Main deck

File:USS Wainwright (DLG-28) underway, circa in 1971.png supports the 5"/54 gun aft, but is not the weather deck for the greater length of the forward portion of the ship.]]

The main deck of a ship is the uppermost complete deck extending from bow to stern.{{cite book |last=Knight |first=Austin M. |author-link =Austin M. Knight |title =Modern Seamanship |publisher =D. Van Nostrand Company |edition =Tenth |date =1937 |location =New York |page =31 }} 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 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.{{cite book |last=Manning |first=George Charles |title =Manual of Naval Architecture |publisher =D. Van Nostrand Company |date =1930 |location =New York |pages =102&103 }}