CON & NA-JUL-2019

Q1. With reference to Roll-on Roll-off ferries – A. Describe the problem of free surface effect B. Explain how it is intended that water should be cleared from car or cargo decks; C. Describe possible methods for improving the stability and survivability of these vessels.

Q2. Give a reasoned opinion as to the validity of the following assertions concerning ship structure: A. Crack propagation in propeller shaft ‘A’ brackets or spectacles frames is indicative of inadequate scantlings and strength; B. The adequate provision of freeing ports is as critical to seaworthiness as watertight integrity.

Q3. (a) What is free surface effect? How can be avoided or reduced.(b) Give the components of ships resistance while vessel is ‘enroute’.

Q4. (a) Draw the mid ships section of an oil tanker with Double Hull & name each part. (b) What is Bow Flare? Why is it so important in Bulk Carriers? 

Q5. (a) Considering the vessel as a compound beam define Bending moment shearing force. Which is the point of Maximum Bending Moment (b) Sketch and Describe Hatch coaming of a large bulk carrier.

Q6. A. Describe how the force on the ship’s bottom and the GM vary when grounding takes place.

B. A ship of 8,000 tonnes displacement takes the ground on a sand bank on a falling tide at an even keel draft of 5.2 metres. KG 4.0 metres. The predicted depth of water over the sand bank at the following low water is 3.2 metres. Calculate the GM at this time assuming that the KM will then be 5.0 metres and that mean TPC is 15 tonne.
 

Q7. 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.
 

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

B. A ship 120m long floats has draughts of 5.50m forward and 5.80 forward and 5.80m aft; MCTI cm 80 tonne m, TPC 13, LCF 2.5m forward of midships. Calculate the new draughts which a mass of 110 tonne is added 24m aft of midships.
 

Q9. The speed of a ship is increased to 18% above normal for 7.5 hours, and then reduced to 9% below normal for 10 hours. The speed is then reduced for the remainder of the day so that the consumption for the day is the normal amount. Find the percentage difference between the distance traveled in that day and the normal distance traveled per day.
 


Q10. With reference to fixed pitch propellers: a. Explain Propeller Slip and Propeller Thrust.

b. The shaft power of a ship is 3000 KW, the ship’s speed V is 13.2 knot. Propeller rps is 1.27. Propeller pitch is 5.5m and the speed of advance is 11 Knots. Find: i. Real Slip ii. Wake fraction iii. Propeller thrust, when its efficiency, η = 70%