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how does hull shape affect the speed of a boat? When trying to get the most speed out of your boat,

you may want to consider how the hull shape affects the speed of the boat. "Hydrodynamic" is a term

that is used when determining the motion or flow of water. It is similar to the more familiar term

"aerodynamic," which relates to the flow of air. The speed of a boat is correlated to its hydrodynamic

efficiency, and the hydrodynamic efficiency is determined by the shape of the hull of the boat.

The hull of the boat is the first area to be hit by water as you speed forward . A round orsquare hull will connect with the water lie a force that is pushing against it. As the force of the water

hits the boat hull straight on, the boat must push the water out of the way before it can attain optimal

speed. This limitation of the boat!s ability to get to a higher speed quicly is nown as drag, and is

affected by the hull shape.

A boat hull shape that is pointed allows the water to flow around the boat quickly . The lesswater that the hull needs to moe out of the way, the faster the boat will go. How hull shape affects

the speed of a boat is one factor that the military had taen into consideration when they started to

build the #$shape hull design. This shape offers the most hydrodynamic efficiency, which gies the

military a boat that can cut across water with little drag and perform well at high speeds.

%ead more& http&''www.mademan.com'mm'how$does$hull$shape$affect$speed$

boat.html(i)**+Wn))-/

How Does the Weight and HullShape of an Object Aect ItsSinking Rate Through Water

Researched by Blaine H. 1999-2000

• PURPOSE

• HYPOTHESIS

• EXPERIE!T "ESI#!

• $TERI$%S

• PRO&E"URES

• RESU%TS

• &O!&%USIO!

• RESE$R&H REPORT

http://www.mademan.com/mm/how-does-hull-shape-affect-speed-boat.html#ixzz3W9nxxM2Phttp://www.mademan.com/mm/how-does-hull-shape-affect-speed-boat.html#ixzz3W9nxxM2Phttp://www.selah.k12.wa.us/SOAR/sciproj2000/BlaineH2.htmlhttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#purposehttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#hypothosishttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#edhttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#mathttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#procedureshttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#rehttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#conhttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#rerehttp://www.selah.k12.wa.us/SOAR/sciproj2000/BlaineH2.htmlhttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#purposehttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#hypothosishttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#edhttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#mathttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#procedureshttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#rehttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#conhttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#rerehttp://www.mademan.com/mm/how-does-hull-shape-affect-speed-boat.html#ixzz3W9nxxM2Phttp://www.mademan.com/mm/how-does-hull-shape-affect-speed-boat.html#ixzz3W9nxxM2P


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• BIB%IO#R$PHY

• $b'() The $()h'r

PURPOSE

The *(r*'se '+ )his e,*erien) as )' de)erine h' (ch )he hydr'dynaic sha*e and ass

'+ an 'b/ec) '(ld a++ec) i)s el'ci)y hen sinin )hr'(h a)er.

I becae in)eres)ed in )his idea hen a)chin a "isc'ery &hannel d'c(en)ary 'n

s(barines3 hich (s) be able )' )rael )hr'(h a)er a) hih s*eeds.

The in+'ra)i'n ained +r' )his e,*erien) can be (sed )' hel* crea)e ne and 'di+ied h(llsha*es +'r s(barines and b'a)s s' )hey can )rael 're 4(icly and 're e++icien)ly. This ill

als' hel* archi)ec)s )' desin ne bride s(**'r) c'l(ns )ha) ill le) a)er +l' ar'(nd )he

're easily.

HYPOTHESIS

y +irs) hy*')hesis is )ha) a sha*e i)h heaier ass ill sin a) a +as)er eih) )han )ha) '+ alih)er eih) in )he a)er )(be.

y sec'nd hy*')hesis )ha) )ha) a sha*e i)h 're s)realined hydr'dynaic *r'*er)ies ill sin

a) a +as)er ra)e in a a)er )(be.

I base y hy*')hesis 'n )he *hysics '+ aer'dynaics and hydr'dynaics )ha) say )ha) a 'res'')h and s)realined sha*e ill be lie a in sha*e and le) 're a)er +l' *as) )he easier

T'* '+ Pae

http://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#bibhttp://www.selah.k12.wa.us/SOAR/sciproj2000/BlaineH2.htmlhttp://www.selah.k12.wa.us/SOAR/sciproj2000/blaineh.html#bibhttp://www.selah.k12.wa.us/SOAR/sciproj2000/BlaineH2.html


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Experiment Design

The c'ns)an)s in )his s)(dy ere5 Sae ass in )he sha*es3 sae dis)ance )' )rael3 sae a'(n)

'+ *ress(re hen i) is dr'**ed3 sae dr'**er3 and sae a)er )(be.

The ani*(la)ed ariables ere )he di++eren) sha*es '+ )he 'b/ec)s and )he ass '+ each sha*e.

The res*'ndin ariable as )he s*eed )he 'b/ec)s )raeled )hr'(h )he )(be.

T' eas(re )he res*'ndin ariable I ill hae s'e'ne dr'* )he 'b/ec) 'n )he c'(n) '+ )hreeand I ill s)ar) )he s)'*a)ch3 and )hen s)'* i) aain hen I hear i) hi) )he b'))' '+ )he )(be.

T'* '+ Pae

MATERIALS

6U$!TITY "ES&RIPTIO!

1+'') clear *las)ic )(be

7One end cl'sed '++8

1 *ers'n )' dr'*

''d s*heres

''d c'nes

''d cylinders

''d c(bes1 s)'*a)ch

PROCEDURES

1. ae *yraids3 s*heres3 c(bes and cylinders.

2. "rill )he c're '() '+ each sha*e.

:. ;ill 'ne '+ each sha*e i)h :0 ras '+ sh') 7sh')(n sh')8.

. ;ill 'ne '+ each sha*e i)h


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?. ;ill )he )(be i)h a)er al's) )' )he )'*.

9. "r'* all '+ )he :0 ra sha*es 'ne a) a )ie.

10. Rec'rd )he da)a.

11. "r'* all '+ )he


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RESEARCH REPORT

INTRODUCTION

Hae y'( eer 'ndered ab'() h' s(barines die and s(r+ace )ha) easily@ They are s' bi

and lany )ha) y'( '(ld )hin )hey '(ld sin )' )he 'cean +l''r and n') be able )' s(r+ace

aain. I+ y'( read )his re*'r)3 y'( ill +ind '() h' s(barines sin and s(r+ace a'n ')her

)hins.

SUBMARINES

S(barines are s(bersible arshi*s (sed +'r s(r*rise a))acs. The +irs) s(barine *lans ereade in 1=>? by Aillia B'(rne. These ere )he +irs) *rac)ical s(bersibles. S(barine

desins hae been chaned any )ies )'' any di++eren) sha*es. 7See s(barine desin8

They rise and sin (sin ballas) )ans )ha) )hey +ill )' )he )'* i)h a)er )' sin and e*)y )he)' rise.

VELOCITY

el'ci)y is )he s*eed in hich an 'b/ec) is 'in in a ien direc)i'n. el'ci)y is sh'n in

)ie and dis)ance as in iles *er h'(r3 e)ers *er h'(r3 e)c. There are )' )y*es '+ el'ci)y3(ni+'r el'ci)y3 hich eans )ha) )he dis)ance and )he direc)i'n )raelin are sae )hr'(h'()

)he h'le ')i'n. el'ci)y ay by ariable3 hich eans )ha) )he dis)ance and )he direc)i'n are

(ne4(al.

HISTORY O SUBMARINES

The ery +irs) 'rin s(barine as a r'b'a) i)h a)er*r''+ hides s)ra**ed )' )he )'* '+ i).

The c'ns)r(c)'rCs nae as &'rneli(s an "ribble. He de'ns)ra)ed his inen)i'n in 1


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DESI!N O SUBMARINES

The desin '+ s(barines as chaned )' )rael +as)er. They are n' a ciar 'r )eardr'* sha*e.This aes )he 'e +as)er and die dee*er beca(se i) red(ces )he a)er resis)ance. $ls'3 )hey

are b(il) ider and can resis) 're *ress(re *(shin in 'n )he. This enables )he )' die )'

(nbelieably dee* leels '+ a)er.


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1) Hull speed or displacement speed is the speed at which the wavelength of the boat's bow

wave (in displacement mode) is equal to the boat length. As boat speed increases from rest, the

wavelength of the bow wave increases, and usually its crest to trough dimension (height) increases

as well. When hull speed is reached, a boat in pure displacement mode will appear trapped in a

trough behind its very large bow wave.

From a technical perspective, at hull speed the bow and stern waves interfere constructively,

creating relatively large waves, and thus a relatively large value of wave drag. hough the term !hull

speed! seems to suggest that it is some sort of !speed limit! for a boat, in fact drag for a

displacement hull increases smoothly and at an increasing rate with speed as hull speed is

approached and e"ceeded, often with no noticeable inflection at hull speed.

he concept of hull speed is not used in modern naval architecture, where considerations of speed#

length ratio or Froude number are considered more helpful.

28 h(ll desin i*lica)i'ns

Wave ma$ing resistance depends dramatically on the general proportions and shape of the hull%

modern displacement designs that can easily e"ceed their 'hull speed' without planning include hulls

with very fine ends, long hulls with relatively narrow beam and wave#piercing designs. hese

benefits are commonly reali&ed by some canoes, competitive rowing boats, catamarans, fast

ferries and other commercial, fishing and military vessels based on such concepts.

essel weight is also a critical consideration% it affects wave amplitude, and therefore the energy

transferred to the wave for a given hull length.

eavy boats with hulls designed for planning generally cannot e"ceed hull speed without planning.

ight, narrow boats with hulls not designed for planning can easily e"ceed hull speed without

planning* indeed, the unfavorable amplification of wave height due to constructive interference

diminishes as speed increases above hull speed. For e"ample, world#class racing $aya$s can

e"ceed hull speed by more than +-, +/ even though they do not plane. 0emi#displacement hulls

are usually intermediate between these two e"tremes.

1ltra#light displacement boats are designed to plane and thereby circumvent the limitations of hull

speed.

http://en.wikipedia.org/wiki/Bow_wavehttp://en.wikipedia.org/wiki/Bow_wavehttp://en.wikipedia.org/wiki/Ship_resistance_and_propulsionhttp://en.wikipedia.org/wiki/Naval_architecturehttp://en.wikipedia.org/wiki/Naval_architecturehttp://en.wikipedia.org/wiki/Froude_numberhttp://en.wikipedia.org/wiki/Planing_(sailing)http://en.wikipedia.org/wiki/Wave-piercinghttp://en.wikipedia.org/wiki/Canoehttp://en.wikipedia.org/wiki/Rowing_(sport)http://en.wikipedia.org/wiki/Rowing_(sport)http://en.wikipedia.org/wiki/Rowing_(sport)http://en.wikipedia.org/wiki/Catamaranhttp://en.wikipedia.org/wiki/High-speed_crafthttp://en.wikipedia.org/wiki/High-speed_crafthttp://en.wikipedia.org/wiki/Planing_(sailing)http://en.wikipedia.org/wiki/Hull_speed#cite_note-1http://en.wikipedia.org/wiki/Ultra_light_displacement_boathttp://en.wikipedia.org/wiki/Bow_wavehttp://en.wikipedia.org/wiki/Bow_wavehttp://en.wikipedia.org/wiki/Ship_resistance_and_propulsionhttp://en.wikipedia.org/wiki/Naval_architecturehttp://en.wikipedia.org/wiki/Froude_numberhttp://en.wikipedia.org/wiki/Planing_(sailing)http://en.wikipedia.org/wiki/Wave-piercinghttp://en.wikipedia.org/wiki/Canoehttp://en.wikipedia.org/wiki/Rowing_(sport)http://en.wikipedia.org/wiki/Catamaranhttp://en.wikipedia.org/wiki/High-speed_crafthttp://en.wikipedia.org/wiki/High-speed_crafthttp://en.wikipedia.org/wiki/Planing_(sailing)http://en.wikipedia.org/wiki/Hull_speed#cite_note-1http://en.wikipedia.org/wiki/Ultra_light_displacement_boat


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eavy 2oats, ight 2oats, and ull 0peed

ere's an attempt to e"plain these things in layman terms..... A boat displaces on its own weight in water. When the boat is moving, it must push that much water outof the way as it goes forward. 0ince a heavy boat has to push more water out of the way, it ma$es biggerwaves. (As a boat moves faster it has to push aside more water in less time, so that ma$es the wavesbigger too.) 3ach boat creates a bow wave and a stern wave. When a boat reaches !hull speed! the bow and sternwaves coincide to ma$e one huge wave system. A heavy boat gets trapped in its own wave system. (Fora 4 foot boat, hull speed is about 5 $nots. For a 6 foot boat, hull speed is about 7.6 $nots.) he best e"ample of this is a tugboat. ugboats are very heavy, since they have huge engines forshoving ships around* and when they are not shoving a ship, they are racing as fast as they can to the

ne"t 8ob. hat's why you see them with a huge bow wave, a huge stern wave, and a deep wave trough inbetween. 9n spite of their enormous horsepower, they can't brea$ loose from the trap of their own wavesystem. hey dig a big hole in the water, and can't climb out of it. A light displacement boat such as a dinghy, a 1:2, or a multihull doesn't have so much water to moveout of the way # so they ma$e smaller waves. When they reach the speed that would be hull speed for aheavy boat the wave system is not big enough to trap them. hey are able to e"ceed the !speed limit!where bow and stern waves coincide. A planning hull actually climbs up its own bow wave and is lifted partially out of the water. ;bviouslyocean waves affect a light boat more strongly, since the weight of the wave is bigger compared to theweight of the boat. any runabouts use the v#bottom design.


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Round bottom boat # hese move easily through thewater, especially at slow speeds. hey do, however, tendto roll unless they are outfitted with a deep $eel or

stabili&ers. >any trawlers, canoes and sailboats haveround bottoms.

Multi-hull boat #


10/17

Boats with planning hulls are designed to rise up and glide on top of the water when

enough power is supplied. These boats may operate li#e displacement hulls when at rest

or at slow speeds but climb towards the surface of the water as they move faster.

• Boats with planning hulls can s#im along at high speed, riding almost on top ofthe water rather than pushing it aside.

• $lat!bottomed and vee!bottomed hull shapes act as planning hulls. "ost small

power!driven vessels, including personal watercraft %&(s), and some small

sailboats have planning hulls, allowing them to travel more rapidly across the water.

H' Plannin H(lls O*era)e

"is*laceen) 'de

planning hull, when operated at very slow speeds, will cut through the water li#e a

displacement hull.

Pl'in 'de

s speed increases, a planning hull will have a raised bow, reducing the operator's vision

and throwing a very large wa#e. void maintaining a speed that puts your boat in

plowing mode.


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Plannin 'de

*our boat is in planning mode when enough power is applied so that the hull glides on

top of the water. +ifferent boats reach planning mode at different speeds.

Hull

S"#pes Hull Illustr#ti$ns A%nt#ges Dis#%nt#ges

l#t

B$tt$m

Hull

This *lannin h(ll has a

shall' dra+)3 hich is ''d

+'r +ishin in sall laes

and riers.

Rides r'(hly in

a)ers.

Deep Vee

Hull

This *lannin h(ll ies a

s'')her ride )han a +la)

b'))' h(ll in r'(h a)er.

Taes 're *'

)he sae s*eed a

h(lls. ay r'll '

shar* )(rns.

R$un%

B$tt$m

Hull

This )y*ical dis*laceen)

h(ll 'es easily )hr'(h

)he a)er een a) sl'

s*eeds.

Has a )endency )

i) has a dee* ee

s)abiliDers.

Multi'

Hull

$n')her e,a*le '+ a

dis*laceen) h(ll3 )he (l)i-

h(ll has rea)er s)abili)y

beca(se '+ i)s ide bea.

!eeds a lare ar

)(rnin.


12/17

+)?lease e"plain the term waterline length. :oes this length of a boat affect howfast a boat can go@

hat is a very good question. Waterline length is the length of the boat from bowto stern where it sits in the water. 9n other words, as it floats in the water if you

were to mar$ the point on the bow where the water touched and mar$ed the pointon the stern where the water touched and then measured that distance this wouldbe the waterline length.

2y the way, if you were to connect the mar$s you made at the bow and stern andpaint a line on the boat's hull you would have created what is called a !boot stripe!.he boot stripe is the line painted on many boats which separates the bottomwhich is underwater from the sides that are above the water.

es, the length of the water line does affect the speed of some boats. 9nparticular displacement type boats. hese are boats that have a large underwater

profile such as sailboats and trawlers. 0ince these type of boats are not able to getup on top of the water and plane they are pushing a tremendous amount of water.

9f you were to watch a displacement vessel move through the water you would notice that theycreate both a bow wave and a stern wave as they push through the water. he faster the boat goesthe larger these two waves become until at some point they become a single wave. 9t is at this pointthat the boat has reached its !hull speed!. hat means that this is as fast as it can go. 9t can't gofaster because it is caught in this wave. he longer the boat, the faster it can !theoretically! gobecause it ta$es longer for the bow and stern wave to become one wave. ou can calculate the hullspeed of a displacement vessel with the following formula.

ull speed B +.6C D (0quare root of W) EW is length waterline

For e"ample, if your displacement sailboat was 65 feet long the hull speed would be calculated asfollows%

0quare root of 65 B 5 ## 5 D +.6C B .C $ts. hull speed

4) ow fast can a boat go, are there speed limits@

his is another good question,


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miles per hour. Gecreational planning vessel may reach speeds of 4H#C miles per hour.

;n the water you will also find speed limits 8ust as you do on land. ou should be on the loo$outfor speed limits and abide by them. Also, 8ust li$e in a car, you should never operate at a speed thatis unsafe for the current conditions. ou should constantly be on the loo$out for other traffic,

visibility, wave action around you, and other elements which may require a reduced speed.

Hull speed and the !atchbo" Analog#

$onsider #our hull as a %atchbo" & not wonderfull# e'cient h#dro d#na%icall#( but

stick with it for a %o%ent) Dissatis*ed with the constraints of %atchbo" li+ing( #ou

decide to double its si,e) -ou add another %atchbo" ahead to double its length( two

alongside to double its bea% and four on top to double its draft) .ow wetted area

has increased b# four( +olu%e and displace%ent b# eight and stabilit# & as theproduct of its %ass and acceleration & has increased si"teen fold) So b# doubling a

hull/s di%ensions( wetted area are s0uared( displace%ent is cubed and stabilit#

increases b# the power of four) With this knowledge and that gained b# carefull#

%easuring applied force and resultant %o+e%ent( 1roude was able to both calculate

and de%onstrate that a relationship e"isted between hull speed and waterline

length & that relationship being known and described in the %etric world as /1roude

.u%bers/)

& See %ore at2 http233www)sailboat&

cruising)co%3hullspeed)ht%l4sthash)56hl778g)dpuf

9oat Hull

A hull is the watertight bod# of a ship or boat) Abo+e the hull is the superstructure

and3or deckhouse( where present) The line where the hull %eets the water surface

is called the waterline)

http://www.sailboat-cruising.com/hullspeed.html#sthash.U3hl776g.dpufhttp://www.sailboat-cruising.com/hullspeed.html#sthash.U3hl776g.dpufhttp://www.sailboat-cruising.com/hullspeed.html#sthash.U3hl776g.dpufhttp://www.sailboat-cruising.com/hullspeed.html#sthash.U3hl776g.dpuf


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The structure of the hull +aries depending on the +essel t#pe) In a t#pical %odern

steel ship( the structure consists of watertight and non&tight decks( %ajor

trans+erse and longitudinal %e%bers called watertight :and also so%eti%es non&

tight; bulkheads( inter%ediate %e%bers such as girders( stringers and webs( and

%inor %e%bers called ordinar# trans+erse fra%es( fra%es( or longitudinals(

depending on the structural arrange%ent) The upper%ost continuous deck %a# becalled the


15/17

I;3% he way 9 tested the e"periment changed because of reasons e"plained later. he graph abovesays !Gesistance Force! but in the end it is the time it too$ to travel the distance of a fish tan$.

VariablesIndependent Variable:ull 0hape

Dependent Variable:Gesistance

Variables That Need To Be Controlled:>aterial of ull

General Plan2uild different hull shapes of the same material, H or so will do. Jet a fish tan$, for sensor, and rubberband


16/17

Data nalysis

Graphs

!esults

Conclusion9n conclusion, the multi chine hull shape, was the fastest. 9t traveled the distance of the fish tan$ in anaverage time of .45 seconds. he ne"t fastest were the


17/17

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