The constructing and designing of a ship’s aft end structure is considering lots of factors such as hydrodynamic efficiency, construction simplicity, flow patterns & aesthetics etc. The aft part is characterized by several entities such as an aft peak tank, stern frame, rudder, rudder stock, propeller and its ancillaries.
Ships have various types of aft end structures, sterns can be broadly classified into the following
> Cruiser Stern
> Transom Stern
Cruiser stern
A cruiser stern was intended to reduce the height of the steering gear located beneath the armor deck. This type of stern has a curved profile going upwards coming from the aft perpendicular to the poop or main deck.
Solid floors are fitted at every frame space, and a heavy center line girder is fitted right aft at the shell and decks. The stern plating is stiffened by cant frames (see pic) or webs with short cant beams supporting the decks and led to the adjacent heavy transverse deck beam. Further stiffening of the plating is provided, or adopted in instead of cant frames, by horizontal stringers extending to the first transverse frame.
Transom Stern
The shape of a transom stern is basically flat all the way to the waterline. This shape produces greater space in the aft deck area
This type of stern design, especially its underside, affects the propulsion efficiency of the ship. If there is less turbulence in the space between the outer shell of the ship above the propeller and the propeller itself, its efficiency will increase
Cant frames are not required where the transom stern is adopted, as the flat stern plating may be stiffened with vertical stiffeners. Deep floors and a center line girder are provided at the lower region of the transom stern construction
