Schedule 6
(Regulation 17(2))
STABILITY
PART I
INFORMATION AS TO STABILITY
The information relating to the stability of a ship to be provided for the master shall include the particulars specified below.
1. The ship's name, official number, port of registry, gross and register tonnages, principal dimensions, displacement, deadweight and draught to the Summer load line.
2. A profile view and, if necessary, plan views of the ship drawn to scale showing all compartments, tanks, storerooms and crew and passenger accommodation spaces, with their position relative to mid-ship.
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3.1 The capacity and the longitudinal and vertical centre of gravity of every compartment available for the carriage of cargo, fuel, stores, feedwater, domestic water or water ballast.
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3.2 In the case of a vehicle ferry, the vertical centre of gravity of compartments designated for the carriage of vehicles must be based on the estimated centres of gravity of the vehicles and not on the volumetric centres of the compartments.
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4.1 The estimated total weight and the longitudinal and vertical centre of gravity of each such total weight of —
4.1.1 the passengers and their effects; and
4.1.2 the crew and its effects.
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4.2 In estimating such centres of gravity, passengers and crew shall be assumed to be distributed about the ship in the spaces they will normally occupy, including the highest decks to which either or both have access.
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5.1 The estimated weight and the disposition and centre of gravity of the maximum amount of deck cargo which the ship may reasonably be expected to carry on an exposed deck.
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5.2 In the case of deck cargo, the arrival condition must include the weight of water likely to be absorbed by the cargo. (For timber deck cargo the weight of water absorbed shall be taken as fifteen per cent of the weight when loaded.)
6. A diagram or scale showing —
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6.1 the load line mark and load lines with particulars of the corresponding freeboards; and
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6.2 the displacement, tonnes per centimetre immersion, and deadweight corresponding to a range of mean draughts extending between the waterline representing the deepest load line and the waterline of the ship in light condition.
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7.1 A diagram or tabular statement showing the hydrostatic particulars of the ship, including the heights of the transverse metacentre and the values of the moment to change trim one centimetre. These particulars shall be provided for a range of mean draughts extending at least between the waterline representing the deepest load line and the waterline of the ship in light condition.
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7.2 If a tabular statement is used to comply with subparagraph 7.1, the intervals between such draughts shall be sufficiently close to permit accurate interpolation.
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7.3 In the case of ships having raked keels, the same datum for the heights of centres of buoyancy and metacentres must be used as for the centres of gravity referred to in paragraphs 3, 4 and 5.
8. The effect on stability of free surface in each tank in the ship in which liquids may be carried, including an example to show how the metacentric height is to be corrected.
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9.1 A diagram or table showing cross curves of stability, covering the range of draughts referred to in paragraph 7.1.
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9.2 The information must indicate the height of the assumed axis from which the righting levers are measured and the trim which has been assumed.
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9.3 In the case of ships having raked keels and where a datum other than the top of keel has been used, the position of the assumed axis must be clearly defined.
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9.4 Subject to subparagraph 9.5, only enclosed superstructures and efficient trunks as defined in paragraph 10 of Schedule 2 must be taken into account in deriving such curves.
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9.5 The following structures may be taken into account in deriving such curves if the Director is satisfied that their location, integrity and means of closure will contribute to the ship's stability —
9.5.1 superstructures located above the superstructure deck;
9.5.2 deckhouses on or above the freeboard deck whether wholly or in part only; and
9.5.3 hatchway structures on or above the freeboard deck.
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9.6 Subject to the approval of the Director in the case of a ship carrying timber deck cargo, the volume of the timber deck cargo, or a part thereof, may be taken into account in deriving a supplementary curve of stability appropriate to the ship when carrying such cargo.
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9.7 An example must be included to show how a curve of righting levers (GZ) may be obtained from the cross curves of stability.
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9.8 In the case of a vehicle ferry or a similar ship having bow doors, ship-side doors or stern doors where the buoyancy of a superstructure is taken into account in the calculation of stability information, and the cross curves of stability are based upon the assumption that such doors are secured weathertight, there must be a specific warning that such doors must be secured weathertight before the ship proceeds to sea.
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10.1 The diagram and statements referred to in subparagraph 10.2 shall be provided separately for each of the following conditions of the ship —
10.1.1 light condition. If the ship has permanent ballast, such diagram and statements must be provided for the ship in light condition both with and without such ballast;
10.1.2 ballast condition both on departure and on arrival. It is to be assumed that on arrival oil fuel, fresh water, consumable stores and the like are reduced to ten per cent of their capacity;
10.1.3 condition on departure and on arrival when loaded to the Summer load line with cargo filling all spaces available for cargo. Cargo must be taken to be homogeneous except if this is clearly inappropriate, for example, in cargo spaces which are intended to be used exclusively for the carriage of vehicles or of containers;
10.1.4 service loaded conditions both on departure and on arrival.
10.2.1 A profile diagram of the ship drawn to a suitable small scale showing the disposition of all components of the deadweight.
10.2.2 A statement showing the lightweight, the disposition and the total weights of all components of the deadweight, the displacement, the corresponding positions of the centre of gravity, the metacentre and also the metacentric height (GM).
10.2.3 A diagram showing the curve of righting levers (GZ). If credit is given for the buoyancy of a timber deck cargo the curve of righting levers (GZ) must be drawn both with and without this credit.
10.2.4 A statement showing the elements of stability in the condition compared to the criteria laid down in Schedule 3 paragraph 2.2.
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10.3 The metacentric height (GM) and the curve of righting levers (GZ) must be corrected for liquid free surface.
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10.4 If there is a significant amount of trim in a condition referred to in subparagraph 10.1 the metacentric height and the curve of righting levers (GZ) may be required to be determined from the trimmed waterline.
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10.5 If in the view of the Minister or person or organization authorized by the Minister the stability characteristics in either or both of the conditions referred to in subparagraph 10.1.3 are not satisfactory, such conditions must be marked accordingly and an appropriate warning to the master must be inserted.
11. A statement of instructions on appropriate procedures to maintain adequate stability in each case where special procedures are applied such as partial or complete filling of spaces designated for cargo, fuel, fresh water or other purposes.
12. The report on the inclining test and of the calculation derived from it to obtain information of the light condition of the ship.
PART II
SHIPS WHICH THE APPROVAL OF MINISTER OR PERSON OR ORGANIZATION AUTHORIZED BY THE MINISTER IS REQUIRED IN RELATION TO STABILITY INFORMATION
13. The ships referred to in regulation 17(3), (4)(a) and (5)(a) of the Regulations are as follows:
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13.1 an oil tanker over one hundred metres in length;
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13.2 a bulk carrier, or an ore carrier, over one hundred and fifty metres in length;
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13.3 a single deck bulk carrier over one hundred metres in length but not exceeding one hundred and fifty metres in length;
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13.4 a single deck dry cargo ship over one hundred metres in length;
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13.5 a purpose built container ship over one hundred and twenty-five metres in length;
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13.6 a column stabilised mobile offshore drilling unit; or
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13.7 a column stabilised mobile offshore support unit.
14. In paragraph 13 —
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“column stabilised” means constructed with the main deck of the unit connected to its underwater hull or footings by columns or caissons.
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“mobile offshore drilling unit” means a ship capable of engaging in drilling operations for the exploration or exploitation of resources beneath the sea bed such as liquid or gaseous hydrocarbons, sulphur or salt;
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“mobile offshore support unit” means a ship used in connection with the offshore petroleum industry to provide ancillary services such as accommodation, cranes or repair facilities; and
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“column stabilised” means constructed with the main deck of the unit connected to its underwater hull or footings by columns or caissons.