US Patent 3,324,822

Surfjet

The motorized surfboard that started it all — the precursor to modern personal watercraft.

Carter testing early Surfjet prototype on lake

Early prototype testing was all about speed - dialing in thrust angle and engine tuning to better match the pump’s power curve.

Original Surfjet prototype with modified surfboard, industrial pump, and go kart engine.

The original prototype combined a modified surfboard, industrial pump, and go-kart engine. It wasn’t fast yet, but it proved the concept could work with purpose-built components.

4 of 6 pre-production prototype Surfjet motorized surfboard hulls

Four of six pre-production prototype hulls. Carter began developing a new surfboard hull designed to house an engine and pump. Needing precision components, he partnered with Phoenix-based aerospace aluminum foundry Presto Casting Co. Following early involvement, the Presto owners identified the value of the concept. Carter subsequently sold his patent rights and continued development work under a two-year agreement.

Surfjet engine compartment shows a water cooled engine and exhaust coupled to an axial flow pump and nozzle.

A look inside - the water-cooled engine and exhaust are coupled to an axial flow pump and nozzle. This early design set the standard still used in personal watercraft today.

All the components that made up the Surfjet.

A closer look at the components that brought the Surfjet to life.

US Patent 3,324,822 filed October 23, 1965

Filed October 23, 1965 - US Patent 3,324,822 predates personal watercraft patents by more than two years.