SANFORD – After years in the design stage, a prototype of a six-seat seaplane called the Centaur will soon take shape in a hangar at Sanford Airport.

Warrior Aero-Marine Inc. unveiled the designs for the amphibious aircraft last week after the state approved several loans that will allow the company to build the prototype with an eye on eventually assembling the planes in Sanford.

The first new seaplane design in 50 years, the Centaur targets a market that includes bush pilots, commuter airlines and upscale recreational fliers who want to go lake or island hopping. The planes carry a price tag of $525,000 to $550,000, and the company hopes to sell 300 a year.

Part airplane, part boat, the aircraft will feature a carbon fiber and fiberglass body fashioned after the flying hull of a racing yacht, wings that fold back and a fuselage that can withstand storm-tossed waters. It was the brainchild of British racing yacht designer James Labouchere.

A one-fifth scale model has been thoroughly tested and the company, a subsidiary of Great Britain’s Warrior Aero-Marine Ltd., is preparing to assemble the prototype at facilities formerly occupied by Lake Aircraft.

David C. Verrill, a Scarborough certified public accountant and vice president of Warrior, said Sanford has a large, skilled labor pool in the area left over from Lake and Pease Air Force Base in Newington, N.H.

“Also, Sanford has a very attractive runway and there are lakes in the area we can use for landing our seaplane,” he said.

Parts are being made by Maine Composite Inc. in Richmond. The assembly manager will be on site in Sanford in two weeks and will be hiring in the next two or three weeks, Verrill said.

By the time the prototype is complete this summer, it will have cost about $3 million. Verrill says it is being financed by private investors and about $1.25 million in loans from the state.

A military version of the Centaur also is under development, and will be aimed at government agencies that do drug surveillance and search and rescue operations, such as the Coast Guard.