Chine

The line or area where the bottom of a hull meets its side.

On a hard-chined hull, the change in angle is distinct and forms a visible edge. A multi-chine hull uses several such changes to approximate a curved form, while a soft-chined or round-bilge hull has a smoother transition without a sharp edge.

The number, position and angle of the chines influence resistance, spray deflection, stability and handling. Hard chines are common on planing craft, but their presence alone does not mean that a vessel is designed to plane; chines are also found on displacement craft and many sailing boats.