An amphibious vehicle (or simply amphibian) is a vehicle that works both on land and on or under water. Amphibious vehicles include amphibious bicycles, ATVs, cars, buses, trucks, railway vehicles, combat vehicles, and hovercraft.
Classic landing craft are not amphibious vehicles as they do not work on land, although they are part of amphibious warfare. Ground effect vehicles, such as ekranoplans, would likely crash on any but the flattest of landmasses so are also not considered to be amphibious vehicles.
General technical notes
Two main categories of amphibious vehicles are those that travel on an air cushion (Hovercraft) and those that do not. Among the latter, many extend the off-road capabilities of land vehicles to all kinds of terrain, including ice, snow, mud, marsh, swamp etc. This explains why many designs use tracks in addition to or instead of wheels, and in some cases have articulated body configurations or other unconventional designs such as screw-propelled vehicles which use auger-like barrels which propel a vehicle through muddy terrain with a twisting motion.
Most land vehicles – even lightly armoured ones – can be made amphibious simply by providing them with a waterproof hull and perhaps a propeller. This is possible as a typical vehicle's average density is less than that of water (mostly due to a large amount of empty space), and thus will float. Heavily armoured vehicles, however, sometimes have a density greater than water (their weight in kilograms exceeds their volume in litres) and will need additional buoyancy, in the form of inflatable floatation devices, much like the sides of a rubber dinghy, or a waterproof fabric skirt raised from the top perimeter of the vehicle, to increase its displacement.
For propulsion in or on the water some vehicles simply spin their wheels or tracks, while others use screw propeller(s) or water jet(s). Most amphibians will work only as a displacement hull when in the water – few can hydroplane, skimming over the water like speedboats.
Early history
Some of the earliest known amphibious vehicles were amphibious carriages, the invention of which is credited to the Neapolitan polymath Prince Raimondo di Sangro of Sansevero in July 1770 or earlier, or Samuel Bentham whose design of 1781 was built in June 1987.
The conestoga wagon, a type of a heavy covered wagon, was popular during the 18th and 19th century in the United States and Canada. The wagon was designed in such a way as to be able to cross rivers and streams.
The first known self-propelled amphibious vehicle, a steam-powered wheeled dredging barge, named the Orukter Amphibolos, was conceived and built by United States inventor Oliver Evans in 1805, although it is disputed to have successfully travelled over land or water under its own steam.
Inventor Gail Borden, better known for condensed milk, designed and tested a sail-powered wagon in 1849. On testing, it reportedly tipped over 50 feet (15 m) from shore, from an apparent lack of ballast to counteract the force of the wind in the sail.
In the 1870s, logging companies in eastern Canada and the northern United States developed a steam-powered amphibious tug called an "Alligator" which could cross between lakes and rivers. The most successful Alligator tugs were produced by the firm of West and Peachey in Simcoe, Ontario.
Until the late 1920s, the efforts to unify a boat and an automobile mostly came down to simply putting wheels and axles on a boat hull, or getting a rolling chassis to float by blending a boat-like hull with the car's frame.Pohl, 1998. One of the first reasonably well-documented cases was the 1905 amphibious petrol-powered carriage of T. Richmond (Jessup, Iowa, USA). Just like the world's first petrol-powered automobile (1885, Carl Benz), it was a three-wheeler. The single front wheel provided direction, both on land and in the water. A three-cylinder petrol combustion-engine powered the oversized rear wheels. In order to get the wheels to provide propulsion in the water, fins or buckets would be attached to the rear wheel spokes. Remarkably the boat-like hull was one of the first integral bodies ever used on a car.
Since the 1920s, many diverse amphibious vehicles designs have been created for a broad range of applications, including recreation, expeditions, search & rescue, and military, leading to a myriad of concepts and variants. In some of them, the amphibious capabilities are central to their purpose, whereas in others they are only an expansion to what has remained primarily a watercraft or a land vehicle. The design that came together with all the features needed for a practical all-terrain amphibious vehicle was by Peter Prell of New Jersey. His design, unlike others, could operate not only on rivers and lakes but the sea and did not require firm ground to enter or exit the water. It combined a boat-like hull with tank-like tracks. In 1931, he tested a scaled down version of his invention.
Wheeled Unarmored Cycles
An amphibious cycle is a human-powered vehicle capable of operation on both land and water. "Saidullah's Bicycle" uses four rectangular air filled floats for buoyancy, and is propelled using two fan blades which are attached to the spokes. Moraga's "Cyclo Amphibious" uses a simple tricycle frame to support three floaters which provide both the floatation and thrust. The wings on the powered wheels propel the vehicle in a similar way to a paddle wheel.
The SBK Engineering Shuttle-Bike consists of two inflatable floats with straps that allow the carrying of a bicycle with a passenger. The ensemble, when deflated, fits in a backpack for carrying by the cyclist.
Several amphibious cycles have been created by engineering students as university projects.
Gibbs Sports Amphibians Inc. introduced a motorized version of the amphibious cycle that resembles a jet ski on water and motorcycle on land. The model can reach up to 80 mph by land and 45 mph by water.
ATVs
Amongst the smallest non-air-cushioned amphibious vehicles are amphibious ATVs (all-terrain vehicles). These saw significant popularity in North America during the 1960s and early 1970s. Typically an amphibious ATV (AATV) is a small, lightweight, off-highway vehicle, constructed from an integral hard plastic or fibreglass bodytub, fitted with six (sometimes eight) driven wheels, with low pressure, balloon tires. With no suspension (other than what the tires offer) and no steering wheels, directional control is accomplished through skid-steeringjust as on a tracked vehicleeither by braking the wheels on the side in the direction of the desired turn or by applying more throttle to the wheels on the opposite side. Most contemporary designs use garden tractor type engines, that will provide roughly 25 mph (40 km/h) top speed on land.
Constructed this way, an AATV will float with ample freeboard and is capable of traversing swamps, ponds, and streams as well as dry land. On land these units have high grip and great off-road ability, that can be further enhanced with an optional set of tracks that can be mounted directly onto the wheels. Although the spinning action of the tires is enough to propel the vehicle through the wateralbeit slowlyoutboard motors can be added for extended water use.
In October 2013, Gibbs Amphibians introduced the long-awaited Quadski, the first amphibious vehicle capable of traveling 45 mph on land or water. The Quadski was developed using Gibbs' High-Speed Amphibian technology, which Gibbs originally developed for the Aquada, an amphibious car, which the company has still not produced because of regulatory issues.
Cars
Amphibious automobiles have been conceived from ca. 1900; however, the Second World War significantly stimulated their development. Two of the most significant amphibious cars to date were developed during World War II. The most proliferous was the German Schwimmwagen, a small jeep-like 4×4 vehicle designed by the Porsche engineering firm in 1942 and widely used in World War II. The amphibious bodywork was designed by Erwin Komenda, the firm's body construction designer, using the engine and drive train of the Kübelwagen. An amphibious version of the Willys MB jeep, the Ford GPA or 'Seep' (short for Sea jeep) was developed during World War II as well. A specially modified GPA, called Half-Safe, was driven and sailed around the world by Australian Ben Carlin in the 1950s.
One of the most capable post-war amphibious off-roaders was the German Amphi-Ranger, that featured a hull made of seawater-resistant AlMg2 aluminium alloy. Extensively engineered, this costly vehicle was proven seaworthy at a Gale force 10 storm off the North Sea coast (Pohl, 1998). Only about 100 were builtthose who own one have found it capable of crossing the English Channel almost effortlessly.
Purely recreational amphibian cars include the 1960s Amphicar and the contemporary Gibbs Aquada. With almost 4,000 pieces built, the Amphicar is still the most successfully produced civilian amphibious car to date. The Gibbs Aquada stands out due to its capability of high-speed planing on water. Gibbs built fifty Aquadas in the early 2000s after it was developed by a team assembled by founder Alan Gibbs before the company's engine supplier, Rover, was unable to continue providing engines. Gibbs and new partner Neil Jenkins reconstituted the company and are now seeking U.S. regulatory approval for the Aquada.
In 2010, a Southern California-based company named WaterCar set the Guinness World Record for Fastest Amphibious Vehicle, with their prototype, The Python, which reached top land speeds of 204 km/h (127 mph) and water speeds of 96 km/h (60 mph; 52 knots). Since then, the company launched their first commercial vehicle, The Panther, which has been featured on ABC's The Bachelor as well as USA's Royal Pains. The WaterCar can do 80 mph (129 km/h) on land, and 44 mph (38 knots; 71 km/h) on sea, and can transition from land to sea in less than 15 seconds. Since its release, WaterCar has been popular in the Middle East, selling to the Embassy of the United Arab Emirates, with six additional vehicles being sold to the Crown Prince of Dubai. The WaterCar has also been sold to tech enthusiasts and residents of Silicon Valley.
Other amphibious cars include the US Hydra Spyder.
Buses Amfibus amphibious buses made by Dutch Amphibious Transport (DAT) in Nijmegen, Netherlands are used to operate tours of Amsterdam, Rotterdam and Lübeck, under the Splashtours brand. The buses have a Volvo chassis and carry 43 passengers. The operation started in 2010 in Katendrecht, Rotterdam, was copied in Amsterdam in 2011 but suspended in 2012 after technical problems, and then relaunched in 2019. A tour of Lübeck was launched in 2014. In 2010 it was tested as a replacement for the ferry at Renfrew, Scotland, but not adopted. A similar service, using different vehicles, operates in Porto.
Boats Some amphibious vehicles, rather than being designed for land transport with the ability to cross water, are designed as water-transport vehicles with the ability to travel on land. The distinction is that the vehicles are designed to be high performing on water, with the land transport ability added to give additional functionality, rather than being the main function. Sealegs Amphibious Craft are an example of this, which are a range of aluminium three-wheeled fabricated boats (mostly RIBs) designed and manufactured in Auckland, New Zealand since 2005. These craft can travel up to 39 knots on water, but travel at only 7.5 km/h on land, showing the preference for water performance in design. Various versions of this type of amphibious boat design have been produced, including the French Iguana Yacht, an amphibious motorboat featuring all-terrain tracks (covered in the "Tracked" section below).