Bulkhead

A bulkhead is a vertical partition that divides a ship's hull into separate compartments, adding structural strength and, when made watertight, subdividing the vessel so flooding can be contained within one space. SOLAS Chapter II-1, Regulation 9 fixes the position of the collision bulkhead — the foremost main transverse watertight bulkhead — at between 5% and 8% of the length between perpendiculars abaft the forward perpendicular, protecting the ship if the bow is breached. Watertight bulkheads are proven by hose or air-pressure test, and their integrity underpins the ship's subdivision and damage-stability calculations.