CD-0033 - Stability I
CD-0033 - Stability I
CD-0033 - Stability I
1 What is the relationship between GM and the righting ability of the ship?
GZ = GM x sin (Angle of Heel)
GM is the righting lever returning the vessel upright
GZ = GM x tan (Angle of Heel)
The Curve of Statical Stability
2 What is the change in the apparent loss of GM due to free surface effect when 2
transverse bulkheads are introduced into the tank holding the liquid?
1/4
1/9
Nothing
1/2
3 What is the danger of having a large bunker tank only partially filled with bunkers?
FSE and virtual loss of GM
Constructional damage due to liquid movement in the tank
Excessive corrosion of the tank sides
Insufficient bunkers to complete the voyage
4 Which of the following items make a small positive transverse M at the start of a voyage
become dangerous during the passage? Select each correct answer.
Consumption of bunkers in a low tank
Consumption of bunkers in a high tank
Partially filled tanks giving free surface effect
Distribution of weights due to bad stowage
6 At what specific point during the dry docking of a vessel, does the effective loss of
internal stability stop decreasing?
When the vessel settles on the block overall.
When the vessel touches the blocks aft
When the water drops below the keel
Never
7 Which of the following items of information can be determined from examining the Curve
of Statical Stability? Select each correct option.
The Initial value of Transverse GM
Angle of Maximum Stability
The Righting Moment of the vessel at a specific angle of heel
Angle of deck edge immersion, where the water comes over the bulkhead deck
9 Which of the following points would be the specific point about which a vessel will roll in
a seaway?
Centre of Buoyancy B.
The Centre of Gravity G
The Centre of Flotation CF
The Centreline CL
10 The ships own derrick is used to discharge a heavy weight from the centreline of deck to
the jetty. At what instant does the most dangerous situation occur with respect to the
ships effective stability?
Weight lifted off the deck.
Weight is landed on the jetty
The weight is being swung over towards the jetty
The weight is swung out over the jetty and is started to be lowered
13 A tank on a vessel can hold 100 tonnes of FW when full. How many tonnes of liquid
(Relative density 0.5) could it take when full?
200 tonnes.
50 tonnes
100 tonnes
150 tonnes
15 A vessel with a large Transverse GM will have which of the following rolling periods?
CD-0033 Stability I
18 Which of the following initial conditions onboard are required to conduct an inclining
experiment? Select each correct option.
No free liquid surface in any tanks
Minimum bunkers, water and ballast
No cargo on board
Minimum of personnel onboard to conduct experiment
19 A ship floating on an even keel and upright has a weight loaded on the port side of the
deck and towards the stern of the vessel. What will be the final condition of the ship after
loading?
Upright and trimmed by the stern
Heeled to port and trimmed by the stern
Listed to port and trimmed by the stern
Listed to port and trimmed by the head
20 The condition of Equilibrium for a floating vessel is which of the following conditions?
When the vessel is upright and even keel and GM is positive
When G is vertically below B with equal and opposite forces of displacement and
buoyancy
When the vessel is upright and the Fore and Aft draughts are steady and the GM is
positive
When the vessel completes loading or discharging cargo
21 How can a ship’s officer change the value of the Transverse Metacentric Height?
Only by loading cargo and changing the position of Centre of Gravity “G” of the ship.
By loading or discharging cargo and in other ways changing the positions of both G
and M
By loading or discharging cargo and changing the position of G only
By vertically shifting cargo already on board and changing the position of both G and
M
22 If a vessel is rolling heavily in a seaway and has a negative GM and a small Angle of Loll,
describe how the vessel will roll.
Roll evenly each side of the angle of loll
Roll evenly either side of the upright position
Roll unevenly flopping over between the Angle of loll on each side
Roll between the angle of loll on each side
CD-0033 Stability I
23 How can the adverse effects of Free Surface on a vessel be reduced by the ship’s officer?
Select each correct option.
Loading more ballast and increasing the displacement
Transferring ballast from high tank to a low tank
The pressing up of the liquid within the slack tank
The draining of the liquid from the slack tank
24 Why is a vessel entering dry dock normally slightly trimmed by the stern?
To allow better manoeuvring when entering into the drydock
To minimise the loss of stability
To allow drainage of water off the decks
To position the vessel easily over the blocks
26 What is minimum value of the GM allowed under the international Load Line Rules?
0.15 m
1.5 m
2.0 m
0.25m
28 Why can the draught amidships not be used to extract the value of displacement from
the displacement table?
The displacement is not dependant on the draught
The draught amidships is not the true mean draught
The draught amidships is not the mean of the draughts at the forward and after
perpendiculars
The arithmetical mean of the end draughts should be used to determine correct
displacement.
30 A weight of 200 tonnes is loaded amidships on the deck at a height of 7 metres above
the keel on a ship of 3800 tonnes and KG 5.0 metres. What is the final KG of the vessel
after loading?
5.2 metres
5.1 metres
5.0 metres
4.9 metres
CD-0033 Stability I