bow section that develops functionally from a compound vee section to a flattened base at the step lift having controlled air film supply to break the step lift generated vacuum and to provide an air film support and pathway for a trailing and air film confining hull portion after the step lift application_number US 59204275 A description as illustrated in fig1 one of the preferred embodiments of the present invention is the application of the improved planing hull design and air film system to a catamaran water craft 10 having two identical pontoons 11 and 12 bridged by a deck 8 the over all hull design of each pontoon 11 12 is a single step lift planing hull wherein the step 14 is located substantially athwartship note fig6 approximately two thirds the distance aft from the bow towards the stern the specifics of the hull design can best be seen in the hull profile views of fig3 7 chines 7 are formed on both sides of the keel line 9 of the pontoon hull and begin shortly aft the bow the chines 7 move down below the 34 stationary floating 34 water line not illustrated and flow smoothly into the side flat parallel relatively narrow edge protrusions 6 which extend all the way to the stern 13 of the hull the protrusions or parallel vertical extensions 6 are in effect chine lines continued aft from the step lift and are most important they serve the additional function of keeping the air film which is delivered aft at the step lift 14 from escaping laterally from under the hull portion behind the step lift these parallel protrusions 6 retain the thin air film which provides an almost frictionless support in the air film area.