Some of the most unusual looking boats on the water are trimarans. By definition, the one thing that makes a boat a trimaran is the presence of three hulls (as compared to a single hull for monohulls,
Some of the most unusual looking boats on the water are trimarans. By definition, the one thing that makes a boat a trimaran is the presence of three hulls (as compared to a single hull for monohulls, and twin hulls for catamarans). But these hulls are not always equal; in fact, more often than not the two on the outside are quite different from the hull in the center. The basic design is derived from “double-outrigger” boats that originated in Southeast Asian islands and were developed by natives for fishing and transportation. Today there are both power and sailing trimarans, though the vast majority of the trimarans on the market are sailboats.
Having three hulls spaced out apart from one another nets many of the same advantages as catamarans enjoy: reduced wave impact, increased stability, and increased deck space since the bow doesn’t come to a point at the end but instead maintains its beam moving forward. However, having that third hull improves the boat’s stability even more, often eliminating the need for a deep, heavy keel, and allows for some different styles of sailing. In many cases, for example, the outside hulls of the boat are significantly narrower and lighter than the middle hull. When heeling over, one may ride out of the water completely, while the other stabilizes the boat.
Building with the trimaran design introduces some interesting and unique possibilities. With some small models, for example, the three hulls can be folded together more or les like an accordion, to reduce the boat’s size for trailering and storage. On some other trimarans the hulls are rigid but the deck bridging the spaces between them is a trampoline, reducing the boat’s weight. And in a few rare cases the flight deck of a littoral combat ship spans between the three hulls of a trimaran.