Float (nautical)

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The British racing seaplane Supermarine S.6B (1931) Supermarine S.6B ExCC.jpg
The British racing seaplane Supermarine S.6B (1931)

Floats (also called pontoons) are airtight hollow structures, similar to pressure vessels, designed to provide buoyancy in water. Their principal applications are in watercraft hulls, aircraft floats, floating piers, pontoon rhinos, pontoon bridges, and marine engineering applications such as salvage.

Contents

During World War II the United States Navy Civil Engineer Corps developed a modular steel box (pontoon) for the Seabees to use. It was a system of pre-drilled pre-cut angle iron and steel plate that could be assembled anywhere for which they became famous.[ citation needed ] 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 across the Rhine and put Marines ashore on Okinawa. They would be used during the Korean War in the landing at Inchon in 1950 and again in Lebanon during the 1958 Lebanon crisis.

Various objects that make use of floats are often referred to synecdochically as pontoons.

Applications

Floats make up the multipart hulls of catamarans and trimarans and provide buoyancy for floatplanes, seaplanes and houseboats. [1] They are used in pontoon bridges, floating piers, and floats anchored to the seabed for recreation or dockage. They are also used in shipbuilding 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. [2] In many parts of the world, pontoon boats are used as small vehicle ferries to cross rivers and lakes. [3]

An anchored raft-like platform used for diving, often referred to as a pontoon Photo of pontoon (buoyant platform) taken at Port Vincent, South Australia.jpg
An anchored raft-like platform used for diving, often referred to as a pontoon

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. [4] [ better source needed ] They may also be called swim floats.[ citation needed ]

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. [5] Seattle in the US and Kelowna in British Columbia, Canada are two places with permanent pontoon bridges, see William R. Bennett Bridge in British Columbia and these in Seattle: Lacey V. Murrow Memorial Bridge, Evergreen Point Floating Bridge and Homer M. Hadley Memorial Bridge.

Amphibian floats on a Cessna 208 Caravan 1 floatplane, Gloucestershire Airport, England (2017) Cessna 208 Caravan 1 floatplane (G-MDJE) at Gloucestershire Airport (England) 24May2017 arp.jpg
Amphibian floats on a Cessna 208 Caravan 1 floatplane, Gloucestershire Airport, England (2017)

Floatplane

A floatplane (float plane or pontoon plane) is a type of seaplane with one or more floats mounted under the fuselage to provide buoyancy.

Construction

Pontoons for marine industrial uses are usually fabricated from steel. [6] Pontoons as parts of watercraft and aircraft are more typically molded in glass-reinforced plastic. Other techniques include those of traditional wooden boatbuilding as well as plywood 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. In model building, floats can easily be carved out of solid blocks or laminated sheets of foam. [7] [ failed verification ]

See also

Related Research Articles

<span class="mw-page-title-main">Naval architecture</span> Engineering discipline dealing with the design and construction of marine vessels

Naval architecture, or naval engineering, is an engineering discipline incorporating elements of mechanical, electrical, electronic, software and safety engineering as applied to the engineering design process, shipbuilding, maintenance, and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation (classification) and calculations during all stages of the life of a marine vehicle. Preliminary design of the vessel, its detailed design, construction, trials, operation and maintenance, launching and dry-docking are the main activities involved. Ship design calculations are also required for ships being modified. Naval architecture also involves formulation of safety regulations and damage-control rules and the approval and certification of ship designs to meet statutory and non-statutory requirements.

Float may refer to:

<span class="mw-page-title-main">Seaplane</span> Aircraft with an undercarriage capable of operating from water surfaces

A seaplane is a powered fixed-wing aircraft capable of taking off and landing (alighting) on water. Seaplanes are usually divided into two categories based on their technological characteristics: floatplanes and flying boats; the latter are generally far larger and can carry far more. Seaplanes that can also take off and land on airfields are in a subclass called amphibious aircraft, or amphibians. Seaplanes were sometimes called hydroplanes, but currently this term applies instead to motor-powered watercraft that use the technique of hydrodynamic lift to skim the surface of water when running at speed.

<span class="mw-page-title-main">Amphibious aircraft</span> Aircraft able to land / take off from both land and water

An amphibious aircraft, or amphibian, is an aircraft that can take off and land on both solid ground and water. These aircraft are typically fixed-wing, though amphibious helicopters do exist as well. Fixed-wing amphibious aircraft are seaplanes which are equipped with retractable wheels, at the expense of extra weight and complexity, plus diminished range and fuel economy compared with planes designed specifically for land-only or water-only operation. Some amphibians are fitted with reinforced keels which act as skis, allowing them to land on snow or ice with their wheels up.

<span class="mw-page-title-main">Pontoon bridge</span> Type of bridge

A pontoon bridge, also known as a floating bridge, uses floats or shallow-draft boats to support a continuous deck for pedestrian and vehicle travel. The buoyancy of the supports limits the maximum load that they can carry.

<span class="mw-page-title-main">Trimaran</span> Multihull boat

A trimaran is a multihull boat that comprises a main hull and two smaller outrigger hulls which are attached to the main hull with lateral beams. Most modern trimarans are sailing yachts designed for recreation or racing; others are ferries or warships. They originated from the traditional double-outrigger hulls of the Austronesian cultures of Maritime Southeast Asia; particularly in the Philippines and Eastern Indonesia, where it remains the dominant hull design of traditional fishing boats. Double-outriggers are derived from the older catamaran and single-outrigger boat designs.

Pontoon may refer to:

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 pilings, which are embedded in the seafloor or by anchored cables. Frequently used in marinas, this type of pier maintains a fixed vertical relationship to watercraft secured to it, independent of tidal, river or lake elevation. The angle of the gangway varies with the water level.

<span class="mw-page-title-main">Floatplane</span> Aircraft with floats for use on water

A floatplane is a type of seaplane with one or more slender floats mounted under the fuselage to provide buoyancy. By contrast, a flying boat uses its fuselage for buoyancy. Either type of seaplane may also have landing gear suitable for land, making the vehicle an amphibious aircraft. British usage is to call floatplanes "seaplanes" rather than use the term "seaplane" to refer to both floatplanes and flying boats.

<span class="mw-page-title-main">Very large floating structure</span> Artificial islands used as infrastructure in aquatic environments

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<span class="mw-page-title-main">Floating airport</span> Infrastructure concept

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<span class="mw-page-title-main">Pontoon boat</span> Flattish boat that relies on floats to remain buoyant

A pontoon boat is a flattish boat that relies on floats to remain buoyant. These pontoons contain much reserve buoyancy and allow designers to create large deck plans fitted with a variety of accommodations including expansive lounge areas, stand-up bars, and sun pads. More horsepower is now able to be applied to the stern due to design improvements. Pontoon boat drafts may be as shallow as eight inches, which reduces risk of running aground and underwater damage; this allows it to come close to shore to pick up and drop off loads.

<span class="mw-page-title-main">Rhino ferry</span> A barge made from pontoons powered by outboard engines

A rhino ferry is a barge constructed from several pontoons which are connected and equipped with outboard engines, used to transport heavy equipment and people. Rhino ferries were used extensively during the Normandy landings and other theaters ; their low draft was well-suited for shallow beaches, and they could also be used as piers when filled with water. An alternative to tank landing craft, they were operated by United States Navy Construction Battalions. They ferried their cargo from the outlying Landing Ships, Tank to the shore.

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<span class="mw-page-title-main">Naval Advance Base Espiritu Santo</span> Major World War 2 base

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References

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