Multihull

A multihull is a sailing ship with more than one hull. The additional hulls provide stability, typically to hold the vessel upright against the sideways force of the wind on the sails. This is in contrast to monohulls which typically use ballast for this purpose.

Multihulls are typically either catamarans, which have two similar hulls, or trimarans, which have a larger hull in the center and two smaller ones on either side. In either case they are typically much wider than the equivalent monohull, which allows multihull sailboats to carry no ballast, so they are typically faster than monohulls under equivalent conditions (see Nathaniel Herreshoff's "Amarylis", also 1988 America's Cup). It also means that multihulls are less prone to sink than monohulls when their hulls are compromised. There are also multihull powerboats, both for racing and transportation.

Multihulls' width is often an issue, especially when docking. They are also more expensive to produce than a monohull of the same length.

Multihulls are substantially faster than monohulls, because the water-line hull-length to width ratio is so large.

Unfortunately, it is common wisdom that in the open ocean, multihull craft are unsafe. If a storm or wave capsizes a small monohull, it will recover. The rigging will probably be severely damaged, but the crew will be able to jury-rig and reach a port. If a multihull capsizes, the crew often dies. Even most rescued crews (in races) have reported that they were unable to dismount the deck-mounted liferaft or emergency radio from the mass of broken, submerged rigging under the capsized craft.

Proponents argue, with some justice, that no careful captain ever finds himself in capsizing conditions. Most crews that have capsized in the open ocean found it an extremely traumatic event no matter what type of boat they sailed.

Multihulls are quite popular for racing, especially in Europe and Australia, and are somewhat popular for cruising in the Caribbean. They're not seen very often in the United States, although they're gradually getting more popular. Until the 1980s most multihull sailboats (except for beach cats) were built either by their owners or by boatbuilders on a semi-custom basis. Since then several companies have been successful selling mass-produced (by boat industry standards) boats.

Brand names include Hobie (small catamarans), Corsair Marine (mid-sized trimarans), and Privilege (large, luxurious catamarans).