Sponsons are projections extending from the sides of land vehicles, aircraft or watercraft to provide protection, stability, storage locations, mounting points for weapons or other devices, or equipment housing.
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
MH-53 Sea Dragon helicopter with massive sponsons below the engines
The sponson-mounted main gun of an M3 Lee tank
A flying boat is a type of fixed-winged seaplane with a hull, allowing it to land on water. It differs from a floatplane in having a fuselage that is purpose-designed for flotation, while floatplanes rely on fuselage-mounted floats for buoyancy.
Short S23 "C" Class or "Empire" flying boat
A PBM Mariner takes off in 1942
Dornier X in 1932
Gabriel Voisin, air pioneer, next to Henry Farman (left), in 1908