Simula ion-d i en design o sailing yach s and mo o boa s
VII In e na ional Con e ence on Compu a ional Me hods in Ma ine Enginee ing
MARINE 2017
M. Visonneau, P. Queu ey and D. Le Touzé (Eds)
SIMULATION-DRIVEN DESIGN OF SAILING YACHTS AND MOTOR
BOATS
Bodo Hasubek∗, S e an Ha ies†
∗D eamca che One
Sonnenblumen ing 39, 86415 Me ing, Ge many
[email p o ec ed], www.d eamca che one.de
†FRIENDSHIP SYSTEMS AG
Benzs . 2, 14482 Po sam, Ge many
[email p o ec ed], www. iendship-sys ems.com
Key wo ds: Simula ion-D i en Design (SDD), Yach Design, Compu a ional Fluid Dynamics (CFD), Pa a-
me ic Modeling, Op imiza ion
Abs ac . The design o yach s and boa s can signi ican ly bene i om simula ion-d i en design (SDD)
using codes o Compu a ional Fluid Dynamics (CFD). In SDD a la ge numbe o i ual p o o ypes is in-
es iga ed nume ically o key objec i es. In hyd o- and ae odynamics objec i es o en ela e o esis ance
and li which go e n he pe o mance o bo h sailing yach s and as mo o boa s. In o de o educe he
dimensionali y o he design space, i.e., he deg ees-o - eedom, a pa ame ic app oach is u ilized. Fo he
low simula ion di e en le els o ideli y a e used, anging om po en ial low analysis o iscous low
simula ion sol ing he RANS equa ions. Design examples applying he SDD app oach will be p esen ed o
bo h a sailing yach and a mo o boa . The sailing yach is a 20m ca ama an o wo ldwide a el and he
mo o boa is a 6m planing boa o day c uises. Pa ame ic models o he wo essels will be discussed,
comp ising he gene a ion o su aces and wa e igh i-meshes, he la e o which can be ed o he CFD
code o choice. He e SHIPFLOW®and FINE™/Ma ine we e applied in connec ion wi h CAESES®which
p o ided bo h he shapes and he in eg a ion o CFD o SDD. To close he simula ion d i en design cycle
o he sailing ca ama an an appended e sion o he pa ame ic model wi h udde s and dagge boa d is used
o i ual ank es ing. Combining hese esul s wi h a sui able sail model allows o an accu a e eloci y
p edic ion (VPP) in an ea ly design s age.
1 In oduc ion
While CFD ship hull imp o emen s and op imiza ions a e qui e common o la ge comme cial essels,
CFD d i en design o saing yach s and small mo o boa s is usually limi ed o mul i-million dolla p ojec s
such as he Ame ica’s Cup. Cos s a e assumed o be p ohibi i e and incen i es a e missing. Fuel consump ion
is no an issue o pleasu e boa s and sailing pe o mance is a ibu ed o a “hea y” design o o he lack o
abili ies o he skippe . Howe e , ecen de elopmen s in pa ame ic design o ship hulls and a o dable CFD
compu a ions ha e changed he playing ield. In his pape he in es iga ion o a new design o a 20m sailing
mul ihull (Fig. 1) is p esen ed and he classic Ri a Junio as planing c a is e isi ed. Bo h designs ha e
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in common ha hey use a ha d chined hull. Ne e heless, he me hods discussed can be eadily applied o
ound-bilge hulls as well.
Figu e 1: D eamCa che One
Fo he sailing ca ama an ha d chines we e chosen o easy
manu ac u ing in aluminium based on de elopable su aces. I
is shown ha a sys ema ic a ia ion o he hull pa ame e s leads
o a signi ican educ ion o o al esis ance compa ed o a man-
ually lo ed hull. A e de ining he op imiza ion goal, a ully
pa ame ic model is de eloped o he canoe body o a single
hull using CAESES®. Fo he design selec ion a mul iple s age
app oach was aken: 4508 models we e in es iga ed using he
po en ial low code o SHIPFLOW® o wa e esis ance. Sub-
sequen ly, he mos p omising pa ame e anges we e chosen
o analyse 521 models wi h ega d o hei o al esis ance us-
ing SHIPFLOW®’s zonal app oach which combines a po en-
ial low solu ion o he wa e esis ance wi h a iscous esis-
ance solu ion o he ea hal o he hull an he wake. The bes
design was selec ed and e i ied by compa ing he esis ance
cu es o he whole ope a ing ange using bo h FLOWTECH’s
SHIPFLOW®and NUMECA’s FINE™/Ma ine. The pa ame -
ic model hen is e ined o include wo hulls as well as ud-
de s and dagge boa ds. This model is used o ind a sui able
dis ance be ween he hulls and o gene a e i ual ank es ing
inpu s o a eloci y p edic ion p og am (VPP) unde di e en
sailing condi ions using FINE™/Ma ine.
The example o he mo o boa a planing speed p esen s
an au oma ic minimiza ion o esis ance ia a design-o -
expe imen (DoE) combined wi h a de e minis ic sea ch. CAESES®and FINE™/Ma ine we e coupled as
an in eg a ed solu ion (Fig. 2). The example se es o highligh he p ocedu e and he a ious elemen s in-
ol ed – namely a iable geome y, high- ideli y CFD and o mal op imiza ion – along wi h imp o emen s
ha could be achie ed.
2 Simula ion-D i en Design o a sailing ca ama an
2.1 Design Objec i es
Figu e 2: Fas mo o boa modeled wi h
CAESES®
Fo mo o d i en essels he design objec i es a e usually
p o ided by he clien in e ms o pay load and eloci y e-
qui emen s. A sailing yach , howe e , ope a es a an a bi a iy
numbe o load and eloci y condi ions which canno be eas-
ily p edic ed. The e o e, o he load condi ion he wo s case
scena io o “ ully loaded” was chosen a a displacemen o 36 .
Due o wa e heo y he o al esis ance s. F oude numbe
cu e shows a ce ain “hump” a a ound Fn=0.3. This hump
can be seen in he esis ance cu e o he e e ence design. Fo
he ca ama an wi h a wa e line leng h o 20 me e s Fn=0.3
ansla es in o a boa speed o 8.2 kno s. Appa en ly, he speed
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Bodo Hasubek and S e an Ha ies
ange be ween 8 and 10 kno s should be wi hin each o a ca ama an o his size e en in ligh winds. The e-
o e, he educ ion o his hump was chosen as he p ima y op imiza ion goal. A he same ime he op imiza-
ion should no sac i ice he speed abili y in no mal wind condi ions. F om analy ical es ima es conside ing
an upwind sail a ea o 270m2 he no mal upwind abili y esul s in a ound 12 o 13 kno s. This leads o a wo
speeds op imiza ion app oach o Fn=0.3 (8.2 kno s) and Fn=0.44 (12 kno s). Consequen ly, all 4508
models we e e alua ed o hese wo speeds o selec he designs wi h he bes o e all pe o mance.
2.2 Pa ame ic Models
The pa ame ic models use h ee sec ions, an a , a main and a bow sec ion. A model wi h h ee pla es
and one wi h ou pla es below he wa e line was de eloped o in es iga e whe he a be e app oxima ion
o an op imum ellip ical shape by using mo e pla es would lead o be e designs. Bo h sec ion models use
gi en, bu a iable wa e line and keel line cu es as well as a la e angle and a dead ise angle cu e o e
he comple e hull leng h. This allows o a lexible posi ioning o he main sec ions. The h ee pla e model
u he uses he sec ional a eas as inpu o gene a e he sec ion.
Figu e 3: Th ee pla e model: sec ion geome y Figu e 4: Fou pla e model: sec ion geome y
Fo educ ion o o al esis ance he we ed su ace a ea needs o be conside ed as well. In he cu en
app oach he leng h o he sec ion cu e (leng h om p1-p2-p3-p4in Fig. 3 ) was minimized using a quad a ic
equa ion o ind he posi ions o poin s p2and p3in dependance o he sec ional a ea, dead ise angle, he
side angle and he la e angle. Using a B en minimiza ion app oach wi hin CAESES® he side angle was
a ied o minimize he leng h p1-p2-p3-p4. The idea ollows he assump ion ha i he cu e leng hs o he
sec ions a e minimal and he ha d chines connec ing he poin s among he a , main and bow sec ions a e
ai , hen he we ed a ea o he su aces c ea ed be ween hese ha d chines is a leas close o i s minimum
as well. Analysing he c ea ed models showed ha he we ed su ace a ea among all designs a ied only by
a maximum o 1.5%.
Many hand-made design a ia ions su e om a ying displacemen alues [1]. In he cu en pa ame ic
app oach he main sec ion a ea is a ied using a second op imiza ion o mee he displacemen o 18 pe hull
wi h a de ia ion o less han 0.1‰. By keeping he displacemen cons an any a ia ions in esis ance can be
di ec ly a ibu ed o he changes in he geome y.
The ou pla e model (Fig. 4) ollows a simila app oach whe eby he geome y depends on 1=Tc, 2,
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Bodo Hasubek and S e an Ha ies
3=BW L as well as dead ise and la e angle. The adius 2hal es he angle be ween 1and 3and is
chosen such ha he leng h p0-p1-p2-p3-p4is educed. The su ace be ween p3and p4is ex ended linea ely
up o a u he chine well abo e he wa e line o a oid he in oduc ion o an addi ional chine a he wa e line.
A hull gene a ed using he ou pla e model is shown in Fig. 5. The wa e line is ma ked in ed.
Figu e 5: Full hull using he ou pla e model
The models comp ise mo e han 20 pa ame e s comple ely de ining he hull’s shape. Se en o eigh
o hese pa ame e s (depending on he model h ee s. ou pla es) ha e been sys ema ically a ied while
he emaining pa ame e s we e ixed o meaning ul alues de e mined in a p elimina y e alua ion phase.
Compa ed o con en ional spline-based app oaches using an uncon ollable la ge numbe o e ices he
numbe o pa ame e s is e y low, bu s ill allows o a wide ange o possible hull shapes. I should be
men ioned ha no all pa ame e combina ions lead o alid hull shapes: Ou o 6000 pa ame e combina ions
o he po en ial low analysis only a ound 4500 esul ed in a easable hull shapes. The numbe o easable
designs wi hin a pa ame e ange is an indica o o he s abili y o he geome y o a pa ame ic model. The
la ge he allowable ange o each pa ame e and he mo e ex eme he allowable pa ame e combina ions a e
he mo e lexible he model is. This is pa icula ly impo an i non-con en ional hull shapes a e o in e es .
I was ound ha he pa ame e s o bow ineness and s e n wid h showed highes sensi i i y owa ds he
op imiza ion goals. I also seems ha he alignmen o he ha d chines wi h he low a ound he hull s ongly
in luences he pe o mance. This does no come as a big su p ise. Howe e , an alignmen o he chines wi h
he low does no lend i sel o easily accessible design pa ame e s wi hou iola ing he ai ness o he lines.
The e o e, only wi h a sys ema ic sea ch he mos a ou able designs could be ound.
2.3 CFD Analysis
The main ad an age o a pa ame ic model c ea ed in CAESES®is i s uni e sal applicabili y o di e en
CFD codes such as SHIPFLOW®and FINE™/Ma ine. Fo SHIPFLOW®a s a ion based geome y expo
was used while FINE™/Ma ine equi es essela ions o he comple e calula ion domain in he o m o mul i-
body STL iles. These simula ions can be highly au oma ed. The simula ion imes a y gea ly om a ound
30 minu es o a wa e esis ance calcula ion using SHIPFLOW®’s po en ial low sol e , ia a ound 4 hou s
o SHIPFLOW®’s zonal app oach, bo h on a con en ional 3,5GHz 4 co e PC wi h 16Gb RAM, all he way
up o mo e han 30 hou s on a 3.0GHz 8 co e PC wi h 64Gb RAM o a iscous esis ance calcula ion wi h
a ee su ace o an appended wo-hull con igu a ion using FINE™/Ma ine.
Fo he selec ed designs hei o al esis ance o e he comple e ope a ion speed ange was calcula ed
o e i y ha he lowe esis ance a Fn=0.3 is no penalized a o he eloci ies. Fig. 6 shows ha he
esis ance hump a Fn=0.3 could be mos ly elimina ed wi hou sac i icing pe o mance a highe speeds.
The ou pla e model e en pe o ms be e a highe speeds han he e e ence design.
In able 1 he nume ical esul as well as some geome ical and hyd os a ic pa ame e s o he designs a e
summa ized. The main objec i e o educing he o al esis ance a Fn=0.3 was well achie ed. The bes
h ee pla e design shows a o al esis ance educed by 13.5%, he bes ou pla e design shows a educ ion o
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Figu e 6: To al Resi ance o he selec ed h ee and
ou pla e designs compa ed o he e e ence design
Figu e 7: To al esis ance o he ou pla e model
e alua ed wi h SHIPFLOW®and FINE™/Ma ine
17.1%. A he same ime he pe omance a Fn=0.44 did no su e and e en sligh ly dec eased as well o
he la e . Mo eo e , an in e es ing esul is ha beyond an L/B a io o 10 i is no gua an eed ha a la ge
L/B alue s ands o be e pe o mance. Figu es 8 and 9 show he wa e pa e ns o he bes h ee and ou
pla e designs compa ed o he e e ence design a Fn=0.3 (8.2kno s) and 0° heel. The imp o emen s in
he wa e pa e ns show a he o e pa o he hull and in he wa e elimina ion in he wake.
Pe o mance Pa ame e s Re e ence Design Th ee Pla e Design Fou Pla e Design
R (Fn=0.3)[N] 1723 1490 1428
R (Fn=0.44)[N] 5277 5274 5195
T im a Fn=0.44 [°] 0.82 0.83 0.86
Hull Pa ame e s Re e ence Design Th ee Pla e Design Fou Pla e Design
LWL [m] 20.1 20.1 20.17
BWL [m] 1.60 1.90 1.84
Tc[m] 1.05 1.02 0.97
We ed su ace [m2]46.7 46.1 46.4
L/B12.6 10.6 10.95
BTR 1.52 1.87 1.9
Cp0.634 0.588 0.595
Table 1: Nume ical CFD esul s and hull pa ame e s o he demi-hull
In o de o e i y he alidi y o he esul s, he esis ance cu e o he bes ou pla e design was e-
e alua ed wi h a di e en CFD code (NUMECA’s FINE™/Ma ine) which uses a ee-su ace RANSE ap-
p oach (Fig. 7). The maximum de ia ion be ween calcula ed alues lies a Fn=0.36 and eaches 5.5%,
while a he op imiza ion poin s Fn=0.3 and Fn=0.44 he de ia ion is 1.8% and 0.1%, espec i ely.
The e o e, he op imiza ion p ocedu e can be assumed o deli e eliable esul s wi hin an accep able ma gin
o e o o a c uising ca ama an. I is no ed ha he ela i e posi ioning o he di e en designs wi h ega d
o hei pe o mance is usually e en mo e eliable han hei absolu e esis ance alue i he compa a i e
e alua ions a e pe o med using he same mesh esolu ion and he same sol e (as was done he e).
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Figu e 8: Demi-hull a Fn=0.3: Re e ence design s. bes h ee pla e design a 0° heel
Figu e 9: Demi-hull a Fn=0.3: Re e ence design s. bes ou pla e design a 0° heel
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One hull Two hulls ca ama an con igu a ion
FnResis ance [N] BCB [m] Resis ance ∆R
0.3 2872 4.25 2908 1.3%
0.44 10568 4.00 12908 22.1%
0.44 10568 4.25 12506 18.3%
0.44 10568 4.50 12258 16.0%
Table 2: Resis ance o one hull s. wo hulls ca ama an con igu a ion
2.4 Closing he design loop
A u he ad an age o a pa ame ic model is he abili y o e-use all he p ope ies o he single hull canoe
body model and e ine i o include a double hull se up and appendages ( udde s and dagge boa ds). Such a
e ined model is used o de e mine he bes comp omise be ween he hull’s cen e lines dis ance (BCB) and
o al esis ance.
Table 2 shows he in luence o a single hull compa ed o a wo hull ca ama an con igu a ion. I can be seen
ha a Fn=0.3 he e is close o no in e e ence be ween he hulls, while a Fn=0.44 he hull in e ac ion
signi ican ly inc eases he o al esis ance. The wa e in e ac ion o Fn=0.44 is shown in igu es 10 and 11.
As expec ed, he da a show ha inc easing BCB educes he o al esis ance, bu he e ec slows down o
la ge BCBs. The e o e, a BCB o 4.25 me e s was aken as a comp omise.
Figu e 10: Wa e pa e n a Fn=0.44 one hull Figu e 11: Wa e pa e n a Fn=0.44 wo hulls
Fo a p elimina y pe o mance p edic ion o he ca ama an design he ully appended pa ame ic model is
used o gene a e he esis ance da a equi ed o a eloci y p edic ion p og am (VPP). Common VPP pack-
ages ely on hull da a ha is de i ed om he Del sys ema ic se ies wi h addi ions o heel and appendages.
While his wo ks sa is ac o ily o monohull designs wi h ounded sec ions, he da a basis o he Del se ies
does no suppo ha d chined mul ihull designs e y well. Fu he mo e, sailing ca ama ans wi h dagge -
boa ds a e no mally sailed wi h he leewa d dagge bo d down only. This esul s in a highly asymme ic
se up ha is no easily accessible o analy ical app oaches.
This p oblem is o e come by calcula ing he esis ance in he di ec ion o mo emen and he side o ces
gene a ed by he hull and appendages o heel angles om 0° o 5°, leeway angles be ween 0° and 4° and
o a eloci y ange be ween 4 and 14 kno s. The limi s we e chosen in acco dance wi h he an icipa ed
ope a ional p o ile. Fo example, he maximum heel was limi ed 5° since his ep esen s he angle a which
hal he maximum s a ic s abili y is eached. A c uising ca ama an should no be sailed beyond his poin o
sa e y easons.
Wi h ou poin s in each o hese dimensions his app oach leads o 64 calcula ions in o al. Fig. 12
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Figu e 12: Wa e igh iangula ion o he appended model
shows he wa e igh iangula ion o he asymme ically appended pa ame ic hull model. The asymme y
equi es a comple e calcula ion domain o a ound 6 million cells. The calcula ions we e pe o med on said
8 co e PC. They ook 77 days. Ob iously his ime ame needs o be educed o e e y day use. Howe e ,
high pe o mance compu e clus e s wi h all he so wa e equi ed p e-ins alled a e a ailable o en and can
pe om such calcula ions wi hin a ew days [5].
The esul ing o ces o he CFD calcula ions depend on he h ee independen a iables heel angle, leeway
angle and eloci y. Fig. 13 and 14 show an example o he esis ance and side o ces o a ixed heel angle
o 2.5°. Fo u he p ocessing in a VPP hese alues a e in e pola ed using a spline based sca e ed da a
in e pola ion [2]. In p e ious wo k [3] Hazen’s his o ic sail model is used o calcula e he equilib ium
o he hyd odynamic and he ae odynamic o ces o de i e he sailing pe o mance unde di e en sailing
condi ions. In he cu en case a mo e accu a e sail model based on he ORC VPP ae odynamic model [4]
is employed. Based on he CFD da a and he ae odynamic model he expec ed sailing pe o mance can be
p edic ed accu a ely in an ea ly design s age.
3 Simula ion-D i en Design o a as planing mo o boa
3.1 Design Objec i e
A small ha d-chine mo o boa o a ound 6 m leng h and 1.3m3displacemen , ypically used as a day
c uise on la ge lakes and as a ende o supe yach s in coas al a eas, was s udied wi h ega d o i s pe o -
mance a a design speed o 18 kn. Wi h a F oude numbe o 1.32, based on he leng h o he design wa e line
a es , his ep esen s a planing hull o which dynamic im and sinkage (o a he li ) and he in luence o
he ee su ace a e c ucial.
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Figu e 13: Resis ance o ces a heel =2.5° Figu e 14: Side o ces a heel =2.5°
Fo his ype o boa s model es campaigns a e o en p ohibi i ely expensi e. A s anda d app oach
he e o e is o ely on se ies da a ound in li e a u e, see [6, 7]. Once he main pa icula s a e se , he
in luence o small changes o he be e o wo se canno be de i ed om he se ies da a. Al e na i ely, a
sui able pa en hull is aken, sligh ly modi ied and subsequen ly buil – na u ally, hoping o easonably good
pe o mance.
Bo h design app oaches canno p o ide answe s o he ypical design ques ions o how dead ise, ocke ,
hollowness o he planing su ace, i s wa p owa ds he ansom, wid h and shape o he sp ay ail and
o he design pa ame e s should be chosen. In his si ua ion an ex ended in es iga ion based on simula ion-
d i en design can help. To his e ec , he geome y o he mo o boa was pa ame ically modeled wi hin
CAESES®while he low was compu ed wi h he high- ideli y code FINE™/Ma ine, coupled o CAESES®
o be au oma ically execu ed in a design loop.
3.2 Pa ame ic Model
As i is common in design wo k, an a ac i e and ele an baseline was chosen as a good s a ing poin .
He e he Ri a Junio , a mo o boa o classic beau y om he mid 1960s, was selec ed. A ully-pa ame ic
model was de eloped wi hin CAESES®[8]. Fo he pu pose o he s udy he pa ame ic model was buil o
suppo wide changes o he hull while being able o closely app oxima e he baseline.
Figu e 15: Building pa e n o he gene ic sec ion (le : sec ion in he a body, igh : sec ion in he o ebody
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