CON & NA-JUL-2021 (2)
Q1. A. Describe the double bottom and framing arrangement used in the machinery space to cope up with the concentrated loads and vibration, together with shaft and thrust block support. B. Give reasons for the choice of thrust block position.
Q2. A. Sketch the cross-section of a bulk carrier with either deep or shallow double bottom showing the type of
framing used;
B. Describe the corrosion problems experienced with ballast tanks and state how such tanks are protected against
extensive corrosion.
Q3. With reference to Underwater Inspection in Lieu of Drydocking
A. Explain in detail, how an underwater survey is carried out;
B. State the requirements to be fulfilled before an underwater survey is acceptable to the surveying authority;
C. Construct a list of the items in order of importance that the underwater survey authority should include.
Q4. With reference to periodically unattended machinery space of a dry cargo vessel discusses the requirements for;
A. Protection against flooding;
B. Control of propulsion machinery from the navigating bridge.
Q5. List SIX hazards that arise with the carriage of liquefied gas in bulk. Describe, with the aid of a sketch, the details of the construction of a prismatic cargo tank within a gas carrier designed to carry liquefied gas(LPG).
Q6. (a) Explain what is meant by the left and right-handed propellers, and also explain the rotation of propellers in a
twin-screw ship.
(b) A propeller 6m diameter has a pitch ratio of 0.9, BAR 0.48 and, when turning at 110 revs/min, has a real slip of
25% and wake faction 0.30. If the propeller delivers a thrust of 300 KN and the propeller efficiency is 0.65. Calculate:
i. Blade area;
ii Ship speed;
iii. Thrust power;
iv Shaft power
v. Torque.
Q7. (a) Explain the concept of dynamical stability. (b) A ship of 5000-tonne displacement has three rectangular double bottom tanks A: 12m long and 16m wide; Tank B: 14m long and 15m wide; C 14m long and 16m wide. calculate the free surface effect for anyone tank and state in which order the tanks should be filled when making use of them for stability correction.
Q8. A. Describe stability requirement for dry-docking.
B. A ship of 8000-tonne displacement floats upright in seawater. KG = 7.6m and GM = 0.5m. A tank, KG is 0.6m above the keel and 3.5m from the centreline, contains 100 tonnes of water ballast. Neglecting the free surface effect, calculate the angle at which the ship will heel when the ballast water is pumped out.
Q9. A. Define longitudinal centre of gravity (LCG) and longitudinal centre of buoyancy (LCB).
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