46 C.F.R. § 179.360 Watertight integrity.
Title 46 - Shipping
(a) A hatch exposed to the weather must be watertight, except that the following hatches may be weathertight: (1) A hatch on a watertight trunk that extends at least 305 millimeters (12 inches) above the weather deck; (2) A hatch in a cabin top; and (3) A hatch on a vessel that operates only on protected waters. (b) A hatch cover must: (1) Have securing devices; and (2) Be attached to the hatch frame or coaming by hinges, captive chains, or other devices of substantial strength to prevent its loss. (c) A hatch cover that provides access to accommodation spaces must be operable from either side. (d) A weathertight door must be provided for each opening located in a deck house or companionway. Permanent watertight coamings must be provided as follows: (1) On a vessel on an exposed or partially protected route, a watertight coaming with a height of at least 150 millimeters (6 inches) must be provided under each weathertight door in a cockpit or a well, or on the main deck of a flush deck vessel. (2) On a vessel on a protected route, a watertight coaming with a height of at least 75 millimeters (3 inches) must be provided under each weathertight door in a cockpit or a well. (3) The height of the watertight coaming for a hinged watertight door need only be sufficient to accommodate the door.
Title 46: Shipping
PART 179—SUBDIVISION, DAMAGE STABILITY, AND WATERTIGHT INTEGRITY
Subpart C—Watertight Integrity Requirements
§ 179.360 Watertight integrity.