![SWATH waterline](https://upload.wikimedia.org/wikipedia/commons/7/7c/SWATH_waterline.svg)
A small waterplane area twin hull, better known by the acronym SWATH, is a
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 ...
design that minimizes
hull cross section area at the sea's surface. Minimizing the ship's volume near the surface area of the
sea
The sea, connected as the world ocean or simply the ocean, is the body of salty water that covers approximately 71% of the Earth's surface. The word sea is also used to denote second-order sections of the sea, such as the Mediterranean Sea, ...
, where
wave
In physics, mathematics, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Waves can be periodic, in which case those quantities oscillate repeatedly about an equilibrium (res ...
energy is located, minimizes a vessel's response to sea state, even in high seas and at high speeds. The bulk of the displacement necessary to keep the ship afloat is located beneath the waves, where it is less affected by wave action. Wave excitation drops exponentially as depth increases, so wave action normally does not affect a submerged
submarine
A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...
at all. Placing the majority of a ship's
displacement
Displacement may refer to:
Physical sciences
Mathematics and Physics
*Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...
under the waves is similar in concept to creating a ship that rides atop twin submarines.
Effects
The twin-hull design provides a stable platform and large, broad decks. Compared with conventional catamarans, SWATH vessels have more surface drag, but less wave drag. They are less susceptible to wave motion but more sensitive to payload, which affects draught. Additionally, SWATH vessels cannot operate in
planing or semi-planing modes and thus gain no drag reduction when operating at speeds normally associated with such modes.They require a complex control system, have a deeper
draft
Draft, The Draft, or Draught may refer to:
Watercraft dimensions
* Draft (hull), the distance from waterline to keel of a vessel
* Draft (sail), degree of curvature in a sail
* Air draft, distance from waterline to the highest point on a vessel ...
, and have higher maintenance requirements. The design of SWATH vessels is also considerably more complex due to the structural complexities inherent to the design.
History
The SWATH form was invented by
Canadian
Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of ...
Frederick G. Creed Frederick George Creed (6 October 1871 – 11 December 1957) was a Canadian inventor, who spent most of his adult life in Britain. He worked in the field of telecommunications, and is particularly remembered as a key figure in the development of the ...
, who presented his idea in 1938, and was later awarded a
British patent for it in 1946. The first full-scale SWATH vessel to be built and put into service was MV ''
Duplus
''Duplus'' was a diving support and sample drilling ship for the petrol industry. She was designed and built for use in the North Sea towards the end of the 1960s. Most probably, she was the world's first ship built to the SWATH design principle. ...
'', a diving support vessel built in the
Netherlands
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, established_title = Before independence
, established_date = Spanish Netherl ...
in 1968. In the 1970s, several units were built in different countries (including the by the US Navy, and an ferry in Japan). Since the 1980s,
oceanographic
Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamics ...
research vessel
A research vessel (RV or R/V) is a ship or boat designed, modified, or equipped to carry out research at sea. Research vessels carry out a number of roles. Some of these roles can be combined into a single vessel but others require a dedicated ...
s, pilot tenders, yachts and other craft are more routinely being built with the SWATH hull type.
[ ]
Specific examples
![Helgoland 1](https://upload.wikimedia.org/wikipedia/commons/3/3f/Helgoland_1.jpg)
* ''
Duplus
''Duplus'' was a diving support and sample drilling ship for the petrol industry. She was designed and built for use in the North Sea towards the end of the 1960s. Most probably, she was the world's first ship built to the SWATH design principle. ...
'' (1969): oil industry support ship, the first SWATH ship built
* ''
Sea Shadow
''Sea Shadow'' (IX-529) was an experimental stealth ship built by Lockheed for the United States Navy to determine how a low radar profile might be achieved and to test high stability hull configurations that have been used in oceanographic sh ...
'' (1984):
US 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 of ...
experimental
stealth ship
A stealth ship is a ship that employs stealth technology construction techniques in an effort to make it harder to detect by one or more of radar, visual, sonar, and infrared methods.
These techniques borrow from stealth aircraft technology, al ...
* (1988):
Canadian Coast Guard
The Canadian Coast Guard (CCG; french: links=no, Garde côtière canadienne, GCC) is the coast guard of Canada. Formed in 1962, the coast guard is tasked with marine search and rescue (SAR), communication, navigation, and transportation issues in ...
survey ship
* (1988): lead ship of class of four US Navy surveillance ships that use a
SURTASS
*
''Hibiki''-class ocean surveillance ships,
(1991): three patrol vessels operated by the
Japan Maritime Self-Defense Force
, abbreviated , also simply known as the Japanese Navy, is the maritime warfare branch of the Japan Self-Defense Forces, tasked with the naval defense of Japan. The JMSDF was formed following the dissolution of the Imperial Japanese Navy (IJN) ...
* (ex-''Radisson Diamond'') (1992):
cruise ship
Cruise ships are large passenger ships used mainly for vacationing. Unlike ocean liners, which are used for transport, cruise ships typically embark on round-trip voyages to various ports-of-call, where passengers may go on tours known as "s ...
, largest SWATH when built, displaces
* (1996):
Monterey Bay Aquarium Research Institute
The Monterey Bay Aquarium Research Institute (MBARI) is a private, non-profit oceanographic research center in Moss Landing, California. MBARI was founded in 1987 by David Packard, and is primarily funded by the David and Lucile Packard Foundation ...
mothership for the research
ROV ''Doc Ricketts''
*
HSS 1500
HSS 1500 was the name of a model of Stena HSS craft developed and originally operated by Stena Line on European international ferry routes. The vessels were the largest high-speed craft in the world. Several design patents were registered to St ...
(1996): class of three
Finnish
Finnish may refer to:
* Something or someone from, or related to Finland
* Culture of Finland
* Finnish people or Finns, the primary ethnic group in Finland
* Finnish language, the national language of the Finnish people
* Finnish cuisine
See also ...
high speed ferries withdrawn after a decade due to high fuel consumption
* (2001): US Navy ocean surveillance ship that uses a SURTASS, additional ships cancelled
* (2001),
University of Hawaii
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, th ...
oceanographic
Oceanography (), also known as oceanology and ocean science, is the scientific study of the oceans. It is an Earth science, which covers a wide range of topics, including ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamics ...
research vessel
* ''
Planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
'' (2005):
German Navy
The German Navy (, ) is the navy of Germany and part of the unified ''Bundeswehr'' (Federal Defense), the German Armed Forces. The German Navy was originally known as the ''Bundesmarine'' (Federal Navy) from 1956 to 1995, when ''Deutsche Mari ...
weapons and sonar research ship
* ''
Sea Fighter'' (2005): US Navy experimental
littoral combat ship
The littoral combat ship (LCS) is either of two classes of relatively small surface vessels designed for operations near shore by the United States Navy. It was "envisioned to be a networked, agile, stealthy surface combatant capable of defeat ...
*
Silver Cloud (2008): private yacht
*
NOAAS Ferdinand R. Hassler (2009), a
NOAA
The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...
hydrographic survey vessel
*
Type 639 oceanographic surveillance ship
Type 639 is a type of ocean surveillance ship is a type of oceanographic surveillance ship developed by China for its People's Liberation Army Navy (PLAN) to replace earlier Type 595. A single unit of Type 639 with pennant number Bei-diao 992 is ...
(2009): class of six vessels for the Chinese Navy
*
M/V ''Susitna'' (2010): ice-capable convertible SWATH/barge
*
''Ghost'' (2011): experimental
super-cavitating stealth ship
*''
Skrunda-class patrol boat
The ''Skrunda'' class is a class of SWATH patrol vessels used by the Latvian Navy. The main duties of the vessels include fisheries inspections, search and rescue, environmental protection, sovereignty enforcement, and participation in NATO a ...
'' (2011): class of five patrol vessels
*
Iranian high-aspect-ratio twin-hull vessels A high-aspect-ratio twin-hull vessel (acronymed HARTH) refers to a certain design of catamaran vessels with small waterplane area. These vessels are built and used by the Islamic Revolutionary Guard Corps (IRGC) of Iran. Such design is considered ...
See also
*
*
*
* , an experimental US Navy ship with multiple SWATH hulls.
*
*
*
References
External links
{{Commons category, SWATH boats, SWATH
Ship types
*
Catamarans