88826_EnergyEfficiency

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Energy Efciency Handbook or

Inshore Vessels

A resource or inshore vessel operators

Vessel Name_____________________________________

Produced by The New Zealand Seaood Industry Council in conjunction with EECA


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EECA provides independent, authoritative advice to help New Zealandbusinesses boost productivity through energy efciency,energy-saving technology and renewable energy.

Successul businesses ocus on improving productivity and reducingwaste - in other words, they do more with ewer resources. Efcientuse o energy is a key part o that process. Many New Zealandbusinesses, including those in the seaood industry, are now startingto see enrgy as a variable input cost they can control, rather than anoverhead they are stuck with.

EECA has a number o programmes than can help you improve theenergy efciency o your business and increase the use o renewableenergy. We oer a range o services, tools and resources to help you

examine your energy spend and manage your energy use asefciently as possible.

For advice and ideas on managing yourenergy costs, whether at sea or on land, visit

www.eecabusiness.govt.nz

Improve Your Energy Efciency


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Contents

Page Chapter

2 Introduction

7 Operating speed

19 Hull resistance and ouling

25 Propellers

35 Vessel maintenance

39 Electricity

45 Trip planning

49 Record keeping

CautionRules and regulations are liable to change over time but were correct at the time o publication (2010).

It is important that operators remain current with their understanding o their obligations. I you are

unsure, please contact your CSO, the New Zealand Seaood Industry Council Ltd or the Ministry o

Fisheries


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A section on record keeping helps you evaluate changes and work out your energy efciency.

Simple calculation sheets, exercises, templates and checklists are included to help you estimate and

measure cost benefts or your vessel and record and evaluate your progress. At the end o the

handbook, space is provided so that you can add new inormation as it arises. Supporting templates and

documents can be ound at www.seaood.co.nz/energyresources.

You will fnd that there are some relatively low-cost changes that can be made quickly and easily, which

can result in signifcant cost saving. There are also some things that will take more time, eort and

expense to net results. In every case there is some trade-o or energy efciency, either in terms o

higher operational costs or longer periods at sea. It is up to you to decide which measures apply and are

suitable in your particular situation.

The inormation in the handbook is taken rom previously published reports and documentation, and has

been updated where possible to include new technical developments.

Dierent vessels may have dierent solutions and priorities. This handbook aims to help you fnd out

what is best or you and your vessel.

Its a simple equation. Less money spent on uel or the same catch o fsh equals greater proft.

Nonetheless, you have to use uel in order to fsh. The best engine or the propulsion o fshing boats

to date has been the compression ignition engine powered by liquid (diesel) uel. It suits fshing or a

variety o reasons:

The engine is relatively simple, robust and reliable,

Diesel uel is sae to use, has a high energy density and is o a consistently high standard,

Engines and uel are readily available, cheap to procure and backed up by good services.

While alternative uels and propulsions continue to be reviewed, it is likely that diesel engines will be

here or some time. The cost o uel is likely to remain high, be volatile and continue to be a signifcant

proportion o turnover.

How do I save?This handbook looks at uel efciency options or existing inshore vessels with diesel engines. It suggests

ways to reduce energy costs without major changes such as commissioning a new vessel or replacing

expensive equipment. Although it does highlight some things you should consider when evaluating

those changes. This handbook helps you identiy dierent areas where uel cost savings could be made.

Each area has a tabbed section. The cost-saving suggestions are in no particular order. What will work

or you will depend on the nature o your vessel, measures previously implemented, the level o capital

investment chosen, and the extent o your records.

This guide helps you improve your energy efciency and bottom line by:

Showing you where energy (and thereore uel) is used

Identiying changes which can reduce uel consumption

Two kinds o changes are discussed. These are operational changes (how things are done) and technical

changes (what equipment is most appropriate to increase efciency).

Saving uel improves your bottom line. The amount o uel used is one o

the largest costs fshers can control.Savings made on uel = money in the bank.

The operational changes looked at are:

Vessel operating speed

Electricity use Frequency o maintenance and cleaning

Trip planning

The technical changes looked at are:

Propeller design, and its relationship with the

engine and gearbox Hull condition and antiouling


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For fshing vessels, uel is generally used to:

supply the vessel with propulsion

generate electricity

generate hydraulic power

At any time, fnding ways to save energy is likely to be easier than catching more fsh or increasing the

value o the catch. I implemented correctly, energy savings will continue to save money or many years

to come.Fuel is only one o the costs o your operation. The cost o an energy efciency solution may or may

not be greater than any potential savings. This handbook can help you work that out. However, even

ater you have worked out what is best or you and your vessel, remember that as fsh prices, uel

costs, labour and other actors change, it is important to recalculate trade-os regularly and review your

energy saving decisions.

Wages, boat ownership costs, and ACE costs are largely fxed costs. So reducing uel costs is one o the

easiest ways to improve proftability. A dollar saved on uel is a dollar directly added to the bottom line.

Think o how many dollars worth o fsh you need to catch to make a dollar o proft.

The operating costs o a fshing operation vary greatly depending on the:

Breakdown o costs or Anne-Louise a Danish seine vessel (Thomas et al. in press).

Type and size o vessel Target species

Fishing method

Average time at sea Distance to fshing grounds


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Where does your revenue go?Can you build a breakdown o costs or your operation? To get an idea o how much dierence saving

uel can make to your bottom line, work through the ollowing table using fgures rom your last fnancial

year.

Expenses Amount

Fuel

Wages

Bait

Ice

Repairs

Maintenance

Shore power

Other

Total expenses

Revenue

Landed catch

Other

Total revenue

Gross proft (=revenue - expenses)

% revenue spent on uel

5% o uel expense (uel expense x 0.05)

Dividing the uel amount by the revenue amount, tells you what percentage o your revenue goes on

uel.

Work out what 5% o your current uel cost is, and put it in the last row. Savings o this amount (and

more) should be easily achievable. Compare this to your gross proft to see what kind o fnancial impact

l i h

uel expensetotal revenue


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Where does your energy go?Just as operating costs o a fshing operation depend on the type o fshing done, so does energy use. An

energy tree can show where the energy is used and help you concentrate on the biggest user frst. An

energy tree or the Anne-Louises diesel is shown here:

Do you know where your energy goes? Think about the equipment you

have on board and the kind o fshing you do. Sections in this guide will

help with this.

Energy tree or Danish seiner, Anne-Louise (Thomas et al. in press).

Getting help to identiy savings

Independent energy surveys or audits o your fshing vessel can help to:

more quickly identiy where your uel is used,

identiy opportunities to reduce uel costs,

identiy which measures will be the most cost eective.

The costs o energy audits may be subsidised through grants rom EECA. For more inormation on

energy audit grants contact the New Zealand Seaood Industry Council Ltd or EECA. Website addresses

are: www.seaood.co.nz/energyefciency or www.eeca.govt.nz

Finding out more about reducing uel useIt is difcult to keep pace with new changes in technology or the outcomes o energy efciency trials

in New Zealand and overseas. The New Zealand Seaood Industry Council has developed a web based

resource centre on energy efciency options: www.seaood.co.nz/energyresources or more inormation.

A clear fle has been included at the back o the guide so you can add new inormation you download.


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Operating speed

Time is money skippers want to get to shing grounds as quickly as possible, and once the catch is

onboard its again tempting to go as ast as possible getting back to port. But greater boat speed comes

at a cost and dramatically increases the uel bill.

The speed a vessel operates at has the largest impact on how much uel it uses.

Why slow down?It takes power to push a boat through the water. The engine provides the power, through the propeller,

which overcomes the actors that slow down the boat. These are:

Skin riction, the drag caused by water rubbing against the hull.

Form drag, which is caused by water fowing

around the hull, rudders and any appendages.

Wave making resistance, which is the energy

sapped rom the vessel to make bow and

stern waves as it moves through the water.

All three kinds o drag increase with speed,

but or displacement vessels the wave making

resistance is the biggest problem as it increases

exponentiallywith speed.

Unortunately, the wave making resistance

at a given speed is essentially xed, as it is

determined by the vessel dimensions. Long

thin hulls have a lower wave making resistance

than short wide hulls, which is one o the main

reasons why high-speed catamarans have long

thin hulls.

A very steep increase in wave making resistance

occurs when the vessel moves at the same speed as a wave its own length. This is oten known as the

hull speed. Exceeding the hull speed takes a huge amount o power or small speed increases. Planing

l t th th i h ll d b i i t th t d l i th

The bottom line is: to save uel and money, slow down.

The Gweny-May, Picton, NZ. (Photo: T. Collins)


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How ast should I go?Deciding how ast to go depends on how quickly you really need to get somewhere and how much uel

the vessel uses at dierent speeds. A uel curve, as in the previous graphs, shows how much uel is used

at dierent speeds and can help make operating speed decisions.

I your boat has an electronic engine management system or uel meter, use Exercise 1 to build a uel

curve or your vessel.

I the vessel does not have a uel meter, consider buying one, getting a uel curve built by a service

provider or energy auditor, or use Exercise 2 to approximate how much you can save by slowing down.

Fuel meters:

I the engine management system does not include uel metering, consider buying a standalone uel

meter. Meters or the diesel engines ound on shing boats, cost $1,800 to $2,500 or analogue models

and $3,400 to $4,000 or models that have a speed input (rom a GPS) and calculate uel eciency in

L/nm automatically. Installation costs are typically an additional $1,000.

As well as helping build a vessel uel curve, uel meters are an invaluable tool or measuring changes in

vessel eciency.

For example, you might have bought new nets and any improvement or decline in uel eciency whiletrawling can be noted. Monitoring uel use also helps detect problems aecting the vessels energy

eciency. Increased uel use could indicate it is time to investigate cleaning the hull, replacing the anti-

ouling or repairing the propeller.

Best operating speedThe best operating speed depends on more than just uel use. The savings rom slowing down are oset

by: more time spent at sea, increased labour costs, delays in getting sh to market and increases in any

other costs that accumulate with time. Some benets and drawbacks o slowing down are listed below.

Many crews are paid a percentage o the catch. As steaming slower means more time at sea, crews

may have little incentive to save uel by slowing down. Finding a way to reward uel savings can help

motivate crews to save uel.

For bonus and reward schemes to work, the uel-use or trips needs to be benchmarked. This may be

litres o uel used per hour o the trip or per kg o sh caught or per distance travelled, or a combination

o all three. The section on Record Keeping has some sheets to help benchmark uel use or trips.

Once uel use has been benchmarked, try to get everyone motivated and saving uel by slowing down.

You could do this by rewarding the crew with a share o the savings or subsequent trips.

Align the crews and owners interests to reduce uel costs with incentives

and bonus schemes.

Benets and Drawbacks o Slowing Down

Benets Drawbacks

Signicant uel savingsOwner and crew may have

dierent motivations

Costs nothing to implement Requires discipline to carry out

Easy to do Can be inconvenient


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To keep any bonus scheme air, some complications need to be considered. For example, travelling

greater distances to shing grounds or going out in rough weather both lead to higher uel consumption.

I these, or any others actors the crew has no infuence over, are not taken into account, crews may be

reluctant to go out in poor weather or go on trips to shing grounds urther away than usual because

they wont be able to make the uel savings in those conditions.

Costs o slowing downThe cost per mile varies as uel prices and other hourly costs change. Knowing the overall cost or an

additional hour at sea can help you decide when to slow down.

Some hourly costs might include:

The price the skipper puts on his time

Any wage costs (i appropriate)

Generator hourly costs - uel and maintenance

Main engine hourly maintenance costs

Any other costs that increment hourly

The vessels uel curve will give an idea o how much can be saved rom slowing down over a givendistance. The extra time taken can be used to see how much additional cost occurs due to arriving later

and a decision can be made on the best speed.

Sometimes the extra time taken caused by slowing down may not matter much. In these situations,

slowing down may save lots o uel without much inconvenience.

For example: I at 10.00 pm its decided to return 50nm to port, a 15.6m trawler could steam back at

9.0 knots, using 2.75 L/nm, travelling the distance in just over 5 hours - arriving back at 3.30 am and

burning 138 litres o uel.

I there is no reason to be back until 6.00 am, (and most o the crew can sleep) then the trip could be

done in 8 hours instead. This would allow the vessel to steam at 6.25 knots - using about 1.0 L/nm and

burning 50 litres o uel. The extra

2 hours o steaming at the lower

speed has allowed uel savings o

88 litres.

Vessels are typically operated at a

set engine speed or steaming, and

the vessel will go the desired speed

most o the time. But, depending

on conditions, it will sometimes be

aster and sometimes slower than

the normal speed.

When the vessel is going aster than

normal due to benecial conditions,

or example due to tail winds,

avourable currents and lower

loadings than usual, gains in uel

eciency can be made by throttling

back a little until the vessel slowsto normal operating speed. This

making hay while the sun shines

will reduce overall uel use.

Save uel by slowing down when the circumstances allow.

Your on board equipment can help you work out how much fuel youuse and at what rate. (Photo: T. Collins)


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Case study: Semi-planing boat operating speedGweny-May a 14m hard-chined semi-

planing boat operating out o Picton

mainly pots or rock lobster. It is

powered by a 374kW diesel engine

driving a three bladed propeller

through a 2:1 reduction gearbox.

With trips lasting up to six days, there

are oten long periods o steaming to

and rom shing grounds. The boat

had typically been operated at 1,800

RPM and the owners were happy with

its perormance, although rising uel

prices motivated them to re-evaluate

the current operating speeds.

The reshly anti-ouled 15 tonne vessel

was loaded with 2,000 litres o uel,

2.5 tonnes o ice, and bait. A record o

speed and uel use at dierent engine

speeds was made using the engines

electronic engine management system,

which already recorded uel use, and

speed inormation rom a GPS unit.

The results o trials to determine its uel

use at dierent steaming speeds are inthe table below and shown graphically

in the two graphs above and right.

The uel eciency is expressed as

the number o litres o uel used to

travel one nautical mile (L/nm). This

is a more useul gure than the more

commonly used litres per hour (L/h) as

the distance travelled depends on how

ast the vessel is going.

Engine

Speed

(RPM)

Speed

(knots)

Fuel Use

(L/hr)

Fuel Use

(L/nm)

1400 9.1 33 3.63

1500 9.5 45 4.74

1600 10.2 52 5.10

1700 10.4 64 6.15

1800 11.0 79 7.18

1900 11.7 94 8.03

2000 12.5 109 8.722100 13.0 118 9.08

Summary of trial data (Collins T. New Zealand SeaoodIndustry Conerence presentation 2008.)

FuelConsumption and Speed vs. Engine RPM

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0.0

2.0

4.0

6.0

8.0

10.0

12.0

800 1000 1200 1400 1600 1800 2000

FuelUsedtoCover

Distance(L/nm)

Engine Speed (RPM)

Vessel Speed Fuel Consumption

Fuel Use to Cover Distance vs. Vessel Speed

0.00

2.00

4.00

6.00

8.00

10.00

8 9 10 11 12 13 14

FuelUsedtoCoverDistance(L/nm

)

Vessel Speed (knots)

Fuel Consumption vs Vessel Speed

Fuel Consumption

The top graph shows the amount o uel used to

cover ground vs. the vessel speed. There is clearly

a large increase in the amount o uel burned per

mile when steaming above 10.2 knots.

The bottom graph shows the vessel speed and

uel consumption at dierent engine speeds;

again, above 1,600 RPM there is a steep increase

in the amount o uel used to cover a set distance.

Based on this inormation, the owners decided

to operate Gweny-Mays engine at 1,600 RPM

instead o 1,800 RPM as they previously had. This

reduced their uel use by about 20% and saved

them $14,600 per year.


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Case study: Displacement vessel operating speedThomas Lovell is a 15.6m trawler

powered by a 172kW diesel engine

driving a our-bladed propeller tted

inside a nozzle through a 3.75:1

reduction gearbox.

The results o trials to determine its

uel use at dierent steaming speeds

are in the table above and shown in the

graphs below and to right.

The graph to the right (uel consumption

vs vessel speed) shows that the amount

o uel needed to go a mile increases

as the vessel goes aster. It takes 20%

more uel to cover the same ground

at 9 knots as at 8 knots, and almost

double i only going 7 knots.

The graph below shows the vessel

speed and uel consumption at dierent

engine speeds.

Fuel Consumption and Speed vs Engine RPM

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

0.0

2.0

4.0

6.0

8.0

10.0

12.0

800 1000 1200 1400 1600 1800 2000

FuelUsedtoCoverDistance

(L/nm

)

Speed(knots)

Engine Speed (RPM)

Fuel Consumption and Speed vs Engine RPM

Vessel Speed Fuel Consumption

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

5.0 6.0 7.0 8.0 9.0 10.0 11.0

FuelUsedtoCoverDistance(L/nm

)

Vessel Speed (knots)

Fuel Consumption vs Speed

Fuel Consumption

The table at let isthe summary otrial data. The two

graphs show uel useat dierent steamingspeeds. (Gilbert L.1983 Fishing vesselsand Fuel Control.

Fishing Industry Board.)

For orms and downloads

to support this handbook,

go to www.seaood.co.nz/

energyeciency

Engine Speed (RPM) Speed (knots) Fuel Use (L/hr) Fuel Use (L/nm)

1000 6.5 6.5 1.00

1100 6.8 7.5 1.10

1200 7.1 10.5 1.48

1300 7.5 14 1.87

1400 8.0 18 2.25

1500 8.5 21 2.47

1600 8.9 24.5 2.75

1700 9.8 30.5 3.11

1800 10.3 37.5 3.64

Using this inormation, i the owners

decided to steam at 8 knots rather than

9 knots, a 40 nm round trip to shing

grounds would take 34 minutes longer

but use 22 litres less uel. Steaming at

7 knots rather than 9 knots would take

an extra 1.25 hours but save 56 litres o

uel.


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Exercise: Building a uel curve with a fow meterI the vessel has a uel fow meter or engine management system, building a uel curve is straightorward.

The speed is read o the navigation system, or a cheap GPS unit can be used. Remember speed rom a

GPS unit is the true speed over the distance and doesnt take into account dierent currents, wind and

the tides.

To gather the data, simply set the engine speed to an appropriate value in the table below, and then

once the vessel speed has settled down, record the uel use and speed. Do this or each applicable enginespeed. This exercise may be repeated a ew times to average out the eects o tides etc.

When the table is lled out, calculate the uel eciency gure (L/nm) or each engine speed. Simply

divide the uel use by the vessel speed. Note: you can download extra exercise sheets rom the website

at www.seaood.co.nz/energyefciency

Once the uel eciency has been calculated or each engine speed, the gures can be plotted on a graph

to create a uel curve. Two blank graphs have been provided: one to plot uel eciency vs. engine speed

and one to plot uel eciency vs. vessel speed.

EngineSpeed(RPM)

Vessel Speed (knots) Fuel Use (L/hr)Fuel Eciency

(L/nm)

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

20002100

2200

Fuel use per nm = (Vessel Speed)So i the vessel used 4.0 litres per hour to go 3.0 knots, the uel eciency

would be:

Fuel use per nm = (3.0 knots) = 1.33 L/nm

Fuel Use

4.0 L/h


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0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

11.00

12.00

13.00

14.00

15.00

FuelConsumption(L/nm)

Engine Speed (RPM)

Fuel Consumption vs Engine Speed

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

11.00

12.00

13.00

14.00

15.00

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 1 1.0 1 2.0 1 3.0 1 4.0 1 5.0

FuelConsumption(L

/nm)

Fuel Consumption vs Vessel Speed


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Engine operating speed and its eciencyThe combination o the propeller, gearbox and engine

determine how eciently the uels energy is used to

propel the vessel through the water. You will need to

think about this combination careully when you are

choosing them. All three must be taken into account

when they are chosen.

When choosing the propeller and gearbox, ensure the

engine operates near its best eciency point.

This is because:

The vessels operating speed determines how much

power is required to move the vessel through the

water.

The propeller choice (and eciency) determines

how much engine power is required to reach the

vessel operating speed.

The engine speed aects how eciently thispower is made.

Most shing vessels use diesel engines, which are

generally the most ecient internal combustion

engines available. However, even a diesel engine

in good repair will only convert 25% to 40% o the

uels energy into work. The rest is lost as heat through the cooling and exhaust systems.

The engines actual eciency depends on both the load and the engine speed. The load at a particular

engine speed in turn depends on the propeller and gearbox combination.

I the propeller has too much pitch (i.e. is over-propped) then the engine will be ully loaded and unable

to reach maximum speed. I there is too little pitch (i.e. under-propped) then the engine will only be

delivering a portion o its potential power once it reaches maximum speed.

While a naturally-aspirated engine will only deliver ull power at maximum engine speed, most

turbocharged engines can deliver their maximum rated power rom about 70% o maximum engine speed

upwards. At the lower speeds this is achieved by higher turbocharger boost, but highly-loaded operation

at lower engine speeds may

not be a good idea as engine

temperatures can rise, reducing

engine lie.

The engines eciency at

dierent speeds and loads ismeasured by the manuacturer

and is graphed as Brake Specic

Fuel Consumption (BSFC) vs.

engine speed. The BSFC is the

amount o uel in grams required

to produce one kW o power at

the engines crankshat, or one

hour. The BSFC will be lower

(better) when the engines

eciency is higher.

The graphs (let and overlea)

are based on published

perormance curves rom a

A typical turbo-diesel engine. (Photo: Energy NZ)

Both turbocharged and naturally-aspirated engines are generally most

ecient when operated at about 80%

o maximum rated speed, although this

depends on the specic engine.

Fuel Consumption and Engine Efciency: 75kW Naturally-Aspirated DieselEngine

20%

25%

30%

35%

40%

45%

50%

0

50

100

150

200

250

300

350

1200 1400 1600 1800 2000 2200

EngineEfficiency(%)

EngineBSFC(g/kWh)

Engine Speed (RPM)

BSFC and Engine Efficiency vs Engine Speed

(Naturally Aspirated Engine)

BSFC

Efficiency


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Both are or naturally-aspirated

and turbocharged versions o

the same engine. The naturally-

aspirated version is rated at 75kW

@ 2200 RPM and the turbocharged

version is rated at 123kW @ 2200

RPM.

Note that the turbocharged versionis more ecient overall than the

naturally-aspirated version. This

is normally true, as turbochargers

extract otherwise-wasted energy

rom the exhaust gases. In

this case, the eciency o the

turbocharged engine is worst at

an intermediate engine speed

and better aster and slower than

this. This shows the importance o

checking the specic curve or thevessels engine.

Unless you are changing the engine or gearbox, you are stuck with the gear you have got. To make the

most o your existing engine, get a copy o the engines eciency curve rom the engine supplier. I the

current normal operating speed o the engine is at a bad point o the curve, consider getting the propeller

repitched or replaced.

Selecting a new engine or gearboxWhen the engine, gearbox or propeller is changed, ensure that the engine is operating at the most

ecient part o its curve at the most common high load it is expected to operate at. For a trawler tted

with the 123kW turbocharged engine,

this would mean picking a propeller

and gearbox so that the engine is at

either 1,500 RPM or 2,000 RPM while

trawling.

The BSFC can vary by as much as 15%

between dierent engines o similar

power outputs. When replacing the

engine, i choosing between two

engines that are otherwise the same,

pick the one with the lowest BSFC.

Once the engine choice has been

made, ensure the gearbox ratio and

propeller pitch allow engine operation

at its most ecient speed.

An expert (marine architect or

engineer) should be consulted when

selecting new engines to ensure a

good choice is made, taking into

account the propeller, gearbox and

vessel characteristics

Get the perormance curve specic to the vessels engine and use it to

help decide the best engine operating speed

Fuel Consumption and Engine Efciency: 123kW Turbocharged Diesel Engine

20%

25%

30%

35%

40%

45%

50%

0

50

100

150

200

250

300

350

1200 1400 1600 1800 2000 2200

EngineEfficiency(

%)

EngineBSFC(g/kW

h)

Engine Speed (RPM)

BSFC and Engine Efficiency vs Engine Speed

(Turbocharged Engine)

BSFC

Efficiency

An example o a diesel engine.


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Exercise: Approximate uel saving rom slowing downThe relationship between uel use and vessel speed can be used to estimate the saving rom slowing

down. This relationship works best or displacement vessels and is less relevant or planing vessels.

An estimate is required o the current uel use at the current normal steaming speed. This may be

worked out by lling the tanks beore and ater a trip over which the speed is airly constant. Then divide

the uel use by the number o hours steaming to give uel use per hour.

For example, i 720 L o uel is used in 18 hours steaming, then the uel use is 40 L/h.

The hourly uel use may also be worked out i the engine specication sheet is available showing uel use

or dierent loads and the engine loading is known rom the governor position.

The current uel eciency can then be estimated by dividing the present uel use per hour by the

steaming speed.

So i the vessel uses about 40 L/hr when travelling at 8 knots, the current uel eciency is:

Fuel Eciency = Fuel Use/Steaming Speed= 40 L/hr/8.0 knots

= 5.0 L/nm

To estimate the uel eciency at a slower speed, use the ollowing ormula:

Fuel eciency at slower speed = (Original Speed)2 x Fuel Use at originalspeed

For example i the vessel was originally using 5.0 L/nm when going 8.0

knots and it now steams at 7.0 knots, it is estimated to use:

Fuel eciency at slower speed = (8 knots)2 x 5.0 litres/nm

=8.0

X8.0

x 5.0= 0.875 x 0.875 x 5.0

= 3.8 L/nm

In this case the estimated saving rom slowing down is 1.2 L/nm or 24%.

New Speed

7 knots

7.0 7.0

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Action checklist Whenever possible slow down.

Get a uel curve made or the vessel.

Use the uel curve to make decisions on when, and by how much, to slow down.

I not already tted, consider installing a uel fow meter.

I a uel meter is tted, monitor uel use over time to detect changes in eciency and allowaction to be taken.

Benchmark uel use and set up a bonus scheme that rewards increased uel eciency.

Get a copy o the engines eciency curve. I the present normal operating speed is at a bad

point o the curve, consider getting the propeller repitched.

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Your vessels hull shape and condition directly aect how much uel it uses. A rough or heavily ouled hull

requires more power to push it through the water, which means higher uel costs.

As mentioned previously, a vessels

power is spent overcoming the

various actors that slow it down.

These are: Skin riction this is the riction

between the roughness o the

hull and the water. A smoother

hull is better and has lower

riction. Skin riction increases

with speed.

Form drag this is due to

eddies made as water ows

around the hull, rudder and any

appendages. A clean design with

the minimum o protrusions is

best.

Wave making resistance see

the section on operating speed.

The importance o these actors

depends on the vessel type. Having

a clean hull is ar more important or vessels that spend a lot o time at high speeds, perhaps steaming a

long way to fshing grounds. Hull cleanliness is a little less important (but still a good idea that will save

uel) or slower boats like trawlers. The drag caused by skin roughness is higher at higher speed and so

is more signifcant when steaming than trawling.

Hull resistance and ouling

Steaming with a dirty hull is like driving a car with the hand brake on.

Rough paint fnish increases skin riction and energy use. Photo courtesyo Stark Brothers, Nelson, NZ.

I a uel meter is tted to the vessel, use this to help determine how benecial

cleaning the hull is and to detect ouling buildup that indicates its time or

another clean.


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Anti-oul paintsFuel-thirsty ouling growth is inhibited by using

either anti-oul paints containing biocides or oul

releasing paints, which work by being very smooth

and non-stick .

Anti-oul paints are oten sel-polishing - meaning

they slowly wear o and conseuqently maintain

surace smoothness and continue to expose resh

biocide. Anti-oul paints need reapplying every year

or two as ouling growth is rapid once the biocide

is exhausted.

The latest oul release paints are especially

slippery. Any marine lie that does attach to the

hull is removed once the speed exceeds 10 knots.

However, i the vessel never goes above 10 knots

then the ouling isnt removed. This makes them

better suited to aster vessels and less useul on

trawlers.

Modern oul release paints are very expensive, are not

generally suitable or wooden boats, and the hull must

be taken back to bare metal beore the application

o special base coats. Osetting this is their longer

lie. They should last 5 years beore reapplication

and achieve uel savings o up to 6% due to their

smoothness and low riction.

On a 22m vessel using 250,000 litres per year that

spends 30% o its time steaming, a 6% saving is about

$5,000 per year.

The next time the anti-oul paint is due to be renewed, consult with an

expert to determine the best option or your vessel.

DisplacementAs vessel weight increases, a greater surace area is exposed to the moving water (leading to higherskin riction) and more water must be moved out o the way (increasing orm drag and wave making

resistance). The hull resistance and thereore amount o uel used is almost directly proportional to

displacement, so a 1% reduction in displacement will reduce uel consumption by about 1%.

Carriage o excess weight may increase over time as redundant equipment accumulates.

Save uel by not carrying unnecessary weight and lowering your vessels displacement. Weight can be

reduced by:

Pumping out bilges requently

Only carrying the uel needed or the trip plus a saety margin

Not carrying more ice than required

Reducing rubbish and packaging, and removing any broken or redundant equipment

For example, a 100 tonne trawler that carries an excess 2.0 tonnes o ice will increase its uel use by 2%.

Photos (let and above) courtesy o Stark Brothers,Nelson, NZ.


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Remove redundant hull appendagesProtrusions rom the hull reduce how easily water ows around it, increasing orm drag and uel

consumption.

External keel cooling pipes or engine cooling increase uel consumption by 2% to 3% at steaming

speeds. Consider replacement with a heat exchanger system.

Rudder and appendage ormThe rudder is directly in the ow o ast water rom

the propeller, which increases the eect o its drag

on efciency. Water ows turbulently around at

plate rudders, causing high drag, but ows more

smoothly around a profled rudder.

Flat plate rudder (above). Rudder detail (right), Photocourtesy o Stark Brothers. Nelson, NZ.

To reduce orm drag, remove any protrusions or air them i removal is not

possible. Examples include old sonar domes and sh-nders that are no

longer operational and old anode bolts.

Consider replacing fat plate

rudders with proled rudders.

You can nd useul

downloads and inormationat www.seaood.co.nz/

energyeciency

An efcient rudder profle will save 3% to

4% o uel use at ree running speeds, or

1.5% to 2% overall.

Any other hull appendages, such as stern

posts, should be aired to allow water to ow

smoothly over them.


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Action checklist

When was the vessel last slipped?

I more than a year ago, get a diver to check the hull condition. I lightly ouled, get a

diver to clean it, i heavily ouled consider slipping the vessel or blasting and recoating

o anti-oul.

When last slipped, what was the extent and type o ouling?

What is the current anti-ouling system used?

When was the anti-oul last maintained?

I more than two years ago and the vessel is not scheduled to be slipped soon, get adiver to check the hull condition. I lightly ouled get divers to clean it, i heavily ouled

consider slipping the vessel to be blasted and anti-oul recoated.

Does the vessel go above 10 knots on occasion? Yes/No

I yes, get a quote or a oul release paint system. To assess i its worthwhile proceeding,

actor in a 6% uel reduction and reduced annual anti-oul costs.

List any hull appendages (sonars etc)

Identiy those appendages that can be removed or aired. Next time the vessel is slipped

remove or air identifed appendages.

What is the size and type o rudder?

I a at plate rudder is installed then consider replacing it. Get a quote or a profled

rudder. For a two year payback, a profled rudder should cost less than 4% o the

annual uel bill i the quote is lower than this fgure, then its worth getting a newprofled rudder.

Identiy and remove any redundant equipment

Is keel cooling used? Yes/No

I yes, get a quote or a heat exchanger system. For a two year payback, consider

replacing keel cooling with a heat exchanger i it costs less than 4% o steaming uel use

(typically about 30% o annual uel use or a trawler).

How much excess ice/uel is carried at the end o a trip?

Try reducing the amount.


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Notes....

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________________________________________________________________Cleaning can be carried out by a diveri slipping is not an option. Photocourtesy o Sea Service Diving andMarine Australia


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Propellers turn the power generated by your engine into movement through the water. The propeller type

and condition greatly inuences how well this happens and overall uel efciency.

Propellers typically only convert 50% to 60% o the energy they absorb into useul thrust but they can

be much worse.

An inappropriate, damaged, or dirty propeller will cost you money whenever the vessel is underway.

The ollowing diagram illustrates where the energy rom the diesel supplied to the main engine goes. Note

the energy loss rom the propeller.

Propellers

Any improvement in propeller efciency directly saves uel and money.


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Increasing your propeller efciencyPropellers are out o sight, out o mind. A lot o people

think that i the vessel still moves then everything

must be ok. Right?

Wrong! Declining propeller efciency and increasing

uel consumption can occur gradually and may not be

noticed. Improving propeller efciency increases howmuch energy rom each litre o uel becomes thrust

that drives the vessel.

To improve efciency:

Take action to make the most o the propeller

youve got

Get the propeller selection checked and investigate

having it modifed or replaced

Getting the most out o your

current propellerImprovements in propeller efciency are rewarded whenever the vessel is moving, ree running, or

fshing, so benefts accumulate the whole time the vessel is underway. Keep the propeller in tip-top

condition to maintain its efciency. To do this:

Clean the propeller

A clean propeller saves 5% to 10% o uel consumption compared to a propeller ouled ater one year o

immersion in water. Weed and slime can build up within months especially i the vessel has been idle.

I the vessel hasnt been out o the water in a year, get a diver to give the propellers a scrub.

Polish the propeller and apply a oul

release coating

Polished propellers use up to 4% less uel when

compared to clean propellers ater one year immersed

in water. Polish propellers when they are next out o

the water and have a oul release coating applied.

Foul release coatings maintain smoothness similar to

a newly polished condition and should only cost a ew

hundred dollars to have applied.

Corrosion increases roughness on uncoated propeller

suraces keep anodes in good condition to slow the

corrosion.

Beore and ater pictures o a propeller cleaned by Stark Brothers o Nelson.

Underwater cleaning o propellers. Photo courtesy o


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Maintain and repair the propeller

Worn and damaged propellers eat uel. Inspect

them every time the vessel is out o the water

and repair any uel-hungry nicks, dings and

dents. Blade tips can wear over time, reducing

efciency, and may need building up. Trailing

edge damage is especially power-sapping and

also alters the propeller pitch. The propellershould ideally be serviced at least every two

years.

Cavitation erosion may be visible as areas o

pitting on the blade - the increased roughness

lowers efciency. As well as repairing the blade,

consult an expert on how to prevent recurrence.

Clear hull upstream o the propeller

The hull upstream o the propeller should

be aired smooth with no sharp corners or

obstructions. I possible, move anodes, fsh fnders, sonar domes and other obstructions to be more than1.3 propeller diameters away. Savings are hard to estimate but i it costs less than 2% o your annual

uel bill to implement then its probably worthwhile.

Cleaning and polishing the propeller while the boat is in the water is a job or divers. How oten it should

be done depends on the cost and the rate at which ouling builds up.

Check the propeller selection

Routine measures or maintaining propeller

efciency are important, but signifcant

urther savings are possible by ensuring

the current propeller is the right one orthe job.

When selecting a propeller, the ollowing

are important points to consider:

The engines power output and shat

speed

The gearbox ratio

The size and operating speed o the

vessel

These actors, and more, are taken into

account when the initial selection ismade. This determines the propeller size

(diameter), pitch, blade area and number

o blades. Changes over time in how the

vessel is used, increased displacement and

engine or gearbox changes may mean the propeller is less suitable than it was. The complexity o

propeller choice means you should consult an expert, either propeller specialist or naval architect, beore

making changes.

Photos courtesy of Stark Brothers, Nelson, NZ

Example: A 23m trawler powered by a 411kW engine typically uses 6,500 litres o dieselper fve day trip. I cleaning and polishing the propeller has uel savings o 5% (3% rom the clean

and 2% rom the polish) then a $500 clean and polish will be paid or in less than two trips.


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Get an expert to confrm correct propeller choice

Get the propeller inspected by an expert the next time the vessel is slipped i the vessels duty, engine

or gearbox has been changed since the propeller was installed. The expert can help decide i it needs to

be modifed (re-pitched) or replaced.

Maximise the propeller diameter

A propellers diameter has a big eect on how efcient it is. A big propeller turning slowly is more

efcient than a small propeller turning quickly. As a rule o thumb, increasing the diameter by 1/3 will

reduce the shat speed by 1/2 and increase its efciency by 1/4.

Measure your propeller diameter and consider replacing it with a larger one i possible - use the worksheetin Exercise 3 to calculate the minimum recommended propeller diameter or a particular vessel.

The maximum propeller size will be limited by the available aperture and cost.

Check or warning signs o incorrect propeller choice

Unsuitable propellers penalise both perormance and uel consumption.

I suspected, an expert should evaluate the current propeller and assess

available options. I the pitch is incorrect, it may be possible to have it

re-pitched rather than replaced.

Signs o an unsuitable propeller include:

Engine overloading

Engine overloading can cause engine damage and may happen i the

propeller has too much pitch, (i.e. over-propped), or is too large. Symptoms

include heavy black exhaust smoke, high exhaust temperatures and the

engine being unable to reach maximum speed. Be especially suspicious i

the propeller has just been changed.

Excessive hull ouling and propeller damage can also cause overloading,

so it may be worthwhile getting a diver to assess both i overloading is

happening and the vessel hasnt been slipped in a while.

Engine underloading

Engine underloading occurs i the propeller has too little pitch, is too

small or i cavitation is reducing the propellers ability to absorb power.

The engine will not be able to achieve maximum power at its maximum

d d i d i th i i d d

Basic Propeller Characteristics

Photo courtesy o Stark Brothers,


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On trawlers, consider ftting a nozzle i

one is not already ftted

Nozzles are specially-designed ducts enclosing

the propeller and can increase uel efciency by

15% to 20% especially at higher loads and

lower speeds i.e. trawling.

They can be relatively expensive to retro-ft but

this must be weighed against the large potential

uel savings.

I considering ftting a nozzle, consult with a

naval architect to determine the overall costs

and benefts.

I a nozzle was previously considered but

not implemented due to cost or reduced ree

running speeds, increased uel prices and more

efcient modern nozzle designs may now make

it worthwhile.

Get the advice o a propeller manuacturer or

naval architect to help make this decision.

Example: Depending on size, ftting a nozzle and new propeller could cost in the rangeo $25,000 to $50,000 with uel savings o 15% to 20% expected at trawling speeds. Trawlers

typically use about 70% o their uel while trawling. This means a 23m trawler burning 250,000

litres annually would save around 26,000 litres each year ater ftting a nozzle paying back the

installation costs within a year or two.

Propeller Nozzle (Olds & Sons Pty. Ltd)

Photo courtesy of Stark Brothers, Nelson, NZ.

Propeller nozzle case study

A trial comparing three 22m trawlers, each with 375 hp

@1800 rpm engines and 6:1 reduction gearboxes, had

the ollowing results:

Nozzle

Type

Propeller

Size

(inches)

Bollard

Pull

(kg)

Maximum

Speed

(knots)

FuelUse

(litres/

day)

Open

Propeller66 x 44 4,708 9.3 1,512

Kort Nozzle 61 x 56 6,646 9.0 1,265

Modern

Nozzle61.25 x 59 7,182 10.0 1,175

Open propeller vs. nozzles (Olds & Sons Pty. Ltd)

The modern nozzle design used 7% less uel than the vessel

ftted with a kort nozzle and 22% less uel than the open

propeller.


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Steaming Speed and Fuel Use Before and After Repitch (Gilbert 1983)

Trawling Speed and Fuel Use Before and After Repitch (Gilbert 1983)

Case study: Propeller repitchCellina was a 14.8m trawler operating out o Tauranga. A 38 x 28 our-blade propeller was

driven by a 132 kW engine through a 2.96:1 gearbox. A trial was done beore and ater the

propeller was repitched, the results are shown in the graphs below.

The frst graph shows how much uel is used to cover 1 nm at dierent steaming speeds. Itclearly shows the maximum steaming speed has increased and uel use per mile has decreased

- ater repitching the propeller Celline used 1/3 less uel to cover the same distance at 10 knots

than beore repitching.

The second graph shows how much uel is used to cover 1 nm at dierent trawling speeds.

Ater repitching trawling speeds were increased, increasing catching power, at the same time

as reducing uel use by over 20%.


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Case study: Propeller choiceGweny-May is a 15 tonne hard chined, semi-planing vessel. Powered by a 374kW engine driving

a three-bladed propeller through a 2:1 gearbox, it generally cruises at 10 knots. A our-bladed

propeller, kept as a spare, was trialled and ound to worsen cruising uel-consumption by 6 L/h,

or 12%, or no improvement in perormance. This shows the importance o confrming the correct

propeller choice.

Controllable pitch propellers

Fixed pitch propellers perorm best or

a set load and speed, so they are most

efcient at towing speeds or steaming

speeds but not both. A controllable

pitch propeller (CPP) can be adjusted to

improve propeller efciency at dierent

speeds; they also allow the engine to beat the optimum speed more oten.

I a vessel typically only goes one speed

a CPP provides no beneft. Also, due

to increased hub size, a CPP is a little

less efcient than a fxed pitch propeller

operating at its best point

CPPs are expensive, especially i

retroftted. They should only be

considered or new vessels or as part

o a major reft. This can be decided inconjunction with a naval architect.

Photo courtesy o Stark Brothers, Nelson, NZ.

Photo: T. Collins.


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Action Checklist

When was the propeller last inspected? I more than two years ago, and the vessel

is not scheduled to be slipped soon, get a diver to check its condition. I it is in poor condition it

may be worth replacing or repairing sooner rather than later.

When was the propeller last serviced? I the propeller hasnt been serviced in

two or more years, ensure this is done when the vessel is next slipped.

Is a nozzle ftted? Yes/No

I no, and the vessel is a trawler then consult with an expert to investigate getting one ftted.

The next time the vessel is out o the water take the opportunity to inspect the propeller and do the

ollowing things.

Is the propeller smooth and ree o nicks and dings? Yes/NoI no, have the propeller serviced or repaired. I not perectly smooth, get the propeller polished.

I uncoated, get a oul release coating applied.

Are there any signs o cavitation (pitting and blade erosion)? Yes/No

I yes then repair and get a propeller expert to assess options

Are there any obstructions within 1.3 diameters upstream o the propeller? Yes/No

I yes, then investigate removing or relocating the obstruction.

Calculate the minimum recommended propeller diameter using Appendix II

Recommended diameter m

Measure the vessels current propeller diameter? Measured diameter m

See i the current diameter is smaller than recommended measure the aperture clearance.

Aperture diameter__________________m

Is the aperture clearance greater than 10% o the propeller diameter? Yes/No

I yes, consult with an expert to investigate replacing with a larger diameter propeller

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Exercise: How to calculate your minimum propeller diameter

The minimum recommended propeller diameter, or useul thrust at all speeds, can be determined

rom the graph below. The minimum recommended may not be achievable i the available aperture

is too small. This graph does not apply i a nozzle is ftted.

Minimum recommended propeller diameter

The above graph is based on the ollowing ormula. (Gerr)

Dmin

= 0.339 x (BWL x Hd)1/2

Where:

Dmin

= Minimum recommended propeller diameter in metres

BWL = Beam on the waterline length in metres

Hd

= Drat o hull, waterline down (excl. keel, skeg or deadwood) in metres

Dmin

or twin screws = 0.8 x Dmin

First determine the beam-on-the-waterline length in metres and multiply this by the depth o the

hull in metres (excluding the keel, skeg or deadwood).

Find this value on the horizontal axis o Graph 1 and move vertically up until the line or the single

screw (or twin screw i appropriate) is reached.

The minimum propeller diameter can then be read o the vertical axis.

Example: For a 15.0m trawler with a waterline beam o 5.1m and a hull drat o 1.2m,the minimum acceptable propeller diameter can be calculated as ollows:

Waterline Beam x Hull Drat = 5.1 x 1.2 = 6.12So or a single screw, the minimum recommended propeller diameter is about 0.85 metres or

33 inches.


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Engines provide the power or almost all activities while at sea rom propelling the vessel to supplying

hydraulic and electrical power. Regular maintenance not only reduces energy consumption but also

minimises those prot-sapping unscheduled repairs.

Engine maintenance

Its best to stick to the engine manuacturers recommended service intervals. Routine maintenancebetween major overhauls and servicing includes:

Checking water traps and uel lters daily.

Oil and uel lters remove contaminants beore they can harm the engine. Over time, contaminants

build-up, clogging lters and obstructing the fow o oil or uel to the engine. This impairs

the engines perormance and eciency and increases uel use. It can also cause engine damage.

This daily check is necessary especially in humid weather when water can condense in uel tanks.

Change the lters at the manuacturers recommended service intervals.

Changing the lubricating oils at the recommended intervals

Engines require lubrication so that moving parts slide smoothly over each other. Insucient or

degraded lubrication can increase engine wear, causing higher riction and increasing uel use.Change the oil at the recommended intervals typically every 350 hours unless an oil analysis

recommends this period to be shortened or lengthened. Oil analysis can also give inormation on

engine wear and condition .

Servicing the injectors at the recommended intervals

Fuel injectors are subject to demanding conditions and inevitably wear out. But they can still work a

long time past their best, but this will lower uel eciency. An injectors condition governs how well

uel burns when sprayed into the engine.

Ideally injectors produce a ne og o uel, but as they wear larger droplets also orm. Droplets burn

more slowly, reduce power output, and

produce visible soot as a result.Service the injectors at the manuacturers

recommended intervals - or more requently

i the uel quality is low or excessive black exhaust smoke indicates the injectors are worn.

Vessel Maintenance

Deerring vessel maintenance is the worst orm o alse economy.

Soot is uel that you have paid or, butisnt doing any work.


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Gearbox maintenanceThe gearbox eciency aects the vessels overall eciency because all the propulsive power goes

through it. Gearboxes are typically more than 90% ecient, but you can make small gains by sticking to

the proper maintenance procedures, including:

Regularly checking oil levels

Gearboxes use oil seals, internally and on the shats, to keep oil in the gearbox and dirt and water

out. A sudden drop in the gearbox oil level may indicate the seals are worn. The loss o oil or oilcontamination can increase the gearboxs rictional losses and the vessels uel consumption. I let

unchecked the gearbox may ail.

Changing the oil regularly

As the gearbox oil breaks down, its lubricating properties diminish. Changing the gearbox oil at the

recommended service intervals helps maintain maximum gearbox eciency, lie, and reliability.

Using the correct grade o oil

Not all oils are the same so use the grade o oil specied by the manuacturer. Using the wrong oil

can increase churning and windage losses within the gearbox, lowering eciency, and gobbling uel.

High quality synthetic oils are more expensive but may extend the service intervals and improve

gearbox eciency. Synthetic oils have several desirable properties over mineral oils, most notablyis that they have better low and high temperature perormance.

Exhaust and air fowsIt is important to supply enough clean air to

the engine room and engine. Oxygen rom air

is needed to burn the diesel. There needs to be

enough air moving through the engine room to

help cool the engine. This is especially important

i the vessel has any air-cooled engines.

As a guide, size the engine rooms air intake

to have an area greater than 11 cm2 per kW

o engine power. Ideally the air intake should

supply cool resh air down low into the engine

room, and hot air ventilated rom the top.

Periodically check air lters and clean or replace

them i they are clogged. Check and clean them more oten i the engine rooms air supply is dirty.

The exhaust system should let the exhaust umes escape easily. The exhaust pipe should be as straightas possible and 90 bends avoided as each sharp bend can reduce the maximum airfow by 25 percent.

I the exhaust pipe is too small, or contains too many sharp bends, backpressure will result in loss o

power and increased uel consumption. The engines manuacturer will stipulate the minimum exhaust

pipe diameter.

Fuel additives and devicesDiesel engine technology has been developing or more than 100 years and small eciency improvements

are still being made. Unortunately however, there are no silver bullets to drastically increase the eciency

o an existing engine.

While there are many additives and gadgets on the market that claim huge improvements in ueleciency, the bottom line is i it sounds too good to be true, it probably is.

Some reports on the perormance o diesel additives and devices that have been trialled or the UK

shing feet are available at www seaood co nz/energyeciency

Restricted exhaust fow can easily cost 10% or more in uel consumption.

An air flter. (Photo: Energy NZ)


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Engine smoke identicationExcessive exhaust smoke is normally an indication o engine trouble. The smokes colour can give some

indication o the cause. (Gilbert 1983), (Simpson 2006)

Black exhaust smokeBlack exhaust smoke indicates that unburned uel (soot) is leaving the engine. This robs power and

prot. Common causes include:

Overloaded engineAn overloaded engine is operating at the limit o its capabilities. Consequently there is increased wear

and it may operate ineciently. Investigation is required to nd the cause o the overloading.

I the engine, gearbox and propeller are not correctly matched, peak propeller loads may occur at too

low an engine speed and cause overloading. When changing the engine, gearbox or propeller, check the

suitability o the retained equipment and ensure everything is well matched.

Overloading that worsens over time may indicate that the vessels hull drag has increased due to ouling

or that the propeller is ouled or damaged.

Shortage o air

Clogged inlet air lters or other inlet restrictions can impede airfows. Change or clean air lters at therecommended intervals and inspect them i clogging is suspected.

Black smoke can also be a symptom o turbocharger problems it may need cleaning or replacing.

Excessive back pressure

Restrictions in the exhaust pipework, perhaps rom being crushed or rom debris entering the pipe, can

impede exhaust fows. Check the exhaust pipe or kinks or obstructions and x any problems ound.

Worn injectors

Ensure the injectors are changed at the recommended intervals

Blue exhaust smokeThis can be rom excessive oil in the cylinders or exhaust, usually rom worn components such as valve

guides, worn or broken piston rings or leaking turbocharger oil seals. It can also be caused by:

an overlled crankcase,

blocked crankcase breather valve or

excessive cooling (aulty thermostat) which prevents the engine rom operating at normal temperature.

Ater a long time idling a short period o blue smoke is normal, but i it is sustained engage a mechanic

to diagnose the cause.

White exhaust smoke

White exhaust smoke that persists or more than a ew seconds, especially i coupled with hard starting,is oten a symptom o low compression - which results in unburned uel. This can be caused by:

Worn or damaged engine components:

Leaking inlet or exhaust valves and damaged or worn piston rings allow gases to escape and lower

compression. A compression test may conrm this.

Mis-timed injectors/valves:

Most likely i the engine has been incorrectly reassembled ater repairs or maintenance. I the engine has

just been repaired or serviced, check the timing.

Water in engine:

White smoke can also indicate that water is getting into the engine. This may be through poor quality

uel, normally accompanied by erratic running, or a cracked cylinder head/blown head gasket whichallows water into the cylinders.

Gilbert, L. (1983). Fishing vessel uel control. Fishing Industry Training Council.

Simpson A (2006) Know your boats diesel engine McGraw Hill


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Maintenance checklist

Engine maintenance

1. What is the check-up requency or water traps and lters _____________________?

I greater than daily change the check-up requency to ensure the engine is operating correctly.

2. When was the oil last changed_______________________________?

I the oil changes havent been to the manuacturers specifcations, change the oil and consider

an oil analysis.

3. Recommended air intake to engine room: Engine kW________ x 11 =________cm2

Actual intake to engine room:

Rectangle height________cm x length_________cm =________cm2

Circle diameter______cm x diameter______cm x 3.14 / 4 =________cm2

I the recommended intake to the engine room is smaller than the actual intake, consider more

ventilation. For air-cooled engines, consult the manuacturers specifcations.

When was the air lter last checked___________________________?

Was there signicant buildup on the lter________________________?

4. When were the injectors last changed_______________________________?

I the injectors have not been changed according to the engine manuacturers specifcations, they

should be replaced even i there is no visible sign o incomplete combustion (black smoke)

Gearbox maintenance

1. When was the last time the oil level was checked_______________________________?

I the oil level has not been checked, ensure that there is an adequate level o oil within the

gearbox

2. What is the manuacturers recommended grade o oil____________________________?

What grade o oil is being used_______________________________?

I dierent, consider changing back to the manuacturers recommended oil grade

When was the oil last changed_______________________________?

I the oil changes havent been to the manuacturers specifcations, change the oil

3. Consider synthetic oils


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Only turn on interior lighting when it is needed. Even i using ecient fuorescent lighting, turning o

lights in unoccupied cabins, galleys, toilets and engine rooms could save hundreds o dollars per year or

a typical vessel. I theres concern about engine room lights turning o while someones in there, install

a low-wattage compact fuorescent lamp to be on permanently.

Manage PCs and electronic equipment

On, but unused, electronic devices like PCs and game consoles sit around quietly devouring electricity

and money. The idle power consumption can be signicant, even i the display is turned o. Two PCs andone modern games console let running unnecessarily at sea or 3,000 hours per year will chew through

$340 o diesel more i they are still on when in port.

PCs have a sleep or hibernate mode where power consumption is nearly zero, but can be resumed

rom almost instantly. This is the best way to leave them when not being used.

Manage space heating

Heating cabins electrically requires large amounts o energy since the heat simply disappears through

the walls. The cost o running our small (1kW) heaters in unoccupied areas adds up to $1,260 per year

i on unnecessarily or 1,000 hours per year.

Make sure they are only on when needed, using thermostats and timers wherever possible. Better yet

scavenge heat rom the engines cooling system (explained later) or ree space heating.

Manage hydraulic pumps

When a hydraulic device isnt in use, turn the hydraulic pump o. For example, i a hydraulic pump is

needed to let the net out, but is not used or trimming, turn the hydraulic pump o until it is need to haul

the net back. The load due to hydraulic pumps can be very large, as shown in the graph below.

This graph shows the net being let out, trimming o the net and then hauling the net back in. Ater

hauling in, the hydraulic pumps are still running with a signicant load o around 20kW.

I your vessel does not use hydraulics or trimming, turn the hydraulics o when nished setting or

hauling in.


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Increase efciency and re-use waste energyThe high cost o diesel-sourced electricity makes conserving energy by using energy-ecient devices

especially important. Going green is worth more than just eel-good points when every litre o diesel

going through the genset comes o the prot. To increase electricity energy eciency, concentrate on

the ollowing:

Ecient lighting

Standard incandescent light bulbs are cheap, but are very inecient

- they produce mostly heat not much little light. A bulbs low cost

is quickly oset by its energy use. Consider compact fuorescent

lamps (CFLs) as an alternative. CFLs produce the same amount o

light using one-th the power, and also last much longer than a

traditional bulb. Replacing a 100W incandescent lamp with a 20W

CFL will pay or itsel ater 160 hours o use and can last or years,

continually making savings.

Likewise, inecient deck lighting such as halogen lamps can also

be replaced with compact fuorescent or metal halide ttings. They

typically use 66-75% less power and last much longer beoreailure. Replacing a 500W halogen foodlight with a 120W CFL

foodlight tting will save $240 per year i used or 2,000 hours at

sea.

Ecient devices

Appliances like rerigerators cost a lot to run. Factoring the operating costs into purchasing decisions

is a good idea. A small extra investment can have signicant ongoing savings. For example, using an

appliances Energy Star rating and the electricity cost allows you to calculate how much youll save in the

long run. This is demonstrated in the example at the end o this chapter. Anything without an eciency

rating should be avoided due to high ongoing costs.

Optimising rerigeration systems

To ensure the rerigeration system on your vessel is working as eciently as possible, do these simple

checks:

Turn o lighting in rerigerated areas when it is not required.The lights cost money to run and they

create heat which must be removed by the rerigeration system.

Keep doors to rerigerated areas closed as much as possible.

Keep door seals in good condition and periodically check or air gaps.

Do not put anything in a rerigerated area that doesnt need to be there.

Clean the condenser periodically as scale tends to orm, especially i seawater is used or cooling.

Check the evaporator is not iced up, i it is then the derost system needs attention.

Improving the perormance o the rerigeration system requires specialist knowledge to ensure saety

and best results. Use a rerigeration consultant to optimise the system or best eciency.

Engine heat recovery

For every unit o uel energy going into the engine, around 35% is removed by the cooling system and

dumped straight into the sea. For a 185 kW engine, that is potentially up to 65 kW o heat, available or

ree to use heating water and cabins.

Investigate installing a heat exchanger and hot water loop on the main engines cooling system. This

could heat the hot water cylinder, reducing electricity use. The hot water loop and radiators could also bethroughout the vessel, providing virtually unlimited ree space heating. For a 23m vessel with our crew,

at sea 4,000 hours per year this could potentially save $3,000 o diesel annually i all water and space

heating were replaced this way.

Energy ecient lightbulbs.


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Shower fow restriction

For electrically heated water, excessive shower fow rates means unnecessary costly energy use.

Restricting the shower fow rate to a standard 9 litres per minute will save both resh water and energy.

It can be achieved by simply installing fow restrictors in the showerhead which cost as little as $20.

Fitting a fow restrictor to a shower using 15 litres per minute, serving our crew who each have one six-

minute shower per day, 180 days per year, would save 25,920 litres o resh water and $228 in genset

diesel annually.

The easiest way to check shower fow rates is time how long it takes to ll a bucket o known volume. I

it takes less than a minute to ll 9-litre bucket, your fow rate may be too high.

Get the most electricity rom a litre o dieselHow much electricity one litre o diesel produces depends on how eciently the genset operates. This

varies with the genset size and loading. To ensure you get the most electricity rom your uel:

Size the genset correctly or the vessel

While the dangers o under-sizing a genset are clear, the dangers o over-sizing are a big risk to yournances. The ollowing graph illustrates the eciency or a typical genset at dierent loads. For most o

the load range the eciency remains airly steady, but it decreases signicantly at low loads. See the

gearset eciency curve in the graph below. For example, a 50kW genset that provides 15kW or 2 hours

per day and 3kW the rest o the time spends most o its time chugging along at 15% eciency, costing

over 60c/kWh.

For 4,000 hours at sea, the genset diesel bill would total about $8,500. I the genset had been sized at

20kW, the diesel bill would be 33% lower at $5,700 or the same amount o electricity.

The trick is to size the genset so it just meets peak operating loads, which should keep the low load

high enough to ensure good eciency. Unortunately, new gensets are expensive so re-sizing is only

an option i the old genset needs replacing or an expensive overhaul. Its best to size it right rom thebeginning, or consider an inverter or times o low load.

Typical genset eciency curve.


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Case studyA trawler studied had a 100kW diesel engine coupled to a 50kVA (40kW) generator. This combination

condemns the engine to run at low load, even i the generator is at maximum output. The vessels

logged electrical load is shown in the graph below, as well as the generating eciency. The

eciency is around 17-18% or almost the entire time, as compared to the maximum eciency o

around 35%. A smaller, more heavily loaded engine would have used signicantly less uel.

Use an inverter

Operating a genset at very low loads is inecient. There may be extended periods o time when only a

small amount o power is needed compared to the gensets rated output, or example overnight. I so,

investigate installing an inverter on the main engines alternator i it keeps running - and switching the

genset o at these times.

An inverter changes 12V or 24V DC power rom the engines battery and alternator into 230V AC electricity

at high eciency (>90%). Since the main engine is oten running anyway, the overall eciency will be

much higher than using a genset at very low load. The gensets operating hours and maintenance costs

will also be reduced.

Use shore power whenever possible

The typical cost o genset-electricity is rom 30c/kWh to 60c/kWh at low loads. By comparison, the

typical cost o electricity rom shore power is around 15c/kWh. I in port or 5,000 hours per year, the

dierence in cost between a 2kW load rom a genset at low loading or rom shore power is around $4,500

annually, not including genset servicing costs.

Case Study Vessel Load and Genset Eciency (Energy NZ)

Use shore power as much as possible, as soon as possible.


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Example: Energy-efcient appliancesEnergy-ecient appliances generally cost more upront, but less to run. An appliance approved by

Energy Star should have a rating o typical energy use per year, which or an average-size ridge/

reezer may be 400kWh.

There may be one rated at 490kWh per year, while another one o the same size might use 280kWh

per year. The better one uses about 210kWh per year less. I there is no rating on one device then

its sae to assume it will use more than the worst Energy Star appliance.

I the vessel is at sea or hal the year and on shore power or the other hal, the annual saving will

be:

Annual Saving = Dierence in Energy Use x (Proportion o Time at Sea x Genset

Electricity Price + Proportion o Time in Port x Port Electricity Price)

= 210kWh x (0.5 x $0.315 + 0.5 x $0.15)

= $48.80

The better ridge will cost $49 less per year to run. This ongoing saving should be compared to thepurchase price dierence and actored into the decision. Its airly sae to use a price o 31.5c/kWh

or electricity rom the genset, though it could actually be much higher i the gensets lightly loaded

or much o the time.

Electricity use checklist Are any deck lights or indoor lights let on unnecessarily? Yes/No

I yes, turn them o and let the crew know to turn them o as well.

Are any PCs, games console or other electronic devices used on the vessel? Yes/NoI yes, make sure the crew turn them o when not being used

Are electric heaters let on in vacant areas? Yes/No

Consider putting them on timers to turn them o at times when no one is around.

Is incandescent or halogen lighting in use on the vessel? Yes/No

I yes, look at replacing these with fuorescent lighting. It will last a lot longer and use a raction o

the power.

Is energy eciency considered when purchasing appliances? Yes/No

I no, try looking at Energy Star-rated appliances. Appendix II shows you how to gure out howmuch you can save.

Is the waste heat rom the engine being used or anything at present? Yes/No

I no, look into using it or space and water heating. Youll probably need to employ the services o

an engineering rm to install the required systems.

Measure the fow rates o the shower(s) onboard using a bucket and stopwatch.

Flow rate = Bucket size (litres)/Time to ll (minutes). I over 9 litres/minute, consider putting in fow

restrictors.

Is shore power used whenever possible? Yes/NoI no, shut the genset o when in port and make use o cheaper shore electricity.


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Remember when vessels used to depart on the tide? Later, big engines and cheap uel made this

unnecessary. Today, increasing uel costs once again mean that taking advantage o tides and timing

departures and returns rom harbours can be a real money saver.

There are many actors to take into consideration when trip planning. They can be highly variable which

makes accurate planning difcult. You probably already trip plan, but check here to see i there are more

things you could include in your planning:

Distance to the fshing grounds

Level o shelter oered

Long term weather orecast

Days at sea allowance

Recent quality o fshing

Supply o fsh to the market

Understanding the true cost o your operations is critical. This can only be determined through proper

record keeping and taking the time to analyse the inormation. You can then assess the economics o

the business or dierent situations, such as poor weather conditions or increased steaming distances to

your destination.

RouteAs well as timing trips with the tides, making the best use o currents also helps reduce uel use. To get

this boost rom nature consult oceanographic charts and try gathering some local knowledge.

The route out may not always be the best route back given the prevailing currents and predicted

weather conditions. I the wind is expected to change in direction or strength beore the return trip, and

you have a choice o destination, you may choose the route most likely to have a tailwind there and a

tailwind back. You will need good weather orecasting inormation.

A UK recent study showed that some skippers were reducing uel costs by minimising their steaming

distances and working closer to shore or even not choosing to fsh at all when the expected fsh quality(and price) was not expected to be high enough to make it worthwhile.

Trip Planning

Planning your trip carefully can save

you fuel.


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Reduce steaming distancesThe rise in uel prices has orced fshermen to reconsider operating practices. Previously, it may have

paid or fshermen to steam long distances to fshing grounds in order to catch the best fsh and get the

best prices. However increased uel prices may make the economics o this less viable.

The expected value o the catch and the distance covered to get it, can aect the choice o target species

and fshing ground. It may be better to target a lower value species that is closer than higher value

species that is urther away. This may require swapping ACE with another operation.

Keeping a true course saves uel by both minimising the total distance travelled and the number o

course corrections. Modern navigation equipment makes this easier.

Record keeping that shows the amount o uel used per dollar or kg o fsh caught helps with making this

decision, as it shows how proftable dierent areas are.

Increase trip lengthsLarger vessels may stay at sea or longer periods o time, returning to port only when the holds are ull.

This limits the time spent steaming to and rom the

Documents

88826_EnergyEfficiency