my seakeeping

8/7/2019 My seakeeping

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UTMUTMUNIVERSITI TEKNOLOGI MALAYSIA

SML 5922 MARINE TECH LAB IISML 5922 MARINE TECH LAB II

SELF PROPULSIONSELF PROPULSION TESTTEST



� Mohd Rahim Amran

� Mohd Asrol Abu Bakar

� Mohd Amirul Affendy Ahmad� Mohd Firdaus Rusli

� Mohd Aiful Amir Awang Noh

� Mohd Izdihar Saleh

� Mohd Hisyamudin Hamid



To obtain heave, pitch and roll Response Amplitude

Operator (RAO).

To obtain significant acceleration at forward

perpendicular in sea state 5

Theoretical study of seakeeping to understanding of

Simple Harmonic Motion. Familiarize with techniques that can predict natural

periods of ship motions.

SEAKEEPING TEST

Objective



SEAKEEPING TEST

The seakeeping experiment done to obtain the motion

characteristic of ship. The excessive motion which are

undesirable since they may impair discomfort to the

crew and passengers.

The significant acceleration at forward speed isimportant for some ship such as warship because

they want to put the missile onboard.

Background



Towing tank and Carriage

I

Apparatus

Function

To run model at

required speed.

Hold instrumentation

equipment.



SEAKEEPI EST

Wave generator

Apparatus

Function

To generate wave at

required wavelength

and wave height.



SEAKEEPI TEST

Wave probe

Apparatus

Function

To measure the

wavelength and wave

height at location in

front of model.



SEAKEEPI TEST

Resistance dynamometer and potentiometer

Apparatus

Function

To measure the

pitching angle of

model.



SEAKEEPI TEST

Accelerometer

Apparatus

Function

To measure the

vertical acceleration of

model at forward and

aft.



SEAKEEPI TEST

Dewetron data processing system

Apparatus

Function

To collect output data

from transducers and

process it into

required output

measurement in

computer screen using Dewisoft.



SEAKEEPING TEST

Theory

1.Surge

2.Sway

3.Heave

4.Roll

5.Pitch

6.Yaw

- Only heaving rolling and pitching are pure oscillatory motions.

- For surging, swaying and yawing, the ship does not return to its

original equilibrium.



TheoryEquation of motion

SEAKEEPING TEST

InertialForce

Dampingforce

Restoringforce

Excitingforce

m = mass of the shipaz = added mass (Have no physical meaning but represents additional

inertia force due to body oscillating in a fluid)b = damping force coefficient c = restoring force coefficient Fo= Amplitude of wave force (exciting force)we= Encounter Frequency, (Where w = we for stationary bodies)



3 TYPE OF OSCILLATORY MOTION

1. Free, Undamped Heaving Motion

When Fo = 0, b = 0

2 2

1 z 2 z

1 2

1 2

( + a ) + cz = 0

and,z = A = sin t + A cos t

where,

A = A

= tan A

z m z

A

A

[ [

F

&&




2. Free Damped Heaving Motion

Where, F = 0( ) 0z m a z bz cz @ !&& &




3. Force Heaving Motion



SEAKEEPING TEST

Heaving Motion Happen when a ship moving oscillates

vertically upward and downward in seaway

will continue oscillated vertical up and

down until the equilibrium position isreached .



Pitching Motion Occur when the bow and stem

of ship will moving trimming

oscillates at Y axis.

SEAKEEPING TEST



SEAKEEPING TEST

The experiment must covers:i. Model run at least 10 times for each speed.

ii. Covering wavelength from 0.5LBP 2.0LBP

iii. Wave height / wavelength ratio about 1:40iv. Covers sea state 5(wave height 2.5 to 4 m)v. Experiment covers for rolling, pitching, and rolling.

Experiment Protocol



SEAKEEPING TEST

(m) T (s) H (m)

Wave

Height

(m)

Wave

Amp.

(m)

Heave

(m)

Pitch

(deg) 3/A

wave

slope

(rad) 5/A

0.5 0.0462 0.3163 0.3338

0.6 0.0479 0.5637 0.5167

0.7 0.0510 0.7471 0.7072

0.8 0.0555 0.7225 0.7295

0.9 0.0579 0.7876 0.8407

1.0 0.0588 0.7908 0.8737

0.0628 0.7627 0.8979

0.0679 0.7187 0.8787

0.0727 0.6768 0.8962

0.0784 0.7041 0.8818

0.0901 0.7070 0.8608

Experiment Protocol



SEAKEEPING TEST

Particulars Unit Ship Model

Length Between Perpendicular, LBP

Breadth, BDepth, D

Draft, T

Displacement (volume)

Displacement (weight)

LCB and LCG

KGTrial Sp d

Block Coefficient, CB

Waterplane Coefficient, Cw

Scal

m

mm

m

m3

tonnes

m

MKnot

-

-

-

138.0

21.812.5

8.7

22171

21635

7 from AP

8.214

2.76

.436.25

.174

.177

.16886

1.4 from AP

.1641. 19(m/s)

.8 6

.9 9

1:5

Preparation



SEAKEEPING TEST

Preparation1. Calculate the total amount of the ballast to be loaded

for the various conditions to be tested.

2. Release the oscillation table of the apparatus for themeasuring ship model inertia moment .3. Adjusted the level of the oscillation table to the

required height .4. Measure height of a specific point at one end of the

model above a certain reference (e.g floor).5. Push one side of the empty oscillation table down and

release it to let it oscillate freely



SEAKEEPING TEST

6. Determine the time for one complete oscillation(natural oscillation period).

7. Calculate the natural oscillation time.8. Position the model on the table & ballast 9. Determine the time for one complete oscillation by

measuring the lime passing for 10 oscillations dividedby 10.

10. Check whether the oscillation time agrees with thecalculated oscillation time

11. Remove the model and fixate the ballast weights. Themodel is now as far as its mass distribution inconcerned ready for the testing in the basin.

Preparation



Attached model to the towing carriage by air struck at LCG

of the model.

When the model is well balanced, it is put on the carriage

The model will towed by towing carriage

The vertical motion will measure by potentiometer

The data is then being analysis and plotted by theprogram in the carriage

SEAKEEPING TEST

Experiment Setup

my seakeeping

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