4.27 Permissible Length of Compartments:

 General

(1) Ships shall be as efficiently subdivided as is possible having regard to the nature of the service for which they are intended and the degree of subdivision shall vary with the length of the ship and with the service, in such manner that the highest degree of subdivision corresponds with the ships of greatest length, primarily engaged in the carriage of passengers.

 Factor of subdivision

(2) The maximum permissible length of a compartment having its centre at any point in the ship's length is obtained from the floodable length by multiplying the latter by an appropriate factor called the factor of subdivision.

(3) The factor of subdivision shall depend on the length of the ship, and for a given length shall vary according to the nature of the service for which the ship is intended and it shall decrease in a regular and continuous manner-

• (a) as the length of the ship increases, and

• (b) from a factor A, to a factor B.

(4) The variations of the factors A and B shall be expressed by the following formulae (1) and (2) where L is the length of the ship as defined in section 1.3-

 Criterion of Service

(5) For a ship of given length the appropriate factor of subdivision shall be determined by the criterion of service numeral (hereinafter called the criterion numeral) as given by the following formulae (3) and (4) where-

C_s = the criterion numeral;

L = the length of the ship (metres), as defined in section 1.3;

M = the volume of the machinery room (cubic metres), as defined in section 1.3, with the addition thereto of the volume of any permanent oil fuel bunkers which may be situated above the inner bottom and forward of or abaft the machinery room;

P = the whole volume of the passenger spaces below the margin line (cubic metres), as defined in section 1.3;

V = the whole volume of the ship below the margin line (cubic metres); and

P₁ = KN

where:

• N = the number of passengers for which the ship is to be certified, and

• K = 0.056L.

• when P₁ is greater than P-

• (3)

• in other cases-

• (4)

(6) Where the value of KN is greater than the sum of P and the whole volume of the actual passenger spaces above the margin line, the figure to be taken as P₁ is that sum or two-thirds KN , whichever is the greater.

(7) For ships not having a continuous bulkhead deck the volumes are to be taken up to the actual margin lines used in determining the floodable lengths’

 Rules for Subdivision of Ships other than those covered by Subsection (14) (Special Subdivision Standards)

(8) The subdivision abaft the forepeak of ships of 131 metres in length and upwards having a criterion numeral of 23 or less shall be governed by the factor A given by formula (1); of those having a criterion numeral of 123 or more by the factor B given by formula (2); and of those having a criterion numeral between 23 and 123 by the factor F obtained by linear interpolation between the factors A and B, using the formula-

• (5)

(9) Nevertheless, where the criterion numeral is equal to 45 or more and simultaneously the computed factor of subdivision as given by formula (5) is 0.65 or less, but more than 0.5, the subdivision abaft the forepeak shall be governed by the factor 0.5.

(10) Where the factor F is less than 0.4 and it is shown to the satisfaction of the Administration to be impracticable to comply with the factor F in a machinery compartment of the ship, the subdivision of such compartment may be governed by an increased factor, which, however, shall not exceed 0.4.

(11) The subdivision abaft the forepeak of ships of less than 131 metres but not less than 79 metres in length having a criterion numeral equal to S, where-

• 

shall be governed by the factor unity; of those having a criterion numeral of 123 or more by the factor B given by the formula (2); of those having a criterion numeral between S and 123 by the factor F obtained by linear interpolation between unity and the factor B using the formula-

• (6)

(12) The subdivision abaft the forepeak of ships of less than 131 metres but not less than 79 metres in length and having a criterion numeral less than S , and of ships of less than 79 metres in length shall be governed by the factor unity, unless, in either case, it is shown to the satisfaction of the Administration to be impracticable to comply with this factor in any part of the ship, in which case the Administration may allow such relaxation as may appear to be justified, having regard to all the circumstances.

(13) The provisions of subsection (12) shall apply also to ships of whatever length, which are certified to carry a number of passengers exceeding 12 but not exceeding:

• or 36, whichever is less.

 Special Subdivision Standards for Ships complying with Section 7.21(2)

(14) In the case of ships complying with section 7.21(2) the subdivision abaft the forepeak shall be governed by a factor of 0.5 or by the factor determined according to paragraphs 5 to 13, if less than 0.5.

(15) In the case of such ships of less than 91.5 metres in length, if the Administration is satisfied that compliance with such factor would be impracticable in a compartment, it may allow the length of that compartment to be governed by a higher factor provided the factor used is the lowest that is practicable and reasonable in the circumstances.

(16) The special provisions regarding permeability given in section 4.26(2) shall be employed when calculating the floodable length curves.

(17) Where the Administration is satisfied that, having regard to the nature and conditions of the intended voyages, compliance with the other provisions of this Chapter and Chapters 6 and 7 is sufficient, the requirements of section 4.27(16) need not be complied with.