(1) A superstructure is a decked structure on the freeboard deck, extending from side to side of the vessel or with the side plating not being inboard of the shell plating more than 4 percent to the breadth. (B). A raised quarter deck is regarded as a superstructure.
(2) An enclosed superstructure is a superstructure with:
(i) Enclosing bulkheads of efficient construction;
(ii) Access openings, if any in these bulkheads fitted with doors complying with the requirements of § 42.15-10; and,
(iii) All other openings in sides or ends of the superstructure fitted with efficient weathertight means of closing.