1

Design of High Speed Craft – The human factor

Dominic A. Hudson

School of Engineering Sciences, Ship Science, University of Southampton, Southampton, UK.

17th Annual Engineering Conference, Malta

17th April 2008

2

High Speed Craft Applications• Planing craft (up to ~80 kts) – now often RIBs

– Life-saving (e.g. RNLI in UK)

– Leisure

• Excursions, dive boats• Personal• Racing powerboats

– Military and para-military

– Offshore industry – variety of roles

3

What is the Problem?

4

100 102 104 106 108 110 112 114 116-2

0

2

4

6

8

10

Time (s)

Acc

ele

tatio

n (

g)

Vertical accleration at bowVertical acceleration at CG

slam impactno slam

slam at bow,no slam at CG

What is the Problem?

• Repeated shock impacts lead to:

– Lower back damage

– Knee injuries

• Depends on:

– Waves

– Hullform

– Boat speed

• 20 Kts

• Sea-state 3

5

Constant Speed Shuttle Run Test

636.9

1063.4

0 200 400 600 800 1000 1200

Pre

Post

Distance run (m)

• 12 subjects

• 8.5m RIB, 40 kts, 1hr 40 min

• Sea-state 0-1

What is the Problem?• Crew effectiveness

reduced:

– Physical performance

– Cognitive ability

• Factors:

– Day/night

– Temperature

– Sound

– Smell

– Everyone is different!

6

Solutions?

• Currently design boats for:

– Speed, strength, range, weight, cost, etc.– Consider people later……… – EU Physical Agents Directive enforced

2010

• Can we design for people from the start?

• Or mitigate problems by

– Structural design?– Seat design?

7

Research Effort• ~ 1 million EPSRC grant₤

• Univ. of Southampton – SES (Ship design)

– Prof. R. Shenoi, Prof. J. Xing, Dr. D. Hudson, Dr. S. Turnock, Dr. D. Taunton, Dr. J. Blake, S. Lewis, T. Coe.

• Univ. of Southampton – ISVR (Signal Processing)

– Prof. R. Allen, Dr. D. Allen

• Univ. of Chichester (Sports Science)

– Dr. R. Dyson, Prof. T. McMorris, Dr. T. Dobbins, S. Myers

• Additional funding:

Royal Academy of Engineering, School of Engineering Sciences

8

Full-scale Tests• Measurement techniques

• Quantify/characterise– Motions– Vibration dose values– Physiological data

• Person in ‘real’ situation

Very difficult

9

Full-Scale Results

67 67.5 68 68.5 69

-4

-2

0

2

4

6

8

Time (s)

Acc

ele

ratio

n (

g)

109.5 110 110.5 111 111.5

-2

0

2

4

6

8

Time (s)131.5 132 132.5 133 133.5-3

-2

-1

0

1

2

3

4

5

6

7

Time (s)

x directiony directionz direction

67 67.5 68 68.5 69

-4

-2

0

2

4

6

8

Time (s)

Acc

ele

ratio

n (

g)

109.5 110 110.5 111 111.5

-2

0

2

4

6

8

Time (s)131.5 132 132.5 133 133.5-3

-2

-1

0

1

2

3

4

5

6

7

Time (s)

Top 3 Acceleration Events at the CG

Top 3 Acceleration Events at the Bow

Results – VDV ‘action levels’

Comparison of Average 'Time to VDV Action levels' for all headings and axis

2.766

4.9536.380

2.356

5.887

4.1544.127

10.075

26.916

9.453

34.811

19.009

0.1641.451

6.268

0.516

6.181

2.979

0

5

10

15

20

25

30

35

40

Head Sea (at sea) Beam Sea (at sea) Following Sea (at sea) Head (in channel) Following (in Chanel) Total Average

Heading (location)

Tim

e to

VD

V A

ctio

n le

vel o

f 15

(h

ou

rs)

Time to 15 X Time to 15 Y Time to 15 Z

~10 mins

Results – Spinal health risk (ISO 2631-5)

Health Effect Predictions from Full Scale Trials Data

0

0.5

1

1.5

2

2.5

3

3.5

Record Attempt Working Life

Hypothetical Situation

Sp

ina

l H

ea

lth

Ris

k F

ac

tor,

R

Head Following Beam Lower Limit Upper Limit

12

Full-scale ResultsHeart rate and Oxygen consumption

0%

10%

20%

30%

40%

50%

60%

70%

1 11 21 31 41 51 61 71 81 91 101 111

Time (minutes)

Perc

en

tag

e m

axim

al

Heart

rate

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

Perc

en

tag

e V

O2m

ax

heart rate VO2

13

Numerical Modelling• 2D strip theory (after Zarnick)

• Wedge-impact model

• Non-linear, time domain

• Regular or irregular waves

• Well-known ‘conventional’ hulls

• Work on

– Validation

– Front-end GUI

• Limits

– hull form (RIB, VSV)?

– speed?

14

Model Tests

• Validate numerical code

• 2 models tested

– Wave-piercing RIB ‘Kali’

– RNLI Atlantic 21 RIB

• Limitations

– Only head seas

– V. short run time (~3 sec)

15

Results - comparison

33 34 35 36 37 38 39 40-2

0

2

4

6Full Scale

Time(s)

47 48 49 50 51 52 53 54-2

0

2

4

6

Acce

lera

tio

n (

g)

Model

39 40 41 42 43 44 45-2

0

2

4

6Numerical

CGBow

Current Work

Human spine model

Flow simulation

+ Design optimisation, ongoing model, full-scale testing

17

See the Posters!

18

Future Aims• Design boat to comply with EU directive

– Test boat = 21 mins

– ‘best’ planing hull = ~1 hour

– Target = 8 hours

• Co-operate with designers, builders, operators, MCA

• Understand human – boat interface

• Trusted design and simulation tools

• Tailor solutions to applications