The same separating effect is desired from the transom stern.

Catamaran hull planing. A semi-displacement hull is a hull design that combines features of the displacement and planing hull. It also helps to keep the rocker straight for most of its length and smooth the water flow exiting the hull aft at higher speeds possibly promoting some planing effect. They claim it worked very well under the right conditions until it crashed and burned.

Asymmetric planing hulls are often used on high-speed catamarans. I guess Yves Parliers boat is the most famous of these. Numerical results are validated with available experimental data and empirical correlations.

Catamarans reduce drag by making use of a very thin and pointed hull design. In this study a linearized potential-flow method is applied for modeling steady hydrodynamics of single asymmetric hulls and their catamaran setups. Catamarans are also very light which further reduces drag and displacement.

The hulls of a catamaran reduce heeling. But unlike the planning catamaran where the power to weight ratio is the major determiner of speed the speed of the displacement catamaran is largely a function of the fineness ratio of the hullsThe displacement is relatively unimportant per se except for how it impacts on the fineness ratio of the hulls the height of the wingdeck off the water and the longitudinal moments of inertia of. The top speed of these craft again are only dependant on the amount of power applied.

Planing hulls can exceed hullspeed by lifting over the water and planing at speeds well exceeding hull speed. Displacement catamarans usually operate near the hydrodynamically unfavorable hump speed F n 05. There is also a lot of data for the round bilge narrow non planing motorboats popular in the 1930-50s which again are similar to a single multihull hull.

Prismatic coefficient C p. Below in figure 24 is a typical planing hull. Planing Catamaran The planing cats ride is still rough compared to dis-placement cats but better than on a planing single hull boat.