Trimaran sailplan. They contribute to drag when heavily immersed, and their level of immersion indicates when to reef. Two types of trimaran exist: the regular trimaran and the open trimaran, which features a trampoline between the hulls instead of plating. Trimarans have a number of advantages over comparable monohulls (conventional, single-hulled sailboats). Given two boats of the same length, the trimaran has a shallower draft, a wider beam, less wetted area, and is able to fly more sail area. In addition, because of the righting moment provided by the wide beam, trimarans do not need the weighted keel that is required
Pontoon effect a trimaran with narrow-beam floats will simply submerge the lee float, exposing only the weather wing and that with a lesser moment. In practical sea situations the windage effect is greater than the buoyancy effect and so cruising trimarans with highly buoyant floats are more, not less, likely to capsize than those with less buoyant floats. A trimaran is best stabilised not by adding buoyancy on the lee float but adding weight to the weather float. This is the basis of the "cool-tubes" stability system invented by Tristan Jones and L. Surtees. A large-diameter pipe closed at the aft end