![Supermarine S](https://upload.wikimedia.org/wikipedia/commons/e/ec/Supermarine_S.6B_ExCC.jpg)
Floats (also called pontoons) are airtight hollow structures, similar to
pressure vessel
A pressure vessel is a container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.
Construction methods and materials may be chosen to suit the pressure application, and will depend on the size o ...
s, designed to provide
buoyancy
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the p ...
in water. Their principal applications are in
watercraft hulls, aircraft floats,
floating pier
{{Unreferenced, date=October 2007
A floating dock, floating pier or floating jetty is a platform or ramp supported by pontoons. It is usually joined to the shore with a gangway. The pier is usually held in place by vertical poles referred to as pi ...
,
pontoon rhinos,
pontoon causeways, and marine engineering applications such as
salvage.
During
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
the
United States Navy
The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
Civil Engineer Corps
The Civil Engineer Corps (CEC) is a staff corps of the United States Navy. CEC officers are professional engineers and architects, acquisitions specialists, and Seabee Combat Warfare Officers who qualify within Seabee units. They are responsib ...
developed a modular steel box (pontoon) for the
Seabee
United States Naval Construction Battalions, better known as the Navy Seabees, form the U.S. Naval Construction Force (NCF). The Seabee nickname is a heterograph of the initial letters "CB" from the words "Construction Battalion". Depending upon ...
s to use. It was an industrial sized
Lego
Lego ( , ; stylized as LEGO) is a line of plastic construction toys that are manufactured by The Lego Group, a privately held company based in Billund, Denmark. The company's flagship product, Lego, consists of variously colored interlocking ...
system of pre-drilled pre-cut
angle iron and steel plate that could be assembled anywhere for which they became famous. They used them to facilitate amphibious landings. With the pontoons Seabees assembled docks, causeways, and rhinos to whatever size needed. They allowed
landings on Sicily where no one thought possible. They ferried
Patton
George Smith Patton Jr. (November 11, 1885 – December 21, 1945) was a general in the United States Army who commanded the Seventh United States Army in the Mediterranean Theater of World War II, and the Third United States Army in Franc ...
across the Rhine and put the Marines ashore on
Okinawa
is a prefecture of Japan. Okinawa Prefecture is the southernmost and westernmost prefecture of Japan, has a population of 1,457,162 (as of 2 February 2020) and a geographic area of 2,281 km2 (880 sq mi).
Naha is the capital and largest city ...
. They would be used during the
Korean War
, date = {{Ubl, 25 June 1950 – 27 July 1953 (''de facto'')({{Age in years, months, weeks and days, month1=6, day1=25, year1=1950, month2=7, day2=27, year2=1953), 25 June 1950 – present (''de jure'')({{Age in years, months, weeks a ...
in the
landing at Inchon
The Battle of Incheon (), also spelled Battle of Inchon, was an amphibious invasion and a battle of the Korean War that resulted in a decisive victory and strategic reversal in favor of the United Nations Command (UN). The operation involved s ...
in 1950 and again in
Lebanon
Lebanon ( , ar, لُبْنَان, translit=lubnān, ), officially the Republic of Lebanon () or the Lebanese Republic, is a country in Western Asia. It is located between Syria to the north and east and Israel to the south, while Cyprus li ...
during the
1958 Lebanon crisis.
Various objects that make use of floats are often referred to
synecdochically
Synecdoche ( ) is a type of metonymy: it is a figure of speech in which a term for a part of something is used to refer to the whole (''pars pro toto''), or vice versa (''totum pro parte''). The term comes from Greek language, Greek .
Example ...
as pontoons.
Applications
Floats make up the multipart hulls of
catamaran
A Formula 16 beachable catamaran
Powered catamaran passenger ferry at Salem, Massachusetts, United States
A catamaran () (informally, a "cat") is a multi-hulled watercraft featuring two parallel hulls of equal size. It is a geometry-stab ...
s and
trimaran
A trimaran (or double-outrigger) is a multihull boat that comprises a main hull and two smaller outrigger hulls (or "floats") which are attached to the main hull with lateral beams. Most modern trimarans are sailing yachts designed for recreati ...
s and provide buoyancy for
floatplanes,
seaplane
A seaplane is a powered fixed-wing aircraft capable of takeoff, taking off and water landing, landing (alighting) on water.Gunston, "The Cambridge Aerospace Dictionary", 2009. Seaplanes are usually divided into two categories based on their tec ...
s and
houseboat
A houseboat is a boat that has been designed or modified to be used primarily as a home. Most houseboats are not motorized as they are usually moored or kept stationary at a fixed point, and often tethered to land to provide utilities. How ...
s.
They are used in pontoon bridges, floating piers, and floats anchored to the seabed for recreation or dockage. They are also used in
shipbuilding
Shipbuilding is the construction of ships and other floating vessels. It normally takes place in a specialized facility known as a shipyard. Shipbuilders, also called shipwrights, follow a specialized occupation that traces its roots to befor ...
and marine salvage, often deployed uninflated then pressurized to raise a sunken object. In military, floats are used as pontoon bridges or transportation platforms for heavier vehicles or machinery.
In popular usage, the term ''pontoon'' can refer to any of several of the following objects that make use of nautical floats.
Pontoon boat
A pontoon boat is a flattish boat that relies on nautical floats for buoyancy. Common boat designs are a catamaran with two pontoons, or a trimaran with three.
In many parts of the world, pontoon boats are used as small vehicle ferries to cross rivers and lakes.
Anchored recreational platform
Raft-like platforms used for diving and other recreational activities are sometimes anchored at beaches and lake shores, often seasonally. Such platforms may be supported by foam-filled plastic floats or air-filled pontoons, and are known simply as "pontoons" in Australia and New Zealand. They may also be called swim floats.
Floating dock
A floating dock, floating pier or floating jetty consists of a platform or ramp supported by nautical floats. It is sometimes joined to the shore with a gangway but can be laid out the whole way from the shore to the end. This type of pier maintains a fixed vertical relationship to watercraft secured to it.
Pontoon bridge
A pontoon bridge (also known as a ponton bridge or floating bridge) uses floats or shallow-draft boats to support a continuous deck for pedestrian and vehicle travel. Most, but not all, pontoon bridges are temporary, used in wartime and civil emergencies.
Seattle in the US and Kelowna in British Columbia, Canada are two places with permanent pontoon bridges, see
William R. Bennett Bridge
The William R. Bennett Bridge is a pontoon bridge in the Okanagan Valley of British Columbia, Canada. Completed on May 25, 2008, the bridge replaced the older Okanagan Lake Bridge built in 1958 to link Downtown Kelowna to West Kelowna across Oka ...
in British Columbia and these in Seattle:
Lacey V. Murrow Memorial Bridge
The Lacey V. Murrow Memorial Bridge is a floating bridge in the Seattle metropolitan area of the U.S. state of Washington. It is one of the Interstate 90 floating bridges that carries the eastbound lanes of Interstate 90 across Lake Washingto ...
,
Evergreen Point Floating Bridge
The Evergreen Point Floating Bridge, also known as the 520 Bridge and officially the Governor Albert D. Rosellini Bridge, carries Washington State Route 520 across Lake Washington from Seattle to its eastern suburbs. The floating span is the ...
and
Homer M. Hadley Memorial Bridge
The Third Lake Washington Bridge, officially the Homer M. Hadley Memorial Bridge, is a floating bridge in the Seattle metropolitan area of the U.S. state of Washington. It is one of the Interstate 90 floating bridges, carrying the westbound lan ...
.
Floatplane
A floatplane (float plane or pontoon plane) is a type of seaplane with one or more slender pontoons mounted under the fuselage to provide buoyancy.
Construction
Pontoons for marine industrial uses are usually
fabricated from steel.
Pontoons as parts of watercraft and aircraft are more typically molded in
glass-reinforced plastic
Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...
. Other techniques include those of traditional wooden boatbuilding as well as
plywood
Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...
over wooden ribs or metal sheets over metal ribs (aluminium or steel), reflecting the prevailing practice in aircraft and boats. In most cases, the decking surface on top of the pontoon is made from glass-reinforced plastic (
GRP) or
composite lumber
Composite lumber is a material that is a mixture of wood fiber, plastic, and some type of binding agent. These ingredients are put together to form a material that is denser, stronger, and heavier than wood alone, a wood-plastic composite.
Hist ...
.
In model building, floats can easily be carved out of solid blocks or laminated sheets of foam.
{{Failed verification, date=September 2021
Gallery
Image:Catamaranedan.jpg, Small open catamaran
A Formula 16 beachable catamaran
Powered catamaran passenger ferry at Salem, Massachusetts, United States
A catamaran () (informally, a "cat") is a multi-hulled watercraft featuring two parallel hulls of equal size. It is a geometry-stab ...
.
Image:Dragonflyextended.jpg, Foldable trimaran with the floats in extended position.
Image:DeHavilland_Single_Otter_Harbour_Air.jpg, Floats in a small floatplane.
File:Port pontoon of a Sikorsky Sea King.jpg, A helicopter pontoon augmented by an inflatable emergency pontoon shown in black
File:RV Chetlo pontoon boat contruction.jpg, The underside of a boat during construction
See also
*
Buoy
A buoy () is a floating device that can have many purposes. It can be anchored (stationary) or allowed to drift with ocean currents.
Types
Navigational buoys
* Race course marker buoys are used for buoy racing, the most prevalent form of yac ...
*
Caisson (lock gate)
A caisson is a form of lock gate. It consists of a large floating iron or steel box. This can be flooded to seat the caisson in the opening of the dock to close it, or pumped dry to float it and allow it to be towed clear of the dock.
Chevron ...
*
Navy lighterage pontoons
*
Outrigger
An outrigger is a projecting structure on a boat, with specific meaning depending on types of vessel. Outriggers may also refer to legs on a wheeled vehicle that are folded out when it needs stabilization, for example on a crane that lifts ...
*
Raft
A raft is any flat structure for support or transportation over water. It is usually of basic design, characterized by the absence of a hull. Rafts are usually kept afloat by using any combination of buoyant materials such as wood, sealed barrels ...
*
Semi-submersible platform
A semi-submersible platform is a specialised marine vessel used in offshore roles including as offshore drilling rigs, safety vessels, oil production platforms, and heavy lift cranes. They have good ship stability and seakeeping, better than ...
References
Buoyancy devices