CON & NA-JAN-2019

Q1. Describe the effect of the following on the ship’s stability; 

A. Ice formation on superstructure 

B. Effects of wind and waves 

C. Changes that takes place during the ships voyage 

D. Bilging of a compartment. While water is being pumped out from the dry dock.

Q2. A. Explain in detail, how an underwater survey is carried out; B. State the requirements to be fulfilled before an underwater survey is acceptable to the survey authority; C. Construct a list of the items in order of importance that the underwater survey authority should include.

Q3. A. List the precautions necessary before an inclining experiment is carried out.

B. A box shaped vessel, 50 metres long × 10 metres wide, floats in salt water on an even keel at a draft of 4 metres. A centre line longitudinal watertight bulkhead extends from end to end and for the full depth of the vessel. A compartment amidships on the starboard side is 15 metres long and contains cargo with permeability 30%. Calculate the list if this compartment is bilged. KG = 3 metres.
 

Q4. A. Describe briefly the significance of the factor of subdivision.

B. A ship of 8000 tonne displacement floats upright in seawater. KG = 7.6m and GM = 0.5m. A tank, KG is 0.6m above the keel and 3.5m from the centreline, contains 100 tonne of water ballast. Neglecting the free surface effect, calculate the angle which the ship will heel, when the ballast water is pumped out.
 

Q5. A. Explain why the GM must remain positive until the critical instant at which the ship takes the blocks overall.

B. A ship of displacement 10,010 tones has a container of 10t at KG = 7.5m. The container is shifted transversely. A pendulum of length 7.5m defects through 13.5m. GM of ship = 0.76m, KM = 6.7m. Find the distance through which the container shifted. Also find the new KG if the container is removed.
 

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. A ship of 15000 tonne displacement has righting levers of 0, 0.38, 1.0, 1.41 and 1.2 m at angles of hell of 0°, 15°, 30°, 45° and 60° respectively and an assumed KG of 7.0 m. The vessel is loaded to this displacement but the KG is found to be 6.80m and GM 1.5m – (i) Draw the amended stability curve; (ii) Estimate the dynamic stability at 60°.
 

Q7: A. What is meant by the Admiralty Coefficient and the Fuel Coefficient?

B. A slip of 14900 tonne displacement has a shaft power of 4460 Kw at 14.55 knots. The shaft power is reduced to 4120 Kw and the fuel consumption at the same displacement is 541 kg/h. Calculate the fuel coefficient for the ship.
 

Q8. A. Define the purpose of cofferdams, B. State where cofferdams are most likely to be found on:(i) Dry cargo ships; (ii) Oil tankers.

C. (i) State what information is available about danger of entering void spaces. (ii) Identify, with reasons, the precaution to be observed before and during entry to cofferdams.

Q9. Describe the arrangement of tank top and double bottom in the machinery space making particular reference to the structure and scantlings below the main engine. Show the method adopted in the arrangement of D.B. tanks to avoid contamination of fresh water, fuel oil and lube oil stored in D.B. tanks.

Q10. A. Explain the effects on stability when a tank is partially filled with liquid.

B. A ship of 11200 tonne displacement has a double bottom tank containing oil. Whose centre of gravity is 16.5m forward and 6.6m below the centre of gravity of the ship? When the oil is used the ship’s centre of gravity moves 380mm calculate – (i) The mass of oil used; (ii) The angle which the centre of gravity moves relative to the horizontal.