any additional structure which is above a baseline EXAMPLE Hull.

Source: IEC 61892-6, Mobile and fixed offshore units – Electrical installations – Part 6: Installation, Third Edition, December  2013. Global Standards



(a) A superstructure is a decked structure on the freeboard deck, extending from side to side of the ship or with the side plating not being inboard of the shell plating more than 4% of the breadth (B).
(b) 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 regulation 12;
(iii) all other openings in sides or ends of the superstructure fitted with efficient weathertight means of closing.
A bridge or poop shall not be regarded as enclosed unless access is provided for the crew starting from any point on the uppermost complete exposed deck or higher  to reach machinery and other working spaces inside these superstructures by alternative means which are available at all times when bulkhead openings are closed.
(c) 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.
(d) The length of a superstructure (S) is the mean length of the part of the superstructure which lies within the length (L).
(e) Bridge. A bridge is a superstructure which does not extend to either the forward or after perpendicular.
(f) Poop. A poop is a superstructure which extends from the after perpendicular forward to a point which is aft of the forward perpendicular.
The poop may originate from a point aft of the aft perpendicular.
(g) Forecastle. A forecastle is a superstructure which extends from the forward perpendicular aft to a point which is forward of the after perpendicular. The forecastle may originate from a point forward of the forward perpendicular.
(h) Full superstructure. A full superstructure is a superstructure which, as a minimum, extends from the forward to the after perpendicular.
(i) Raised quarterdeck. A raised quarterdeck is a superstructure which extends forward from the after perpendicular, generally has a height less than a normal superstructure, and has an intact front bulkhead (sidescuttles of the non-opening type fitted with efficient deadlights and bolted man hole covers) (see figure 3.4). Where the forward bulkhead is not intact due to doors and access openings, the superstructure is then to be considered as a poop.
figure 3.4
<Chapter I, regulation 3>.

Source: IMO Resolution MSC.143(77), amendments to Annex B to the 1988 Load Lines Protocol, 5 June 2003, International Maritime Organization. Legislation

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