seaplanes

A seaplane is a fixed-wing aircraft designed to take off and land (or "alight") upon water. Seaplanes can be divided into separate categories such as float planes, flying boats, and amphibious aircraft ("amphibians").

These aircraft are occasionally called hydroplanes, based on usage in several Romance languages, which is rare in english.

• A floatplane has slender pontoons mounted under the fuselage. Two floats are common, but many floatplanes of World War II had a single float under the main fuselage and two small floats on the wings. Only the "floats" of a floatplane normally come into contact with water. The fuselage remains above water. Some small land aircraft can be modified to become float planes.
• In a flying boat, the main source of buoyancy is the fuselage, which acts like a ship's hull in the water. Most flying boats have small floats mounted on their wings to keep them stable.

The term "seaplane" is used by some to refer only to floatplanes (aircraft with floats as landing gear), with the flying boat being a distinct type of craft. This article treats both flying boats and floatplanes as types of seaplane.

An amphibious aircraft can take off and land both on conventional runways and water. A true seaplane can only take off and land on water. There are amphibious flying boats and amphibious floatplanes, as well as some hybrid designs, e.g., floatplanes with retractable floats. Modern production seaplanes are largely amphibious and of a floatplane design.

In the post war period the availability of large paved runways and the greatly expanded performance of land based planes meant that both commercial and military use of seaplanes was much reduced. Anti-Submarine Warfare was just as easily carried out with land based aircraft, which often had better performance, and Search and Rescue could more easily be carried out with helicopters, which had the advantages of being operated from smaller ships, and in higher sea states. The compromises that came from being able to float and rise again from the water caused excessive drag and added considerably to the weight of the aircraft. In commercial service this translated into increased costs, and for a military aircraft, into reduced warloads, speeds and ranges.

Only in specialized roles were they able to remain competitive, such as waterbombing, where their ability to quickly reload was a huge asset. A number of surplus WW2 seaplanes including the Consolidated Catalina and Martin Mars were initially used in this role but their advancing age has required a new specially designed aircraft in the form of the Canadair Waterbomber which operates alongside an entire air force of second-hand land-based bombers and transports.

The only amphibian aircraft produced for post war commercial usage was the Grumman Mallard which was designed as a true airliner, with modern technology and longer ranges, greater passenger and cargo loads. The Mallard saw production from 1946-1951. Only 59 were delivered, used mostly by corporations and some regional commuter carriers.