Singlehull

Singlehull refers to a watercraft built with a single primary hull. This distinguishes it from multihull designs such as catamarans and trimarans. The term is commonly used for sailboats and many powerboats.

Construction and layout: Monohulls are built from materials including fiberglass-reinforced plastic, wood, aluminum, or composites. A single hull provides most buoyancy, while stability at sea is primarily achieved through ballast and hull form. Keels may be traditional long keels, modern fixed fin keels, or retractable keels; some smaller boats use centerboards or daggerboards. The rig, hull shape, and weight distribution determine stability, motion, and performance.

Performance and handling: When sailing, monohulls heel to leeward under wind pressure. The righting moment generated by ballast and crew stabilizes the vessel. Traditional designs with long keels emphasize tracking and sea-kindliness, while many modern monohulls use deeper fins and lighter ballast to improve speed and agility.

Advantages and drawbacks: Monohulls are typically less expensive per unit length and easier to repair than many multihulls. They provide familiar handling, broad availability of parts, and a wide range of sizes. Interiors are often more traditional in layout, but for the same overall length, monohulls generally offer less deck and living space than multihulls.

Notes: Singlehull remains the dominant form for many yachts and sport boats, in contrast to multihull classes that prioritize stability and roomy interiors.