A turret deck ship is a type of merchant ship with an unusual hull, designed and built in the late 19th and early 20th centuries. The hulls of turret deck vessels were rounded and stepped inward above their waterlines. This gave some advantages in strength and allowed them to pay lower canal tolls under tonnage measurement rules then in effect. The type ceased to be built after those rules changed. The last turret deck ship in existence was scrapped in 1960.
Turret Chief running light; stepped hull form and raised midline "turret" are shown.
Cross-section of a turret ship amidships
Assembling frames of Grängesberg in Pallion in 1903
The turret deck ship Orange Branch in Townsville, Queensland about 1901. This view, almost bow-on, shows her hull's distinctive profile.
A whaleback was a type of cargo steamship of unusual design, with a hull that continuously curved above the waterline from vertical to horizontal. When fully loaded, only the rounded portion of the hull could be seen above the waterline. With sides curved in towards the ends, it had a spoon bow and a very convex upper deck. It was formerly used on the Great Lakes of Canada and the United States, notably for carrying grain or ore. The sole surviving ship of the "whaleback" design is the SS Meteor, which is docked in Superior, Wisconsin, as a museum ship.
Joseph L. Colby, built 1890, scrapped 1935, was the second whaleback built by McDougall
SS Meteor, the only remaining whaleback in existence, now a museum ship
An early photograph of a whaleback barge circa 1888-1890 from All The Decor
SS Thomas Wilson in the Soo Locks, unladen, with two consort barges, also whalebacks
