Subdivision draft

The subdivision draft, or deepest subdivision draft (often written d_s), is the waterline corresponding to the deepest draft at which the subdivision and damage-stability requirements are assessed, the draft used to define the deterministic floodable length and, in the probabilistic SOLAS 2009 scheme, the required and attained subdivision index. It is one of the three reference drafts of the probabilistic method, with the partial subdivision draft d_p and the light service draft d_l, between which the attained index A is computed as a weighted sum. The subdivision draft is normally the summer load waterline or just below it; the floodable-length curve and the margin-line check are referenced to it for the deterministic rules.