A hull is the watertight main body or shell of a boat or ship, excluding masts, rigging, and rudder, providing buoyancy and structural integrity. It enables the vessel to float, affects stability, and determines speed/fuel efficiency, encompassing the bottom and sides.

Common Hull Types:
Displacement: Pushes water aside, typically rounded or S-bottomed.

Planing: Lifts up and rides on top of the water, often with harder chines.

Round Bilge: Smoothly curved hulls.

Hard Chine: Hull with a distinct angle between the side and bottom.

Monohull: A boat with a single hull.

Multihull: A boat with more than one hull, such as a catamaran (two hulls) or trimaran (three hulls).