A sage-green motorboat with a futuristic-looking cantilevered shade appeared without fanfare recently at the public landing in Belfast Harbor. According to Peter Webb of boatwrights French and Webb, Zogo, as the boat is named, was finished a year ago but still needs some work.

Not because French and Webb — the company that simultaneously launched three, identical, fully reconstructed Nathanael Herreshoff racing yachts two summers ago — aren’t capable of getting things right the first time, but because the hybrid diesel and electric powered boat is one of a very few such vessels in the country.

Late last week, the boatbuilders and designers Stephens Waring and White Yacht Design of Brooklin were working on the “controlability” of the 29-foot launch, which included testing the boat with a larger rudder. “It’s generally there,” Webb said. “but it’s been a bit of a process to get it done.”

The engine generator combo — made by Steyr, an Austrian company — uses a diesel engine, which in turn charges a bank of lithium ion batteries while the engine is running. A solar array on top of the canopy provides some additional power to the batteries.

Speaking last year, Webb estimated that the launch could run for three hours under electric power, at a speed of seven nautical miles per hour (knots), or five hours at five knots. The back-up diesel engine running at 18 knots would use one gallon of fuel per hour from the boat’s 35-gallon tank, meaning the diesel engine could carry the boat three-and-a-half times as fast for seven times as long.

Webb said Zogo was at the Maine Boat Show in Portland in March and may make an appearance at the Maine Boats, Homes and Harbors show in Rockland in August.

Asked if there would be a formal launch for Zogo, he said probably not.

“The owners aren’t into that kind of stuff,” he said.