DieselShip's Online Content Library

Q1. A. Sketch the cross-section of a bulk carrier with either deep or shallow double bottom showing the type of framing used;

B. Describe the corrosion problems experienced with ballast tanks;

C. state how such tanks are protected against extensive corrosion.

Q4. A. Describe a method of the attachment of bilge keels;

B. State THREE reasons for not extending bilge keels the entire length of the vessel;

C. Evaluate the effectiveness of bilge keels for large wall sided vessels;

D. Explain TWO principles of roll damping those bilge keels exploit.

Q1. (a) What is significance of the area under the curve of statical stability or the GZ curve? Explain using a neat diagram, how this curve is used to assess the stability of the ship against a heeling arm.

(b) In a grain carrier, how the shifting of grain affects the curve of statical stability. With a neat diagram explain the existing minimum criteria for stability of grain carrying ships. (8).

Q4. Explain the purposes of the collision bulkhead. Describe with the aid of sketches the construction of a collision bulkhead paying particular attention to the strength and attachment to the adjacent structure.

b) Define "Pounding". Describe with the aid of sketches the arrangement provided to resist pounding.

Q5. With respect to Induced Vibrations in a ships hull:

A. State FOUR sources of excitation that may induce vibration into the main hull girder;

B. Suggest methods for reducing the vibration levels induced by EACH of the exciting forces in A.

Q6. A. With reference to dynamical stability, describe the effect of an increase in wind pressure when a vessel is at its maximum angle of roll to windward.

B. An oil tanker 160m long and 22m beam floats at a draught of 9m in seawater. Cw is 0.865. The midships section is in the form of a rectangle with 1.2m radius at the bilges. A midships tank 10.5m long has twin longitudinal bulkheads and contains oil of 1.4 m3/t to a depth of 11.5m. The tank is holed to the sea for the whole of its transverse section.  Find the new draught.

Q7. A. What factors influence the frictional resistance of a ship and what formula is used to calculate the resistance?

B. A ship 120m long displaces 10500 tonne and has a wetted surface area of 3000m2. At 15 knots the shaft power is 4100KW, propulsive coefficient 0.6 and 55% of the thrust is available to overcome frictional resistance; calculate the shaft power required for a similar ship 140m long at the corresponding speed.  f= 0.42 and n = 1.825

Q8. A. Explain the purpose of non-watertight longitudinal subdivision of tanks.

B. A ship 160m long and 8700-tonne displacement floats at a waterline with ½ ordinates of 0, 2.4, 5.0, 7.3, 7.9, 8.0, 8.0, 7.7, 5.5, 2.8, 0m respectively. While floating at this waterline, the ship develops a list of 10° due to instability. Calculate the negative metacentric height when the vessel is upright in this condition.

Q9. A. Explain the term volumetric heeling moments.

B. A ship 85m long displaces 8100 tonne when floating in seawater at draughts of 5.25m forward and 5.55m aft. TPC 9.0, GML 96m, LCF 2m aft of midships. It is decided to introduce water ballast to completely submerge the propeller and a draught aft of 5.85m is required. A ballast tank 33m aft of midships is available. Find the least amount of water required and the final draught forward.

Q10: A. What is meant by the Admiralty Coefficient and the Fuel Coefficient?

B. A rectangular watertight bulkhead 9 m high and 14.5 m wide bas sea water on both sides, the height of water on one side being four times that on the other side. The resultant centre of pressure is 7 m from the top of the bulkhead. Calculate:

i) The depths of water

ii)  the resultant load on the bulkhead