Small Waterplane Area Twin Hull

The Small Waterplane Area Twin Hull (SWATH) is a twin-hull ship design that minimizes hull volume in the surface area of the sea. By minimizing hull volume in the sea's surface, where wave energy is located, the vessel becomes very stable, 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, as wave excitation drops exponentially with depth. Placing the majority of the ship's displacement under the waves is similar in concept to submarines, which are also not affected by wave action.

Effects

The twin-hull design provides large, broad decks and a stable platform. The main disadvantages to the SWATH hull form are that they are more expensive than conventional catamarans, require a complex control system, have a deeper draught than catamarans and mono-hulled ships, and a higher maintenance requirement. Furthermore, SWATH vessels can use up to 80% more power than an equivalent catamaran, and are more limited in speed compared to equivalent catamaran vessels. [British Columbia Ferry Corporation: "Fast Ferries Technical Notes" 1995]

History

The SWATH form was invented by Canadian Frederick G. Creed, who presented his idea in 1938 and was later awarded a British patent for it in 1946. It was first used in the 1960s and 1970s as an evolution of catamaran design for use as oceanographic research vessels or submarine rescue ships.

Specific examples

*"CCGS Frederick G. Creed", a Canadian Coast Guard survey ship.
*"Sea Shadow", a US Navy experimental stealth ship.
*"Sea Fighter", a US Navy experimental littoral combat ship.
*" [http://www.asiacruiser.com/eng/ship/omarstar.htm Asia Star] ", formerly the " [http://www.rssc.com/ships/ship.jsp?code=DIA Radisson Diamond] ", a 350 person all balcony luxury cruise ship with 20295 tonnes gross tonnage.
*" [http://dejongandlebet.com/642_sun_cruz_vi.htm SunCruz VI] ", a USCG certificated casino vessel for 600 passengers.
*" [http://www.soest.hawaii.edu/UMC/KiloMoana.htm R/V Kilo Moana] ", a University of Hawaii research vessel.
*" [http://www.cloudx.com/ Cloud X] ", a passenger ferry running between Florida and the Bahamas.
*" [http://www.swacat.com/swacat80.htm Nekton Rorqual/Swacat 80] ", an 80 foot cruise ship operated by Nekton Diving Cruises.
*" [http://www.loodswezen.nl/page.aspx?ID={21AA9C41-49F4-4421-9330-F448E37786D1} Cetus and Perseus] ", pilot vessels for the Netherlands Loodswezen.
*" [http://www.elbe-pilot.de/aktuell4.htm Döse, Dunen] ", pilot vessels for the German Brotherhood of Elbe - Pilots.
*" [http://www.elbe-pilot.de/stationallg.htm Elbe] ", pilot station vessel for the German Brotherhood of Elbe - Pilots.
*"Planet" Type 752, weapons + sonar research ship of the German Navy.
*The "Goya" in Dan Brown's book Deception Point is a Swath.

See also

*Multihull
*Catamaran
*Hydroairy Ship, another twin hull design
*Trimaran
*Swath Width

References

External links

* [http://www.swath.com/concept.htm The Swath Ship Concept]
* [http://www.swathocean.com/ Swath Ocean Systems]
* [http://www.abeking.com/ Swath@A&R]