1. (1)of Two Pages
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NOTE: CALCULATIONS MUST BE INCLUDED & SKETCHES MUST BE NEAT.
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Answer the Following Questions
1-a) What are the types of ship launching? At what special cases do
we perform ship end launching by fore-end? 3 marks
1-b) Define Tipping and pivoting moments, 3 marks
1-c) Explain and determine using sketches and dimensions,
i- What is a Nautical mile? What is a Knot?
ii- What is the Longitude Line of the International Date Time?
3 marks
2-) A ship has a launching weight of 28,500 tons. The fore poppet is
located at 72 m from ship's CG. The AEGW is located at 155 from
CG before starting to move.
The following end launching data are available:
Travel of CG; m 120 135 150 157.5 165
Buoyancy; ton 9,000 15,600 24,400 29,200 35,000
CB aft of AEGW; m --- 7.5 21.5 28.0 33.0
Draw the ship end launching diagram and then, determine the following
requirements:
i-Travel when the stern lifts,
ii- Load on the fore poppet when the stern lifts,
iii- Minimum anti-tipping moment,
iv- How much buoyancy was remaining when ship drops into water?
20 marks
3-a) Define and explain briefly the following:
i- Added mass, damped heave motion, and its equation of motion,
ii- For a progressive wave in deep water define: profile and its
equation, height, amplitude, length, period, wave number,
frequency and velocity,
iii-Head sea, and irregular sea.
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(2)of Two Pages
PORT SAID UNIVERSITY
FACULTY OF ENGINEERING
DEPARTMENT OF Naval Arch. & Marine ENGINEERING
PROGRAM/ YEAR NAVAL ARCH. & MARINE ENG. 2021-2022 SEMESTER FIRST
COURSE TITLE: Naval Architecture (2) COURSE CODE: 207 NME
DATE:
02/02/2022 TOTAL ASSESSMENT MARKS: 60 TIME ALLOWED: 3 HOURS
FRESH
EXAM.
2. 3-b) A progressive wave has different lengths of 5, 10, 15, 20, and 25 m, draw
a curve of the wave celerity Vs. the wave period.
3-c) A box shaped vessel has 90 m, 15 m, and 6 m, for its length, breadth,
and draft; and has a KG = 5 m and also has the following data:
Added mass coefficient in PITCH = 0.40 ,
Added mass coefficient in HEAVE = 0.90 .
Determine the un-damped Pitch and Heave motions natural periods,
Determine the critical head wave celerity if the wave length is equal to
1.5 times of the vessel’s length. 12 marks
4-a) Explain briefly, how the lifting force is developed on ship’s rudder?
2 marks
4-b) How should the ship’s rudder be deflected, to make a starboard turn?
Why the maximum rudder angle is 35 deg.? 2 marks
4-c) The normal force acting on a rudder plane at an angle is given by:
FR = 196 A Vk
2
Newton
Where,
A is in m 2
, and
Vk is in m/sec
A ship has a single screw with single balanced rudder, which is supported
from below.
The rudder has a trapezoidal profile with a vertical leading edge of 3.0 m in
height, the distance between ship’s stern, and rudder upper edge is 0.4 m at the
rudder stock axis.
The upper large base is 1.8 m wide, and the lower small base is 1.2 m wide.
The axis of the rudder stock is 0.36 m abaft the rudder leading edge.
If the ship maximum speed is 16 knots, allow a 20% increase in the rudder
flow velocity because of the propeller race effect.
Calculate the rudder stock diameter if the allowable stress of the rudder stock
material is 70 MN/m2
. Also, explain what actions must be done, if the ship goes in
the astern direction?
15 points
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GOOD LUCK AND ALL THE BEST !!
Prof. Dr. Mo’men Gaafary
