Abstract: A thrust collar is disclosed for mounting around the upper portion of the propeller of an inboard/outboard engine. Each thrust collar supports a horizontal hydrofoil wing extending laterally from the collar. A second, similar wing can be provided on an opposing side of the collar. Where the collar is used in pairs on paired engines on a catamaran hull, a single hydrofoil wing can be supported between the thrust collars. The thrust collar is preferably used in conjunction with hull lifting structures. One hull mounted hydrofoil structure is supported at the lower end of the strut extending and includes a generally curvilinear gull-wing shaped lower surface. For V-type hulls, a pair of elongataed mechanical lifting structures, symmetrically positioned on either side of the keel substantially in the vicinity of the keel are attached to the hull so as to extend generally traversedly to the sloping side surfaces of the hull intersecting at the keel.