application of at least one slot notch or groove to or near the rear of a single or pair of towed planing boards or surfaces . such slots or the like induce a water geyser at speed that improves the appearance and / or directional control of such boards . such slots or the like are especially effective and practical for deep displacement type boards whose zero and low speed efficiency and stability is especially improved for paired boards or ski when such are fitted with a rigid or preferably semi - rigid connector as hereinafter described . the addition of slots or the like , and where applicable suitable connectors , to generally improve combination displacement - planing boards by : economically providing an aesthetically pleasing water spout induced at speed for planing boards , economically providing a novel and improved apparatus for establishing directional control and stability , improving the lateral stability of ski sets especially at zero and low velocities , practically reducing the bulk or required net displacement of ski sets especially at zero and low velocities and more simply providing a foot restraint .