Division .2.8 The diameter ‘d’ of the main and branch bilge suction pipes shall be calculated according to the following formulae. However, the actual internal diameter may be rounded off to the nearest standard size acceptable to the Administration of the flag State: main bilge suction pipe:F1

$d=25+\mathrm{1,68}\sqrt{L\left(B+D\right)}$

branch bilge suction pipes between collecting boxes and suctions:

$d=25+\mathrm{2,15}\sqrt{L_1\left(B+D\right)}$

where:

d

is the internal diameter of the bilge main (millimetres),

L and B

are the length and the breadth of the ship (metres),

L ₁

is the length of the compartment, and

D

is the moulded depth of the ship to bulkhead deck (metres) provided that, in a ship having an enclosed cargo space on the bulkhead deck which is internally drained in accordance with the requirements of paragraph .1.6.2 and which extends for the full length of the ship, D shall be measured to the next deck above the bulkhead deck. Where the enclosed cargo spaces cover a lesser length, D shall be taken as the moulded depth to the bulkhead deck plus lh/L where l and h are the aggregate length and height respectively of the enclosed cargo spaces.