Exam 1 March 2010, questions and answers PDF

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SQA written exam 2005 questions and answers...

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School of Nautical Studies STABILITY AND OPERATIONS No 01 (Mar 2005) Attempt ALL questions Marks for each question are shown in brackets Section A 1.

(a)

Explain the reasons for loadlines.

(b)

A vessel is loading in port in a Tropical Zone.

(5)

Summer load draught 10.62m; FWA 280mm; Dock water density 1.009tm-3. Calculated TPC (Dock Water) 26 (constant). The water line is 205mm below the Summer load line. Calculate EACH of the following: (i)

(ii)

2.

the sinkage required in port in order that the vessel will be on her Tropical marks in the open sea; the quantity of cargo to load to be on her Tropical marks at sea.

(12) (3)

(a)

Explain the difference between an angle of list and an angle of loll.

(5)

(b)

Describe a safe procedure for correcting an angle of loll.

(6)

(c)

A box shaped vessel is presently at a mean draught of 6.24m and is listed 4° to port. KG 8.2m; KM 9.Om (constant); TPC 32; Displacement 10 400t

(d)

Calculate the quantity of cargo to be loaded in the tween deck, 13.5m off the centreline in order to finish upright.

(5)

The vessel in Q2(c) now loads 700t of cargo. Calculate the draught on completion of loading this parcel.

(4)

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School of Nautical Studies Section B

3.

With reference to a vessel moored alongside having completed all cargo operations: (a)

(b)

4.

(a)

(b)

5.

(a) (b)

produce a checklist to indicate the deck duties of the Officer of the Watch (OOW) whilst waiting for the next sailing tide;

(12)

explain the initial emergency procedures the OOW should take in the event of discovering a fire.

(8)

Describe the precautions and equipment required when using a gangway as a means of access to a vessel.

(7)

Explain the procedures and precautions to be observed before entering an enclosed space.

(13)

Outline the objectives and purpose of the International Safety Management (ISM) Code.

(11)

Describe the legal status and purpose of EACH of the following: (i)

the Code of Safe Working Practices for Merchant Seamen (COSWP);

(ii)

Merchant Shipping Notices (MSNs).

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(5)

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School of Nautical Studies STABILITY AND OPERATIONS No 01 (Mar 05) Q1 1.

(a)

To survive a breach of the hull, a vessel requires a certain amount of reserve buoyancy. This requires a minimum freeboard. The required loadlines are measured and marked on the ships side by the vessels classification society. These marks on the ships side allow the crew and officials to see whether the vessel is overloaded.

(b) 11.020 m

T

DWA = 0.179 m 10.841 m

S – T = 0.221 m Sinkage

S 10.620 m 0.205 m 10.415 m

To Calculate S - T S – T = 1/48 x SD

= 10.620 48

=

0.221 m

To Calculate the DWA DWA =

= DWA =

FWA x

(1025 ~  DW) 25

280

(1025 - 1009) 25

x

179 mm = 0.179m

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School of Nautical Studies To Calculate Sinkage Required Sinkage

Required Sinkage

=

Required Draught – Present Draught

=

11.020-

=

0.605 m = 60.5 cm

10.415

To Calculate the Cargo to Load

Cargo to Load

Cargo to Load

=

Sinkage x TPCDW

=

60.5 x 26

=

1573 t

The Cargo to Load is 1573 tonnes

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School of Nautical Studies Q2 (a)

LIST A vessel is said to be listed when inclined by an INTERNAL FORCE e.g. by a weight shifted transversely within the vessel. G is off the centreline. The vessel is initially stable.

ANGLE of LOLL An Angle of Loll is caused when the vessel is initially unstable in the upright condition. As the vessel inclines, M moves in a circular motion upwards. If M moves above G, then the vessel will come to rest at that angle. This angle is known as the angle of loll. In this case G is on the Centreline.

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School of Nautical Studies (b) If an angle of Loll does develop on a voyage, the v/l’s COG may be lowered to restore positive GM, either by moving cargo to a lower position in the v/l, jettisoning topweight (in an emergency), or by filling low ballast spaces, such as Double Bottoms (DB’s). Filling DB’s is the most usual course of action decided upon, but it must be remembered that filling a previously empty tank will, during the operation, cause a further ‘virtual rise’ in G due to FSE until the tank is completely full. To ensure the operation is carried out safely, therefore, it is essential that the following procedures are adopted:

1. top up tanks that are already slack. 2. calculate the FSE which will arise before pumping into empty tanks. This will ensure that the rise of G during the operation is acceptable. 3. fill empty tanks one at a time. 4. start with the smallest tank on the LOW side first. If a tank on the high side is filled first, the ship will start to right herself but will then tend to roll over suddenly in an uncontrolled fashion as she passes through the upright. She will then ‘whip’ through to a larger angle of loll on the other side. She may even capsize if the momentum gathered is sufficient. When the low side is filled first, the angle of list will increase initially, but in a slow and controlled fashion. After some time, the weight of the ballast water added will be sufficient to lower the ship’s COG (despite the extra FSE), to cause the angle of list to decrease. By this method the inclining motions of the v/l take place in a gradual and controlled manner (see over page). 5. now fill the opposite tank on the high side. 6. fill tanks alternately, low side first, until the v/l returns to positive GM. 7. ensure that all tanks are completely filled.

(c)

KM KG GM

9.000m 8.200m 0.800m

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School of Nautical Studies

To Calculate the amount of cargo to load For a vessel to be upright: Moments to Port

=

Moments to Starboard

Δ x GGh

=

wxs

(Since GGh = GM Tan θ) Δ x GM Tan θ=

wxs

10400 x 0.8 tan 4º =

w x 13.5

581.791

=

13.5w

581.791 13.5

=

w

43.1

=

w

43.1 tonnes are to be loaded in the Starboard Tween Deck

(d)

To Calculate Sinkage Total Cargo Loaded = 43.1 + 700 = 743.1 tonnes

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School of Nautical Studies Assuming that the TPC remains contant Sinkage

=

Sinkage

=

Sinkage

=

Weight Loaded TPC 743.1 32 23.2 cms = 0.232m

To Calculate the Final Mean Draught Old draught 6.240m Sinkage + 0.232m New draught 6.472m The Completion draught will be 6.47m (4)

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