DieselShip's Online Content Library

Q1. For a ship the center of buoyancy and the metacenter are in the line of action of the buoyant force.

(a) Only when there is positive stability

(b) Only when there is negative stability

(c) Only when there is neutral stability

(d) At all times

Justify your answer.

Q2. Explain the meaning and purpose of EACH of the following terms:

(a) Duct keel (4)

(b) Margin line (4)

(c) Sheer (4)

(d) Round of Bilge (4)

Q4. With reference to hull protection against corrosion describe how EACH of the following operate:

a) Sacrificial anodes (8)

b) Impressed current system (8)

Q4. 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 (16)

Q5. (a) What is the significance of GM-GZ curve (10)

(b) What is meant by stability criteria of a ship (6)

Q6. (a) Define angle of loll (6)

(b) A box barge 60 m long and 10m wide floats at an even keel draught of 4 m. It has a compartment amidships 12 m long. Calculate the new draught if this compartment is laid open to the sea when: (10)

(i) µ is 100%

(ii) µ is 85%

(iii) µ is 60%

Q7. (a) Describe the function of the stern frame. (6)

(b) A ship displacing 10000 tonne and travelling at 16 knots has a fuel consumption of 41 tonne per day. Calculate the consumption per day if the displacement is increased to 13750 tonne and the speed is increased to 17 knots. Within this speed range, fuel consumption per day varies as (speed)3/8 (10)

Q8. (a) Compare fixed pitch with controllable pitch propellers. (6)

(b) A ship of 12400 tonne displacement is 120 m long, 17.5 m beam and floats at a draught of 7.5 m. The propeller has a pitch ratio of 0.75 and, when turning at 100 rev/min, produces a ship speed of 12 knots with a real slip of 30%. Calculate the apparent slip, pitch and diameter of the propeller. The wake fraction w may be found from the expression. w = 0.5Cb - 0.05 (10)

Q9. (a) Describe water pressure loads on the ship's hull. (6)

(b) The 1/2 ordinates of a waterplane 120 m long are as follows: (10)

Section AP 1/2 1 1½ 2 3 4 5 6 7 8 8½ 9 9½ FP

½ ord 1.2 3.5 5.3 6.8 8.0 8.3 8.5 8.5 8.5 8.4 8.2 7.9 6.2 3.5 0 m

Calculate:

(a) Waterplane area

(b) Distance of centroid from midships.

Q2. A virtual rise in the centre of gravity of a ship may be caused by (16)

(a) Filling a partially filled tank

(b) Using an onboard crane to lift a freely swinging heavy object

(c) Emptying a partially filled tank

(d) Transferring pipe from the setback area to the pipe rack Briefly Justify your Answer

Q2. Explain the meaning and purpose of EACH of the following terms:

(a) Bulbous bow (4)

(b) Hawse pipe (4)

(c) Spurling pipe (4)

(d) Cable stopper (4)

Q2. Define the main purpose of the following with respect to tank and pumping system.
(a) Weighted cocks on tank sounding pipes (4)

(b) Remote operated gear for bilge valves (4)

(c) Ventilation pipes for double bottom tanks (4)

(d) Explain why gauze is sometimes fitted to tank ventilation pipes and explain the effect of mesh size. (4)

Q4. Sketch a plain bulkhead, showing connections to deck, sides and double bottom and the arrangement of stiffeners (16)

Q5. Write short notes on each of the following with respect to their contribution to the strength of ships:

(a) Strake (4)

(b) Bracket (4)

(c) Stringer (4)

(d) Girder (4)

Q6. (a) Describe the provisions of additional structural strength to withstand pounding. (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) Show by means of diagrams how the center of gravity of the liquid in a partly filled tank moves during rolling. (6)

(b) A box barge is 15 m long, 6 m wide and floats in water of 1.016 t/m3 at a draught of 3 m. 150 tonne of cargo is now added. Calculate the load exerted by the water on the sides, ends and bottom. (10)

Q8. (a) Explain what is meant by 'assigned summer freeboard' (6)

(b) A box-shaped vessel 60m long, 10m beam, and 6m deep, is floating in salt water at drafts 4m Forward and 4.4 m. Aft. Find how far forward of amidships a weight of 30 tonnes must be loaded if the draft aft is to remain at 4.4m. (10)

Q9. (a) Explain why the TPC for a given draught will vary with the density of the water in which the ship floats. (6)

(b) A box shaped ship with 12m beam is floating upright at a draft of 6.7 m. Find the increase in draft if the vessel is now listed 18 degrees. (10)