A seaplane is a fixed-wing aircraft capable of taking off and landing (alighting) on water. Seaplanes can be divided into separate categories such as floatplanes, flying boats, and amphibians. These aircraft are occasionally called hydroplanes, a term rarely used in English.
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.
The first autonomous flight by a seaplane was done by the French engineer Henri Fabre in March 1910. Its name was Le Canard ('the duck'), and took off from the water and flew 800 meters on its first flight on March 28 1910. These experiments were closely followed by the aircraft pioneers Gabriel and Charles Voisin, who purchased several of the Fabre floats and fitted them to their Canard Voisin airplane. In October 1910, the Canard Voisin became the first seaplane to fly over the river Seine, and in March 1912, the first seaplane to be used militarily from a seaplane carrier, La Foudre ('the lightning').
In the United States, early development was carried out at Hammondsport, New York by Glenn Curtiss who had beaten Alexander Graham Bell and others in the Aerial Experiment Association. The first American seaplane flight occurred on January 26, 1911.
Englishman John Cyril Porte joined with Curtiss to design a transatlantic flying boat, and developed a more practical hull for Curtiss' airframe and engines with the distinctive 'step' which enabled the hull and floats to cleanly break free of the water's surface at take-off. In the UK the Curtiss flying boat was developed into the Felixstowe series of flying boats, which were used in the First World War to patrol for German submarines. Curtiss N-9 seaplanes were used during World War I as primary trainers, and over 2,500 Navy pilots learned to fly in them. A handful of N-9s were used in the Hewitt-Sperry Automatic Airplane project to develop an "aerial torpedo", an early RPV.
Due to the lack of runways and the perceived safety factor over water, many commercial airlines including Imperial Airways (fore-runner of BOAC), and Pan-American World Airways used large seaplanes to provide service for long distance service across the Atlantic, Pacific and Indian Oceans. Aircraft specially built for these routes included some of the largest aircraft built between the wars.
Smaller carriers found them useful as well for operating into areas without prepared runways. Popular with bush operators, sportsmen and explorers, a huge variety of designs were built. Examples include:
Typical for the above types, the Grumman Goose came about in 1936, when a group of wealthy industrialists, including Henry Morgan, Marshall Field and E.R. Harriman, wanted an easier way to commute from their homes on Long Island, New York, to the financial district of Wall Street. They commissioned Roy Grumman to build ten airplanes that could take off from their private air strips and land on the water near the financial district. Grumman re-engineered their amphibians after the war and built a commercial version of their durable amphibians, called the Grumman Mallard.
During World War II, most navies used seaplanes for reconnaissance, search and rescue, and anti-submarine warfare. Possibly the most commonly known was the Consolidated PBY Catalina which was flown by the United States, United Kingdom, Russia, and Canada, among many others. Similar aircraft were used by Japan, Germany, Italy.
The US Navy utilized a fleet of seaplanes for reconnaissance, rescue and had many fitted with machine guns and bombs. Most battleships carried one or two (some cases as many as four) catapult-launched seaplanes to spot targets over the horizon for the big guns, or to fight off enemy reconnaissance planes. The failure of the German battleship Bismarck's Arado 196 seaplane to hunt down a PBY is said to have contributed to that ship's demise. Examples include:
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 PBY 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 CL-215 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.
The British and the US experimented with jet powered seaplane fighters such as the Saunders-Roe SR.A/1 but despite some successes these did not enter service. An attempt was made in the early to mid-1950s to develop a large jet-powered flying boat (the Martin P6M SeaMaster) for the U.S. Navy. Although several prototypes were built and tested, the project, like those of the fighters, was eventually terminated.
The U.S. Navy, however, continued to operate seaplanes and seaplane tenders, especially in the Far East, until the mid-1970s. Both Japan and Russia continued operating military seaplanes even later, including the Shin Mewa PS-1 and Beriev Be-12, primarily for Anti-Submarine Warfare, where they can take advantage of their range and speed over helicopters, while still able to land on water.
Seaplanes are still being used for firefighting and sightseeing, but have been replaced in nearly all military roles by helicopters.
Numerous modern civilian aircraft have a floatplane variant, usually for light duty transportation to lakes and other remote areas. Most of these are offered as third-party modifications under a supplemental type certificate (STC), although there are several aircraft manufacturers that build floatplanes from scratch, and a few that continue to build flying boats. Many older flying boats remain in service for fire-fighting duty, and Chalk's Ocean Airways operated a fleet of Grumman Mallards in passenger service until service was suspended after a crash on December 19, 2005, which was linked to maintenance, not to design of the aircraft. Purely water-based seaplanes have largely been supplanted by amphibious aircraft.
Seaplanes can only take off and land on water with little or no wave action and, like other aircraft, have trouble in extreme weather. The size of waves a given design can withstand depends on, among other factors, the aircraft's size, hull or float design, and its weight, all making for a much more unstable aircraft, limiting actual operational days. Flying boats can typically handle rougher water and are generally more stable than floatplanes while on the water.
Rescue organizations, such as coast guards, are among the largest modern operators of seaplanes due to their efficiency and their ability to both spot and rescue survivors. Land-based airplanes cannot rescue survivors, and many helicopters are limited in their capacity to carry survivors and in their fuel efficiency compared to fixed-wing aircraft. (Helicopters may also be fitted with floats to facilitate their usage on water, though not referred to as seaplanes.) These are even more limited in range.
Water aircraft are also often used in remote areas such as the Alaskan and Canadian outback, especially in areas with a large number of lakes convenient for takeoff and landing. They may operate on a charter basis, provide scheduled service, or be operated by residents of the area for private, personal use.
Greece uses seaplanes to connect its many islands to the mainland. In the Western Hemisphere, there are numerous seaplane operators in the Caribbean Sea that offer service within or between island groups.
In August 2007, Scottish based commercial operator Loch Lomond Seaplanes launched the only European city based seaplane service. They offer a daily service from Glasgow, Scotland's largest city, to the west coast town of Oban, as well as charters and excursions elsewhere.