTING TIPS• Use properly sized wire. Just because a manufacturerprovides #18 AWG leads doesn't mean you can addanother .9m (3') of the same wire. Chances are thatyou'll be coming up short in the supply voltage.

• Purchase a good crimp tool and learn to use it cor-rectly. Use the properly-sized marine-grade crimp termi-nals. Use proper circuit protection, whether fuses or cir-cuit breakers. Be aware, though, neither will directly pro-tect your electronic equipment. Circuit protection devicesare solely intended to protect wiring.

• Periodically inspect your entire electrical system.Tighten all connections and check for corrosion.

• Carry a spare fuse kit. Fuses do fail on occasion, oftenhaving nothing to do with excessive current. Label themas to which device they go with.

• When replacing a blown fuse, replace it just once. If itfails again, immediately fix the problem before sacrific-ing another fuse. Don't substitute a larger one hopingthat it will work long enough to get you home — in mostcases it won't!

• Label all wiring. Use the existing color or number code(if any) that you have on the boat or create your own. Itwill save you time later.

• When all else fails, consult a professional. If you'reuncertain that you've installed something properly, call apro before you apply power. Once turned on, it may betoo late to avoid an expensive mistake.

Problem SolvingAround 75% of the time you’ll use your DMM for volt-age checks, such as determining whether a battery ischarged or your VHF radio is receiving DC power. Therest of the time you’ll be checking fuses, lamps or wiresfor continuity using one of the resistance scales.

To trace a short circuit, disconnect the circuit, set theswitch X1 ohms scale and place leads on a hot andground side. Any value other than infinite ohms indicatesa short, possibly frayed or worn wires. Also, use yourDMM to check loads or voltage drop on an existing cir-cuit before adding accessories, unless you opt to runnew wires. Turn on all loads to obtain a correct currentreading. Another common use for the current scale is tocheck DC bonding wires to prevent electrolysis prob-lems. Leakage currents are often in the milliamp (0.1 to0.001 amp) range. Most top-rated DMMs do an excel-lent job measuring this which lets you know that yourzincs are working -– or not!Larry Douglas has 30-years experience as a technician, productdeveloper, and a consultant in marine and industrial electronicssystems and cruises the West Coast in a 12m (40') Tollycraft.

way, as are voltage or resistance measurements. Theyrequire electrically inserting the DMM in series with oneof the load wires. This usually requires relocating one orboth probes intosockets on theDMM that are usedonly for currentmeasurements.Form the habit ofalways returningthe probes to theproper locationsfor voltage andresistance measure-ments immediatelyupon completingthe current mea-surement. If you forget, you’llcause a short circuit the nexttime you use the DMM for avoltage measurement. Mostdigital meters have internalfusing and often a spare fusefor such an occurrence.

Top: Use the low-resis-tance scale to test a fuse.Left:To test equipment forresistance, disconnect thecircuit (otherwise, you willmeasure the entire circuit),set selector switch to theproper resistance scaleand connect test leads, redto the positive side.Defective equipment willhave no resistance reading.

MEASURING THE LINE

When troubleshooting electronicequipment, don’t overlook the obvious.

Connections on a boat eventually work loose. Fuseholders corrode. Batteries need constant attention.Any wire that moves will eventually fail and will doso at the worst time. Starting at one end of the cir-cuit, use your meter to measure all components inthe line. Often it’s a minor problem that’s easilyfixed.

TIPS

DMM checks loads or voltage drop onan existing circuit before addingaccessories.

Ventilation is vital to controllingdampness, mildew and musty odors.Install opening ports, cowl or mush-room vents in every compartment andat least two solar- or electric-poweredvents (i.e. Vetus Fan12, US$62) onthe cabin top, one exhaust, oneintake, for a continuous supply offresh air. If the boat is divided intostaterooms, and if your budgetallows, install a vent in each separateliving area. Vents eliminate condensa-tion build-up and associated moistureand odor problems. If space allows,a 110-volt household dehumidifierworks wonders.

COLOR-MATCHED SEALANTSStar brite supplies most of the majorboatbuilders with silicone sealants,some in custom colors. If you need tomatch your boat’s gelcoat, call thecompany’s customer service depart-

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By Jan Mundy

MILDEW CONTROL: Clean,Exterminate, Ventilate Boats and mildew go together likeducks and water. It attacks carpeting,drapes, cushions, lifejackets, clothing,plastics, gear stashed in sealed lock-ers — anything stored in a humidenvironment where mildew sporesflourish and multiply.

In the many years of owningboats, I’ve found removing mildewstains with a mildew remover orbleach solution gives only temporaryrelief. Spores remain in an inactivephase, lingering in nooks and cran-nies, once again waiting for thereturn of humid conditions. Mildewseems nearly impossible to destroy;preventatives we’ve tested only workwhen applied every few months; ifnot, the first time a humid conditionexists, spore colonies sprout again.

Follow these three steps to van-quish the enemy. Scrub surface with aspecially-formulated mildew remover,bleach solution diluted 10:1 (do atest spot in an non-critical area), TSP,vinegar or other cleaner of choiceand a soft brush, scrub pad or house-hold power carpet cleaner. Spray on,wait per the label instructions, orovernight if using bleach, then rinsethoroughly with freshwater, and letdry. Wear plastic gloves.

If you only clean, mildew likelywill reestablish in a week or so in aclosed boat. Use of chemical dehy-drants help control moisture in smalllockers, but usually won’t keep theentire cabin dry. You could rent orbuy an ozone generator, running itevery few months when damp. Aless-expensive, more compact anddisposable alternative is Star brite’sMDG Mildew Control Bags. Contain-ing Aseptrol, a fungi growth inhibitor,it releases trace amounts of chlorinegas that’s completely non-toxic tohumans, pets, plants, fabrics orequipment. A box contains two foilpacks and hangers (US$8). For bestresults, replace every three months.We’ll let you know the effectivenessof this product after testing this sea-son.

A C O L L E C T I O N O F U S E F U L

Every year, tell-tale black mildew stainsreoccur after a four-month layup in ansealed boat. Even after cleaning, mildewspores continue to remain active in adamp environment.

Vanquish theenemy withMDG MildewControl Bagsthat releasenon-toxic chlo-rine gas smellto kill sporeson contact.

Maintenance

ADVICE, TIPS AND TRICKS

ment toll-free (800/327-8583) andprovide your boat’s year, manufac-turer and model. We’re told the com-pany has a good inventory of gel-coat-matched colors, especially forboats built in the last four years.

ERASE AWAY VINYL STRIPING

Removing vinyl striping, lettering orgraphics using a heat gun and scrap-ing with a putty knife followed by asolvent wipe to remove adhesive usu-ally damages the surface finish. Wehave found a better method: StripeEliminator is a 9cm- (3-1/2"-) diame-ter, 3.8cm (1-1/2"-) thick disk"eraser" that strips away vinyl andadhesive residue in one pass. No dis-coloration, or damage to surfaces, noneed to scrape; just wipe off rubberresidue with a rag and the surface isready for reapplication.

We tested this unique tool cou-pled to a portable drill to remove 10-year-old stripes on one of our testboats. Operating the drill at lowspeed, 800 to 1,200 rpm is recom-mended, we sampled a small area atthe transom. With the drill runningslowly, we "rubbed" the Eliminatorover the stripes in an up-downmotion, starting at the top edge andapplying slight pressure. It "erased"stripes fast, removing triple stripes

If disk edge "erases" unevenly, reducedrill speed, and if it becomes lopsided,reverse disk in the arbor.

ShopTested

Maintenanceand all adhesive residue over a91cm (3') area in less than five min-utes. Except the faded surface underthe vinyl, the hull is prepped for refin-

BRIGHTWORK Clean teak then coat with apremium finish, such as Cetol or Star briteTropical. Follow steps outlined in "Teak 101,"DIY 1999-#2 issue. CANVAS Examine all canvas for broken orchafed stitching and seams. Do the drip test:pour a cup of water onto an indent in the can-vas. If it instantly leaks through, apply a qualitywater repellant. ELECTRONICS To check for electrical interfer-ence, turn on all electronics then switch on fluo-rescent lights. Some lights have noise suppres-sion circuitry but may still cause interference incertain conditions. Moving the lights may benecessary. ENGINE Warm up engine, then turn off. Tocheck for leaks, place a finger under all hosesand connections. Inspect hoses and fuel lines for

chafe. Put a wrench on every nut and bolt tomake sure they are tight. Check engine zinc(s)and replace as needed. Examine all wiring con-nections for corrosion and all wire leads for sup-port. FLOOD TEST When properly installed andsized, cockpit scuppers should empty a water-filled cockpit in about two minutes or less. Tocheck your boat, cork the scuppers, fill the cock-pit with water to the top of the cockpit lockers orto deck level, then pull the plugs. Time the dis-charge rate. When empty, check the lockers forleaks and reseal if needed. HATCHES Check hatch gaskets and replace ifbrittle or cracked. Inspect hinges, support andlatch for corrosion. Check companionway slid-ers.HOSES Check hoses for chafe and add chafing

strips at contact points -— wrap slit spare hosearound primary hose. LIGHTS Remove all bulbs and check sockets forrust. Insert new ones with a dab of petroleumjelly on bulb end. STANCHIONS Tighten all screws and examineall ends, gate hooks and wire for cracks (use amagnifying glass), wear and corrosion. Plasticcoated stainless-steel wire will corrode under theplastic and should be replaced with non-coatedwire.TANKS Look for corrosion in steel and alu-minum tanks around fuel pickup, fuel gaugesending device, inspection hatch and welds.Read "The Weak Leak" on page 37.UPHOLSTERY Check for wear, tear, brokenseams. Move zippers, check for corrosion andadd canvas lubricant to improve sliding action.

ishing in one-easy power stroke. With the correct drill speed,

proper pressure and a little practice,this tool quickly removes vinyl withoutany friction, abrasion or heat build-up. Made of a flexible rubbery mater-ial, but harder than an eraser, if the

disk wears evenly, reduce speed, andif needed, reverse the disk in thearbor. Contact Ferro Industries at800/343-3776 or Fax: 810/792-6006. At the same time, buy the spe-cial half-circular pad to smooth vinylfor a professional finish.

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DIY M E C H A N I C

Attention to proper routine maintenance is the key to continued low-cost operation of your engine. The fol-lowing pages will help you maintain, troubleshoot and repair the most common gasoline and diesel inboardand stern drive engine component failures; namely, cooling systems, starters, thermostats and fuel tanks, anitem that is seeing more failures as boats age. Some work may require special tools and we suggest invest-ing in the proper equipment if you plan to own the boat long and do the work yourself. If this is a one-timerepair, you may opt to hire a trained mechanic to do the work. Whatever you decide, follow our recommen-dations, refer to your shop manual and follow all safety precautions. — Jan Mundy

THE WEAK LEAK

Story and photos by Nick Bailey

Unfortunately, metal fuel tanks— domestically, aluminumand stainless steel; iron in

some trawlers and other boats builtin the Far East — are unlikely to lastthe lifetime of your boat. Eventuallythey will leak. If you’re lucky, you’llfind a tiny pinhole leak first ratherthan have a welded seam on thetank bottom suddenly split open.Suddenly discovering you have abilge full of fuel, particularly gaso-line, is a true test of character. If youlive to tell the tale, you’re blessed.Such incidents are surprisingly com-mon and becoming more so asboats age.

.Rotting MetalEven the best alloys designed formarine use can suffer from subtlecorrosion damage over the longterm and usually only occur in loca-tions that are not obvious to casualinspection. Aluminum and stainlesssteel are normally protected fromcorrosion by a natural layer of shinyoxide on the surface. This layerinstantly forms when in contact withair or oxygen dissolved in water.

Problems occur in covered areas,such as under tie-down straps orwhere the tank bottom rests onstringers or flotation foam. If the tankis in contact with stale, immobile,oxygen-starved water, the lack ofoxygen prevents the oxide layerfrom renewing itself and the protec-tive coating erodes away exposingthe metal. The presence of water,particularly saltwater, provides anelectrolyte and a tiny galvanic cell isformed on the surface of the metalor in a tiny crack. The spontaneouselectrical activity in the cell dissolvesthe metal and transfers metal ionsfrom one grain to another of thesame piece of metal. As long as itstays wet the tiny spot or crack fromwhich the metallic ions are removedbecomes a steadily growing pit orcrevice, a process referred to as pit-ting corrosion and crevice corrosion.Welded seams in tanks are particu-larly susceptible to corrosionbecause the weld metal is a slightlydifferent alloy than the surroundingplate, thus accelerating the galvanicreaction.

Some tanks fail from metalfatigue. The right angle welded

seams where tank sides join the topor bottom are subject to mechanicalstresses, particularly in tanks built oflight gauge metal and fitted withskimpy internal baffles. In this case,the fuel sloshes back and forthunhindered and beats relentlessly onthe tank walls, flexing seams andleading eventually to a split and thesudden release of fuel into the bilge.

Leaking fuel tanks are becoming a common and serious problem in olderboats. Here’s the latest info on tank materials, step-by-step tank repairmethods, replacement options and installation tips.

Had boatbuilders originally installedtanks so they could easily be main-tained or removed, it would not be nec-essary to remove the cockpit floor inthis runabout; large cruisers oftenrequire removal of the cabin sole, aftcabin berth, or hole cut in the transom.

DIY M E C H A N I C

Removing the TankThe tank goes into the boat beforethe deck or the floor. In manysmaller stern drives you have nochoice but to cut open the floor toremove the tank. If you need to hirea professional yard, the cost ofremoval and installation can be inthe thousands, high enough to con-stitute a write-off with an older boat.

Larger boats are often no eas-ier. On one occasion, a nearly new9.9m (33') cruiser suffered a badfuel tank leak from a cracked seam.The long rectangular tank wasremoved and replaced through ahole cut in the transom, the holethen fiberglassed and painted. [Ed:Yard labor averages 150 hours in atwin tank reinstallation, at an esti-mated cost of US$14,000.Obviously, the most cost-effectivetime to replace tanks is whenrepowering, as discussed in DIY1999-#4.]

If the tank cannot be maneu-vered through the hatch, removingthe engine may allow the necessaryaccess. Alternatively, it may be pos-sible to chop the tank (make sureit’s purged of all fuel vapors) andpassed though the hatch one pieceat a time. The replacement tank isthen downsized to fit through thehatch, or if concerned about losingfuel capacity, it may be practical to

fit two or more small tanks in thesame location as the original singletank.

When faced with major recon-struction, one solution may be toabandon the original tank in placeand mount a new one elsewhere.This, however, often results in asmaller tank placed in a location(i.e. bow) that compromises trim orstability.

When removing the originaltank pay close attention to the causeof the failure to avoid a repeat. Ifthe tank, for example, was sur-rounded by soggy flotation foam, orsitting on a wet carpet pad, thereshould be no surprise that it cor-roded. You’ll have to devise amethod of keeping the new tank (if metal) dry and well supported.

Integral Tanks

Leaking integral or built-in tanks —not legal for gasoline, only fordiesel — present other problems.Such tanks utilize the boat’s hull orinterior structure; the hull twistingand flexing, causing a crackedweld or separated fiberglass bondusually causes failure. If you canpositively identify the exact sourceof the leak and have access, youcan probably repair it successfully— a brief respite until it leaks againdue to repeated flexing and twist-ing. If the leak is hidden or inacces-sible, you are probably out of luckas repair may involve removing theboat’s interior. It may be possible tofit a fuel bladder tank into the origi-nal space, though these tend to floparound, making it difficult to restrainthem against chafe as well as keep-ing all connection fittings intact.

Repair VersusReplacementAny tank with suspect seams orwidespread corrosion should bereplaced. If you can remove thetank in one piece is repair a viableoption?

If the problem is a small leak,

confirm the leak location. To do this,purge all fumes from the tank, plugthe vent, fill and pick-up fittings andusing a pressure tester, inflate thetank to 3 psi, the recommendedminimum test pressure. Apply soapand water to the outside and checkfor bubbles. Providing the tank exte-rior is corrosion free, welding fixesa single pinhole leak but weldedrepairs are only practical where themetal gauge is relatively heavy. [Ed:Vapors from empty fuel tanks areextremely flammable. To preventcombustion when welding, onemethod is to displace the oxygenwith carbon dioxide (severalpounds of dry ice or a fire extin-guisher), or an inert gas, such asargon.]

Another option is hire a contrac-tor to apply an internal coating. Thismay stop minor leaks for a shortterm but it makes me nervous, espe-cially with gasoline tanks. Check thesupplier’s warranty for marine ser-vice before proceeding.

New TanksAny new gasoline tank is required tobe tested for compliance with U.S.Coast Guard (USCG) standards andlabeled as such. These tests are alsorecommended by the American Boatand Yacht Council (ABYC) for dieselfuel tanks, but are voluntary.

Crevice corrosion on the surface ofthese aluminum gasoline fuel tankscaused by poor installation.

The end of the line: fuel tank replace-ment costs can be high enough to senda boat to the junkyard.

Non-corrosive XLPE fuel tanks are a better choice but onlyavailable in stock sizes and shapes.

ABYC recommends that aluminum tanks be fab-ricated of 5052, 5083 or 5086 alloy with a mini-mum sheet thickness of 2.29mm (.090") for gas anddiesel. At this thickness an Underwriters Laboratories(UL) study done in 1994 postulates a theoretical ser-vice life of only 6-1/2 years in marine service. It’sworth specifying the more commonly used 3mm(.125") sheet, which has a projected service life of17.4 years. In general, the actual service life of anymetal tank is dictated more by the characteristics ofthe installation (see "Installation Tips" on page 40).A corrosion-resistant paint applied to the tank exte-rior may help, but it’s no guarantee against local-ized corrosion at a tiny scratch in the paint. Copperalloy (brass or bronze) fittings are not recommendedfor direct connection to aluminum tanks because theypromote galvanic corrosion at the fitting. Stainlessinserts or adapters are required as a barrierbetween the tank and typical brass fuel fitting.

Stainless tanks have a reputation for quality butin the past have been just as likely to corrode as alu-minum, especially when using lower grade alloyssuch as 304 stainless. ABYC has recently amendedits recommended materials for diesel fuel tanks toinclude 14-gauge (.0747"/1.90 mm) or heavier316L or 317L alloy stainless steel for 75.7L (20 gal)tanks or larger. Smaller capacity cylindrical tanksare permitted to use lighter 22 gauge.

ABYC’s new standard only recommends stain-less when special provision is made to mount thetank to avoid crevice and pitting corrosion fromentrapment of moisture. To assure air circulation totank surfaces, ABYC advises supporting tanks onwelded brackets of like material permanentlybonded to the tank surface with impermeable non-hydroscopic adhesive.

There are also new stainless steels that have a6% molybdenum content compared to the usual2.5% or 3.5% found in 316 and 317 respectively.These new alloys, though more expensive, promiseenhanced corrosion resistance.

Fiberglass (FRP) can be anexcellent tank material, but thereare no builders of production tanks.Any FRP tank will need to be cus-tom made and this makes USCGcertification for gasoline impracti-cal. A custom FRP diesel tank maybe practical for a skilled amateur tobuild, provided he or she is familiarwith glass lay ups.

Roto-molded, cross-linked poly-ethylene (XLPE) is the most commonplastic tank material (not suitablefor potable water).

It’s immune to corrosion andcan install in the lowest, wettest partof the bilge. Care must be taken tosupport the tank over as much ofthe length as possible to avoidchafe or mechanical damage. XLPEtanks permanently expand in alldirections by about 2% within thefirst month or so after being in con-tact with gas or diesel so allowancemust be made for this during instal-lation. This characteristic alsomeans an XLPE tank should not befoamed into place. XLPE tanks arestrong but can be vulnerable at theconnection point for fittings. Do notover-torque the threaded connectorsor install a hose in such a way thatit applies too much side load on theconnector, and can crack the tankat the connection point.

COPING WITH ALEAK EMERGENCY

You’ve got a leaking fuel tank. Ifthe fuel is gasoline, and is mostlyin the bilge, the boat is a tickingtime bomb so call the fire depart-ment. A fuel spill may prove to bea do-it-yourself job simplybecause many marinas or yardswon’t touch it due to employeesafety and liability concerns.

Evacuate the area and closeoff the dock entrance. If con-nected to shorepower, shut off thebreaker on the dock and discon-nect the shorepower cord. Openall hatches to ventilate the boatand, if practical, push the boatby hand to an isolated dock. Turnoff the master battery switch firstand then make sure all electricalequipment is turned off at the dis-tribution panel. Once the maincabin has been ventilated, youcan turn on the main switch tooperate the bilge blower. Do notuse any fans, pumps or any otherelectrical equipment that is notcertified as "explosion proof" or"ignition safe." Small amounts ofgasoline will evaporate quicklyespecially in dry, breezyweather, but a big spill may needto be pumped out. A hand-

pumped oil changer (i.e. Pela) orcertified fuel-transfer pump willwork. Do not, under any circum-stances, use a shop wet/dry vac-uum to slurp up fuel-contaminatedbilge water. You risk an EarthShattering Ka-boom (ESK) and theresults aren’t pretty. Use a solu-tion containing fuel-eatingmicrobes to clean up any residue.

Once the boat is ventilatedand the chance of an ESKreduced, any remaining fuel inthe tank should be debunked. Ifit’s impractical to get a hose intothe tank through the fuel fill,access can usually be gained byremoving the fuel gauge sendermounting plate. If the boat has asecond tank that is intact, youcan transfer fuel from the leakerto the good tank. Otherwise,debunk it into fuel-certified jerrycans or drums for re-use or dis-posal by a toxic waste outfit.

Diesel fuel leaks are a hugenuisance but there is little risk ofan ESK. After cleaning up thespill you are sure to have diffi-culty getting rid of the reek ofdiesel fuel. An odor-remover,such as Captain Phab Odor &Stain Remover, helps to mask thesmell, unless of course, you likethe fragrance. — Nick Bailey

Properly installed, a polyethyl-ene tank should last the life of yourboat, and, in fact, the USCG rec-ommends replacing any failedmetal tank with one constructed ofXLPE. The only drawback is thatthey are available in a limited num-ber of stock shapes and sizes.

Installation Tips The ideal location of the fuel tankfrom the standpoint of stability andtrim is low in the boat on centerline.This is also usually the dampest

location in the boat so care mustbe taken to keep any metal tankdry and exposed to air — no bilgewater in contact with the bottom,no water pooling on the tank top,no having the flat tank bottom incontact with a flat mounting sur-face, no self-wicking material (car-pet or foam) in contact with thetank, etc.

About the author: Nick Bailey is service manager of Bristol Marine inMississauga, Ont.

For diesel only, sheet steel, spec ASTM-A93 in 14-gauge, is a lower-cost alterna-tive to stainless steel, but not as long-lived.

DIY M E C H A N I C

WATER COOLING SYSTEMS

Story by Robert Hess

There are two types of marinecooling systems: open or raw-water, and closed. A cooling

system that pumps water into theengine and circulates it through thehot engine water jackets beforepumping it overboard along withthe heat it collects is called an"open" or "raw-water" system(Figure 1). This system uses onepump, a raw-water pump, to bringthe water into the boat and circu-late it through the engine. Waterdrawn into the engine is usuallyfirst passed through a strainerbefore entering the pump to pre-vent blockage of the system by sea-weed and debris. Quite often tworaw-water strainers are used: anoutboard grate covering the thru-hull water inlet (sometimes incorpo-rating a forward facing scoop toforce extra water into the intake);and an inboard strainer to preventthe ingestion of small particleswhich may damage the waterpump or clog the cooling systemand usually fitted with a removablebasket to simplify cleaning. Someengine manufacturers specify thatexterior scoops should not be fittedto the raw-water intake — whenthe boat is moving at top speedthey force too much water into thecooling system, flooding water lockmufflers and backing water up intothe engine through the exhaustmanifold and exhaust valves.

Raw water circulated through

Everything you need to know about raw-water and closed cooling systems — components, corrosion protection, pressure testing for leaksand blockages, and converting to a closed-cooling system.

Figure 1

Details of a raw-water cooling system.Typical small horsepower diesel

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Standard raw-water cooled MerCruiser engine installation.

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the engine rises in temperature as it absorbs engine heat.When it reaches a temperature of 71°C (160°F), itbegins to precipitate out the salts and other minerals heldin solution and deposits them in the cooling system. In thehottest part of the water jackets, such deposits build upscale and gradually restrict the flow of cooling water untilthe engine begins to overheat. Because the water jacketsare intricate passages cast into the engine block andhead, it’s very difficult to remove these deposits. Enginesoperated in saltwater build up scale much faster due tothe higher mineral concentration. In order to reduce scaleformation in water jackets, raw-water cooling systems usethermostats to maintain water temperature as hot as pos-sible but lower, approximately 65°C (150°F), than the71°C (160°F) precipitation limit.

Engines run more efficiently at hotter temperatures. Ahot coolant temperature allows the engine oil temperatureto reach 100°C (212°F), at which point it boils off anywater absorbed from condensation or produced by theengine and reached the oil pan as piston ring blowby.(Water in the oil forms acids that attack bearings.)Because engines use pure water or water-based solutionsas coolant, the optimum engine operating temperature isabout 87°C (190°F). This allows coolant temperatures toexceed the thermostat temperature by about 10°C (20°F)in very hot weather or very heavy loads without thecoolant boiling. (Engine components are machined sothey have the correct clearances when operating at anoptimum temperature.)

Closed CoolingIn order for engines to run at optimum temperature(87°C/190°F) but prevent precipitation of minerals inwater jackets, many cooling systems incorporate a heatexchanger (Figure 2). This assembly circulates raw

water through one section, called the raw-water side,and at the same time circulates a separate liquid used asan engine coolant through the other section, called thefresh-water side or engine coolant side. Heat collectedby the engine coolant can be exchanged to the raw-water side without the two liquids actually coming in con-tact. Water containing the heat transferred from theengine coolant is then discharged as it does in a conven-tional raw-water system. Known as a closed-cooling sys-tem it uses two pumps: a raw- or sea-water pump, and acoolant pump to circulate coolant through the engine andheat exchanger.

Since raw water is only circulated through the heatexchanger and never touches the engine, scale is cre-ated only in the raw-water side of the heat exchanger,where it’s easily removed through inspection panels. Thefitting of a heat exchanger allows the standard thermo-stat used with raw-water systems to be replaced with an87°C (190°F) unit.

Typical diesel inboard.

Figure 2

Closed Cooling Systems

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MerCruiser470.

Heat ExchangerMost marine heat exchanger cores are the shell and tubetype, which consists of a bundle of copper tubes encasedin a shell so that the liquid "freshwater" to be cooled flowsthrough the tubes while the cooling "raw water" enters theshell and flows around the tubes. The separated liquidstransfer heat from one to another without actually being incontact. In some designs this process is reversed and theraw water flows through the tubes and the freshwater flows

through the shell. Coolant used in the

heat exchanger’s enginecoolant side is automo-tive antifreeze-coolantsolution in normally a50:50 mixture. Thissolution improves heattransfer, reduces foam-ing, prevents coolingsystem metal corrosion,lubricates the water

pump and inhibits the formation of mineral scale in thecooling system. It also protects against freezing down toapproximately –23°C (–40°F) and raises the boiling pointto approximately 104°C (220°F).

Maintenance is easy: use an antifreeze hydrometerto check the freezing point of the antifreeze, and drainand replace the coolant about every three years.

Header TankThe freshwater side of the heat exchanger systemincludes a header tank. Usually incorporated into anextra section of the heat exchanger assembly or theexhaust manifold water jacket, it’s a storage tank forextra coolant to allow for coolant loss, coolant expansionand contraction. Where space is a problem it’s mountedseparately from the heat exchanger and connected byhoses. To prevent air locks, remote header tanks arealways mounted at the highest point of the system.

The header tank is usually fitted with an automotive-style radiator cap. This allows the system to be filled, thelevel checked, and the system sealed so it can self-pres-surize itself when coolant expands due to heat build up.The cap incorporates a spring-loaded pressure releasevalve to prevent pressure from exceeding 7 pounds persquare inch (psi), though some systems use a cap with ahigher-pressure setting (15 psi). Pressurizing the systemraises the boiling point of the coolant and preventscoolant vapor loss.

MEASURINGCOOLANT LEVELS

Your pre-start check before starting theengine should include a check of the heat

exchanger coolant level. To do this, remove theheader tank cap. If only a stub hose is fitted, the"cold" coolant level in the header tank is always aninch or two below the level of the cap — after theexpanding hot coolant is forced out of the stub hoseit’s replaced with air when the cooling coolant con-tracts. On a heat exchanger fitted with a stub hose,the expansion of the coolant as the engine warmsup forces coolant out the stub hose. Therefore, thereis no point in continually topping up the coolant inthe header tank when the engine is cold, since thelevel will expand to fill the system to the top whenthe coolant is hot. Unless, there are leaks in the sys-tem, which is also a good reason for checking thelevel. Never remove the header tank cap when theengine is running or when hot.

TIPS

Heat exchanger located insideheader tank.

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Managing OverflowThe header tank cap neck includesa hose fitting connected to a shortoverflow hose called a stub hose.This hose leads overflowing coolanteither to the side of the engine so itcan drip into the bilge, or to a hoseconnected to the bottom of a sepa-rate small tank, called an overflow,expansion or catch tank mounted inan accessible location near theengine. [Ed: Refit kits are availablefor many engines not equipped withcatch tanks.] The cap incorporates avacuum release valve: when theengine is shut off and coolant is con-tracting as it cools down, the vac-uum created by the contractingcoolant can be eliminated by allow-ing air to flow into the header tankthrough the stub hose, or by suckingcoolant back into the header tank

If you suspect a leak in the enginecoolant side of the heat exchanger,pressure test the system with an auto-motive radiator pressure tester con-nected to the header tank cap neck.

HEFTYFINES FOR

COOLANT SPILLSClosed cooling systems requirea coolant recovery tank, a.k.a.expansion or catch tank, to prevent toxic antifreeze that isexpelled by the cooling systemfrom discharging into the bilgeand pumped overboard. Thefine for dumping contaminantsinto waterways is US$5,000,not to mention the potential environmental damage.

TIPS

from the catch tank, which is usuallymade of clear plastic so it’s easy tocheck the coolant level.

Corrosion ProtectionIn both open and closed cooling sys-tems, raw water is in contact withother metal parts, such as a thru-hullvalve, water pumps, engine, shaft orpropeller, so a sacrificial zincanode(s) is often fitted in the raw-water side of the system, either inthe engine, the heat exchanger, orin a raw-water hose with the zincwired to the engine and heatexchanger ground.

Sacrificial anodes should bechecked monthly by removing themand comparing them in size to anew one. Replace when they are25% of the size of a new zinc.Always carry spares, since strayelectrical currents in some marinascan cause rapid depletion andmake frequent changes necessary.

Detecting Leaks To locate leaks in the engine coolantside of the heat exchanger system,pressurize the heat exchanger withan automotive radiator pressuretester connected to the header tankcap neck. Inspect the system care-fully to determine the source of theleak.

To seal the raw-water side of thesystem and pressurize it for leak test-ing, squeeze together a section ofthe raw-water hose just before theexhaust water-injection elbow withVice Grips (clamp these over sparehose or two pieces of curved woodto prevent hose damage). Fabricatean adapter to allow an automotiveradiator pressure tester to connect tothe hose at the raw-water intakeafter removing it from the thru-hullseacock. Never pressurize the sys-tem more than the rating of the cor-rect radiator cap (i.e. 7 psi or 15psi), since it’s possible to over-pres-surize the system and rupture theheader tank or damage water-pumpseals.

TROUBLESHOOTING STARTING SYSTEMSEngine won’t start? This step-by-step diagnosticguide will get your engine running again.

By Robert Hess

Problems with starter motors andsolenoids account for mostengine no-starts. All engines

must be rotated long enough to gothrough one or more intake-compres-sion-firing strokes, thus drawing fuelinto the combustion chamber, com-pressing it, igniting and starting.Diesel motors only start very quicklywhen fitted with glow plugs; other-wise, they need to rotate quickly sev-eral times to generate enough heat tostart.

Most marine engines are conve-niently equipped with an intermittent-duty electric starter motor, exceptsmall horsepower outboard engines,fitted with a small driving gear thatdrives a large crankshaft-mountedring gear (usually incorporated onthe circumference of the flywheel). Atypical starter gear to flywheel ringgear ratio of approximately 12:1turns the starter motor at a speed ofapproximately 2,400 rpm, whileturning the ring gear at about 200rpm, the minimum rpm required tostart most engines.

Because diesel engines need tobe rotated faster than gasolineengines to start — diesels haveapproximately three times the com-pression ratio — they are fitted withmore powerful starters. Many dieselshave an automatic decompressionsystem (some have manually oper-ated decompression levers). Thisholds exhaust valves off their seatsduring starting, allowing the starter torotate the engine up to starting speedwithout having to overcome cylindercompression. Once the engine turnsfast enough to start, the decompres-sion system fully closes the exhaustvalves and the combined momentumof the flywheel plus the starter motorovercomes cylinder compression,

and the engine starts. Diesel enginesusually need to be rotated at approx-imately 400 rpm to start, or 200 rpmwhen fitted with glow plugs. Theseplugs improve ignition by heating thecombustion chamber when theengine is cold which aids in startingand warm-up.

DesignStarter drive gear on most modernmarine engines is usually a positiveengagement Bendix type, which usesa gear with an internal helix threadon the end of the starter drive shaft.A solenoid assembly (a.k.a. mag-netic switch) mounted on the starteracts as a heavy-duty switch to powerthe starter motor. It also incorporatesa lever system that positivelyengages the starter gear with thering gear. When activated, the sole-noid forces the starter gear outagainst the ring gear, the gearsbegin to mesh and then a split sec-ond later begin to rotate the starter.Rotation direction of the starter drivegear and the angle of the internalhelix thread causes the starter drivegear to move further out and fullyengage the ring gear as it begins torotate the engine. When the enginestarts and begins to rotate faster thanthe starter, the ring gear then drivesthe starter drive gear, rotating it inthe opposite direction on the internalhelix. When the operator releasesthe start button, the gear quickly

Overheating TestEngine overheating can be causedby a lack of cooling water flow ineither open or closed systems. Lackof flow is caused either by a restric-tion in the intake or outlet side of thewater (or coolant) pump, or a dam-aged pump.

A pressure gauge installed at thepump outlet in either a fresh-water orraw-water system can determinewhether the system pressure is toohigh, indicating a blockage in thesystem after the pump (i.e. blockedmixing elbow), or too low, indicatinga restriction in the pump intake or adamaged pump (usually theimpeller).

Raw-to-FreshConversion Converting from an open to a closedsystem by installing a heat exchangerand 87°C (190°F) thermostat alsoinvolves installing a second pump forthe engine coolant, and addingcoolant. Plumb the raw-water side ofthe new closed system from the raw-water seacock to the raw-waterstrainer, to the raw-water pump, tothe raw-water side of the heatexchanger, and finally to the exhaustwater-injection elbow (see Figure2). Plumb the engine coolant side ofthe system from the engine coolantside of the heat exchanger to theengine coolant pump, to the enginewater jackets and exhaust manifold,and then back to the engine coolantside of the heat exchanger. Kits areavailable for most engines completewith all components that make this ahalf-day job. It’s recommended youeliminate all engine scale build-upbefore converting.

About the author: Robert Hess oper-ates Atomic Four Engine Service inVancouver, B.C.

DIY M E C H A N I C

rotates down the starter drive gear tothe rest position.

Voltage CheckDesigned to operate in short bursts of10 seconds with a cool-down periodbetween each burst, starter motorsdemand hundreds of "cranking"amps. If the cranking battery is notfully charged, or there is any resis-

tance in the starter cables or connec-tions, the resultant voltage droprestricts the current and prevents themotor from rotating the engine fastenough for it to start. Low voltage atthe solenoid sometimes causes eithera single clunk sound as the solenoidpushes the Bendix gear against thering gear, or just a rapid clickingsound as it tries to hold the contactstogether against the contact spring.

Some diesel engine startingproblems are simply low voltage. Thestarter turns the engine over at whatsounds like an acceptable speed, butit’s not sufficient to allow the engineto develop enough heat to start,especially in colder-than-normal tem-peratures.

While the starter is rotating theengine, a multimeter (see "ElectricalTroubleshooting" on page 30) with

the red (positive) probe connected tothe starter positive terminal and theblack (ground) probe to the metalbody of the starter, should read atleast 9.6 volts. If voltage dropsbelow 9.6 volts, then check the bat-tery cell condition with a hydrometerand ensure it’s fully charged to 12volts. Remove and clean the batterycable terminals and battery posts (acommon source of many batteryproblems), then remove and clean

the engine block ground cable ter-minals. Use your meter tocheck for a voltage dropbetween the starter and sole-noid terminals, while ahelper activates the starter.

If voltage checks verifythat the battery is fullycharged and battery andstarter cables are in good

condition and properly sized (novoltage drop), either the engine hasa serious mechanical problem, whichis preventing the starter from crank-ing it quickly (i.e. a partial bearingseizure), or the solenoid and/orstarter needs repair.

Engine or StarterFailure?If the engine is stiff, the starter andcables usually get very hot becausethey are drawing more current thanintended. To verify that the engineturns freely and smoothly, you musteliminate engine compression. To dothis on gas engines, disconnect theignition coil leads (to prevent sparks)

and remove the spark plugs; removeglow plugs or fuel injectors fromdiesels, or disengage manual decom-pression lever. Place a socket wrenchon the crankshaft and turn over theengine in the normal direction ofrotation (check direction in owner’smanual). Any noticeable stiffness orresistance may foretell of some inter-nal engine damage; however, beforemaking any assumptions, inspectengine-driven attachments such aswater pumps, alternator, transmis-sion, etc. Now rotate the engine viathe starter. As it doesn’t have to over-come engine compression, the startershould turn the engine at a higherthan normal speed. If the engineturns freely when rotated by hand,but doesn’t turn quickly with thestarter, the starter likely needs repair.

Bench TestTo test the starter, first remove fromengine and use a set of booster

To test the starter, remove from engineand connect it via booser cables directlyto a fully charged battery.

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Exploded view of starting motor circuit.1. Stationary contact 2. Series coil 3.Ignition switch 4. Solenoid 5. Shunt coil6. Plunger 7. Return spring 8. Shift lever9. Drive pinion 10. Ring gear 11. Pinionsleeve spring 12.Armature 13. Movablecontactor 14. Battery

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DIY M E C H A N I C ENGINE TEMP CONTROL

A faulty thermostat causes an engine to over-heat or to operate too cold, either conditionresulting in costly damage. Here’s how to test,remove and replace your engine’s thermostat.

By Robert Hess

Early raw water-cooled marineengines had a gate or needlevalve fitted in the block exit to

act as an operator-adjusted manualtemperature control valve. Later ver-sions were fitted with a wax pelletthermostat, installed in the blockcoolant exit in place of the operator-controlled valve.

The introduction of the fiberglassor plastic waterlock muffler in the‘70s, resulted in substituting a dou-ble-acting type thermostat. Thisdevice controls the direction of waterflow: if the coolant in the block iscold the exit at the top of the block isclosed to stop the flow of coolingwater and force the block to heat up.At the same time the water isdiverted through the bypass loop tocool the exhaust manifold and water-lock. Conversely, when the coolant inthe block is too hot, the block exit isopened fully and the bypass isclosed, so that the water is divertedthrough the block to the exhaust sys-tem.

Once the engine has reachedthe thermostat's rated temperature, itgradually assumes a partially open

state of equilibrium based on thethermostat temperature rating, the ini-tial coolant temperature, the engineload, throttle setting, and ambienttemperature of the engine room.

Optimum Temp RatingsRaw-water cooled engines (especiallythose operated in saltwater) shouldbe fitted with thermostats rated at62°C to 65°C (145°F to 150°F) toavoid scale build up in the waterjackets caused by temperatures over71°C (160°F). Removing the thermo-stat so

COOLBUT DEADLY

Traditional ethylene glycolautomotive antifreeze that fillsan engine’s heat exchanger isextremely appetizing to petsbut fatally toxic. Never leaveany in an open container,always drain engine coolantinto a sealable container, andconsider switching to a non-toxic propylene glycol (plumb-ing) coolant.

TIPS

Two-stage gas engine thermostat openat 62°C (145°F).

cables to connect it directly to a fullycharged battery. A starter fitted witha positive mechanical solenoidshould immediately move the Bendixgear out to the end of the startershaft, and the shaft should begin tospin quickly. If the Bendix gear does-n’t move to the end of the shaft or theshaft turns slowly, the solenoidand/or starter needs rebuilding,likely worn-out brushes and burntwindings. If the solenoid snaps theBendix gear out to the end of theshaft, and the starter begins to spinquickly, it’s probably okay. If thestarter hasn’t been serviced for sev-eral years, now may be a good timeto have it cleaned and checkedbefore reinstalling, just to make sureit’s in good condition.

Note: When bench-testing astarter, as soon as it begins to turnquickly, immediately remove one ofthe battery cables and let it stop.Most starter motors are not meant torun without a load and are easilydamaged when allowed to rotatefaster than their designed limit.

About the author: Robert Hess oper-ates Atomic Four Engine Service inVancouver, B.C., and specializes insales and rebuilding of Universal gasand diesel marine engines.

ture stamped on the ther-mostat. If warm-up takesa long time and the tem-perature rises onlyslightly suspect a thermo-stat stuck wide open. Ifwarm-up takes a longtime but the temperaturefinally gets close to nor-mal, the thermostat maybe stuck partially open.If the temperature goesup quickly and exceeds

the temperature stamped on the ther-mostat, the thermostat may be seizedclosed. If the engine temperature istoo hot, try removing the thermostatand running the engine to see if itsuddenly runs cold, which may indi-cate the thermostat is sticking closed.

Many thermostats have the ratedopening temperature stamped on thebody. This temperature can be mea-sured and the thermostat tested forerratic operation by placing the ther-mostat in a pot of water and heatingit on a stove while monitoring thewater temperature with a cookingthermometer. Once the thermostat

the engine runs extremely cold is notrecommended, since cold runninggreatly increases problems, such asvalve guide and piston ring sticking,high fuel consumption and acceler-ated engine wear. Removing two-stage thermostats, such as those fittedto older Universal Atomic Fourengines, can eventually cause headgasket failure and cylinder headcracking. Heat exchanger-equipped

engines should befitted with ther-mostats rated at82°C to 87°C(180°F to 190°F)to take advantageof the exchanger'sability to cool the

engine without circulating raw waterthrough the water jackets.

Testing Tools Since thermostats are mechanicaldevices that are constantly openingand closing all the while the engineis running, they gradually wear outand should be replaced regularly,roughly every 1,000 hours. A rebuiltengine should always be fitted with anew thermostat.

A sticking thermostat can causeerratic temperature fluctuation; butthe most common thermostat failure isa total seizure, usually in a closedposition that causes extreme over-heating. To monitor thermostat opera-tion, run the boat at moderate speedand load (do this at the dock) andattach a surface thermometer to thethermostat housing or cylinder head.Using the control panel water temper-ature gauge, a water temperatureprobe in the header tank of closedcooling systems or waterlock mufflerof raw-water cooled systems, com-pare temperatures — the exteriortemperature of the cylinder headmetal is usually the same temperatureas the engine coolant.

A cold engine should quickwarm up to the operating tempera-

Single-stage diesel engine ther-mostat showing coolant bypasshole.

On closed-cooledsystems, thermo-stat is located onthe header tank,often on theside.

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To remove, disconnect coolant hose,remove thermostat housing and liftthermostat.

has opened fully, test it for sticking: remove from the hotwater and place it in cold water, where it should closequickly and completely.

Removal and ReinstallationRemove thermostats for inspection or replacement onlywhen the engine is cold to reduce the risk of burns. If theengine is equipped with a heat exchanger remove theheader tank cap, then drain the engine coolant into abucket so that the level in the engine is below the thermo-stat. Remove the thermostat housing or cover, and care-fully remove the thermostat without damaging it. Checkthe housing against a straight edge to make sure it isn’twarped; in the case of double-acting thermostats such asthose fitted to Universal Atomic Four engines inspect thethermostat housing bypass boss for corrosion damage.Replace or repair as necessary.

Scrape the gasket and old gasket cement from boththe block and ther-mostat housing, andinstall the thermostatwith a new gasket orsilicone gasketcement. (Loctite isrecommended.) If thethermostat fits into alip or depression,make sure it’sinstalled properly toavoid cracking thehousing when youtighten it down.Torque the housingfasteners to the speci-fied torque using atorque wrench. (Referto your owner’s man-ual for proper proce-dures.)

For a closed-cooled engine equipped with a heatexchanger, fill the header tank with 50:50 antifreeze-water solution, and if there is an air bleed valve on thethermostat housing or the top of the head open it torelease any air trapped under the thermostat. Leave theheat exchanger cap off until the engine has warmed upand the level of coolant has stabilized, and then top upthe level to make sure the header tank is full beforereplacing the cap. If the header tank overflow hose isconnected to a catch tank, make sure it’s about half full ofcoolant, and check it again after first-time run of theengine.

About the author: Robert Hess operates Atomic FourEngine Service in Vancouver, BC.

Testing the thermostat: place inwater-filled container and heat,then place in cold water. It shouldopen then close quickly withoutsticking.

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R i g g i n g

By Jan Mundy

Whether you’re cruising in the shal-lows, landing on a beach or launch-ing at a concrete ramp, MegawareKeelGuard (Tel: 800/292-9835) pro-tects keels from abrasion, chafe,dents, rocks — whatever lurks below.Ideal for all wood, aluminum, fiber-glass, plastic or rubber boats, it con-sists of an extremely durable andabrasion-resistant polycor compositeband held permanently in place with3M VHB (Very High Bond), a pres-sure-sensitive acrylic industrial adhe-sive. It bonds so well, the companyoffers a lifetime warranty.

Available in 13 colors, twowidths and in lengths in 30cm (1')increments from 1.2m to 3.6m (4' to12') to fit boats 9m (30') and longer.Kit prices range from US$100 forboats up to 4.8m (16') to US$235for 30-footers and larger. No curingtime is needed, so allow an hour forinstallation before launching.

For our 6.6m (22') test boat, weordered the 2.1m (7') white kit in thelarger width of 12.7cm (5") at a costof US$156, which is a lot less expen-sive than major fiberglass surgeryshould we hit a submerged rock.

1 Clean keel area, remove anyalgae or dirt with an acid cleanerand antifouling paint.

2 Beginning at the forefoot, pencilmark the centerline and width,extending 6.3cm (2-1/2") out oneither side. Continue measuringdown the keel the length of the

KeelGuard, adding an extra 5cm(2") at the end (aft) to allow for thecurvature;otherwise,after layingdown thematerial itmay benecessaryto cut off any excess or reprime anyuntreated keel surface.

3 Mask along pencil marks with3M Fine Line or 233 tape to preventmarring the gelcoat when sanding.

Tape also acts as an edge line forapplying primer and attaching band.

4 Sand the surface hard to removehull wax, pencil marks and other con-taminates with 3M Scotch Brite pad(provided). Sight down the keel line

— anyglossyareasrequireadditionalsanding.Follow witha solventcleaning.

5 To apply 3M primer, push foamapplicator hard against the hull until

foam is wetwith glue.Draw applica-tor sidewaysover surface,applying athin coat,extra alongthe edges.Primer isodorless and not messy, so glovesare not necessary. Wait five minutesfor glue to cure. Unroll KeelGuardand lay flat in sun until supple, aboutfive minutes in 32°C (90°F) temps.

6 Starting at the bow, pull backabout a foot of the red plastic linerand align theband.Working fromthe center, oneside at a time,pull back thetape and presson by hand oruse the bur-nishing tool toremove alltrapped air.Position carefully as the bondbecomes permanent immediatelyupon contact. Continue workingtowards the stern and once com-pletely attached, press entire surfacedown firmly with burnishing tool.

Make sureall edgesare down.Removetape,wipe offanyexcessadhesiveand goboating.

KEEL ARMORProtect your boat’s keel with this ultra-toughbumper. Easily installed in less than one hour, justpeel and stick — no holes to drill, no fasteners.

Powerboat

By Zora and David Aiken

Solar panels are practical add-ons,but their installation can present acouple of problems. One is thevery real in-your-way, toe-stub-bing kind of problem. Theother is one of perception:the black-glass squares arenot particularly yachty look-ing, but you can hardly hidethem. Recently, we saw a sail-boat whose owner had man-aged to minimize both.

Buy a solar panel, then buytwo teak handrails of the samelength as the panel, or slightlylonger. The ultimate placement ofthe panel will be a compromise: itmust have sun exposure for thelongest possible time each daywithout being directly underfoot ina high traffic area. In this case, thepanel was positioned on the star-board side cabin top, far enoughbehind the mast so that sail han-dlers would not step on it.

Cut (or router) an L-shapednotch into the intended inner edgeof each handrail. The size of thesolar panel’s frame will determinethe finished depth of the cut. Thepanel mounts on top of the cut sur-face, flush with the uncut top por-tion of the rail, and is positioned sothat screws pass through the rail’souter edge and into predrilled holeson the panel frame. Naturally, if thebrand of panel you purchase usesa different mounting method, it canbe adapted to this application.

Assemblethe panel and

rails, and placeinto position. Measure

and mark the appropriatespots where screws go through thecabin top to attach the handrails;screws install from inside the boat.Drill pilot holes first to check foraccuracy. Rails likely won’t requirestrong backing plates that an actualgrab rail needs, but depending onthe type of overhead or headlinerin your boat, such a plate makes amore secure attachment. Mount awatertight deck

connection to lead the panel’swiring harness through the cabintop to the battery.

About the authors: David and ZoraAiken are the authors of "GoodBoatkeeping" and "Good Cruising"published by International Marine.The Aikens currently live aboard"Atelier," berthed in Grasonville,Maryland.

BUMPGUARD FOR SOLAR PANELSCustomized handrails add a decorative touch and protect solar panelsfrom side impact.