From the Brooklyn marina towards Governors Island, along New York's East River, a test ride on the VS-9 feels like a ride on any other catamaran - until the boat speeds up. Then, instead of starting to bounce and slam into the water like any boat about nine metres long, the hull lifts above the surface. Underneath are two hydrofoils, and computer-controlled flaps keep it calm and steady. The front foil carries most of the weight, the rear one around 20 per cent.

The startup Vessev raised 19 million dollars (around 16 million euros) in a Series A round in August. It builds the electric motor, housed in the rear foil, itself. The only thing it buys ready-made is the batteries. "They've already become a commodity," says founder and CEO Erik Lackman. His logic is simple: to keep costs under control, the motor sooner or later has to be made in-house, so it's better for that to happen during development.

Why foils? When the hull is out of the water there's less drag, and on an electric boat every kilowatt-hour counts. With a full cabin, the VS-9 has a range of 74 kilometres. But a hydrofoil is no miracle. It only glides smoothly while the waves are lower than around 75 centimetres. Above that, the water starts hitting the hull, the ride gets rough and efficiency drops. The open sea isn't for it - its terrain is lakes, rivers and bays.

The first target is public transport. Lackman believes that combining electric propulsion with hydrofoils can cut costs for small boats and make them comfortable enough to become part of city transport. New York, for example, could use them to quickly ferry people to Brooklyn or Queens without much new infrastructure. Next on the list are hotels and tour operators, and at public demonstrations, he says, wealthy buyers looking for one more toy turn up too.

Hydrofoils aren't a new idea - shipbuilders have been experimenting with them for more than a century. For now the VS-9 is a one-off, but Vessev plans to build more, and in the longer term it may sell electric hydrofoil kits so other boatbuilders can design their own boats around them. Lakes are exactly the terrain this technology was made for. Will we ever see a ferry like this on Lake Ohrid - and who would be the first to dare to pay for it?