maneuverability characteristics of ships with a single · pdf filemaneuverability...

(c) 2010 Hideo YABUKI 1

Maneuverability characteristics of ships with a single-CPP and their control

during in harbor ship handlingduring in-harbor ship-handling

Hideo YABUKI Professor, Ph.D., Master Mariner

Tokyo University of Marine Science and Technology

Contents

1. Introduction2. Comparative full-scale experiments between CPP &

FPP using 5,880 G.T. training shipg , g p2.1 Coasting tests2.2 Stopping tests

3. Simulation studies3.1 Stopping motion prediction3.2 Estimation of the critical range of stopping maneuver3.2 Estimation of the critical range of stopping maneuver3.3 Effective stopping maneuver for berthing under

windy condition3.4 Steering control of CPP ships during stopping

maneuver


CPP (Controllable Pitch Propeller) and FPP (Fixed Pitch Propeller)

1. Introduction

Highly skewed CPP Conventional FPP

Maneuverability characteristics of ships with CPP

FPP; thrust is controlled by changing the engine revolution& i i di i

advantage

& its rotating direction. (When the propeller is turned astern while rotating to ahead, the engine must be stopped & re-started in reverse with compressed air. )

CPP; pitch & thrust are controlled by rotating the blades about their length axis using a hydraulic servomotorabout their length axis using a hydraulic servomotorinstalled in the boss.(allows for the engine to work in a constant direction)

CPP can provide smooth speed control.


Maneuverability characteristics of ships with CPP

difficulties

1. During coasting maneuver of ships with CPP pitch feathered to zero, the control of head turning motion by steering is difficult especially under windy condition.

2. During stopping maneuver of CPP ships, their turning motion is less stable than that of FPP ships particularly

d i d diti d it i diffi lt t t l th iunder windy condition and it is difficult to control theirhead turning motion by steering.

Coasting; proceed with the ship’s inertia with the engine stopped(without ahead propulsion)

1. Turning motion during the coasting maneuver

Results of full-scale experiments to investigate the maneuverability characteristics of ships with CPP

Topics

g g g2. Stopping motion under windy condition.

Results of the simulation study to develop the in-harbor ship-handling method of CPP ships

1. Method to estimate the critical range of stopping ith t t i tmaneuver without tug assistance.

2. Effective stopping maneuver for berthing under windy condition.

3. Control of stopping motion by maximum rudder angle steering.


2. Comparative full-scale experiments between CPP & FPP using 5,880 G.T. training ship

2.1 Coasting tests

(1) Course keeping tests at coasting with propeller

pitch zero operation

(2) Course keeping tests at coasting with MHP

(minimum ahead pitch ) operation

2.2 Stopping tests

(1) with CPP(1) with CPP

(2) with FPP

MHP; smallest blade angle of CPP for ahead propulsion which ensures adequate steerage

Test ship

Principal Particulars

Length: Lpp (m) 105.00 Ar (㎡) 10.034Breadth: B (MLD, m) 17.90 Ar/Ld 1/63.4Depth: D (MLD, m) 10.80 Aspect Ratio 1.865Cb 0.5186draft: d (m) 5 96

Principal ParticularsHull Rudder (Flap Rudder)

5,884 G.T. Training Ship with CPP

& Direct reversing system for Diesel Engine

draft: d (m) 5.96

Prop. Brade No. 4Prop. Dia.: Dp (m) 4.70

P.R. (Brade Angle)1.050(25.5°)

Propeller (CPP)


The ship turns her head into the wind even though the wind is very weak. The head turning motion can’t be controlled by steering

Coasting with the propeller pitch zero operation

2.2 Coasting tests

0

2

4

6

Ψ, C

PP

(deg.)

0

10

20

30

40

(deg.

)

CPP

U

δ

30 60 90

Pitch Zero

-6

-4

-2

0

U (

knots

),

Ψ

-40

-30

-20

-10

0

δ (

ΨWind : 1 (m/s)

CPP blades at the propeller pitch zero operation

Ast. Pitch (Tip)

Ahead Pitch (Boss)

Generation of unstable flow

Reduction of steering ability


CPP pitch distribution at Propeller pitch zero operation(stop)

Pitch zero operationTip; Pitch changes

Generation of

p; gto the reverse side

Boss; Advance pitch remains


Reduction of steering ability

Coasting with MHP operation

6

.) 30

40 MHP

MHP; smallest blade angle of CPP for ahead propulsion which ensures adequate steerage

4

-2

0

2

4

nots

),

Ψ

, C

PP

(deg.

-20

-10

0

10

20

30

δ (

deg.

)

δ

U

Ψ

CPP

Wind : 5～6 (m/s)

30 60 90

-6

-4

U (

kn

-40

-30

The ship can keep her original course under strong wind by applying the appropriate helm.

The head turning motion can be controlled sufficiently by steering.


(1) Indexes for expressing the stopping ability

Ψ

YG

2.2 Stopping tests

X

Ψ

Stopping time t’ = t / (Lpp/U0)U0 ; Initial speed

Stopping distance (Track reach) S’ = S / Lpp

X’ = X / Lpp ; Head ReachY’ = Y / Lpp ; Side ReachΨ ; Final Heading Angle

S’ = S / Lpp

Lpp ; Length between Perpendiculars

Initial Advancing Constant

0 0 /( )SJ u n p

0SJ

Stopping ability can be expressed as the function of 0SJ

(1)

0u

0 0 /( )SJ u n D or

(2)

where; initial speed

t l ti

D

n

p

; astern revolution

; propeller diameter

; propeller pitch (nominal pitch)*

* for CPP, effective pitch is used instead of nominal pitch


CPP effective pitch calculation

1 1( ) ( ) / ( )

( ) ( ) 1

C CP P r W x dx W x dx

W x x C x

(1)

Effective pitch at pitch angleα, radius r

( ) 2 tan( ( ) )P r r r

( )r

( ) ( ) 1W x x C x

x ( / )r RC ; Boss ratio

; pitch at pitch angleα, radius r

; non-dimensional radius ; standard pitch angle at radius r

Blade Angle (deg.) Pitch Ratio -5.5 (D. Slow Ast.) -0.189 -10.0 (Slow Ast.) -0.354 -14.0 (Half Ast.) -0.505 -18.0 (Full Ast.) -0.661

Effective pitch of the test ship

(2) Results of full-scale stopping testsfor various combination of advance speed &

astern operation( i e Initial Advancing Constant )0 0 /( )SJ u n p ( i.e., Initial Advancing Constant )

Condition

0 0 /( )SJ u n p

CPP FPP Wind (m/s) 1～４ 2～6W ( ) 0 2 0 3 Wave (m) 0.2 0.3

df (m) 5.90 5.85 da (m) 6.22 6.19 Trim (m) 0.32 B/S 0.34 B/S Displacement (ton) 5,955 5,910


(i) Crash Stop Astern Comparison

20.5kts to Full Ast.

FPP CPP

t’

S’

X’

28.25

15.17

14.31

15.82

8.63

8.47

Y’

Ψ

3.57

70°

0.09

71°

(ii) Comparison of Astern Maneuverat Low Speed

4 kts to Full Ast.

FPP CPP

JS0

t’

S’

X’

-0.46

1.21

0.74

0 74

-0.47

1.54

1.02

1 01X’

Y’

Ψ

0.74

0

0

1.01

-0.04

-6°


12

16t

● CPP△ FPP

9S'Stopping distance

(iii) Comparison of stopping ability

0

4

8

1 6 1 2 0 8 0 4 3

6

● CPP △ FPP

-1.6 -1.2 -0.8 -0.4

Jso

0

3

-1.6 -1.2 -0.8 -0.4

Jso

Stopping time

t’ & S’ of CPP ships are shorter than those of FPP ships

n ; maneuvering speed

Difference of the reversing operation between FPP and CPP

n ; reversible


(iv) Comparison of the final head turning angle

between FPP & CPP

Ψ( )

C ＰＰ

40

80

120Ψ(deg.)Wind ; Starb'd Bow

Wind ; Port Bow

Helm ; +35

Helm ; -35

Right

ＦＰＰ

0

40

80

120

Ψ(deg.)

Wind ; Starb'd Bow

Wind ; Port Bow

Helm ; +35

Helm ; -35

-80

-40

0

40

-1.6 -1.2 -0.8 -0.4

Jso

Right turn

Left turn

R

-80

-40

0

-1.6 -1.2 -0.8 -0.4

Jso

Turning motion of CPP ship is less stable than that of FPP ship.As to CPP ship,control of the turning motion direction by steering is difficult & the direction seems to be fixed by the relative wind direction.

L

Shifting Process to Reversing Thrust

FPP CPP

Short transition time from propeller idling to reversing

Need some transition time forattaining the ordered reverse pitch


CPP pitch distribution at astern blade angle

Astern operationSmall advance

pitch remains nearpitch remains near the Boss


Unstable turning motion

3.1 Stopping motion prediction

MMG type Mathematical model

3. Simulation studies

Vw

Ψw

Uu

v

2 2

1tan ( / )

U u v

v u

Coordinate system


mu mvr X

mv mur Y

H P R W

H P R W

X X X X X

Y Y Y Y Y

MMG type Mathematical model

(1) (2)

mm

zzI r NH P R WN N N N N

; mass of ship

; moment of inertia of ship in yaw motion

; axial velocity, lateral velocity, rate of turn

mzzI

, ,u v r ; axial velocity, lateral velocity, rate of turn

The terms X, Y and N represent the hydrodynamic forces and moment. The subscripts H, P and W refer to the hull, propeller and wind force respectively.

, ,u v r

Hydrodynamic derivatives & coefficientswere obtained by captive model tests

Model ; 4.29 m (1 / 24.48)

Model ship (stern) Model ship (bow)

Model Propeller

Rudder Bow thrusterPropeller


captive model tests

Force & moment induced by propeller

Propeller backing force XP

2 4(1 ) ( , )

/( )

P p T P P

P P P

X t n D K J

J U n D

,P PJ ; blade angle, propeller advance coefficient

, , , , ,T P PK t n D U

; thrust coefficient, rate of thrust deduction, propeller revolution, propeller diameter, propeller advance speed, water density


2 '( / 2) ( ) ( , )p pY Ld nP Y J

lateral force YP, moment NP

2 2 '( / 2) ( ) ( , )p pN L d nP N J

/J U nP

, ,L d p ; length between di l d ftperpendiculars, mean draft,

propeller pitch

-0.01

0

0.01

0.02

-2 -1.5 -1 -0.5 0

/2ρ

Ld(nP)2 )Lateral force & moment

exerted by reversing propeller(n>0, P = -13.26°)

-0.03

-0.02

J=U/nP

0.004

0.006

0.008

0.01

Y/(1/

L2d(nP)2)

-0.004

-0.002

0

0.002

0.004

-2 -1.5 -1 -0.5 0

J=U/nP

N/(1/2ρ

L


Wind forces & moment

2

2

( / 2)

( / 2)

W a T X R

W a S Y R

X A C U

Y A C U

( / 2)W a S N RN A LC U

, ,X Y NC C C ; wind force coefficients and moment

, ,a RU L ; air density, relative wind velocity, ship’s length

A A ; longitudinal projected area of hull and,T SA A ; longitudinal projected area of hull and transverse projected area of hull above water line

Wind forces & moment

Wind tunnel test(Model ; 1.5 m )

-0.2000

0.0000

0.2000

0.4000

0.6000

0.8000

0 45 90 135 180

Cx

With Rough Board

-0.8000

-0.6000

-0.4000

Relative Wind Direction(deg.)


Wind force & moment

-0.400

-0.300

-0.200

-0.100

0.000

0 45 90 135 180

Cy

-0.800

-0.700

-0.600

-0.500

0 020

0.040

0.060

0.080

With Rough Board

-0.100

-0.080

-0.060

-0.040

-0.020

0.000

0.020

0 45 90 135 180

Relative Wind Direction(deg.)

Cn

Validation of stopping motion prediction

0

1Y's

Simulated

Measured

4 knots to Slow Ast.

X's

0

-1

3210

[m/s][deg]UΨ Right Wind 9 m/s

4 Knots, Slow Ast.

Right beam wind9 m/s

150 Sec1209060

0

-300

30

30

2

0

U

-2

Ψ


Stopping motion prediction under windy condition (3 knots, Slow Ast.)

2.5

3

0.5

1

1.5

2

Xs/

Lpp Head Reach

0

0 90 180 270 360

Wind Direction(deg.)

7 m/s 10 m/s 15 m/s 20 m/s

4-202468

0 90 180 270 360

Ys/

B

Head Turning Angle

200

20406080

Ψ(d

eg.

)

-10-8-6-4

Side Reach

-60-40-20 0 90 180 270 360

Wind direction (deg.)

Ψ

7 m/s 10 m/s 15 m/s 20 m/s


1.5 BCritical range of

3.2 Estimation of the critical range of stopping maneuver under windy condition

Typical shiphandling

fordocking

Critical range of stopping maneuver

Ys/B>1.5Ψ>20º

20º B ; ship’s breadth

Critical range of stopping maneuver

-2

02

46

8

0 90 180 270 360

Ys/

B

-10

-8-6

-4

-20

0

20

40

60

80

0 90 180 270 360Ψ(d

eg.

)

-60

-40

20 0 90 180 270 360

Wind direction (deg.)

7 m/s 10 m/s15 m/s 20 m/s

Critical RangeYs/B>1.5Ψ>20º


3.3 Effective stopping maneuver under windy conditionDifficulty of stopping maneuver in the follow wind

Follow wind 10 m/s3 knot, Slow Ast.

2

Xs / LppHead wind 10 m/s3 knot, Slow Ast.

Xs / Lpp

2

11

0

-0.5 0.50.5-0.5 -0.5 0.5

Ys / Lpp

0

-0.5 -0.5-0.50.5 0.5 0.5Ys / Lpp

Effective stopping maneuver for berthing under windy condition

Stopping motion is fixed by apparent advance constant

0 0 /( )SJ u n p

0SJ

Stopping motion is fixed by apparent advance constant

at the initial stage of propeller reversing

Stopping motion indexes increase in proportion to

0SJThe size of stopping motion can be reduced by maneuveringso that becomes smaller


Effective stopping maneuver in the follow wind

Head wind 10 m/s3 knot, Slow Ast.

Xs / Lpp

2

Follow wind 10 m/s3 knot, Half Ast.

Xs / Lpp

2

11

0

-0.5 -0.5-0.50.5 0.5 0.5

Ys / Lpp

0

-0.5 -0.5 -0.50.5 0.5 0.5

Ys / Lpp

3.4 Steering control of CPP ships during stopping maneuver

(1) Control of stopping motion by maximum rudder angle steering

The direction of turning motion of CPP ships seems to be fixed by the yaw moment at the initial stage of

propeller reversing.

steering

ProposalApplication of the head turning moment by the

maximum rudder angle steering prior to propeller reversing.


1

0

1

0

Y's Left Wind 10 m/s

With Rudder Angle +35

Midship

Effect of the proposed stopping maneuver under windy condition

Left wind 10 m/s

2

[m/s]U

[deg][deg]Ψ,δ

15

[deg]θ

2

[m/s]U

[deg]

30

[deg]Ψ,δ

15

[deg]θ

δ

U

-1-1

3210-1X'sStopping maneuver

with the rudder amidships.

0

-2

1501209060300

0

-30

[sec]1501209060300

0

1501209060300

0

-15

0

-2

1501209060300

0

1501209060300

0

1501209060300

0

-15

Ψ

θ

Initial speed 3 kts, Slow astern

The ship drifts leeward & turns her head into the wind.

1

0

1

0

Y's Left Wind 10 m/s

With Rudder Angle +35

MidshipStopping maneuver that

applies maximum rudder angle steering to

leeward prior to

Left wind 10 m/s

2

[m/s]U

[deg][deg]Ψ,δ

15

[deg]θ

2

[m/s]U

[deg]

30

[deg]Ψ,δ

15

[deg]θ

δ

U

-1-1

3210-1X's

propeller reversing

The yaw moment can

The ship drifts leeward.

0

-2

1501209060300

0

-30

[sec]1501209060300

0

1501209060300

0

-15

0

-2

1501209060300

0

1501209060300

0

1501209060300

0

-15

Ψ

θ

Initial speed 3 kts, Slow astern

ybe reduced sufficiently. The original heading is well maintained.


(2) Application of MHP operation & stopping maneuver with steering control to the anchoring

under windy condition

Anchoring procedure

Approaching

Stopping

Proceeding on the planned trackReducing speed

Controlling ships heading into the wind & tide

MHP operation

Stopping maneuver with rudder control

Laying out anchor

Fetching up

Result of actual anchoring

Proceeded on the planned track with MHP

Coasting

4

6

8

1 0

2 0

4 0

6 0

8 0

U

C P P

Ψ

1 6 0 6 M in im u m A h e a d

1 6 1 4 S lo w A s te rn

1 6 1 5 L e t g o a n c h o rPP

(deg

.)

deg

.)

Tra jectory

Slow ast.MHP

Hard-starb’d steering to windward

Yaw moment increased

Ch d C f

- 1 0

-8

-6

-4

-2

0

2

- 8 0

- 6 0

- 4 0

- 2 0

0

2 0

d

1 6 1 0 H a rd -a -S t a rb 'dU(K

ts),

CP

d,

Ψ (

Tim e h istory

+35 steeringShip stopped with her heading to windward

Changed CPP from MHP to Slow ast. directly


(3) Application to the crash stop astern maneuver

Crash stop astern maneuver

T h hi i h hTo stop the ship with the shortest distance

To turn the ship’s head to the starb’d as great as possible

Full astern operation

Hard starb’d steering

Put the propeller to full astern after applying the starb’d head turning moment by the maximum rudder angle steering.

1

0

1

MidshipStarboard 35°

2Y's

Crash ast. with rudder amidships

Ship stopped turning her head slightly to starb’d -1

3210-1 4X's

2

0

[m/s]

U

30

0

[deg]

Ψ,δ

15

0

[deg]

θ

U

ΨδBoth Ψ & Y’s are not

enough to avoid collision.

head slightly to starb d on the original track

0

-2

1209060300

0

-30

[sec]

0

-15

θ

Initial speed 6kts, Full ast., Calm

Crash ast. with +35 steering

Both sufficient Ψ & Y’s to avoid collision are obtained.


Crash ast. Maneuver under windy conditionInitial speed 6kts, Full ast. Wind 10 m/s

Head wind 10 m/sX’s

Midship Rudder +35

Tail wind 10 m/sX’s Tail windHead wind

Rudder +35Midship

Y’sY’smidships midships+35 +35


Right beam wind 10 m/s

Midship Rudder +35

X’s

Left beam wind 10 m/s

Midship Rudder +35

X’sLeft wind Right wind

Y’s

Y’smidships midships+35 +35



Thank you for your attention.

The test ship T.S. Seiun Maru

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