Multihull

Multihull history

Main article: Outrigger boat, Catamaran

Single-outrigger boats, double-canoes (catamarans), and double-outrigger boats (trimarans) of the Austronesian peoples are the direct antecedents of modern multihull vessels. They were developed during the Austronesian Expansion (c. 3000 to 1500 BC) which allowed Austronesians to colonize maritime Southeast Asia, Micronesia, Island Melanesia, Madagascar, and Polynesia. These Austronesian vessels are still widely used today by traditional fishermen in Austronesian regions in maritime Southeast Asia, Oceania and Madagascar; as well as areas they were introduced to by Austronesians in ancient times like in the East African coast and in South Asia.

Greek sources also describe large third-century BC catamarans, one built under the supervision of Archimedes, the Syracusia, and another reportedly built by Ptolemy IV Philopator of Egypt, the Tessarakonteres.

Modern developers

Modern pioneers of multihull design include James Wharram (UK), Derek Kelsall (UK), Tom Lack (UK), Lock Crowther (Aust), Hedly Nicol (Aust), Malcolm Tennant (NZ), Jim Brown (USA), Arthur Piver (USA), Chris White (US), Ian Farrier (NZ), LOMOcean (NZ), Darren Newton (UK), Jens Quorning (DK) and Dick Newick (USA).

Multihull types

Single-outrigger ("proa")

A single-outrigger canoe is a canoe with a slender outrigger ("ama") attached by two or more struts ("akas"). This craft will normally be propelled by paddles. Single-outrigger canoes that use sails are usually inaccurately referred to by the name "proa". While single-outrigger canoes and proas both derive stability from the outrigger, the proa has the greater need of the outrigger to counter the heeling effect of the sail. The outrigger on a proa can either be on the lee or windward side, or in a tacking proa, interchangeable. However, more recently, proas tend to keep the outrigger either to leeward or to wind which means that instead of tacking, a "shunt" is required, whereby the bow becomes the stern, and the stern becomes the bow.

Catamaran (twin-hull)

Main article: Catamaran

A catamaran is a vessel with twin hulls. Commercial catamarans began in 17th century England. Separate attempts at steam-powered catamarans were carried out by the middle of the 20th century. However, success required better materials and more developed hydrodynamic technologies. During the second half of the 20th century catamaran designs flourished. Catamaran configurations are used for racing, sailing, tourist and fishing boats.

The hulls of a catamaran are typically connected by a bridgedeck, although some simpler cruising catamarans simply have a trampoline stretched between the crossbeams (or "akas"). Small beachable catamarans, such as the Hobie Cat, also have only a trampoline between the hulls.

Catamarans derive stability from the distance between the hulls—transverse clearance—the greater this distance, the greater the stability. Typically, catamaran hulls are slim, although they may flare above the waterline to give reserve buoyancy. The vertical clearance between the design waterplane and the bottom of the bridge deck determines the likelihood of contact with waves. Increased vertical clearance diminishes such contact and increases seaworthiness, within limits.{{Citation | access-date = 2016-01-15

The twin-hull (catamaran) design is effective in enhancing the stability of very small, lightweight and narrow personal boats designed for paddling and powering with portable outboard motors. The 100 lbs (45 kg), 38 inches (96 cm) wide Wavewalk S4 Microskiff catamaran is sufficiently stable to allow for three adult anglers to stand in it and fish in full confidence, and it allows for three adults to stand in it and paddle in full confidence.

Trimaran (double-outrigger)

Main article: Trimaran

A trimaran (or double-outrigger) is a vessel with two outrigger floats attached on either side of a main hull by a crossbeam, wing, or other form of superstructure. They are derived from traditional double-outrigger vessels of maritime Southeast Asia. Despite not being traditionally Polynesian, western trimarans use traditional Polynesian terms for the hull (vaka), the floats (ama), and connectors (aka). The word trimaran is a portmanteau of tri and (cata)maran, a term that is thought to have been coined by Victor Tchetchet, a pioneering modern multihull designer, born in Ukraine (at that time part of the Russian Empire).

Some trimaran configurations use the outlying hulls to enhance stability and allow for shallow draft, examples include the experimental ship RV Triton and the Independence class of littoral combat ships (US).

Four and five hulls

Some multihulls with four (quadrimaran) or five (pentamaran) hulls have been proposed; few have been built. In 2018 a Swiss entrepreneur sought funding to build a sail-driven quadrimaran called Manta that would use solar power to scoop plastic from the ocean. Manta was still under development as of the end of 2023. A French manufacturer, Tera-4, produces motor quadrimarans which use aerodynamic lift between the four hulls to promote planing and reduce power consumption.

Design concepts for vessels with two pair of outriggers have been referred to as pentamarans. The design concept comprises a narrow, long hull that cuts through waves. The outriggers then provide the stability that such a narrow hull needs. While the aft sponsons act as trimaran sponsons do, the front sponsons do not touch the water normally; only if the ship rolls to one side do they provide added buoyancy to correct the roll. BMT Group, a shipbuilding and engineering company in the UK, has proposed a fast cargo ship and a yacht using this kind of hull.

SWATH multihulls

Multihull designs may have hull beams that are slimmer at the water surface ("waterplane") than underwater. This arrangement allows good wave-piercing, while keeping a buoyant hydrodynamic hull beneath the waterplane. In a catamaran configuration this is called a small waterplane area twin hull, or SWATH. While SWATHs are stable in rough seas, they have the drawbacks, compared with other catamarans, of having a deeper draft, being more sensitive to loading, and requiring more power because of their higher underwater surface areas. Triple-hull configurations of small waterplane area craft had been studied, but not built, as of 2008.

Performance

Each hull of a multihull vessel can be narrower than that of a monohull with the same displacement and long, narrow hulls, a multihull typically produces very small bow waves and wakes, a consequence of a favorable Froude number.{{Citation | editor-last = Wu | editor-first = You-Sheng | editor2-last = Zhou | editor2-first = Guo-Jun | editor3-last = Cui | editor3-first = Wei-Cheng

In 1978, 101 years after catamarans like Amaryllis were banned from yacht racing{{Cite web

Sailing multihulls and workboats

The increasing popularity of catamaran since the 1960s is down to the added space, speed, shallow draft, and lack of heeling underway. The stability of a multihull makes sailing much less tiring for the crew, and is particularly suitable for families. Having no need for ballast for stability, multihulls are much lighter than monohull sailboats; but a multihull's fine hull sections mean that one must take care not to overload the vessel. Powerboats catamarans are increasingly used for racing, cruising and as workboats and fishing boats. Speed, the stable working platform, safety, and added space are the prime advantages for power cats.

"The weight of a multihull, of this length, is probably not much more than half the weight of a monohull of the same length and it can be sailed with less crew effort."{{Cite book

Racing catamarans and trimarans are popular in France, New Zealand and Australia. Cruising cats are commonest in the Caribbean and Mediterranean (where they form the bulk of the charter business) and Australia. Multihulls are less common in the US, perhaps because their increased beam require wider dock/slips. Smaller multihulls may be collapsible and trailerable, and thus suitable for daybooks and racers. Until the 1960s most multihull sailboats (except for beach cats) were built either by their owners or by boat builders; since then companies have been selling mass-produced boats, of which there are more than 150 models.

Notes

References and Bibliography

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• {{Cite book |author-link=Gavin Le Sueur
• Harvey, Derek, Multihulls for Cruising and Racing, Adlard Coles, London 1990,

References

1. Dubrovsky, V (2004) Ships with Outriggers, Backbone Publishing Co, {{ISBN. 0-9742019-0-1
2. Mahdi, Waruno. (February 2020). "Archaeology and Language III: Artefacts languages, and texts". Routledge.
3. (1981). "Wangka: Austronesian Canoe Origins". Texas A&M University Press.
4. (23 February 2011). "Inheritance, ecology and the evolution of the canoes of east Oceania". Proceedings of the Royal Society B: Biological Sciences.
5. (1932). "Was the Double-Outrigger Known in Polynesia and Micronesia? A Critical Study". The Journal of the Polynesian Society.
6. (1974). "Outrigger Ages". The Journal of the Polynesian Society.
7. Casson, Lionel. (1971). "Ships and Seamanship in the Ancient World". JHU Press.
8. Athenaeus. (1854). "The Deipnosophists". [[Henry G. Bohn]].
9. Athenaeus. "The Deipnosophists".
10. Such as some [[James Wharram. Wharram]] designs
11. Dubrovsky, V, Laykhovitsky, A (2001) Multi Hull Ships. Backbone Publishing Co. {{ISBN. 97809644311-2-6
12. Garrett, Ross. (January 1, 1996). "The Symmetry of Sailing: The Physics of Sailing for Yachtsmen". Sheridan House, Inc..
13. As in all the [[Catalac catamarans. Catalac]] designs
14. White, Chris.. (1997). "The cruising multihull". International Marine.
15. Collins English Dictionary – 2007 – Harper Collins – {{ISBN. 978-0-00-780072-8
16. "Victor Tchetchet". Multihull Maven.
17. "Northern Patrol Vessel ACV Triton Fact Sheet Australian Customs Service".
18. "US Navy Fact File: Littoral Combat Ship Class – LCS". US Navy.
19. William Hockberger. (2007). "Quadrimaran Ferries". Transportation Research Record.
20. Müller, Kristina. (January 3, 2018). "Ein Quadrimaran für saubere Meere".
21. Staff. (2018-04-11). "Mit einem Quadrimaran will Schweizer Plastik aus Meer holen".
22. "The SeaCleaners {{!}} The SeaCleaners in action: retrospective 2023".
23. (April 10, 2017). "Tera-4 signe la vente de son tout premier quadrimaran".
24. (June 21, 1999). "Five Hulls Make Ships Faster".
25. (December 11, 2001). "In the ocean fast lane". BBC News.
26. Martin, Jack. (September 4, 2008). "Project Veloce - 130 metre 40 knot Pentamaran Super Yacht".
27. (December 7, 2005). "Ships power into faster future". BBC News.
28. Misra, Suresh Chandra. (2015). "Design Principles of Ships and Marine Structures". CRC Press.
29. Kaharl, Victoria. (May 4, 1986). "Ships on Stilts".
30. Dubrovsky, V.. (2008-08-22). "An example of a triple-hull SWA ship of ultimate longitudinal shift (hull structure mass estimation)". Ships and Offshore Structures.
31. Most ships (excluding hydrofoils and planing hulls) stay afloat by displacing their weight in water. A multihull can divide that displacement between multiple, narrow hulls. A monohull must be deeper, longer, or wider to displace the same amount of water. A single long, deep hull would be unstable and hard to maneuver, so monohulls are almost always wider than the individual hulls of a multihull vessel.
32. ''u'' is the relative flow velocity between the sea and ship, {{math. ''g'' is in particular the [[Gravitational constant. acceleration due to gravity]], and {{math. ''L'' is the length of the ship at the water line level, or {{math. ''L''_wl in some notations. It is an important parameter with respect to the ship's [[drag (physics). drag]], or resistance, especially in terms of [[wave making resistance]].
33. Instructors. "Resistance and powering of ships".
34. Randy Thomas. (June 1985). "Multihulls Discovered: Part 1: Their origins, myths, magic, mana... and caveats that go along with these craft that have evolved from ancient heritage".
35. "Sailor's Multihull Guide" - 3rd edition