46 C.F.R. § 72.05-35 Hatch covers and shifting boards.
Title 46 - Shipping
(a) Wood hatch covers may be used between cargo spaces. Hatch covers in other locations shall meet the requirements for deck construction noted in tables 72.05–10 (f) and (g). (b) Tonnage openings in “A” Class bulkheads shall be closed by means of steel plates.
Title 46: Shipping
PART 72—CONSTRUCTION AND ARRANGEMENT
Subpart 72.05—Structural Fire Protection
§ 72.05-35 Hatch covers and shifting boards.

