Developments in the velocity prediction based on the Delft Systematic Yacht Hull Series

Delft University of Technology

Developments in the Velocity

Prediction based on the Delft

Systematic Yacht Húll Series

Dr.ir. J.A. Keuning

Ing U.B. Sònnenberg

Report 1132-P

March 1998

Published in: International Conference

on The Modern Yacht, Royal Institutiòn

of Naval Architects, Portsmouth, March

18 & 19, 1998

'I'(.J 1T)elft

Faculty ofMechanical Engineering and Marine Technology Ship Hydromechanics Laboratory

INTERNATIONAL CONFERENCE

on,

THE MODERN YACHT

18 .& 19 MARCH 199:8 PORTSMOUTH

PAPERS

THE ROYAL INSTITUTION OF NAVAL ARCHITECTS

1O UPPER BELGRAVE STREET, LONDON, SWIX 8BQ Telephone: 0171-235-4622

RINA

SMALL CRAFT GROUP

¡n auociation with the

ROYAL YACHTING ASSOCIATION

INTERNATIONAL CONFERENCE

on

THE MODERN YACHT

at the

Posthouse Forte Hotel, Portsmouth

18 & 19 March 1998

© 1998 The Royal Institution of NavalArchitects

The Institution is not, as abody, responsiblefor the opinions expressed by the individual authorsor speakers

THE ROYAL INSTITUTION OF NAVAL ARCHITECTS 10 Upper Beigrave Street

London SW1 X 880 Telephone: 0171-235-4622 Fax: 0171-245-6959

J.A. Keuning

Groenstraat5

4797 BA Wfflemstad

SESSION i - MEGAYACHTS - THE STATE OF THE ART

i

LARGE PRIVATE YACHTS

- THOUGHTS ON THE ST. ATE OF ThE ART

by J Bannenburg,. Jon Bannenburg Ltd. _(UK)

2..

TECHNICAL AND STYLING ASPECTS OF LARGE HIGH PERFORMANCE

SAILING YACHTS

by L Argento, Luca Brenta & C Yacht Designers

3.

MEGAYACHT DEVELOPMENT

by D L Blount and R J Bartee, Donald L Blount and Associates Inc.

5.

_{THE DESIGN OF A SAILING YACHT WITH A BOW RUDDER,}

by Ir J J Porsius, Ir H Boônstra, Drir J A Keuning, Deift University of Technology

C W van Tongeren, Van de Stadt Design

SESSION III - SAILING YACHT PERFORMANCE ANALYSIS

6.

WINDWARD PERFORMANCE OF THE AME CRC SYSTEMATIC

YACHT SERIES

by B McRae J Binns and K Klaka Australian Mantime Engineenng CRC Ltd

and A Dovell, Murray1 Bums & Dovell Pty. Ltd. (MBD) _(Australia)

(ITALY)

(USA)

(Netherlands)

7.

_{DEVELOPMENTS IN THE VELOCITY PREDICTION BASED ON THE}

DELFT SYSTEMATIC YACHT HULL SERIES

by Dr ir J A Keuning and Ing U. B Sonnenberg _{(Netherlands)}

SESSION Ii- SAIUNG YACHT APPENDAGE DESIGN

4.

PRACTICAL ANALYSIS OF THE HYDRODYNAMIC PERFORMANCE OF

THE REFLEX 28 KEEL AND RUDDER

by Dr S R Turnock and J E T Smithwick, University of Southampton _(UK)

J.A. .Keuning

Groenstraat5

4797RA Wfflemstad

CONTENTS

8.

THE PERFORMANCE OF OFFWIND SAILS OBTAINED FROM WIND

TUNNEL TESTS

by I Campbell, Wolfson Unit MTIA, University of Southampton

EXPERIMENTAL. INVESTIGATION OF THE HYDRODYNAMIC

PERFORMANCE OF A BOC 5Oft SAILING YACHT N CALM WATER

by Dr G J Grigoropoülosand.S EPerissakis

National Technical University of Athens (NTUA)

SESSION IV - DESIGN

COMMERCIAL YACHTING - THE DEVELOPMENT OF YACHTS IN THE

CHARTER INDUSTRY

by I A Garaty, Independent Consultant,

A NEW APPROACHTO AN INTEGRATED CAD METHOD FOR SAILING

YACHT DESIGNS

by KT Wan and Prof T P Bligh, Cambridge University Engineering Department

14.

STABILITY ANDSTRENGTH ÄNALYSISONYACHT RIGSWITH

CRP-SPARS

by Dipl. Ing, H Hoffmeister, GermanischerLloyd

(UK)

(Greece)

(UK)

(UK)

THE DESIGN OF A 52 FT. AERORIG CRUISING CATAMARAN

by John Shuttleworth (UK)

SESSION V - CARBON FIBRE RIG TECHNOLOGY

CARBONSPARS FOR SUPERYACHTS AND SMART MAST TECHNOLOGY

by O Roberts, Carbospars Ltd., and Dr? Foote, British.Aerospace Sowery

(UK)

Research Centre

SESSION VI

- HULL STRUCTURES

J.A. Keuning

Groenstraat5

4797 BA Willerustad

STRUCTURAL DESIGN CONSIDERATIONS FOR IMINATED WOOD

_YACHTS

by Dr R Loscombe, Southampton Institute _(UK)

RETHINKING OF STRUCTURES FOR ENHANCED PERFORMANCE OF LIGHTWEIGHT

SAILING CRAFT

by G I Robinson, .G I Robinson Yacht Designs Inc. _(USA)

17

_{ADVANCED COMPOSITE STRUCTURES FOR YACHTS}

by'RFogg, SP Technologies Ltd.

_(UK)

18.

_{OCEAN-RACING YACHTS.- STRUCTURAL CRITERIA}

by R Curry, American Bureau of Shipping _(UK)

19.

_{DEVELOPMENT OFHARMONISEDSTANDARDS FOR THE.}

_EU

RECREATIONAL CRAFT DIRECTIVE

by P R Handley, CEN _(Belgium)

DEVELOPMENTS IN THE VELOCITY PREDICTION BASED ON THE

DELFT SYSTEMATIC YACHT HULL SERIES

by Dr ir J A Keuning and Ing U B Sonnenberg, Netherlands

PAPER NO.7

4

Paper presented at the International Conference

on

THE MODERN YACHT

18 19 MARCH 1998 PORTSMOUTH

Dr. Jan A Keuning is Associate Professor in the Delit

Shiphydromechanics Laboratory at the :Delft University

of Technology. He previously worked in the Deift

Hydraulic Laboratory.

i

INTRODUCTION

Since the first publication of the original results of the

Delft Systematic Yacht Hull Series (DSYHS) by

Gerritsma e a. in 1981. which have been used by many

authors to develop their Velocity

Prediction (VPP)

methods for sailing yachts, much has been changed ¡n the design, the geometry and the appendages of sailing

yachts. The present day designs

differ sometimes

considerably from the lines of the Standfast 43 designed

by Frans Maas which was used as the parent model of

the original Series 1.

This has led in 1983 to the introduction of a new parent model designed by Van Der Stadt Design ¡n

Wormerveer more closely following the lines of that era.

Recently a third additional parent model has been

introduced in. the Series according to the lines given by Sparkman and Stephens of New York. The tests carried

out with the derivatives of these three different parent

models within the framework oCthe Deift Systematic

Yacht Hull Series and the expressions derived from

these results are believed to be covering a conveniently wide range of possible yacht hull shapes at the moment. However new developments in yacht design may make additions In the future inevitable.

In order to be able to evaluate the performance of

yachts with a large variety of appendage designs, such

DEVELOPMENTS IN THE VELOCITY PREDICTION BASED ON THE DELFT SYSTEMATIC YACHT HULL SERIES

Dr ir J.A. Keuning, Ing UB. Sonnenberg

SUMMARY

In the past few years new techniques used for prediction of the performance of sailing yachts (in waves) have been developed. In thispaper two aspects wllI.be dealt with In moredetail:

First the calm water resistance of sailing yachts has been further developed In order to be able to predict the

performance of a wider variety of sailing yacht designs with an Improved accuracy. New extensiOns to the well known

Deift Systematic Yacht Hull Series (DSYHS) have been tested in the towing tank of the Deift Shiphydromechanics Laboratory. These tests have been performed with the bare hull models as well as with the models with keel and

rudder.

The results of these experiments yielded new expressions which will be used to formulate new polynomial

approximations in the Velocity Prediction Program as developed a/o. bythe Delft Shiphydromechanics Laboratory.

Secondly in this paper the results of large number of towing tank experiments carried out with a series of five models of the DSYHS in waves and their analyses will be presented. The results of these experiments will be compared with the previously obtained approximations based on the results of systematic 2-D strip theory calculations of the added resistance of sailing yachts in waves In order to be able to validate these results.

AUTHOR'S BIOGRAPHY

1

as seen on the water nowadays, ¡t was already decided in

1992 to split the experiments carried out

in the framework of the DSYHS ¡n two parts: i.e. one part with the unappended (bare) hulls only and one part with the

appended hull (hull with keel and rudder). Obviously

tests with the heeled and yawed yacht models are

meaningless without the addition of a keel and rudder

and for the sake of consistency throughout the Series ¡t was decided from the beginning of the DSYHS to carry

out all tests with the

DSYHS

models equipped with

physically the same keel and rudder. in addition all

models, i.e. the new models from 1992 onwards but

also almost all models tested previously within

the DSYHS,

have been

(re)tested in the upright

condition without keel and rudder to be able to derive

expressions for the resistance's etc. of the canoe

bodies only.

Until 1992 this was not a regular procedure, which

implied that all the upright resistance data included the

resistance of the standard appendages and it was not possible to subtract these from the results. Up to 1985

this was not too big a problem, but after that quite

different appendages started to appear, in particular

smaller, thinner and with higher aspect ratios than the

DSYHS

standard keel and on the other side of the

scale, when the resUlts were used for the handicapping purposes, the introduction of the International

Measurement System (IMS) led also to the application

of the formulations on much 'older' yachts with very

large (and thick) keels.

The prediction of the bare hull resistance however

implied that for the real' yacht the resistance of the keel

(and rudder) has to be added to these bare

hull

resistances in order to obtain the total resistance of the

actual yacht fitted with an arbitrary keel. Separate

systematic tanktests with appendages of various

shapes nder different hulls have been carried out in

order to derive appropriate expressions for this

appendage drag.

In conjunction With this change in approach a new

method for assessing the resistance of the yachts under heel and leeway has been developed In this paper only

the results of the research on the 'heeled resistance

withoUt sideforce production will be presented because

the results on the indùced resistance due to sideforce

are

still being elaborated. In this new approach the

effects of the resistance increase due to heel and yaw

are being separated in order to obtain a physically more

correct expression for the induced resistance when

compared with the previously presented ones. This is dueto the fact that the 'heeled and induced' resistance of a yacht is no longer considered as the difference between the total resistance in the heeled and yawed

condit ion with sideforce compared with the total

resistance in the upright condition. Now the change in

the viscous part of the resistance due to change in

wetted area and asymmetry of the hull is taken off first

and the induced resistance

is

only related to the

additional resistance due to sideforce.

This change in approach of the heeled and yaWed

conditions was necessitated by the introduction of

yachts with much higher beam to draft

ratib's than

tested in the original Series. No. 1 of the DSYHS.

Finally some information had to be gained on the

dependency of the added resistance of the yachts in waves, because considerable discrepancy between

different methods of

approach based on different

calculation methods did exist. Therefore it was decided

to test a small 'sub' series of models belonging to the

DSYHS in regular waves to measure the dependency of

the heave and pitch motions and the added resistance in, head waves on some principal design parameters.

The attention

_{of the analysis was focused on the}

resistance aspects of the yacht in waves and the

dependency of the added resistance on the Length to

Beam ratio,

the Beam to

Draft ratio, the Length

Displacement ratio and the Pitch Gyradiús. The results

of these tests were compared with results

of the

approximation method as presented previously by

Gerritsma et al, which lends ftseif very well for

implementation in a VPP.

2. CALM WATER RESISTANCE

2.1 CANOEBODY RESISTANCE

Based on the results of the DSYHS as they were

originally presented (Gerritsma et al, Ref. [11)) ail

polynomial approximations of the upright Residuary Resistance (Rr) included the presence of the keel and the rudder, because all the models were only tested

with these appendages. The change in appendage

2

design over the years since the introduction of the

DSYHS made a change in approach with respect to this necessary.

The influence and contribution of the appendage volume

and wetted surface on the overall values Is presented

by Keuninget al, [Ref. 12].

Based on the experiments with a large number of the.

bare hulls of the models in the DSYHS belonging to the

Sùb-Sries No.

1,

No. 2, No. 3 and No. 4 a new

polynomial expression

for assessing the Residuary

Resistanceof the canoe body has been developed

The difference between the different Sub-Series is

originating fromthe difference In theshape of the parent

hull form from which the systematic variations have been derived, i.e. Standfast 43 for Sub-Series No. l Van Der Stadt Design 40 for both Sub-Series No. 2 and No. 3 and Sparkman and Stephens IMS-40 for

Sub-Series No. 4.

An impression of the linesplans of the three models together with their main particulars are presented for

each of the parents in Fig. 1, Fig. 2 and Fig. 3,

PARENTFORM

Fig. 1: Bodyplan Parent Sub-Series 1

An additional improvement over the results

of the

DSYHS as originally presented was accomplished by testing ali the bare hull models to. speeds as high as

Fn = 0.70 at least. By doing so a single polynomial

expression for the calculation of the Residuary

Resistance covering the whole speed range from

Fn = 0.10 to Fn = 0.70 could be derived for all models

and the split In theprevious 'high speed' and 'low speed' expression at Fn = 0.45 be avoided.

s,

6

¡n whkth:

/Y//47

The polynomial expression for the Residuary Residuary Resistance (Rr'), for one particular Froude

Resistance per ton of Displacement, 'i.e. the, Specific number now reads:

and thecoefficients aOto à8 are presented for 8 different Froude numbers in the range from Fn = 0.10 to Fn = 0.60:

Rr Residuary resistance of canoe body N

L1

Length on waterline _m

B1

Beam on watériine _m

C,, Prismatic coeff icient

Volume of displacement of canoe body

-m3

LCB,,

Longitudinal center of buoyancy measured fromforeperpendiculär m

LCFf,,,, Longitudinaicenter of floatation meáthired'from'fore perpendicular' Area' of 'waterline surface

m

rn

S Area, of wettedsurface of canoe body m2

g gravitation constant 9.81 m/s p 'density' of water kg/rn3

R

_r

₍

LCB

_B1

+a3+a4i---+

=a0+ia1

+a2C

L1

_{'L.) L1}

LCB

(LCB,

2 I

+a C

e-+:a

LCF1,

'

.I

L,

₎

8 p

_L1

PARENTFORM 2 PARENTFORM.3

Although the use of the polynomial is intended for

design purposes mainly still some attention has been paid in making the term of the expression robust' with

respect to possible exploitation. This has led a/o, to the

introduction of a term such as the Displacement to

Wetted Surface ratio instead of the Beam to Draft ratio.

The Frictional Resistanöe (Rf) of the hull is determined

using the same procedure as the one used in analysing

the model' test data in order to obtain the Rr of the

mode!:

The Wetted Area is determined using the waterline at zero speed as a referenbe. The well known 'ITTC-57' extrapolation line is used for the determination of the friction coefficient as function of the Reynolds number,

i.e.:

0.075

- (log

Re-

2)2 in which the Reynolds number Re:

VL

Re=

1.) where: V Velocity rn/s L Characteristic Length m

y Kinematic Viscosity m2Is

For the determination of the Reynolds number 70% of

the still water wateiline length Is used as the

characteristic length L. Due to the absence of a proven or generally accepted formulation for'the form factor 'k'

as function of the main parameters of the hull geometry no 'formfactor' Is used in the calculation of the frictional resistance. It is possible to the determine the

tprmfactor for each model within the DSYHS and this was done. In general it appeared that the 'formfactor

found during the experiments using Prohaska's method ranged from 2% to 6%.

4

Some results of the determInation of the residuary

resistance for the bare hull using the above given

calculation procedure are presented in the Figs.

4,

5 and 6 for few of the more extreme models belonging to Sub-Series No. 1, few from Sub-Series No. 4 and a model along the lines of the IACC not belonging to the DSYHS. From these results it may be concluded that the correlation between the calculated and measured

results 's quite satisfactory in general.

2.2 APPENDAGE RESISTANCE.

The respective resistance components of the

appendages are added to the bare hull resistance in the upright condition separately. i.e. the viscous resistance of the appendage, composed by the frictional resistance and the form dragó as well as the residuary resistance of the appendage, due to any wave making phenomena.

To be able to formulate expressions for the resistance

of the appendages an extensive study has been carried out by Keuning and Kapsenberg Ref. [17] and Keuning

and Binkhorst Ref. [18]. In these studies experiments

have been carried out with appendages underneath two

different hulls which were instrumented separately in order to be able to measure the lift and the drag of the

appendages separate from the forces on the hulls. Four different appendages have been used and the

measured results

have been compared with CFD

calculations.

First of

all a reliable approximation method for the

viscous resistance of the appendage was found by

using the well known ITTC-57 formulations for the

frictional

resistance based on the

'local' Reynolds

number using the 'local' chord length of the appendage.

For the assessment of the viscous drag the use of the well known forrnfactor as presented a.o. by Hoerner

Ref. [1:3] proved sufficiently reliable, l.e

(1+k)=

Fn aO

ai

a2 a3 a4 a5 a6

al

a8 0.10 -00011 0.0134 0.0546 -00226 -0.0101 0.0162 -0.0083 -00037 0.0605 0.15 0.0008 -0.3042 0.2708 -0M052

0108

0.0356 -0.0047 0.2882 -0.2520 0.20 0.0019 -0.2531 0.1738 -0.0021 0.0153 0.0389 0.0015 0.2399 -0.1600 0.25 0.0034 -0.2138 0.0810 -0.0024 0.0263 0.0248 0.01 22 0.1841 -0.0588 0.30 0.0067 -1 .2345 0.8451 -0MO23 0.0491 00560 0.0310 1.1359

-6731

0.35 0.0047 -0.2380 -0.0034 -0.0745 0.0327. -0.0293 0.0717 0.1627 0.0978 0.40 -0.0026 2.0402 -1.4961 0.0563 -0.0691 -0.3757 0.1865 .2.2030 1.1861 0.45 '0M143 2.7460 -1 .5509 0,3024 01403 -0.6665 : 03066 -2.9032 0.9853 0.50 -Q0172 6.1913 : 55973 0.5120 0.1598 -0.1730 0.5165 -6.2597 4.6126 0.55 0.0524 -0.74.34 -4.0591 0.7613 1.1479 2.0372 0.9483 -0.0103 3.6522 0.60 .0.0853 -6.4030 -0.3355 0.8627 1.6084 3.0899 08388 5.7329 0.4062

Fig 4: Bare HuIlResiduar,y Resistance of 4 models öt Series No: i

Fig; 5: Bare Hull Residuary Resistance of 3 models of Series No. 4

5

Measured & Calculated R?

Cd

0.14

---

I I I

I;'

--I i 'I

,4'i.-iS oi'O

______

I i I. I i I

/

/

---Measured: 14 I I I I

-0.04 i....

L

_j...,ì

j.___

0.02 I

r

r

i',,

r

r

-a

- i.__.__,. r 0.00 --I. I D1 0.2 0.3 0.4 _{05 06} Fn 0.14

-Measured & Calculated Rr _Calculated:

--

i,

L

I I

T

i

L

I LV20.08 I I .

-T

I

L_LL'

I/

--

_4:3 44 Measured:

Fig 6: ResiduaryResistanòeot IACCmodèl No. 329

Fig. 7: Residuary resistanceappended hull using original polynome model No. 329

6

T

Measured & Calculated Rr . CaicuId:

0:14

-- I I I I

012-I I I O1O

L

L---I I I I

r

T---

_Measured:

.0

0 -D .0.D6

4---

--0.04 I, I.

f

f

.

f

I I I I 0.02

r

.. - -I I

I.

0:00

-

. ' .1 o, b.2 0.3 0.4 05 0.6 Fn Measijred.&CalcùlatedRrhkr . . .Cálculated: 0.14

r

TTT

I.

0.12 0.i0

L

i

.

f

0.08 -

f

f

r r

-I I

.1

Measured: .0 2Ø 0.04

---L---L_________

H

I

L

0.02

r

t

,.-

----r--j---0.0Ó -I - I j:

--Y

-,.. 01 0.2 0.3 0.4 0.5 .0.6 Fn

where:

t Thickness of section

c Chord length of section

The residuary resistance of the appendages in

the

upright resistance proved to be small when related to

the overall resistance, i.e. circa 6-7%, and afthough not

a very robust formulation has been found until now the following formulation proved to yield reliable resufts for

the keels and hulls investigated:

2.3, RESISTANCE OF THE BARE HULL DUE TO HEEL

The resistance increment of the bare hull due

to heel can be assessed at different ways. In the

present paper the following approach will be

used:

SC(W) =SC

.[1±.[so+si

in which:

When analysing the results of the measurements with the bare hull models of the DSYHS under heei special

attention has been paid to the possible systematic

change of the form factor k with heel. The indUced

asymmetry of the heeled hull is believedto influence the

viscous resistance which might be dependent on the

hull form parameters. Such an analysis

is cntical

however, because lift generation all be it small, along the length of the hull may contribute to a small Induced resistance component. Such an analysis :however did

not reveai a systematic change in the form factor due to heei and was therefore notfurther taken into account.

7

R

=A0+A1._L+A2

V.p.g

where:

('r0 +Zk)3

The frictional resist'ance of the bare hull under the given heeiing angle is calculated using the knoWn lines of the

huIl If in the stage of the design process where the VPP is being used the lines of the hull are not yet drawn the

wetted surface of the hull may be approximated by the

use of a polynomial expression valid for the hulls within

the DSYHS and look aiikes'. This expression reads:

s2

..L±s

'Cm])

Using the results oftheDSYHS the residuary resistance ofthe bare hulls when heeled (without leeway) has been

analysed using the same polynomial expression as for the upright hulls but with a new regression to derive a new set of coefficients for the speeds investigated The

geometrical properties of the models had not been

adjusted to account for the possible change due to the heel, i.e. length, beam, draft etc. are unchanged with

respect to the. upright condition. This yields coefficients

for the three different heeling angles. Only one set of the new set of coefficients is given here for the case of

20° of heel and then reads (see Table below): Fn 0.20 0.25 0.30

-

0.35 0.40 0.45

030

0.55 0.60 A,. 0.00185

00385

0.00663 f101160 0.02510 0.04880 0.07880 0.10400 0.12500 A, 0.00556 -0.00025 -0.00192 0.01030 0.02820 0.01740 -f104410 -0.09150 -0.13900 A,

00026

f100032 0.00050. 0.00080 0.00137 0.00237 . 0.00358 0.00434 0.00485 5 10 15 20 25 30 s,. -4.112

4522

-3291 1.850 6.510 12.334 14.648 s1 -0.027 -0.077 -0.118 -0.109 -f1066 0.024 0.102 f1054 -0.132 -0.389 -1.200 -2.305 . .3.911 -5.182 s, 6.329 8.738 8.949 5.364 3.443 1.767 . 3.497

Volume of displacement of keel m3

T Total draft of hUll plus keel m Zb,

Verticai centre of buoyancy of m

keel

and with the coefficients A0 A1 and A, as function of the Froude number (related to the hull):

C.,. Max. cross sectional area coefficient ofthe unappended hull

30 28 26 4 c'J

.20

o 18 12 10 C---a. e---o 5

Ag. 8(a): Measured and calcuiated wetted surface of three models

In general It may be stated that the change in residuary

resistance due to the heel of the bare hull only is quite small, leaving a few exemptions in particular with the

high beam to draft ratio huIls Some resuits Will be

showniaterin this paper.

Another approach to the same phenomenon is under

investigation at present where the change of residuary.

resistance due to heel of the bare

hull is being

addressed. Such an expression is believed lo be more robust in-particular at smaller angles of heel arid Is more easily incorporated in a VPP environment

2.4 APPENDAGE RESISTANCE UNDER HEEL

The resistance increäse due to the presence of the

appendages when the yacht heels over and so brings the appendage volume closer to the free surface has

10 15 20 25

Heeling Angle PHI [DEG]

Measured and Calculated Wetted:Surface.

y

-8

30

been analysed. lt should be noted that It refers to the

situation without sideforce and therefor it should not be conf used with induced resistance.

This induced resistance Is treated In a separate Way

and related to the sldeforce. produced and the efficiency of the hull-keelcombinatlon.

When analysing the resUlts of the DSYHS for the

barehull and the appended hull condition it was found

that the following formulation for the resistance Increase

due to the appendages under heel correlated reasonably well:

dR

rk((p)

p. g

-35 meas 16 meas 25 meas 26

callS

caic 25 calc 26

.FnL

_(p Fn aO

al

a2 a3 a4 a5 a6 a7 aS 0.10

-00Ol0

0.i892 -0.0928 -0.0237 -0.0071 0.0293 -002;l7 -01580 00746 0.15 0.0002 0.2125

-0.l7i7

-0.0012 0.0103

Oi 16

-0.0166 -0.1861 0.1475 0.20

o:ooio

0Ó407 -00238 -0.0078 0.0161

0305

-0.0153 00335 0.0.141 0.25 O0030 -0.0914 0.0011 0.0069 0.0321 0.0087 0.0008 0.0778 0.0095 0.30 00080 1.1i546 _{0.6868 00284 0.0629}

_003l3

_{0.0471 1.0325 -0.5212} 0.35 . 0.01 tO -0.0362 -0.5497 0.0365 0.0987 -0.1237 . 0.1460 -0.1408 0.5957 0.40 0;0290 3.0739 -3.7531 0.3505 0.2250 02615 0.2232 -3.2648 3.2784 0.45

00402

6.2962 -7.1807 0.9689 0.3433

-8963

0.4295 H -6.4137 6.1788 0.50 . 0.0599 0:5707 -3.5819 0.8972 0.7345 0;3677 0.8341 1 .3154 2.7915

7000 5000 4000

i.

3000 2000 1000 7000 6000 5000 4000

z

3000 80l0 o 2000 1000

Resistance Measured vs. Calculated 20 deg heel I I

i

L

'J

9

--- :

-I

L

./'__j

I..,..,,-..

---t

Fig. 8(b): Measured and calculatedwetted surface of three models

Resistance'Measured vs. Calculated 20deg heel

r

i

L.

j

0 . I 0.2 0.25 0.3 0.35 0.4 0.45 Fri

s--calc Riti2O

v--$ cale Rik V cale Rfh2D

6-* caic Rut + cale Rfr caIc CRrk2O meas R120, I 1

H

-1---J---1----+- alcRm2Q

I I

J.

L

calcRdt

I-

-i

caIc RftiO cate Rrr caJC dRrk2O meas R120

FIg. 9:. Measured and calculated resistance of heeled Sysser 24 with zero side force

05

os 0.2 0.25 0.3 0.35 0.4 0.45

in which:

CH. = H1

.i+H2

..!L±H3 -.--+H4

T

_T

T

the coefficients

H' have, been determined using a

regression teòhnique and are presented in the following tabie 7000 6000 5000 4000 3000 2000 lOCO o 0.2

-r

0.25 0.3 ResistanceMeasuredvs Calculated 20'deg heel

L

'----J

m-+Ce$c Pd * cele R1h20 caic R caic Rh cicdRrlO -meas tO 05

Fig. 10: Measured and calculated resistance of heeled Sysser 43 with zero side force

¡3

3. ADDED RESISTANCEOF THE HULL-IN WAVES

Another important component of the total resistance of

a sailing yacht which may become qUite significant

dependent on the prevailing conditions, is the added resistance due to the motions of the yacht ¡n the wind

generated waves. The Incorporation of this added

resistance component into the VPP may be of interest

to the designer because It InflUences the way a design

maybe optImlsed

The inflUence of some design parameters on the added resistance is opposite to their ¡ntlûance on the

caimwater condition and therefor an additional

optimisation procedure with respect to a given design

may arise.

io

For the approximation of the added resistance of sailing

yacht in

waves which may be used

in

a VPP

environment Gerrltsma and Keuning Ref. [.11] presented a method in 1993. In their approach they used the well

known Gerritsma/Beukelman method for the

assessment of the added resistance as described in

Ref. '[6]. In this method-the added resistance of -a ship ¡n regular waves is approximated by. the calculation of the radiated energy ôf the damping waves of the Sections of the ship, accordingto:

in which

? Wavelength m

t Time s

b' Cross sectionaldamping coefficient, corrected for the forward speed

V Relative vertical;.velocfty of the considered cross section with respect:to .the water

T0 Period of waveencounter s

Xb Length ordinate of the hull m The vertical relative velocity Vz depends on the vertical motions heave and pitch and the vertical component of

the Incident wave velocity.

In this approach Vz is

calculated usIng the well known and relatively simple

2-D striptheory without threedimenslonal effects. LwITe

RAW=-'-

_jJ

i IbI.V2.dxbdt

00

Hi

H2 H3 H4 0.1162 0.0436 -0.1165 -0.0059. °35 Fn

1-0.4 I J

-

-e-cacRm2O

In irregular waves for a known wave spectrum the mean

value of the added resistance may be calculated using

the linear superposition principle yielding:

RAW

=2f'

Sç(We)iCOe

in which:

wave amplitude added resistance spectral density

encounter frequency of the waves

In general the added resistance operator dépends on the hull geometry, the longitudinal pitch gyradius the

wave period and the angle of incidence of the incoming waves.

Gerritsma et al, carried out these calculations for a large number of wide varying models belonging to the DSVHS

to determine this added resistance RAO for three

different speeds (i.e. corresponding to Froude numbers

Fn = 0.35, Fn = 0.45 and Fn = 0.60)

5 different headings ranging from 140° (bow quartering waves) to

90° (beam seas). To obtain the mean values

in a

realistic seaway these !RAO's were applied to a. large

number of realistic wavespectra for fully developed sea conditions.

In these calculations the Brettschneider

formulation for the energy distribution of the waves over thefrequency range was used, according to:

S = A

in which:

H

A = 173

i;4

and:

s

wave energy spectral density encounter frequency of the wave H11 significant wave height

T, average period

By analysing the results obtained from these calculations it

appeared that

for constant Froude

number and constant average period of the spectrum

non-dimensioniised by the

shiplength a significant relation between:

the product of the displacement-length ratio and the longitudinal radius of gyratIon

L1 L1

691

j4

11

the mean added resistance non-dimensionlised by division

through the

waterline

length and the

significant waveheight squared:

RAW

.10

= a

102.

.Yf..

b

L1 L1

could be found which yielded a high correlation between calculated and approximated results.

A typical example of such a relation is given in the

Figs. 11 and 12 for two different conditions with respect to the non-dimensional average perIod of the spectrum.

In their original approach Gerrltsrna and Keuning Ref. [7] carried out model tests with two different models

belonging to

the DSYHS which covered each

a

completely different end of the spectrum of

boats

available, Le. one narrow, deep and heavy and the

other beamy, shallow and light. In their experiments it

was shown that there was no real influence of a

possible leeway the hull and s!deforce production on

the appendages on the added resistance of both

hulls.

There was some

influence on the added

resistance due to heel but only for the narrow and deep draft hull.

To further validate these resuits it was decided to carry out additional towing tank tests with a series of models from the systematic Sub-Series No. 4 of the DSVHS in

order to investigate further the applicability of both the strip theory calculations used and the approximation method derived therefrom. The work and the analysis

have been carried out by M Levadou as part of his

Masters Thesis at the Shiphydromechanics Department of the OeUf University of Technology.

The main parameters

of

influence on the added

resistance in waves wereconsidered to be,:

the length -displacement ratio the length to beam ratio

the longitudinal radius of gyration.

So five models from Sub-Series 4 of the DSYHS were selected to be tested in regular waves, i.e. the models

IMS-40-1 to IMS-40-5. Of these models IMS-40-3 is the parent models of the DSYHS Sub-Series 4.

Based on the experience gained from the previous

experiments the models were not equipped with a keel

or rudder. The main particulars of the models and the

variations in the parameters investigated are presented in the Table on page 14.

The experiments have been carried out in the large

(No. 1) towing tank of the Delft Shiphydromechanics Laboratory. This tank is 145m long, 45m wide and has

a waterdepth of 2.5m. A hydraulic actuator type of

wave generator is installed at one side of the tank.

The maximum speed

of the towing carriage is

w

/

r

---.

---. i

I

i

---. I

___-_. I

I

I

-- I

! I

I

L- 3D...i '.3 12 ¿f b

ItAVtAVit

i

Vii

_11T,I, / II I / I.

_{EI VIA VII}

/ ! '1

II.

I!

_\tW%

_{VIA VII}

II

TMiWAWriW

Ikiii

lillA WIIIII

VIJIl 1111111!

1W%. IIMIIWT //

11iIJIIÎ11I

'k1tilEIlA7I

IMS-40-1

IMS-40-4

IMS-40-2

IMS-40-5

(m

!IAr,iptu,1,,

UW%%i NiWDAIIVIW

vzrzisan

-J 0.5 I -q 1.5 o o

Fig. 11: Mean added wave resistance for Fn = 0.35 and T, = 2.475

13

-i aIoN

pioo

j1125'

jj=l35'

. . -. .

/

. . -.

./.:

j

/

;:V..

2'

I/t

/

.1 -W! 3UCTIW

p= 115'

-p= 125rn'

p=135'

I

_qr.-.'4l

..-.

i.-d'f'Y-.. ;. .- 1 o 2 3 vcW

i

Lçt

T-'L

Fig. 12(a): Mean added wave resistance for Fn = 0.35 and T, = 4.4

All tests have been carried out at two different forward speeds of the model corresponding to Fn = 0.265 and Fn = 0.325. For each model a calm water resistance curve has been measured both in the upright condition as well as with 20° of heel (without leeway). Heave

and pitch-motions as well as the added resistance

in waves has been measured with all models in at least

8 different wavelengths and in each wavelength with at least two different wave steepnesses. All tests have

been carried out in head waves only. The results of

these measurements are presented in the Figs. 12(b) to

14 together with computational results. In the present

paper the results for the added resistance in waves

0.3 0.4 0.3 0.1 Added re000u.nce. FN - 0.325, ,----., LmI. ¡36 3 - - - C L1FDsp ¡23 O- - -Q'LTh.p - ¡04

Experiments

Fig 12(b): Dependency of. added resistance on iengthdlsplacement ratio

In Fig. 13 the dependency of the added resistance on the length to. beam ratio Is depicted. From comparison

between the measured and calculated results It may be

seen that the resonance wavelength Is

rather good

predicted by the calculations. There is some discrepancy however in the value of Raw: the

calculations show hardly any influence on LIB and the

measurements considerably less resistance for the

Model Hull Variations

Main Dimensions Models

14

are presented only.

In Fig. 12(b) the Influence of the length-displacement

ratio on the added resistance Is presented, both as

found from the measurements as obtained through

calculation. From these results ft is obvious that the

added resistance. decreases with increasing

displacement when the waves are shorter than the

resonañce wavelength, but Increases With Increasing

displacement for the longer waves. The correlation

between the measurements and the calculations is

good, both quantitatively as qualitatively.

narroW model. For waves shorter than the resonance wavelength the calculations and the measurements

show the same trend:

decreasing resistance with

decreasing beam. In waves longer than the resonance

wavelength the measurements show considerable lower

resistance for the narrow model when compared with

the calculations.

Variation

Model No. L/B . L3,v kyy/L

'Basekull

IMS-40-3 331 123

025

L/B ratio lMS-402 IMS-40-4 2.71 4.16 L3/V ratio .lMS-4O IMS-40-5 . . 104 156

k/L ratio

IMS-40-3 0.30

6 IMS-40-1 IMS-40-2 IMS-40-3 IMS-40-3

: IMS.40-4 IMS-40-5 L... [m 1.71 1.71 1.71 1.71 1.71 1.71

L

[ml 2.09 2.16

2i.i

2.11 2.08

216

B fm] 0.52 0.62

52

0.52 0.41 0.52 T.[mJ

014

0.10 0.12 0.12 0.15 0.09 kyy/L 0.25

0.25:

025

0.30 0.25 0.25 Mass [kql 48.13 40.53 40.53 40.53

453

32.07

i

0.5 1.13 '.159 3.504 O---0 3.13 0.013

Experiments

.A

.

'\

/, 7'1«.,\

8

/

* b. Added resisoance,F0 0.323,., ¡ Lit

FIg. 13: Dependency of the added résistance on the Length to Beam ratio

Of particular interest are the results as presented in

Fig. 14, in

which the dependency

of

the added

resistance on an increase of the longitudinal radius

of gyration is

presented for the parent model of

Sub-Series 4. Here it is obvious that both the

experiments and the calculations predict a considerable

Added reaisoance. FN - 0.325,, -0

Experiments

Fig. 14: Dependency of the addedresistance on the pitch gyradius of the parent model

In general it may be concluded that the 2-D strip theory

calculations together with the Gerritsrna/Beukelman

approximation for the added resistance of a ship in

regular waves yields quite satisfactory results when

compared with the actual towing tank measurements for a wide variety of yacht hulls.

Based on these results the added resistance of the

5 yachts. in irregular waves as also been calculated

using the method as described earlier. The results

of these calculations have been compared with the

15 0.5 0.0 0.l Seaway, FN -.0.325.t 180 -Q 1.13 '45$ 0 LII - 0.497 q LII 3.004

G-0 LII

3j

Q-0 LIB . 3.071

SEAWAY....

Lit

increase in the added resistance with waves longer than the resonance wavelength. For the shorter waves there is hardly any difference. The calculated results show in

general a somewhàt higher added resistance than the

measured resultsaithough the trends arefully identical.

approximation method as given by the same authors in

Ref. [il].

These results have been found to fit fairly well within the accuracy bandwidth of the presented

method.

However an extension of this approximation method to

take 'into account the more pronounced effect on the added resistance of the Length to Beam ratio is been considered at the moment: This appears to be quite

possiblewithin the framework of the presented method.

4 X 04

o---0

- 0:0 0.a 04 04 03 0.: 0.I

4. CONCLUSIONS

From the results presented above it may be concluded

that he original method to predict the resistance of a sailing yacht hull (without sidelorce) as presented in Ref. [li] has been extended considerably. The present

method makes It possible to. calcuIate this resistance of

a wider variety of designs in calm water and in waves

with an improved accuracy.

REFERENCES

[ii

GERRITSMA, J., and KEUNING, JLA.:

Performance of light, and heavy displacement

sailing yachts in Waves, The SecOnd Tampa Bay

Sailing Yacht Symposium St Petersburg Florida

1988.

MONHAUPT, A;: Comparative study of different polynomial formulations for the residuary

resistance of the Systematic Delft Series

Model ito 28', lTG.

REUMER, J.G.: Een ontwerp voor een

eenvoudige polynoombenadering van de

toegevoegde weerstand ban zeiljachten in

golven', Technische Universiteit Delft

Afstudeerwerk, Rapport No. 874-S, 1991.

GERRITSMA, J.,

and MOEVES, G.:

The

seakeeping performance and steering properties

of sailing yachts', 3rd HISWA Symposium, 1973

Amstèrdam.

GERRITSMA, J., MOEYES, G.. and ONNINK, R:

'Test results of a systematic yacht hull series',

5th HISWA Symposium, 1977, Amsterdam.

GERRITSMA, J., ONNINK. R, and VERSLUIS, A:

'Geometry, resistance and stability of the DeIft

Systematic Yacht Hull Series', 7th HISWA

Symposium, 1981, Amsterdam.

GERRlTSMA J;, KEUNING, J.A;, and ONNINK,

R.,: 'The Deift Systematic Yacht Hull Series Il

experIments', 10th Chesapeake Sailing Yacht

Symposium, 1991. Annapolis.

GERRITSMA, J., and BEUKELMAN W;: Analysis of the resistance increase In waves of a

last cargo ship', International Shipbuilding

Progress, Vol. 19, No. 21:7, 1972.

GERRITSMA, !ONNINK, R, and VERSLUIS, A.

'Geometry, resistance and stability of the Dettt

Systematic Yacht Hull

Series', International

Shipbuilding Progress, Vol. 28, No. 328, 1981.

16

[10) GERRITSMA, J., and KEUNING J.A.:

'Performance of light and heavy displacement

sailing yachts In waves', Marine Technology,

Vol. 26, No. 1, 1989.

[il]

GERRITSMÄ, J., KEUNING, J.A., and

VERSLUIS, A.: 'Sailing yacht performance in

calm water and waves',

11th Chesapeake

Sailing Yacht Symposium, SNAME, 1993.

KEUNING, J.A;, ONNINK R., VERSLUIS, A.,

and VAN GULIK, A.: 'The bare hull reslstance of the DeIft Systematic Yacht Hull Series',

International

HISWA Symposium on

Yacht

Design and Construction, Amsterdam RAI, 1996.

HOERNER: 'Fluid-Dynamic Drag', 1965.

TALLOTE, C.: 'Adaption de procedures

experimentales au òas de voiliers en gite et

derive, comparaison des resultats experimentaux et numenques', Doctors thesis Ecole Doctorale

Sciences pour L'lngenieur de Nantes, 1994.

TEETERS, J.R.: 'Refinements in the techniques

of tank testing sailing yachts and the processing

of test data', 11th Chesapeake Sailing Yacht

Symposium, SNAME, 1993.

ABBOTT, l.H.,

and VON DOENHOFF, A.E.:

Theory of wing sections'.

KEUNING, J.A., and KAPSENBERG, G.: 'Wing

-body interaction on a sailing yacht

Report

1019-P, 1995.

KEUNING, J.A.,. and BINKHORST. B.J.:

'Appendage resistance of sailing yacht hull',

13th Chesapeake Sailing Yacht Symposium,

1997.

[191 SCLAVOUNOS, P.D., and NAKOS, DE.:

'Seakeeping and added resistance of IACC

yachts by a three-dimensional panel method',

i ith Chesapeake Sailing

Yacht Symposium,

SNAME, 1993.

[20] KEUNING, J.A., GERRITSMA, J., and

TERWISGA, P.F.: 'Resistance tests of a series

planing hull forms with 30° deadrise angle, and a

calcUlation model based on this and similar