CON & NA-APR-2019

Q1. 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.

Q2. 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.

Q3. With reference to Underwater Inspection in Lieu of Dry docking 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.

Q4. Describe a method of the attachment of bilge keels; State THREE reasons for not extending bilge keels the entire length of the vessel; Explain TWO principles of roll damping those those bilge keels exploit.

Q5. List SIX hazards that arise with the carriage of liquefied gas in bulk. Describe, with the aid of a sketch, the details of construction of a prismatic cargo tank within a gas carrier designed to carry liquefied gas (LPG).

Q6. A ship of 15000 tonne displacement has an Admiralty Coefficient, based on shaft power, of 420. The mechanical efficiency of the machinery is 83%, shaft losses 6%, propeller efficiency 65% and QPC 0.71. At a particular speed the thrust power is 2550kW. Calculate: (i) Indicated power; (ii) Effective power; (iii) Ship speed.

 

Q7. A. Describe stability requirement for dry-docking.

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.

 

Q8. A. Define longitudinal centre of gravity (LCG) and longitudinal centre of buoyancy (LCB).

B. The immersed cross-sectional area of a ship 120m long, commencing from aft are 2,40,79,100,103,104,104,103,97 and 58 m2 calculate – (i) Displacement; (ii) Longitudinal position of the centre of buoyancy.

 

Q9. With respect to Buoyancy of a vessel: A. What do you understand by reserve buoyancy what happen if the lost buoyancy is greater than the reserve buoyancy?

B. A forward deep tank 12 m long extends from a longitudinal bulkhead to the ship’s side. The widths of the tank surface measured from the longitudinal bulkhead at regular intervals are 10, 9, 7, 4 and 1 m. Calculate the second moment of area of the tank surface about a longitudinal axis passing through its centroid.
 

Q10. A ship of length 140m , Breadth of 18.5m, draught of 8.1m and a displacement of 17,025 tonnes in sea water, has a face pitch ratio of 0.673. Diameter of the Propeller is 4.8m. The results of the speed trial show that true slip may be regarded as constant over a range of 9 to 13 knots and is 30%, w = 0.5CB-0.05. If fuel used is 20t/day at 13 knots and fuel consumption/day varies as cube of speed of ship, Determine the fuel consumption, when propeller runs at 110 rpm.