DieselShip's Online Content Library

Q1. What do you understand by margin line? With a neat diagram explain following terms:

(a) Floodable length curve

(b) Permissible length curve

(c) Factor of subdivision

Q2. With reference to cargo hatch covers on large container ships:

(a) describe how they are tested for water tightness

(b) explain how the weight of the hatch and containers is transferred to the ship's structure whilst allowing for deflections of the hull in a seaway

(c) describe, with the aid of a sketch, the type and location of damage that can occur due to wear of the hatch supporting arrangements.

Q3. With reference to the classification of ships, explain each of the following:

(a) why ships are built to classification society rules.

(b) the meaning of the notation 100A1.

(c) how a ship remains in class throughout the life of the vessel.

Q2. 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?

Q4. With reference to the prevention of hull corrosion discusses:

A. Surface preparation and painting of new ship plates.

B. Design of the ships structure and its maintenance. C. Catholic protection by sacrificial anodes, of the internal and external areas of the ship.

Describe the effect of cavitation’s on

(i) The thrust and torque

(ii) the propeller blades.

(b) A ship of 355190 tonne displacement is 325 m long, 56m wide and floats in sea water of density 1025 kg/m3 at a draught of 22.4 m. The propeller has a diameter of 7.4 m, a pitch ratio of 0.85, and when rotating at 1.5 rev/s the real slip is 48.88% and the fuel consumption is 165 tonne per day.

The taylor wake fraction Wt=0.5Cb-0.05.

Calculate

a) The speed in knots

b) The reduced speed at which the ship should travel if the fuel consumption in a voyage is to be halved.

C) the length of the voyage if the extra time on passage is six days when travelling at the reduced speed.

d) The amount of fuel required onboard before commencing on the voyage at the reduced speed.

Q7. A) Why is an inclining experiment carried out? Write short account of the method adopted.

b) An inclining experiment was carried out on a ship of 8000 tonne displacement. The inclining ballast was moved transversely through 12 m and the deflections of a pendulum 5.5m long, measured from the centreline, were as follows

3 tonne port to starboard 64 mm S

3 Tonne 116 mm S

Ballast restored 3 mm S

3 Tonne starboard to port 54 mm P

3 tonne starboard to port 113 mm P

Calculate the metacentric height of the vessel. (10)

Q8. A. Explain the use of KN curves.

B. The half breadths of the load waterplane of a ship 150 m long commencing from aft, are 0.3. 3.8. 6.0, 7.7, 8.3.9.0,8.4.7.8, 6.9.4.7 and 0 m respectively. Calculate: (a) area of waterplane (b) distance of centroid from amidships (c) second moment of area about a transverse axis through centroid.

Q9. A. Describe how water tightness is maintained where bulkheads are pierced by longitudinal beams or pipes.

b) The length of a ship is 7.6 times the breadth, while the breadth is 2.85 times the draught. The block coefficient is 0.69, prismatic coefficient 0.735, waterplane area coefficient 0.81 and the wetted surface area 7000 m2. The wetted surface area S is given by Denny's formula.

Calculate: (a) displacement in tonne (b) area of immersed midship section (c) waterplane area.

Q10. A. List the main factors which affect the rolling period of a vessel; B. A box-shaped vessel is 20 m long and 10 m wide.  The weight of the vessel is uniformly distributed throughout the length and the draught is 2.5 m.  The vessel contains ten evenly spaced double bottom tanks, each having a depth of 1m. Draw the shear force diagrams: With No.1 and No.10 tanks filled; With No.3 and No.8 tanks filled; With No.5 and No.6 tanks filled. Which ballast condition is to be preferred from the point of view of strength?