The main deck of a
ship is the uppermost complete
deck extending from
bow to
stern. A steel ship's hull may be considered a structural
beam with the main deck forming the upper flange of a
box girder and the
keel
The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...
forming the lower
strength member. The main deck may act as a
tension member when the ship is supported by a single
wave amidships, or as a
compression member when the ship is supported between waves forward and aft.
References
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Nautical terminology