CON & NA-AUG-2021

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) The stresses acting on a ship during its lifetime can be divided into two categories, with respect to still water stresses and dynamic stresses. State the different stresses in EACH category, explaining how EACH stress is caused. (b). Explain how the structure is designed to combat longitudinal stresses..

Q3. With reference to International Load Line Statutory Certification,

A. State the reasons for the freeboard requirements;

B. (i) Explain the term conditions of assignments

(ii) List the items that may be examined during a related survey after major repairs in the drydock.

Q4. With reference to a 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 propeller has a pitch ratio of 0.95. When turning at 120 rev/min the real slip is 30%, the wake fraction

0.28 and the ship speed 16 knots. The thrust is found to be 400 KN, the torque 270 KN-m and the QPC 0.67.

Calculate:

i. The propeller diameter;

ii. The shaft power;

iii the propeller efficiency;

iv. The thrust deduction factor.

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 any one tank and state in which order the tanks should be filled when making use of them for stability correction.

Q8. A. Why is it important in a tender ship to keep the double bottom tanks pressed up? B. A ship of 6000-tonne displacement has a wetted surface area of 2500 m2 and a speed of 15 knots. (i) Calculate the corresponding speed and wetted surface area of a similar ship of 2000 tonne displacement. (ii) If the ship resistance is of the form R=0.45 S V1.83 N; find the resistance of the 6000 tonne Ship.

Q9. A. Define longitudinal centre of gravity (LCG) and longitudinal centre of buoyancy (LCB).

B. The immersed cross-sectional area of a ship 120m long, commencing from aft are 2,40,79,100,103,104,104,103,97, 58 and 0 m2 calculate – (i) Displacement; (ii) Longitudinal position of the centre of buoyancy.

 

Q10. The breadth of the upper edge of a deep tank bulkhead is 12 metres. The vertical heights of the bulkhead at equidistant intervals across it are 0.3, 5, 6, 5, 3 and 0 metres respectively. Find the depth of the centre of pressure below the waterline when the tank is filled to a head of 2 metres above the top of the tank.