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. With reference to bilge keels:

(a) Describe how the design and method of attachment reduces the possibility of damage to the shell plate. (8)

(b) State what testing must be carried out. (4)

(c) Explain why the bilge keels do not extend the full length of the vessel. (4)

Q5. With reference to large bulk carriers:

(a) Sketch a cross section of a bulk carrier through the mid-ship. (8)

(b) Explain the design features that have evolved to minimise the possibility of failure. (8)

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) What do you understand by ‘coffin plate’?

(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) What are the water pressure loads on the ship's hull. (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)