Superstructure
(j) Superstructure. (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. (3) The height of a superstructure is the least vertical height measured at side from the top of the superstructure deck beams to the top of the freeboard deck beams. (4) The length of a superstructure (S) is the mean length of the part of the superstructure which lies within the length (L).