Sponson

Model of a Pan Am Boeing 314 flying boat with its left sponson visible

MS Princess of Scandinavia, a cruise-ferry with a side sponson

Sponsons may contain weapons in military craft, such as pre-Dreadnought warships and some early British tanks

Sponsons are projections extending from the sides of land vehicles, aircraft or water craft to provide protection, stability, storage locations, mounting points, or equipment housing.

Among their uses sponsons:

• Extend a watercraft hull dimension at or below the waterline to increase flotation or add lift when underway.

• Serve as a mounting or enclosure for a gun projecting in part or whole beyond warship's hull, particularly in the pre-Dreadnought era.

• Serve as a mounting or enclosure for a gun projecting in part or whole beyond the hulls of land vehicles and aircraft, notably on British heavy tanks during World War I.

• Take the form of a short wing on the fuselages of flying boats, providing hydrodynamic stability when travelling through the water during take off and landing, as pioneered by German aerospace designer and engineer Claude Dornier on the Zeppelin-Lindau Rs.IV during World War I.

• Provide storage for fuel or housing for landing gear on larger helicopters such as the Sikorsky S-92 and Bell 222.

• Provide layers of bullet-proof protection and storage space, as found over the tracks of the Bradley Fighting Vehicle.

See also

• Costa Concordia salvage – an example of sponsons in use
• Ship Camel – related technology of external floatation tanks affixed on a ship to reduce her draught.