DieselShip's Online Content Library

Q1. Explain in principle, the process of corrosion on the underwater steel plates of the hull. Describe how protection is provided by sacrificial anodes. (16)

Q2. What are the main functions of:

(a) Fore peak (4)

(b) After peak (4)

(c) Deep tank (4)

(d) Double bottom (4)

Give examples of liquid carried in these tanks.

Q3. (a) Define any six types of ship motions. (6)

(b) In the context of ship stability, what does static stability refer to: (10)

(i) The ship's resistance to rolling in waves.

(ii) The ship's ability to return to equilibrium after a displacement without wave action.

(iii) The dynamic response of a ship in irregular seas.

(iv) The resistance to hull slamming.

Briefly justify your answer.

Q3. (a) Sketch a water-tight door and frame showing manner of attachment to bulkhead and the additional reinforcement carried by the bulkhead to compensate for the aperture. (8)

(b) Explain how water-tightness of the door and frame mating surface is ensured with an hydrostatic pressure tending to force the faces apart. (4)

(c) Describe the means of remote closing operation of the door and state how many closing stations there are and their position. (4)

Q5. Describe with the aid of sketches how each of the following contribute towards improving the propulsive efficiency of a ship: (16)

(a) Ducted propeller

(b) Costa bulb as fitted to rudder

(c) Grim wheel vane as fitted aft of the propeller

Q6. (a) Define Centre of Flotation. What happens to the draught and trim of a ship if a small mass is added to the ship at the Centre of Flotation? (6)

(b) A vessel travelling at 17 knots turns with a radius of 450 m when the rudder is put hard over. The centre of gravity is 7 m above the keel, the transverse metacentre 7.45 m above the keel and the centre of buoyancy 4 m above the keel. If the centripetal force is assumed to act at the centre of buoyancy, calculate the angle of heel when turning. The rudder force may be ignored. (10)

Q7. (a) Explain in brief the term 'bulwark' and 'freeing port'. (6)

(b) The pitch of a propeller is measured by means of a batten and cord. The horizontal ordinate is found to be 40 cm while the vertical ordinate 1.15 m at a distance of 2.6 m from the centre of the boss. Calculate the pitch of the propeller and the blade width at that point. (10)

Q8. The half-ordinates of a ship’s water-plane, which is 80 m long, commencing from forward at equal intervals, are as follows: 0.2, 4.0, 5.0, 5.2, 5.0, 4.0 and 0.2 m respectively. Calculate the area of the water-plane using Simpson’s First Rule.

Q9. A ship’s length at the waterline is 180 meters, with a maximum beam of 30 meters and a draft of 9 meters. If the ship’s volume of displacement is 38,880 cubic meters, calculate its block coefficient. (16)