CON & NA-JUN-2019

Q1. Discuss the need for adequate support of engine room gantry cranes, detailing the following (a) Sketch section through the engine room casing showing how the crane is supported by the ship structure; (b) State what restricts the forward and aft limits of the crane and what is fitted to prevent the crane damaging the forward and aft bulkheads or casing. (c) State the Second Engineer’s responsibilities for the engine room gantry crane.

Q2. Vessel has gone through very heavy weather. On arrival at safe anchorage, you are conducting your inspection to determine damages to hull. A. List the areas you will inspect. B. List your findings of any significance. C. Write a report to company suggesting repairs if any.

Q3. Explain how the period of roll varies with – A. The amplitude of roll; B. The radius of gyration; C. The initial metacentric height; D. The location of masses in the ship.

Q4. A. Describe the relationship between frictional resistance and:(i) Ship speed; (ii) the wetted area; (iii) surface roughness; (iv) The length of the vessel.

Q5. If a ship is seriously damaged under water in way of a large fuel side bunker tank what is the immediate effect and what may ultimately happen? What features in the ship would enhance safety?

Q6. The following data applies to a ship operating on a particular voyage with a propeller of 6 m diameter having a pitch ratio of 0.95:Propeller speed = 1.8 revs/s Real slip = 34% Apparent slip = 7% Shaft power = 10000 Kw Specific fuel consumption = 0.22 kg/kW-hr Calculate EACH of the following: (a) The ship speed in knots; (b) The Taylor wake fraction; (c) The reduced speed at which the ship should travel in order to reduce the voyage consumption; (d) The voyage distance if the voyage takes 3 days longer at the reduced speed; (e) The amount of fuel required for the voyage at the reduced speed.
 


Q7. A ship of length 120 m displaces 11750 tonne when floating in sea water of density 1025 kg/m3. The center of gravity is 2m above the center of buoyancy and the waterplane is defined by the following equidistant half-ordinates given in Table
station AP 1 2 3 4 5 6 7 FP
½ breadth m 3.3 6.8 7.6 8.1 8.1 8.0 6.6 2.8 0
Calculate EACH of the following: (a) The area of the waterplane; (b) The position of the centroid of the waterplane from midships; (c) The second moment of area of the waterplane about a transverse axis through the centroid; (d) The moment to change trim one centimeter (MCT1cm).
 

Q8. A box shaped vessel is 80 m long, 12 m wide and floats at a draught of 4m. A full width midships compartment 15 m long is bilged and this results in the draught increasing to 4.5 m. Calculate EACH of the following, (a) The permeability of the compartment; (b) The change in metacentric height due to bilging.(A) and (B).The equivalent base area (Ab) is required because of the fineness of the bottom shell.
 

Q9. A ship 100 m long floats at a draught of 6 m and in this condition the immersed cross-sectional areas and water plane areas are as given in Tables Q1 (A) and Q1(B).The equivalent base area (Ab) is required because of the fineness of the bottom shell.
The equivalent base area (Ab) is required because of the fineness of the bottom shell.
Section AP 1 2 3 4 5 FP
Immersed cross section area(m2) 12 29 64 78 70 48 0
Draught (m) 0 0.6 1.2 2.4 3.6 4.8 6.0
Waterplane area (m2) Ab 560 720 876 942 996 1028
Calculate EACH of the following:
(a) The equivalent base area value Ab; 
(b) The longitudinal position of the center of buoyancy from midships;
(c) The vertical position of the center of buoyancy above the base.
 

Q10. A ship 150 m in length, 24 m breadth, displaces 25000 tonne when floating at a draught of 9 m in sea water of density 1025 kg/m3. The ship’s propeller has a diameter of 5.8 m, a pitch ratio of 0.9 and a blade area ratio of 0.45. With the propeller operating at 2 rev/sec, the following results were recorded: Apparent slip ratio = 0.06 Thrust power = 3800 kW Propeller efficiency = 64% The Taylor wake fraction is given by: WT = 0.5CB – 0.05 Calculate EACH of the following for the above condition: (a) The ship’s speed; (b) The real slip ratio; (c) The thrust per unit area of blade surface; (d) The torque delivered to the propeller.