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A surface effect ship (SES) or sidewall hovercraft is a
watercraft A watercraft or waterborne vessel is any vehicle designed for travel across or through water bodies, such as a boat, ship, hovercraft, submersible or submarine. Types Historically, watercraft have been divided into two main categories. *Raf ...
that has both an air cushion, like a
hovercraft A hovercraft (: hovercraft), also known as an air-cushion vehicle or ACV, is an amphibious craft capable of travelling over land, water, mud, ice, and various other surfaces. Hovercraft use blowers to produce a large volume of air below the ...
, and twin hulls, like a
catamaran A catamaran () (informally, a "cat") is a watercraft with two parallel hull (watercraft), hulls of equal size. The wide distance between a catamaran's hulls imparts stability through resistance to rolling and overturning; no ballast is requi ...
. When the air cushion is in use, a small portion of the twin hulls remains in the water. When the air cushion is turned off ("off-cushion" or "hull borne"), the full weight of the vessel is supported by the
buoyancy Buoyancy (), or upthrust, is the force exerted by a fluid opposing the weight of a partially or fully immersed object (which may be also be a parcel of fluid). In a column of fluid, pressure increases with depth as a result of the weight of t ...
of the twin hulls. The SES has two advantages over a hovercraft for open sea operation: it is more resistant to slipping sideways when acted on by air or sea, and it can use water jets for propulsion since the inlet nozzles are always covered by water.


History


United States Navy

The
United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
initiated the SES model test program in 1960. By 1963, a 10-
ton Ton is any of several units of measure of mass, volume or force. It has a long history and has acquired several meanings and uses. As a unit of mass, ''ton'' can mean: * the '' long ton'', which is * the ''tonne'', also called the ''metric ...
test craft called the XR-1 was designed and built to test the surface effect concept. The first version of the XR-1 used fixed
plywood Plywood is a composite material manufactured from thin layers, or "plies", of wood veneer that have been stacked and glued together. It is an engineered wood from the family of manufactured boards, which include plywood, medium-density fibreboa ...
seals at the fore and aft ends of the captured air bubble section. A
jet engine A jet engine is a type of reaction engine, discharging a fast-moving jet (fluid), jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition may include Rocket engine, rocket, Pump-jet, water jet, and ...
providing of thrust was used for main propulsion. A separate gas engine was used to drive lift fans, and also to power out-drive units that were used for off-cushion slow-speed maneuvering. During the first year of testing, the XR-1 was fitted with more powerful main propulsion and flexible fore and aft seals were tested as well. The XR-1 was also used to test the concept of water-jet propulsion. The ship was modified in 1964 and equipped with gas turbine engines driving the water jet propulsors. The ship's weight increased to 17 tons.


Rohr Industries 1970 to 1980

Rohr Industries became involved in SES history in 1970, taking over the XR-1 test program for the Navy. Rohr continued to use the XR-1 to test propulsion and seal concepts. Their eventual goal was to develop a 3000-ton (3,050 tonne) SES, the ''LSES'' (''L''arge ''S''urface ''E''ffect ''S''hip) or ''3KSES'', capable of utilizing vertical launch missile
systems A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and is exp ...
and anti-submarine helicopters & various
VTOL A vertical take-off and landing (VTOL) aircraft is one that can takeoff and landing, take off and land vertically without relying on a runway. This classification can include a variety of types of aircraft including helicopters as well as thrust- ...
aircraft. The proposed ship was to have a length of 270 feet and a beam of 105 feet The proposed main power units were to be four LM 2500 gas turbines, each driving an Aerojet water jet propulsor. A cushion height of 18 feet was to be generated with two LM 2500 turbines driving six Aerojet centrifugal fans. It was to carry a crew of 125. The 3000-ton ship development contract was canceled in 1980.


The SES-100

Two experimental SESs (the SES-100A and 100B), both of around 100 tons, with length and beams, were developed for the US Military in the 1960s and 70s. They both attained speeds in excess of the program goal of . The SES 100B, was built by Bell Aerospace (
Textron Textron Inc. is an American industrial Conglomerate (company), conglomerate based in Providence, Rhode Island. Textron's subsidiaries include Arctic Cat, Bell Textron, Kautex, Textron Aviation (which itself includes the Beechcraft and Cessna b ...
Corporation) at the NASA Michoud Assembly Facility. It had three lift fans powered by 600 horsepower gas turbines, and two 3.5-foot semi-submerged, supercavitating controllable, reversible propellers each powered by a 4,500-horsepower gas turbine. achieved speeds in excess of in the
Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...
outside St. Andrews Bay in
Panama City, Florida Panama City is a city in and the county seat of Bay County, Florida, United States. Located along U.S. Route 98 in Florida, U.S. Highway 98 (US 98), it is the largest city between Tallahassee, Florida, Tallahassee and Pensacola, Florida, Pe ...
. The speed was verified by the
USAF The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...
ARIS radar. It also fired the Navy's first vertically launched missile (an SM-2) while doing . It was also used to test automatic ride control and high speed collision avoidance and navigation systems. The 100A ship was used to test waterjet propulsion, variable geometry inlets and automatic ride control systems. The 100A and 100B were both capable of operating almost completely out of the water on an air cushion with only of sidewall, the propellers or the waterjet inlets entering the water. The 100-ton SES 100B was built for the US Navy as a 1/10 scale model to test the feasibility of using hovercraft and other Surface Effect Ships in combat situations. The top-secret specifications called for a ship capable of entering a combat zone at a speed of over and disgorging a tank and 100 soldiers onto a beach, turning back out onto water and escaping at high speed. Unlike the hard sidewall SES's, the full skirted AALCs, JEFF A&B were the prototype vehicles for the
LCAC LCAC may refer to: Hovercraft * A generic term for an Air-cushioned landing craft, air cushioned landing craft, taken from US Navy designation "Landing Craft, Air Cushion". ** Landing Craft Air Cushion, a US Navy hull classification symbol for the ...
's used by the Navy with such success in the
Persian Gulf War , combatant2 = , commander1 = , commander2 = , strength1 = Over 950,000 soldiers3,113 tanks1,800 aircraft2,200 artillery systems , page = https://www.govinfo.gov/content/pkg/GAOREPORTS-PEMD-96- ...
. The 3000-ton SES concept was never designed to go up on the beach, like a landing craft. The AALC (Amphibious Assault Landing Craft) and the SES were very different concepts from the beginning. The AALC was a pure hovercraft that is capable of high-speed insertion of troops and vehicles onto a beach. As a hovercraft, the LCAC, derived from the AALC has no rigid hull parts that extend past the air cushion. It therefore can operate across the beach. The SES has rigid side hulls that enclose the air cushion, permitting water propulsion but allowing it to only go to the shore when conducting amphibious operations. Design concepts for a 6000-plus-ton cargo SES's that Rohr and Ingalls Shipbuilding proposed relied on the idea of the ship loading and unloading from beach, lighter,
causeway A causeway is a track, road or railway on the upper point of an embankment across "a low, or wet place, or piece of water". It can be constructed of earth, masonry, wood, or concrete. One of the earliest known wooden causeways is the Sweet T ...
or conventional dock facilities. On 10 November 1972 contracts were let to four firms to conduct 2200-ton prototype preliminary design; these designs were to be completed in August 1973. The prime contractors were
Bell A bell /ˈbɛl/ () is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator. The strike may be m ...
, Aerojet, Litton, and Lockheed.


Aircraft carrier surface effect ship

Proposed concepts for an aircraft carrier surface effect ship were considered.


Hovermarine SES Ferries

The UK based company Hovermarine developed the HM.2 SES ferry at their factory in Woolston, Southampton in the 1960s. The first HM-2 craft was operated by Seaspeed in 1968 between Ryde Pier and
Portsmouth Harbour Portsmouth Harbour is a / biological Site of Special Scientific Interest between Portsmouth and Gosport in Hampshire. It is a Ramsar site and a Special Protection Area. It is a large natural harbour in Hampshire, England. Geographically it ...
. The early HM2 suffered from mechanical problems and during a financial crisis in 1969, Hovermarine went into voluntary liquidation and the major assets were acquired by a new company, Hovermarine Transport Ltd, this was subsequently taken over by the American company, Transportation Technology Inc. Production of HM.2s for North and Central America was undertaken by Hovermarine's factory at
Titusville, Florida Titusville is a city in and the county seat of Brevard County, Florida, United States. As of the 2020 United States census, 2020 census, the population of the city was 48,789, up from 43,761 at the 2010 census. Titusville is located along the ...
. A brief trial of 2 HM.2 took place in
Toronto Toronto ( , locally pronounced or ) is the List of the largest municipalities in Canada by population, most populous city in Canada. It is the capital city of the Provinces and territories of Canada, Canadian province of Ontario. With a p ...
from July to late fall 1974 to
Niagara-on-the-Lake Niagara-on-the-Lake is a town in Ontario, Canada. It is located on the Niagara Peninsula at the point where the Niagara River meets Lake Ontario, across the river from New York (state), New York, United States. Niagara-on-the-Lake is in the R ...
to Youngstown, New York. The service managed by Can-Am Hover Express used two craft, Toryoung I and Toryoung II, but an accident with the latter craft led to the demise of the service. Over 110 HM.2's were manufactured in the United Kingdom and United States.


Japan

In Japan, two type of SES were built: and . Kibou was operated as a car ferry between Shimizu port and Shimoda port in Shizuoka prefecture. It was 2780-ton, 74m long with 2×MFT8(JT8D) engines. Vessel was decommissioned in 2005. Superliner Ogasawara was planned to operate between Tokyo port and Ogasawara island in Tokyo prefecture, but it was cancelled because of high jet fuel cost in 2005. It stayed in Ishinomaki Port as a hotel ship for victims of the Tunami disaster in 2011. It was later scrapped in 2018. Vessel was 14500-ton, 140m long powered by 2×LM2500 engines


Operational use


Russia

The
Soviet Navy The Soviet Navy was the naval warfare Military, uniform service branch of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy made up a large part of the Soviet Union's strategic planning in the event of a conflict with t ...
built two 1050-ton ''Bora''-class surface effect corvettes in the late 1980s and early 1990s. The ships were passed on to the
Russian Navy The Russian Navy is the Navy, naval arm of the Russian Armed Forces. It has existed in various forms since 1696. Its present iteration was formed in January 1992 when it succeeded the Navy of the Commonwealth of Independent States (which had i ...
and remain in active service with the
Black Sea Fleet The Black Sea Fleet () is the Naval fleet, fleet of the Russian Navy in the Black Sea, the Sea of Azov and the Mediterranean Sea. The Black Sea Fleet, along with other Russian ground and air forces on the Crimea, Crimean Peninsula, are subordin ...
.


Norway

Umoe Mandal built 9 Alta and Oksøy class surface effect vessels for mine warfare for the
Royal Norwegian Navy The Royal Norwegian Navy () is the branch of the Norwegian Armed Forces responsible for navy, naval operations of Norway, including those of the Norwegian Coast Guard. , the Royal Norwegian Navy consists of approximately 3,700 personnel (9,450 i ...
. The Norwegian Navy also operates six Skjold class surface effect patrol boats. These ships are the fastest warships in the world with service speeds of . The prototype ( KNM Skjold) was leased and tested for one year by the US Navy.


Sweden

HSwMS Smyge, which acted as a small-scale pre-prototype testbed for the Visby-class corvette is now used as a training platform for
Swedish Amphibious Corps The Amphibious Corps (, Amf) is the Marines, marine infantry arm of the Swedish Navy, with an emphasis on coastal defence. It has its roots in the Swedish Coastal Artillery, coastal artillery (, KA) but after the end of the Cold War it was seen as ...
Clearance diver A clearance diver was originally a specialist naval underwater diving, diver who used explosives underwater to remove obstructions to make harbours and shipping channels safe to navigate, but the term "clearance diver" was later used to include ...
s.


North Korea

The Korean People's Army Naval Force operated 6 Nongo-class warship.


See also

* Air cavity system is a related technology. * Ground-effect vehicle *
Aerodynamically alleviated marine vehicle An aerodynamically alleviated marine vehicle (AAMV) is a high speed marine vehicle configuration that uses aerodynamically generated forces (Lift (force), lift) to 'alleviate' its weight. The advantage is that the hydrodynamic lift required to sust ...
* List of amphibious warfare ships


References


External links


US Navy's SES-100B Surface Effect Ship
{{DEFAULTSORT:Surface Effect Ship Air-cushion vehicles Ship types ja:地面効果翼機