previous sailing yachts seakeeping investigation in...

Previous sailing yachts seakeeping

investigation in view of a new set of rules

Adrien Combourieu

Academic Supervisor: Prof. Dario Boote, UNIGE

Industrial Supervisor: Flavio Faloci, RINA

External Reviewer: Prof. Leonard Domnisoru, UGAL

La Spezia, 25th of January 2013

Contents

Introduction

Method for quick pitch RAO estimation

State-of-the-art method for motion in irregular sea prevision

Conclusions

Erasmus Master Course in Advanced Ship Design

3

25/01/13

Introduction - Objectives

Yacht dismasting investigation

Seakeeping => inertial loads

Acceleration mainly due to pitch

Hydrostar: potential seakeeping code in frequency domain (BV)

Classification society => quick method

Key parameters?

25/01/13 Erasmus Master Course in Advanced Ship Design

4

Introduction – Database


5

7 modern sailing boat hulls

name

LOA (m)

Lwl (m)

B (m)

T canoe (m)

Displacement (kg)

ballast mass (kg)

kyy (m)

SW 31.3 30.4 6.8 1.08 83856 18700 8.70

swan 90 26.8 24.9 6.6 0.95 56726 18400 7.08

oyster 82 24.8 20.9 6.3 1.29 61085 20243 6.33

swan 66 20.3 17.8 5.4 0.90 31030 9400 5.37

ref2 14.5 12.8 4.3 0.66 12877 4507 3.63

AME004 11.3 10.3 3.1 0.44 5381 1883 2.79

J80 8.0 7.0 2.5 0.34 1825 635 2.11


6

Waterline length Lwl



RAO: 2 representations


7

0 10 20 30 40 50 60 70 80 900

0.2

0.4

0.6

0.8

1

amplitude pitch.rao

lambda (m)

pitch.r

ao(r

ad/r

ad)

180°

0 0.1 0.2 0.3 0.4 0.5 0.6 0.70

2

4

6

8

10

12

14amplitude pitch.rao

f (Hz)

pitch.r

ao

(

deg/m )

180°

L1

L0

f0 f1 fres

pmax



8

λ>L1

λ<L0

L1≈2*Lwl

L0≈0.5*Lwl



9

Regression on 7 hulls

λres = 1.2485Lwl + 0.0331

R² = 0.9909

0

5

10

15

20

25

30

35

40

45

0,00 10,00 20,00 30,00 40,00

λre

s (m

)

Lwl (m)

λres

Linéaire (λres)

fres = 1.118/sqrt(Lwl)



10



pmax = 39.985e-0.06Lwl

y = 39.985e-0.06x

R² = 0.9728 0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

0,00 10,00 20,00 30,00 40,00

ma

xim

um

pit

ch a

mp

litu

de

(°)

waterline length (m)

pitch max

Expon. (pitch max)



11



pmax = 39.985e-0.06Lwl

y = 0,4287x + 0,6819

R² = 0,9883

0

2

4

6

8

10

12

14

16

0,00 10,00 20,00 30,00 40,00

λ0

(m

)

Lwl (m)

λ0(5%)

Linéaire (λ0(5%))

L0 = 0.429Lwl



12



pmax = 39.985e-0.06Lwl

y = 2,4512x - 6,5245

R² = 0,8352 0

10

20

30

40

50

60

70

80

90

0,00 10,00 20,00 30,00 40,00

λ1

(m

)

Lwl (m)

λ1 (95%)

Linéaire (λ1 (95%))

L0 = 0.429Lwl

L1 = 2.5Lwl



13

Results on Kiboko

0 0.1 0.2 0.3 0.4 0.5 0.60

1

2

3

4

5

6

7

8

amplitude pitch.rao

f (Hz)

pitch.r

ao

(

deg/m )

180°

Pitch in irregular sea


14

0 0.1 0.2 0.3 0.4 0.5 0.6 0.70

2

4

6

8

10

12

14amplitude pitch.rao

f (Hz)

pitch.r

ao

(

deg/m )

180°

X

2

Frequency domain



15

Time domain

0 5 10 15 20 25 30 35-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

0.25wave time serie

t (s)

Wave a

mplit

ude (

m)

0 5 10 15 20 25 30 35

-3

-2

-1

0

1

2

3

pitch.rao time serie

t (s)

deg/m

*m



16

Comparison with experimental results for J80

•In pure front waves

•speed = 5 knots.

•Hs=0.3m

•Tp = 2.251s

•ɣ=3.3 (closed basin)

•No heel angle

Augier, B., Bot, P., Hauville, F., Durand, M., (2012), “Experimental validation of unsteady models for fluid

structure interaction: Application to yacht sails and rigs”. Journal of Wind Engineering and Industrial

Aerodynamics, 101 (2012), pp 53–66

Experimental

Numerical



17

Results for kiboko in irregular head sea without speed

Numerical

Empirical

Conclusion


18

Critical parameters: Lwl, kyy, V, stern (bow) shape, heading

Simplified method for head sea without forward speed using only

Lwl. To be improved taking into account more parameters.

Regression on bigger database

Method for pitch prediction in function of wind speed to be

compared with experimental results

Thank you for your attention

Questions ?


19

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