A planing hull is a sailboat design that rises up and skims on top of the water's surface at high speeds, rather than pushing through it, using hydrodynamic lift rather than displacement. Characterized by a flatter or shallow-V bottom, these hulls reduce surface friction and drag, allowing for speeds significantly faster than traditional displacement vessels.

Key Characteristics and Mechanics
Hydrodynamic Lift: At high speeds, the shape of the hull creates lift, causing the bow to rise and the boat to "climb out of the hole," riding on the surface.

Reduced Drag: As the boat rises, less of the hull touches the water, reducing viscous pressure resistance and enabling high-performance, high-speed sailing.

Shape: Unlike rounded displacement hulls, planing hulls (typical in dinghies and skiffs) feature flatter sections, often with sharp chines to release water flow cleanly.

Transition Phase: The speed at which a boat moves from displacing water to skating over it is called "planing speed".