Dualhull

Dualhull refers to a watercraft design that utilizes two hulls. In most cases, the two hulls are connected by a bridgedeck and longitudinal or transverse beams, creating a stable, wide platform. The term encompasses various two-hull configurations, with catamarans being the most common modern embodiment, while other twin-hull boats may use different hull shapes or offsets.

Historically, dualhull boats appear in Polynesian double-hulled canoes, which demonstrated the stability and efficiency of two slender hulls connected by a frame. In contemporary use, dualhull designs span sailing yachts, motor launches, research vessels, and ferries. The bridgedeck often provides protected deck space and living accommodations, independent from the hulls.

Advantages of dualhull designs include increased initial stability from a wider beam, improved buoyancy distribution, and the potential for reduced hydrodynamic drag per hull on certain scales. This can translate to higher speeds and smoother motion in choppy seas. They also allow for expansive deck areas and flexible interior layouts.

Disadvantages include higher construction and maintenance costs, more complex rigging or propulsion systems for two hulls, and sometimes less interior volume within each hull compared to a comparable monohull. Handling and docking can be more challenging due to the beam and rudder placement across two hulls.

Materials commonly used in dualhull construction include fiberglass or other composites, aluminum, and steel. Design considerations focus on hull spacing, stability, righting moment, bridge clearance, and the balance between wetted surface and overall performance.