MODULE I : SEAKEEPING
Topic: Regular Water Waves
Question 1
Consider a towing tank of length 150m with a wave-maker at one end. For a regular
water wave of period 2 sec. and amplitude 0.2m being generated by the wave
maker, determine:
(i)
(ii)
(iii)
(iv)
MODULE I : SEAKEEPING
Topic: Ship in Wave: Encounter Frequency
Question 1
A ship is advancing at a speed of 16 knots in a regular wave-field of wave-length
200m. For heading angles 180,135,90,45 and 0 deg., determine the encounter
periods.
Answer:
Encount
MODULE I : SEAKEEPING
Topic: Ship Motion in Irregular Waves
Question 1
The energy spectrum of a wave is as follows:
Sw ( )
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0.0 1.0 4.0 12.0 20.0 16.0 10.0 2.0 1.0 0.1
For a ship speed of 20knots in head waves, the h
MODULE I : SEAKEEPING
Topic: Uncoupled Heave, Roll and Pitch
Question 1
(i)
Write the expressions for undamped natural periods of heave, roll and pitch
motions.
(ii)
Determine the scale factors for these natural periods between model and
prototype.
Answer
MODULE I : SEAKEEPING
Topic: Irregular Waves and 2DSspectrum
Question 1
From an irregular wave record, the following statistical information could be found:
wave-height average wave Number of
intervals (m) height (m)
occurrences
0.25-0.75
0.5
15
0.75-1.25
MODULE II : MANEUVERABILITY
Topic: Motion Stability, Equations of Motion and Hydrodynamic Derivatives
Question 1
Describe by suitable sketches different types of motion stability for a surface ship
Answer:
Motion stability refers to the ships behavior aft
MODULE II : MANEUVERABILITY
Topic : Definitive Maneuvers
Question 1
Draw a schematic diagram of a 20/10 zigzag maneuver and identify all the terms.
Answer:
The figure is shown below and the terms like (time of) 1st,2nd,3rd executes, (time to)
reach, perio
MODULE II : MANEUVERABILITY
Topic: Experimental Determination of Hydrodynamic Derivatives
Question 1
In a straight line test to determine the hydrodynamic derivatives conducted on a 2m
long ship model at a tow speed of 1 m/s, the measurements are as follo
MODULE II : MANEUVERABILITY
Topic: Estimation of Hydrodynamic derivatives by Theoretical/Empirical
Methods
Question 1
An estimate for linear damping derivatives can be made from the relations:
'
Yv' = (T / L )2 ; Yr' = 0.5 (T / L )2 ; Nv = 0.5 (T / L )2 ,