Page 426 - statbility for masters and mates

414 Ship Stability for Masters and Mates
COMMAND ENDORSEMENT (LIMITED EUROPEAN)
Ship Construction and Stability
2 hours. Attempt all questions. Marks for each question are shown in brackets.
1. A ship has a light displacement 435 tonnes with KG 3.25 m.
On board this ship there are 40 tonnes of fuel, water, stores and crew effects at Kg 3.80 m with a free surface moment of 35 t m.
The single hold is rectangular of length 40m, width 9.4m and depth 5.1 m and is to be ®lled with a bulk cargo (stowage factor 1.4 m3/tonne). When ®lled the Kg of the hold is 3.34 m.
Calculate the GM of the ship in its loaded condition if the loaded KM is 4.05 m (30)
2. A ship is at displacement 1700 tonnes with draughts 3.20 m forward 4.05 m aft. The following is the appropriate hydrostatic data:
Length BP: 55 m TPC: 5.2 MCTC: 22.8 Centre of Flotation 2.5 m abaft amidship.
Calculate:
(a) the drafts forward and aft produced by loading 100 tonnes 40 m
forward of the aft perpendicular; (20) (b) from the initial condition, the weight to load 37 m forward of the aft perpendicular to bring the ship to a trim of 0.6 m by the stern.
3. Use Worksheet Q.3: Simpli®ed Stability ± Deadweight Moment Curve. (Ensure that all points plotted on the diagram can be identi®ed in the
working).
The load displacement is 1175 tonnes.
The ships present condition: displacement 800 tonnes. Deadweight moment 600 t m.
Cargo to be loaded: 250 tonnes at Kg 2.8 m.
From the above condition:
(a) Determine the maximum weight of cargo that can be taken at Kg
4.5 m so that stability is adequate. (10)
(b) It is anticipated that 30 tonnes of fuel and water at Kg 1.6 m will be used on passage producing a free surface moment of 100 t m. Determine the maximum weight of cargo that can be loaded at Kg 4.5 m so that stability is adequate on arrival at the discharge port. (20)
4. (a) Explain clearly the meaning of the term `reserve buoyancy'. (15) (b) Describe the items that maintain the integrity of reserve buoyancy giving a brief indication of any maintenance that may be required. (15)
5. (a) (i) Sketch a typical GZ curve for a stable ship and indicate the features that may be found from it. (15) (ii) The ship in (a) (i) is now further loaded with deck cargo. Show on the same curve how the GZ might change due to this. (7)