Regulation 7 - Combined Longitudinal and Transverse Subdivision
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Statutory Documents - IMO Publications and Documents - Resolutions - Assembly - IMO Resolution A.265(VIII) – Regulations on Subdivision and Stability of Passenger Ships as an Equivalent to Part B of Chapter II of the International Convention for the Safety of Life at Sea, 1960 – (Adopted on 20 November 1973) - Annex - Regulations on Subdivision and Stability of Passenger Ships as An Equivalent to Part B of Chapter II of the International Convention for the Safety of Life at Sea, 1960 - Regulation 7 - Combined Longitudinal and Transverse Subdivision

Regulation 7 - Combined Longitudinal and Transverse Subdivision

  (a) Regulation 6 is predicated upon the condition that transverse bulkheads ordinarily extend from side to side. However, an Administration may also accept a combination of transverse and longitudinal watertight bulkheads wherein some of the transverse watertight bulkheads extend inboard only to longitudinal watertight bulkheads, provided that:

  • (i) A horizontal watertight division located not less than 0.1B 1 above the base line is fitted in the centre space between the longitudinal bulkheads, and the space below the horizontal division is subdivided by watertight bulkheads in line with the watertight transverse bulkheads in the wings or by equivalent means.

  • (ii) Compliance with the provisions of Regulation 5 is demonstrated.

  • (iii) The Subdivision Index A, calculated according to paragraphs (b) and (c) of this Regulation is not less than the required Subdivision Index R.

  (b) To calculate the contribution of the wing compartments to the attained Subdivision Index A:

  • (i) “a” is calculated as in Regulation 6(b) using the distances from the aft terminal of Ls to the transverse bulkheads bounding the considered wing compartment or group of compartments.

  • (ii) “p” is obtained by multiplying the values obtained by application of formulae (IV) of Regulation 6(c) by the reduction factor “r” according to formulae (X), which represents the probability that the inboard spaces will not be flooded.

    • (1) Where l/Ls is equal to or more than 0.2 b/B 1:

    • (2) Where l/Ls is less than 0.2 b/B 1, r shall be determined by linear interpolation between 1.0 for l/Ls = 0 and the r-value calculated by formulae (X) for l/Ls = 0.2b/B1.

    In formulae (X) the terms have the following meaning:

    l = the distance between the longitudinal limits used for the calculation of “a” and “p” as defined in Regulation 6(b) and (c).

    b = the mean transverse distance measured at right angles to the centreline at the subdivision loadline between the shell and a plane through the outermost portion of and parallel to that part of the longitudinal bulkhead which extends between the longitudinal limits used in calculating “a”.

  • (iii) “s” is calculated as in Regulation 6(d), treating the inboard spaces as not floodable, i.e. μ = 0.

  (c) If the attained Subdivision Index A obtained by application of the procedures in paragraph (b) of this Regulation is less than the required Subdivision Index R, the additional contribution to the attained Subdivision Index A attributable to flooding of spaces inboard of the longitudinal bulkheads together with the outboard spaces may be included. For the purposes of this contribution:

  • (i) “a” is calculated as in sub-paragraph (b)(i) of this Regulation except that the distances from the aft terminal of Ls are taken to each transverse bulkhead bounding either a wing or an inboard compartment or group thereof.

  • (ii) “p” is obtained by multiplying the values obtained by application of formulae (IV) through (VII) of Regulation 6(c) by (1-r).

  • (iii) “s” is calculated as in Regulation 6(d). In so doing, the assumed extent of flooding of both wing and inboard spaces shall be that which would result from an assumed longitudinal extent of damage coincidental with the longitudinal limits used in calculating “a” and “p” and extending in to the ship's centreline.

Parent topic: Annex - Regulations on Subdivision and Stability of Passenger Ships as An Equivalent to Part B of Chapter II of the International Convention for the Safety of Life at Sea, 1960
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