Boats perform in the water based on the physical shape of the hull, and how it sits in the water. The two general types of hulls are displacement and planing. Other types of hull construction combine features of the displacement and planing hulls and are called semi-displacement or semi-planing.
Displacement hulls push through the water as they have no hydrodynamic lift, or the boat does not rise out of the water as speed increases. The maximum speed of these hulls is typically between 1 and 1.5 times the square root of the boat length based on hull design. Some general characteristics of a displacement hull are:
Planing hulls are designed to run on top of the water at high speeds. To achieve this they typically have a very flat stern. The hull design (shape) does not limit the maximum attainable speed but does affect the power required for it to get on plane (on top of the water). Some general characteristics of a planing hull are:
Semi-displacement or semi-planing hulls have features of both planing and displacement hulls. They have a maximum hull design speed. Exceeding this speed can result in erratic handling and unstable operation. There is not one hull design characteristic that differentiates semi-displacement from semi-planing hull. The greater the hydrodynamic lift and higher the hull design speed the more likely it will be referred to as a semi-planing hull. Some general characteristics of a semi-planing/displacement hull are: