Hull Construction Regulations (C.R.C., c. 1431)

Calculations of Stability in Damaged Condition

• 1 The sufficiency of intact stability of every ship to which Part I of these Regulations applies shall be determined by calculation, which has regard to the design and construction of the ship and the damaged compartments and is in accordance with the following assumptions:

  • (a) the ship shall be assumed to be in the worst condition as regards stability that is likely to be experienced having regard to the intended service of the ship;

  • (b) the volume permeabilities and surface permeabilities shall be assumed to be as follows:

    Spaces	Permeability
    Appropriated to cargo, coal or stores	60
    Appropriated to accommodation for passengers and crew	95
    Appropriated to machinery	85
    Appropriated to liquids	0 or 95, whichever results in the more onerous requirements;

  • (c) the minimum extent of damage shall be assumed to be as follows:

    • (i) longitudinal extent: 3.05 m plus 3 per cent of the length of the ship, or 10.67 m, or 10 per cent of the length of the ship, whichever is the least,

    • (ii) transverse extent: 20 per cent of the breadth of the ship (measured inboard from the ship’s side at right angles to the centre line at the level of the deepest subdivision load water line),

    • (iii) vertical extent: from the top of the double bottom up to the margin line,

    • (iv) if any damage of lesser extent than that indicated in subparagraphs (i), (ii) and (iii) would result in a more severe condition regarding heel or loss of metacentric height, such damage shall be assumed for the purposes of the calculation;

  • (d) where the ship is fitted with decks, inner skins or longitudinal bulkheads of sufficient tightness to restrict the flow of water, regard shall be had to such restrictions in the calculation.

Sufficiency of Stability in Damaged Condition

• 2 The intact stability of the ship shall be deemed to be sufficient if the calculation mentioned in section 1 shows that, after the assumed damage and after equalization measures have been taken, the final condition of the ship is as follows:

  • (a) in the event of unsymmetrical flooding, the metacentric height is positive;

  • (b) in the event of unsymmetrical flooding, the heel does not exceed seven degrees, except that in special cases the Board may allow additional heel, but in no case shall the final heel exceed 15 degrees; and

  • (c) in the event of unsymmetrical flooding, the margin line is not submerged.

• 3 Automatic equalization measures are preferable and complete details in this regard shall be submitted with the calculations; all pipes concerned shall be of suitable area to permit rapid counter flooding; where air and filling or overflow pipes are led to a common main, care shall be taken that in the event of damage there is no leakage to intact compartments through these or any other pipes.