Appendix 1 - Transverse subdivision
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Statutory Documents - IMO Publications and Documents - Resolutions - Assembly - IMO Resolution A.684(17) – Explanatory Notes to the Solas Regulations on Subdivision and Damage Stability of Cargo Ships of 100 Metres In Length and Over – (Adopted on 6 November 1991) - Annex - Explanatory Notes to the SOLAS Regulations on Subdivision and Damage Stability of Cargo Ships of 100 Metres in Length and Over - Appendix 1 - Transverse subdivision

Appendix 1 - Transverse subdivision

 This appendix illustrates, by means of examples, how to divide the ship length Ls into discrete damage zones. The subdivision of Ls into damage zones should not only take account of existing transverse bulkheads but also separate smaller local watertight compartments, the flooding of which has significant influence on the damage stability results.

  1 Figure A-1 shows the elevation of a part of a ship containing two compartments named A and B. Compartment A is divided by local subdivision into the spaces A1 and A2. For the purpose of calculating the products ps which contribute most favourably to the attained subdivision index, three fictitious compartments or damage zones are considered. The bases for calculations of the p and s-values are given below:

.1 Zone 1 of length l1 : p based on l1
  s based on flooding of space A1
.2 Zone 2 of length l2 : p based on l2
  s based on flooding of space A1 only or of A2 only, or of A1 and A2, whichever results in the least s-value
.3 Zone 3 (or space B) of length l3 : p based on l3
  s based on flooding of space B
.4 Zones 1 + 2: p based on l1 and l2
  s based on flooding of A1 or of A1 and A2, whichever results in the lesser s-value
.5 Zones 2 + 3: p based on l2 and l3
  s based on flooding of A1 and A2 and B or of A1 and B or of A2 and B, whichever results in the least s-value
.6 Zones 1 + 2 + 3: p based on l1 , l2 and l3
  s based on flooding of space A1 and B or of A1 and A2 and B, whichever results in the lesser s-value

  2 It would also be compatible with the regulations to ignore the local subdivision with respect to the calculations of the p-value. In this case, the following compartments and group of compartments would be considered:

.1 Zone a of length l3 = l1 + l2 : p based on la
  s based on flooding of space A1 or of space A2 or of spaces A1 and A2, whichever results in the least s-value
.2 Zone b of length lb (= l3 ): p based on lb
  s based on flooding of space B
.3 Zone a + b: p based on la and lb
  s based on flooding of A1 and B or of A2 and B or of A1 and A2 and B, whichever results in the least s-value

  3 Obviously, the approach given in paragraph 1 above will generally lead to an attained sub-division index which is higher than (or at least equal to) that defined by the approach of paragraph 2. Also, the error made by neglecting the actual distribution of damage in the vertical direction is much smaller in the first case.

  4 Another example of local subdivision is shown in Figure A-2. The following tables illustrate how this can be handled.

Figure A-1 Transverse subdivision into zones

Figure A-2 Transverse subdivision into zones

Table A-1 p-value calculated including the effect of local subdivision

Damage zones measuring length of space opened p based on length(s) S based on the flooding of space(s) resulting in the poorest stability
1 l1 space A
2 l2 space A or space B or spaces A and B‡
3 l3 space B or space C or spaces B and C‡
4 l4 space C or space D or spaces C and D‡
1 + 2 l1 , l2 space A or spaces A and B‡
2 + 3 l2 , l3 space B or spaces A and C or spaces A, B and C‡
3 + 4 l3 , l4 space C or spaces B and D or spaces B and C and D‡
1 + 2 + 3 l1 , l2 , l3 spaces A and B or A and C or A and B and C‡
2 + 3 + 4 l2 , l3 , l4 spaces A and C or B and D or A and B and C and D‡
1 + 2 + 3 + 4 l1 , l2 , l3 , l4 spaces A and C or A and B and D or A and B and C and D‡

  ‡ whichever results in a smaller s-value.

Table A-2 p-value calculated ignoring local subdivision

Damage zones measuring length of space opened p based on length(s) S based on the flooding of space(s) resulting in the poorest stability
A lA = l1 + l2 space A or space B or spaces A and B‡
C lc = l3 + l4 space C or space B or space D or spaces C and B or spaces B and D or spaces C and D or spaces B and C and D‡
A + C lA , lC space B or spaces A and C or spaces B and D or spaces A and B and C or spaces A and B and D or spaces A and B and C and D‡

  ‡ whichever results in a smaller s-value.

Parent topic: Annex - Explanatory Notes to the SOLAS Regulations on Subdivision and Damage Stability of Cargo Ships of 100 Metres in Length and Over
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