8 Simplified stability proof test procedure and assumptions
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - International Codes - SCV Code - Code of Safety for Small Commercial Vessels Operating in the Caribbean - Chapter III - Freeboard, Stability and Watertight Integrity - Part B - Stability - 8 Simplified stability proof test procedure and assumptions

8 Simplified stability proof test procedure and assumptions

  8.1 A vessel shall be in the condition specified in III/8.2 to III/8.8 inclusive when a simplified stability proof test is performed.

  8.2 The vessel shall be moored in a quiet, sheltered area free from extraneous forces such as propeller wash from passing vessels, or sudden discharges from shore-side pumps, and in a manner to allow unrestricted heeling.

  8.3 The construction of the vessel shall be complete in all respects

  8.4 Ballast, where necessary, shall be in compliance with regulation III/9 and shall be on board and in place.

  8.5 Each fuel and water tank shall be approximately three-quarters full.

  8.6 A weight equal to the total weight of all passengers, crew, and other loads permitted on the vessel shall be on board and distributed so as to provide normal operating trim and to simulate the vertical centre of gravity causing the least stable condition that is likely to occur in service. For the purposes of regulation III/8 the crew shall be counted as passengers.

  8.7 Unless otherwise specified, weight and vertical centre of gravity is assumed to be as follows:

  • .1 the weight of primary lifesaving equipment shall be simulated at its normal location, if not on board at the time of the test;

  • .2 the weight of one person is considered to be 75 kg (166 pounds) except where the vessel operates exclusively on protected waters, when passenger loads consist of men, women and children, the weight of one person is considered to be 65 kg (143 pounds);

  • .3 the vertical centre for the simulated weight of passengers, crew, and other loads shall be at least 760 mm (2.5 feet) above the relevant deck; and

  • .4 where the vessel carries passengers on diving excursions, the total weight of diving gear shall be included in the loaded condition, in the positions they would normally be carried, as follows:

    • .1 the total weight of individual diving gear for each passenger carried is assumed to be 36 kg (80 pounds), which includes the weight of scuba tanks, harness, regulator, weight belt, wet suit, mask, and other personal diving equipment; and

    • .2 the weight of any air compressors carried.

  8.8 On vessels having one upper deck above the main deck available to passengers, the vertical weight distribution shall not be less than the following:

  Weight on Upper Deck = (# of passengers on upper deck) x (Wt per passenger) x 1.33
  Weight on Main Deck = Total Test Weight - Weight on Upper Deck

  8.9 All non-return closures on cockpit scuppers or on weather deck drains shall be kept open during the test.

  8.10 A vessel shall not exceed the limitations in III/8.12, when subjected to the greater of the following heeling moments:

    Mp =(W)(Bp)/6; or
    Mw =(P)(A)(H)
       
where:      
Mp = passenger heeling moment in kilogram-metres (foot-pounds);
W = the total passenger weight using 75 kg (165 pounds) per passenger, or, where the vessel operates exclusively on protected waters, 65 kg (143 pounds) per passenger may be used;
Bp = the maximum transverse distance in metres (feet) of a deck that is accessible to passengers;
Mw = wind heeling moment in kilogram-metres (foot-pounds);
P = wind pressure of:
    (a) 36.6 kilograms/square metre (7.5 pounds/square foot) for operation on protected waters;
    (b) 48.8 kilogram/square metre (10.0 pounds/square foot) for operation on coastal waters;
      or
    (c) 73.3 kilograms/square metre (15.0 pounds/square foot) for operation on exposed waters;
       
A = area, in square metres (square feet), of the projected lateral surface of the vessel above the waterline, including each projected area of the hull, superstructure and area bounded by railings and structural canopies. For sailing vessels this is the bare poles area, or, where the vessel has no auxiliary power, with storm sails set; and
H = height, in metres (feet), of the centre of area (A) above the waterline, measured up from the waterline.

  8.11 For sailing vessels the heeling moment used for this test shall be the greater of the following:

  • .1 Passenger heeling moment from III/8.10.

  • .2 Wind heeling moment from III/8.10.

  • .3 Wind heeling moment calculated from the wind heeling moment equation in III/8.10 as

        Mw =(P)(A)(H),
           
    where:      
    Mw = wind heeling moment in kilogram-metres (foot-pounds);
    P = 4.9 kilograms/square metre (1.0 pounds/square foot);
    A = the windage area of the vessel in square metres (square feet) with all sails set and trimmed flat;
    H = height, in metres (feet), of the centre of effort of area (A) above the waterline, measured up from the waterline.

  8.12.1 When a vessel is subjected to the greater of the heeling moments determined in regulation III/8.10, the immersion of the loading mark shall not exceed the percentage of the freeboard specified in the following:

  • .1 on a flush deck vessel, 50 per cent;

  • .2 on a well deck vessel that operates on protected waters and has non-return scuppers or freeing ports, 100 per cent where the full freeboard is not more than one-quarter of the vertical distance from the waterline to the gunwale;

  • .3 on all other well deck vessels, 50 per cent

  • .4 on a cockpit vessel, the percentage is calculated from the following:

      on exposed waters: (2L - 1.5LN)/4L
      on protected or coastal waters: (2L - LN)/4L
        where:
        L = length of the weather deck; and
        LN = length of cockpit in the same units as L.

  • .5 on an open boat, 25 per cent;

  • .6 on a flush deck sailing vessel, 100 per cent

  8.12.2 Notwithstanding the percentages specified in regulation 8.12.1, when the vessel is subject to the greater of the heeling moments determined in regulation III/8.10, the immersion shall not exceed a value equivalent to one eighth of the beam of the vessel measured at the point of minimum freeboard as defined in regulation III/1.1

  8.13 Where during a simplified stability proof test a vessel fails to meet the requirements of regulation III/8.12, the entire test shall be repeated with a reduced load equivalent to a reduced number of passengers or a reduced weight of cargo or by utilising any other corrective measures available to enable the vessel to meet the requirements of regulation III/8.12.

  8.14 A ferry shall also be tested by using equivalent weights, by calculation, or other method acceptable to the Administration to determine whether the trim or heel during loading or unloading will submerge the deck edge. A ferry passes this test where, with the total number of passengers and the maximum vehicle weight permitted on board, the deck edge is not submerged during loading or unloading of the vessel.

  8.15 The Small Commercial Vessel Stability Test Procedure is given in Annex 2 .

Parent topic: Part B - Stability
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