Watertight door openings.

(a) The opening for a watertight door must be located as high in the bulkhead and as far inboard as practicable. (b) No more than one door, other than a door to a bunker or shaft alley, may be fitted in a main transverse watertight bulkhead within spaces containing the following: (1) Main and auxiliary propulsion machinery. (2) Propulsion boilers. (3) Permanent bunkers.