In 1964 Daniel Savitsky reviewed published material on planing hulls
and formulated simple computational prodecures to predict the
horsepower requirements and porpoising stability of prismatic hulls.
This web-page lets you investigate the required thrust [kg] and horse
power [hk] as well as trim angle and porpoissing stability for a given
planing boat and a given velocity range. The interested
reader should read the original paper which gives more data on
several topics : lift, drag, wetted area, center of pressure,
porpoissing stability as a function of speed, trim angle, deadrise
angle and loading. The paper may also help you to better understand
Please remember that the calculated HP is the effect required from the
propeller. The motor effect should be larger. For a good propeller :
motor effect = HP/0.7
Results from the Savitsky procedures.
The calculatons on this page is valid for planing hulls only.
lcg = longitudional distance of center of gravity from transom
vcg = vertical distance of center of gravity above keel-line
b = beam of planing surface
beta = angle of deadrise of planing surface
See also the definitions in the
Savitsky, Daniel : "Hydrodynamic design of planing hulls", Marine
Technology, Vol. 1, No.1, 1964.