A high performance automatic wingsail auxiliary propulsion system for commercial ships

Journal of Wind Engineering and Industrial Aerodynamics, 20 (1985) 83---96 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands

A HIGH PERFORMANCE AUTOMATIC WINGSAIL AUXILIARY PROPULSION SYSTEM FOR COMMERCIAL SHIPS by JOHN G. WALKER (WALKER WINGSAIL SYSTEMS LIMITED)

ABSTRACT Wingsail

auxiliary

0304-3908/85/$03.30

ship propulsion

systems.

© 1985 Elsevier Science Publishers B.V.

83

84 WINGSAIL HISTORY

It m u s t

have

occurred

to t r y f i t t i n g already

been

a remarkable

So f a r as w e German

know,

Anton

the

Flettner,

wings to p r o ~ l

He o b t a i n e d

to m a n y

experimenters

the new fangled

aeroplane

plan

first who

the backing

in 1712 to propel engineer

in the e a r l y

the "Buckau",

in the e a r l y

to

twenties

at H a m b u r g ,

w h e n F l e t t n e r b e c a m e o b s e s s e d w i t h his famous of persuasion, got her

rotors,

course.

The project

reappeared War

and the "Barbara"

as a

then fizzled

leading

figure

and designs

Flettner

were well

metal

advanced

By an a m a z i n g

their a l l e g i a n c e . were a l s o

not surfacing

helicopter

the

fitted again

progra~e

feat

"Buckau" in due

until

he

during World

II.

We b e l i e v e , effect work,

of c o u r s e ,

rotor suffers

The next working

but w i n d w a r d

experimenter in N o r w a y

excellent

little

that

a major

from the very

of a f u n d a m e n t a l l y

in plenty,

poor

to m a k e

a

in t h e y e a r s

known

to us.

occupying

forces as "a potential

ratio.

significant immediately

She

of

was,

judgment

w a s made.

disadvantage,

tends to be

boat "Flaunder"(Fig.

vessel

2

error

serious

lift/drag

efficiency

trimming

Fig.

out,

was

i).

rotor concept.

in the G e r m a n

system

self-tricing

(Fig.

and the "Baden Baden"

century

there had

w i t h a wind turbine.

a workable

suggested

he caused the Krupp b o a r d to transfer

of this

After all

a vessel

propose

a 150 tonne b a r q u e n t i n e

of K r u p p s

years

w i n g s t o ships.

Thus o f f w i n d

force

contribution the

was

Fin

Second

2) w a s t h e f i r s t f u l l y

w e a p o n of war"

is a v a i l a b l e

lacking.

before

most

The Magnus

for s h i p p r o p u l s i o n

sadly,

destroyed

Utne,

World

who was

War.

His

worked out self by

the

German

85 Our own work in the field started in the late sixties, with P l a n e s a i l a 10m long wingsail aerofoil

p r o p e l l e d cruiser.

(Fig. 3),

She shared a simple symmetrical type of

section with "Flaunder" but had four main

sail

panels

instead of one,

to provide extra thrust, and she worked e x t r e m e l y well. In p a r a l l e l

with these ventures

in the field of self

were many attempts to fit wings to boats and to control by c o n v e n t i o n a l is b e c a u s e

of

sheets, the

far

push rods, higher

motors etc.,

demands

efficient high aspect ratio wing.

made

A c l o t h sail

ratio wingsail) is much "easier on the sheets." in Fig.

their angle to the wind

of which had failed. the

trimming

This

system

(or a low efficiency,

by

an

low aspect

This is g r a p h i c a l l y i l l u s t r a t e d

4, which shows curves of crosswind force against angle of incidence for

a typical wide

all

upon

trimming w i n g s a i l s there

efficient wingsail and a low efficiency cloth

tolerance

shown

c o n t r o l l e d by slow, inexorably

by

the

low

efficiency

even manual means.

device

(or rigid) device. means

that

it

can

The be

The search for high efficiency leads one

t o w a r d s s y s t e m s n e e d i n g v e r y r a p i d a n g l e t r i m m i n g rates, and t h u s

l o g i c a l l y to the self trimming wingsail. Fig. 3

8B 3.0

"~.0

4.o

Fig.

c~ AN~L~-

4

OF- A - [ T A C ~

SYSTEM DEFINITION

Modern

motor

ships

r u n n i n g costs,

have

bunker

and the p r e s e n t

of the b u n k e r cost r e d u c t i o n s To e n a b l e

a given

system

should p e r f o r m well

2.

High course efficiency. course c i r c l e

at a n o m i n a l

Safety,

in structural,

4.

Low or n e g l i g i b l e

thrust

o p e r a t i o n and failsafe

directly

period.

while

from

the wind;

figures b e l o w

terms.

This

a maximum

of

is

the

result

of

an

a w i d e range of course angles,

a m o u n t s of f u e l , r e l i a b l e for

system;

towards

c r e w demands.

strongly over

attainable.

it

in the v e s s e l

Thus 100% w o u l d o n l y be a v a i l a b l e

of g i v i n g

for a w i n g s a i l

aim

field,

This we d e f i n e as the p e r c e n t a g e of the 360 d e g r e e

system effectiveness.

pay-back

in t h e

o v e r w h i c h forward thrust can be a p p l i e d

60% suggest rather poor overall

Short

cost by such systems.

contribution

80% w o u l d be a v e r y good figure

thrusting

of total

arises b e c a u s e

levels in a given w i n d per unit size.

system capable

3.

5.

40-60%

assistance

low c a p i t a l

a worthwhile

i0 knot forward speed.

turbine

a m o u n t to some

against the f o l l o w i n g criteria:

High m a x i m u m t h r u s t

a wind

costs w h i c h

o f f e r e d at quite

to m a k e

I.

total

fuel

thrust t o w a r d s w i n g s a i l

and cheap to maintain,

3 years,

and

1.5 to

with

2.5 y e a r s

efficient saving

system,

considerable

l o w f i r s t cost. seems

likely

to

We be

87 THEORY AND PRACTICE

All

the aerodynamic d e v i c e s

proposed to extract solar energy from the wind for

ship p r o p u l s i o n work on e x a c t l y the same principle, and using the r e s u l t a n t reaction force in some way. opposed

reactions,

and so the o u t p u t

transmission system. the vessel,

Auto-rotation

so do all

is a t o r q u e

systems

of d e f l e c t i n g

the air flow

Turbines have s y ~ n e t r i c a l l y calling

for

some

f o r m of

(autogyros) react direct force on to

Magnus effect rotors,

circulation

control

columns,

wings

and cloth sails. The

best

plotting

way

to

visualise

crosswind

force

this

deflection

coefficient

against

is p e r h a p s downwind

the

drag

envelope force

curve,

coefficient,

giving a characteristic symmetrical butterfly shape (Fig. 5).

L/D =

/

(

1oPPo~crE

TkCv..

CI

FO ~ C £

Fig. 5 The three main parameters measured by this graph are: m a x i m u m crosswind force coefficient

All

(A)

optimum crosswind force/drag ratio

(B)

maximum downwind force coefficient

(fully stalled)

vessels

apart from specialised

a b l e to p e r f o r m

(C and C')

o n e - t r a c k o n l y r e c o r d b r e a k e r s n e e d to be

just as w e l l on the p o r t t a c k as on s t a r b o a r d .

s y m m e t r i c a l l y i n v e r t a b l e configurations,

This requires

which can fall into one of two possible

types: Symmetry across the wind line.

This group includes all square rigged ships, and

the Nippon Kokan system for example. Symmetry

along

the wind

line.

This group includes

all

fore and aft r i g g e d

yachts, and our own self trimming wingsail systems. The c h o i c e is i m p o r t a n t , e s p e c i a l l y

for h i g h l y e f f i c i e n t c o m p u t e r c o n t r o l l e d

systems suitable for fitment to modern minimally manned commercial vessels.

88 In Fig. 6 a c r o s s w i n d wingsail device.

force/angle

of a t t a c k c u r v e is d r a w n for a h y p o t h e t i c a l

It can easily be seen that if X is a "maximum permitted" anq[~

c h o s e n to p r e v e n t u n w a n t e d s t a l l i n g ,

( u n d e s i r a b l e b e c a u s e of s h a r p l y r e d u c e d

c r o s s w i n d force, i n c r e a s e d d r a g and the l a r g e " h y s t e r e s i s establish

a s m o o t h flow)

- then a t r i m m i n g

angular excursions from the set level, a less e f f i c i e n t the set level

will

system,

loop" n e e d e d to re-

A, p e r m i t t i n g

only

small

produce a higher mean thrust B than

t r i m m i n g system, C, p e r m i t t i n g w i d e r a n g u l a r e x c u r s i o n s

and giving a mean thrust level

device.

D, from exactly

/ ) M E A N T H R U S T OF C O N T R O L SYSTEM

B CROSSWIND FORCE

from

the same wingsail

~

' A'

D

CONTROL

Fig. 6 ANGLE

The efficiency of a trimming to rotate the wingsail

SYSTEM

'B'

0Y ATTACK

system is a function of the energy

against inertia and air

loads.

levels required

The "crosswind symmetry"

style of wingsail

system suffers in this respect because the pivot axis must be

at

in the

the

50%

point

chord

width,

while

the

c a m b e r e d s u r f a c e u s u a l ly acts at a p p r o x i m a t e l y leading edge

total

output

force

from

a

33% of the c h o r d b a c k from the

(or "luff").

Thus, t h e r e w i l l ship p r o p u l s i o n

always

be a m o m e n t of some 0.17 x c h o r d x force, a m o u n t i n g in

sized systems to many tonnes.metres of torque,

to be reacted by

the trimming system in addition to the effects of inertia, when the system tries to turn the wingsail

so as to avoid the highly undesirable stal 1 (Fig. 7).

FORCE

F

SUSTAINING

Fig. 7

MOMENT

REQUIRED

89

AIR DIRECTOR

Fig.

8

"Wind-line placed

symmetry"

by the d e s i g n e r s

system.

Thus,

automatic

governing

The aerofoil no less vital

when configured downwind

external

torques

easily

hold

Its

centre

thick

rounded internal

minimal

thrusting.

it c l o s e

zone should. resistance,

to p o i n t

a simple

'X' o n

and a longer

chord

cambered

(to port or,

image,

mode, useful

manoeuvring.

(Fig.

in mirror

8),

gives

for power-off

a

tests

of

spent

on this

tested

low downwind

drag when configured are

specifically avoiding

free,

with

reliable curve

safe,

control 6),

for

the n e e d for

extremely

(Fig.

at

drag

adapted

zone behaves

This a l l o w s combined

exactly

power-off low

system

airmay

giving

real

section,

with

predictions.

a short

chord

flap both c o u p l e d

modes

flat

very

design,

and

and we have

tunnel

of pressure

output

of three main elements,

T h e r e are t w o p r i m a r y

envelope,

the

very close to theoretical

consists

elements

structural

Thus

trimming

capable

independently

3.0, with

and its centre

air

on the

designs

of wind

has b e e n

than

section

hinges.

The

series

section

of more

of pressure

with

when

an air director

demands

trimmed

axis can be

can be produced.

separate

JW05-3

thrust

and stiff

w o r l d effectiveness

The section

torque

tail

for upwind work, and very high downwind

a light

as a wingsail

load

operation

and t w e l v e

masts or bracing wires;

weather-cocking

air

reliable

and the pivot

to be u s e d is of c o u r s e m o s t i m p o r t a n t ,

crosswind

running.

to a l l o w

fast,

Our present

of

this disadvantage,

and fail-safe

section

subject.

avoid

to m i n i m i s e

efficient,

than nine years

coefficients

load

systems

of o p e r a t i o n

leading

to it by simple

- flat

and robust

(or s y m m e t r i c a l )

and

to starboard).

low-drag,

alongside

low

situations

maximum and

thrust

performance

low speed close quarters

90

I

---4 /

l

Fig.

9

Maximum

cross-wind

mode,

while

(Fig.

9).

In

the

cambered

carefully

crosswind to s o m e

2.0; JW05-3 force

Fig.

force

flap

and

slotted

air

before

3.0.

director

of i n c i d e n c e

of

stall,

up to 35 to 40 degrees of

one third

of t h a t

move

flap configuration

of Flaunder

coefficients

20 d e g r e e s

turns

is a p p r o x i m a t e l y

is less t h a n t h a t of an e q u i v a l e n t

in a n g l e

wingsails

coefficient

i0

the

single

increases

p l a i n symmetrical

rotate

drag

mode

profiled

considerable

with

thrust

downwind

before

and Planesail 1.0;

highly

giving before

to p o s i t i o n s (Fig.

stall. stall

giving

This

a

allows

For e x a m p l e ,

cambered

with

i0).

the

at 12 to 15 degrees, unslotted

coefficients stall,

in the c a m b e r e d m a s t or d e r r i c k

rather

a maximum

shapes

less t h a n crosswind

91 SO far as m a x i m u m

downwind

very

can achieve

few devices

specially

designed

on s i n c e about

and

much more

parachutes

our early

0.5,

d r a g is c o n c e r n e d ,

and spinnakers.

symmetrical

we

now

than

days,

achieve

for s a i l i n g

over

f r o m t h e wind,

of a b o u t

1.2,

even

Our section design work has m o v e d

with downwind

just

away

a coefficient

1.3,

drag

quite

coefficients close

to

of o n l y

the

maximum

theoretical ly obtainable.

All

our primary wind tunnel

one metre JW05-3

span and 0.3m chord,

section

displays

the g r a p h s

for 10 m / s

interested

in t r i p l a n e

model,

work has been performed with m o d e l s

with which

fitted with end p l a t e s

extremely a n d 75 m / s

tolerant

and tested at 25 m/s. Number

characteristics,

a r e v i r t u a l ly i d e n t i c a l .

configurations,

such v a r i a b l e s

Reynolds

we also

as spacing

and

of a p p r o x i m a t e l y

have

Since

a triplane

stagger

have

we

are

wind

The and very

tunnel

been e x h a u s t i v e l y

analysed.

While more where

our e a r l y recent the

work

wind tunnel has

been

enthusiastic

test was carried

done

support

at

Cambridge

and

In

1976

prototype

we

initiated

2 form

2.7, as against

ii

over

(capable

of

Aerospace

University,

Engineering

Professor

the

Department,

Austyn

Mair

has

Filton.

- THE FLYER PROGRAMME

a programme

and demonstration

in its D a s h

Fig.

TESTING

University

encouragement

been a very great h e l p to us, and at British

FULL SIZE PROTOTYPE

out at Southampton

craft

aimed called

of a m a x i m u m

3.0 for the present

at

the

Flyer.

construction She

crosswind Dash

3).

utilizes force

of

a full

the JW05

coefficient

size

section of s o m e

92 Flyer

(Fig.

II)

free r o t a t i o n tail

vane

Filton are

a

the water,

controlled

Flyer

switched

to

yet

thrust

The

we

Flyer our

have

Fully

has shown

product

by

designed power

and the w h o l e

by

pack,

system

has

satisfaction,

thrust very

drag.

In

stationary

standing

silent

now

from zero to force

when

when

and

valves,

availability

low

lie quite

chaseboat

giving

control

5,

the

so desired,

the

computer

is

seen

sailing

and m o s t

she runs a w a y than

be be reliable, identical

of

the

of our Flyer

of

the

silent

f r o m the w i n d q u i e t l y not

only

on

and this

strong and c o n t r o l l a b l e , in M o d u l e

and gives

2 will

provide a

for ship propulsion.

JW05-3

and sought

section

criteria

trimming,

using

trace

a comparatively

may go a l o n g s i d e circle"

a tail

vane,

is t h a t

large

quays and other is

propulsive

configuration.

A natural

well

vessels,

within

thrusting

Here a central

the

area

the

vane

into

on

its

this

main sail panel

boom

view.

it is n a t u r a l l y We

according

for v e r y

to

careful

of the decision to go

in p l a n

beam.

place.

of ships,

2, c a l l e d

corollary

circle

product needs very

in the market

to the p r o p u l s i o n

testing work.

for s e l f

out

but a v i a b l e

after

set out in S e c t i o n

tends

possible

25 d e g r e e s

and e x h i l a r a t i n g

Planesail,

technology

t e s t s a n d t h e o r y are a l l v e r y w e l l ,

"trimming

within

abundant

2 SYSTEM DESIGN

evaluation

triplane

will

performance

if it is to be valuable

application

maximum

specially

The h y d r a u l i c

with

70hp

stalled,

itself

definition

this

union

are

to the h u l l

a DC e l e c t r o h y d r a u l i c

of great

already

far greater

the s y s t e m

vessel

actuation

but on a l l o t h e r s as w e l l .

THE MODULE

to

vane

the s a i l s e t

Franklin,

progressive

"closehauled",

showing

most acceptable

Wind tunnel

including Spencer

give

us e v e r y hope that the v i r t u a l l y

much more,

rotary

direction

leaving

but

when

p o i n t of s a i l i n g ,

TOWARDS

four-way

as p l a n n e d .

experienced,

off the wind.

The sailset

and

on a ratio

"Ahead".

wind

effectively,

Flap

connecting

been a source

exactly

and

boom.

mounted

by a low a s p e c t

and sensitivity.

crosswind

away

continue,

apparent

has

wingsail

It is t r i m m e d

pathways

hydraulics,

by microprocessor,

wind

lower

friction

reliability

thrust

accelerating

a 7.2m x 2.5m s i n g l e

Ltd and p a r t l y

in e i t h e r

highest

Tests

low

by U C C

controllable

maximum

a single

The other

partly

with

four hydraulic

through Ltd.

long,

ring type bearing.

on

means,

worked with great

On

10m

mounted

hydraulic passing

is

slewing

desirable

therefore,

circle,

to

decided

is flanked

or b o o m s

So t h a t

the that

get

the

upon

the

by two

93 lighter ones, all three being c o n t r o l l e d by a single tail vane assembly. is of course some 5%-8% m u l t i p l a n e

loss in using such a layout.

There

The triplane

a l s o p r o v i d e s quite high e f f e c t i v e aspect ratios for good course efficiency. Module

2 has therefore three main panels, almost identical

rib h i n g e d e t a i l s The r e s u l t i n g

to M o d u l e

sailset

I, but e a c h p a n e l

in c h o r d w i d t h and

is 13.5m h i g h i n s t e a d of 7.2m.

(Fig. 12) has a n o m i n a l t h r u s t a r e a of 101 sq. m., and is

r a t e d at 2.5 t o n n e s of s t a t i c t h r u s t in a 25kt (13 m/s) b e a m wind.

The m a x i m u m

force a v a i l a b l e is 6 tonnes. The s a i l s e t s

are of m a i n l y

aerospace m a t e r i a l s panels

have

the c e n t r a l loads.

reinforced

plastics

such as p o l y m e t h a c r i l i m i d e

identical

external

design,

foams

section profiles,

calling

and epoxide

upon modern resins.

to reduce tooling

All

costs,

but

p a n e l h a s a v e r y r o b u s t s t e e l m a i n s p a r c a r r y i n g a l l the b e n d i n g

At the b o t t o m ,

this

is f l a n g e m o u n t e d

to a p r o p r i e t a r y

low friction

slewing ring main bearing.

I

1

Fig. 12 Both vane and flap have closed accepts

information

loop servo control

from transducers

g i v i n g wind

systems. speed,

The computer itself

apparent wind angle

to

the ships c e n t r e l i n e and apparent wind a n g l e to the sailset centreline. In operation,

the computer system configures and angles

optimum thrust available. the wingsails, for.

The

main

and whether close hauled, engine

will

be

reaching or running settings are c a l l e d

automatically

throttled

s t r e n g t h rises, or the c o u r s e a n g l e or w i n d d i r e c t i o n then

the

main

engine

p r o g r e s s i v e l y more fuel.

or

the sailset to give the

This process includes deciding on which tack to angle

engines

will

reduce

power

back.

If the

wind

become more favourable, further,

thus

saving

94 If

the

chosen

computer w i l l

A

full

diagnostic

approximately are

course

bridge,

the

+/-

If

the

the

checking

weather-cocking

s a f e l y until

NAVAL A R C H I T E C T U R A L

the f a u l t

our

It w i l l

be

sailsets

are a b o v e

noticed

a

fault

for

and m e c h a n i c s

which

at

procedures

there

shewing a red

go to i t s

the drag.

is

no

light on the

symmetrical

settings,

CONSIDERATIONS

that the b r i d g e has as full

most cases panel

to w i n d w a r d ,

can be a t t e n d e d to.

It is i m p o r t a n t

of the s a i l s e t s

dead

thrust and m i n i m a l

hydraulics

cut its power,

automatically

therefore

mount

zone

electronics,

discovers

the s y s t e m w i l l will

degree

and a range of p h a s e d c l o s e - d o w n

computer

sailset

20

g i v i n g no c r o s s w i n d

one second i n t e r v a l s ,

available,

and

in

programme,

available.

redundancy

lies

feather the sailsets,

that

on t u b u l a r

a f i e l d of v i e w as possible,

steel

columns,

so that

the upper edges of the b r i d g e w i n d o w s

only

heights will

very

moderate

approximate

height

sailsets

the

(Fig.

are

and we

lower

edges

13).

specified

- in

to the b e a m of the ship.

\

. . . . .

Fig.

F

±__

13

There are further benefits

small maxima,

heel

resulting

angles,

from these m o d e s t

averaging

2 to 3 d e g r e e s ,

e v e n in the worst conditions.

sailset specifications:

with only

5 to 8 d e g r e e

95 low column

-

loads,

of the s a m e o r d e r

a v e r a g e deck crane installation, plates

of rhythmic

to 50%, w i t h reduction.

later

constant

first

vessel

level

to speed

bridge

monitor

speed/economy

most

course

pitch

control

energy

course

installations

will

emerge

propulsion

ship

propeller

over

and

perhaps

speed

tend

the m i n i m u m

level

Eventually,

with

main p r o p u l s i o n

for

data

scheduled

a

the

range

of

permit

Cargo handling

enough

blend

until

crane.

in

the

levels,

wingsail

of

controllable

installations

being

specified.

both engines

would

run at say 90%

being

progressively

raising

again

the output

progressively

ie 20% to 25% of t o t a l

installed

direction

with

both are at say 40% MCR.

completely,

very

rpm

with

wingsail

well

with

this

against

load

for

pitch

ranges

are not predicted

operation

area

problems

"Eastgate",

and

In

throttled

The next stage of the remaining

throttling

back to

installed

rating.

a strong

wind,

- the w i n g s a i l s

each

of operation,

different

all

used,

rating.

115 d e g r e e s ,

to add a p p r e c i a b l y

as

Fully already

to i n s t a l l e d

costs,

stopped.

importance

owned

pattern

of a p p r o x i m a t e l y

with main engines

is of c o u r s e of v i t a l

to vessels.

handling

for

in due

be shut down.

to o p t i m i s e designs,

vessels,

adapted

further

output

for e x a m p l e ,

improve,

a high

could

exist at Stone Vickers,

cargo

distance/time

onto existing

move

engine

of 40% to 50% MCR,

c.p p r o p e l l e r s

handling

the

systems can a l s o be used,

specifically

to

engine at the same time to 80% M C R before

wingsails

only

the vessel

for the same

recommendations

in l o w w i n d c o n d i t i o n s ,

be to cut out one engine

and w i l l

and profit.

can a l l o w

memorising

roll

l o s s or d a m a g e

is of course

later,

be retrofits

multiple

as wind conditions

present,

above

information

range of power

back,

feathering

aerodynamic

cargo

crew effectiveness

conditions,

designs

will

a wide

would

at

being cut by 30

using our products.

specifications

operation

for s e r v i c e

Modern

active

Later generations

planning

will

such a design with twin engines MCR

full

in light winds

based weather

amplitudes

resistance,

system described

possible.

wind

showing

early

engine

flexible

as the

options.

there

auxiliary

Main

speed

Satellite

affording

can reduce

lower speed running

time.

in beam sea,

and increase morale,

up in f a v o u r a b l e

arrival

While

versions

of sophistication

so as to permit

rolling

This effect

and seasickness,

The

for e x a m p l e

o n l y for simple deck d o u b l i n g

etc.

reduction

-

of m a g n i t u d e

calling

in c o n s i d e r i n g

by R o w b o t h a m

Tankships

must

be kept

simply

the fitment Ltd,

clear

presents of

the

of no

hose

96 LOW

level

horizontal

cranes m o u n t e d on the wingsail

to s o l v e

most reefer,

vessels

alongside

confident

container

high

walls

that the innovative

s o l v e most of the snags

Car

carriers

adapted

and R o - r o

to benefit

are also

at

low tide

skills

support c o l u m n s

cargo problems, may

present

of t h e c a r g o

seem l i k e l y

although

smaller

difficulties

handling

- we a r e

specialists

will

l i k e l y to arise.

vessels,

provided

from w i n g s a i l

favoured,

prove e s p e c i a l l y

and general

the reduced

valuable

that

auxiliary

stability

propulsion,

noise and vibration

is adequate, while

seem w e l l

passenger

levels

seeming

vessels

likely

to

in the c r u i s e market.

SUMMARY

We are of

confident

this

new

considerable wingsail

that

no m a j o r

industry's quantities

installations

technical

progress of bunker

becoming

fuel

an

or o p e r a t i n g

towards each

saving year.

increasingly

problems the

lie in the path

shipping

We t h e r e f o r e normal

sight

on

industry

look forward to the

oceans

of

the world.

BIOGRAPHY

John W a l k e r since

1965,

developing computer

is 47, and was o r i g i n a l l y he

has

aerofoil

control

been

t r a i n e d as an a i r c r a f t

concentrating

sections,

self

virtually trimming

engineer.

exclusively

systems

and

to their p r e s e n t high level of s o p h i s t i c a t i o n .

However,

on wingsails,

their

associated