DieselShip's Online Content Library

Q1. With reference to corrosion processes

a) Explain the mechanism of: (8)

i) Stress corrosion.

ii) corrosion fatigue.

b) State where the following types of corrosion may occur, and the materials commonly involved in each case. (8)

i) Fretting corrosion

ii) Impingement corrosion

iii) Galvanic corrosion

iv) Crevice corrosion

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)

Q3. (a) With reference to refrigerated hold spaces describe using simple sketches: (8)
(i) A tween deck scupper.

(ii) An insulated brine pipe passing through a watertight bulkhead.

(b) With reference to draining water from decks, describe using simple sketches (8)

(i) A scupper pipe leading from the waterway in the tween decks to the outside of the Vessel.
(ii) A bulwark freeing port with the flap hinged at the top and opening outward.

Q3. With regards to the metacentric height, which of the following statements is true? (16)

(a) It is used to indicate the quality of initial stability.

(b) It is located below the center of buoyancy.

(c) It is measured vertically above the center of buoyancy.

(d) Its determination is the objective of the inclining experiment. Briefly justify your answer.

Q5. (a) Explain the importance of reserve buoyancy. (6)
(b) A box barge is 75 m long, 9 m beam and 6 m deep. A similar barge having a volume of 3200 m3 is to be constructed. Calculate the length, breadth and depth of the new barge (10)

Q8. (a) Describe the function of the stern frame. (6)

(b) The water plane area of a ship at 8.4 m draught is 1670 m2. The area of successive water planes at 1.40 m intervals below this are 1600,1540, 1420, 1270, 1080 and 690 m2 respectively. Calculate the displacement in fresh water at 8.4 m draught and the draught at which the ship would lie in sea water with the same displacement. (10)

Q7. (a) Explain why the draught of a ship decreases when it passes from fresh water to seawater and vice versa. (6)
(b) A ship travels 2000 nautical miles at 16 knots and returns with the same displacement at 14 knots. Find the saving in fuel on the return voyage if the consumption per day at 16 knots is 28 tonnes. (10)

Q8. (a) Define the terms 'pitch ratio', 'real slip ratio' and 'blade area ratio'. (6)
(b) The pitch of a ship's propeller is 6m. At 105 rev/minute the apparent slip is 10% and the real slip is 24%. Calculate the slip and the wake fraction. (10)

Q9. (a) With aid of a simple sketch, show the normal positions of centre of gravity of a stable ship relative to keel, centre of buoyancy and meta centre. (6)

(b) A ship has 300 t of cargo in the hold, 24 m forward of the midships. The displacement of the vessel is 6000 t and its centre of gravity is 1.2 m forward of midships. Find the new position of the centre of gravity if this cargo is moved to an after hold, 40 m from midships. (10)