#WeirdBoats The Trimaran Hydrofoil Keeps Popping Up

E1 electric boat racing Chartwell Marine — The Chartwell Marine trimaran hydrofoil (left) and an E1 'Racebird' (right)

At first glance, it's easy to look at a trimaran hydrofoil and assume it's a novelty -- some abstract idea cooked up by a marine engineer with time on their hands and eccentricity in their heart. They look a little like a Star Wars X-Wing, or a wind-up children's toy meant for scooting around the bathtub. But, even with all their quirks, you'll probably see more of them soon. Why? Because, despite their radical appearance, they work. Last week, British company Chartwell Marine announced the development of a trimaran hydrofoiling electric ferry. Amidst the myriad electric boating announcements these days, one could overlook the news as another R&D project rooted in concept more than reality. But that's not the case.

The boat is a collaboration between Chartwell, Solent University, and Newcastle Marine Services, and its mission is to develop a cost-effective zero-emission foiling ferry for commercial purposes.

In other words, Chartwell and its collaborators are designing a hydrofoil that will ferry passengers by boat instead of bus, car, or train. It's intended to get commuters away from noisy and polluting diesel ferries and into public transportation that is quieter, more efficient, and more sustainable. The premise is growing in popularity -- California’s Lake Tahoe just added an electric hydrofoiling ferry to its public transport system to ease road congestion around the popular tourist destination.

The Chartwell trimaran concept in testing

The 'TriFoiler' from Chartwell features a lightweight trimaran hull, a fixed main foil, and a foiling actuating rudder. Arguably it's most unusual detail is that it places the batteries in the sponsons, away from the passenger area, to enhance safety and maximize space onboard. The placement also changes the boat's weight distribution and center of gravity to affect the boat's lift and performance during acceleration and cruising.

“Given that electric power has a lower energy density compared to traditional fuels, minimizing energy usage is crucial for achieving optimal results. Finding the balance between efficiency and reliability is key. We are very excited about the TriFoiler concept," says Andy Page, Managing Director of Chartwell Marine.

The Tri-Foiler is currently undergoing sea trials and the findings are expected to be shared at the end of April 2025. If the boat performs as expected, Chartwell intends to move forward with a full-scale, 24-metre (78 foot), 40-passenger foiling ferry capable of speeds up to 28 knots (32 mph).

If you look at the Tri-Foiler close enough, you might also notice the resemblance to something else — an E1 'Racebird.'

What's a Racebird, you might be asking? It's the electric racing foil used by the E1 Racing Series -- a hull designed in secret and used exclusively in the new league. When the series launched in 2024, E1 took the old template for offshore powerboat racing and flipped it on its head. They’re taking a radical new hydrofoil and power source and pushing the potential of electric boating forward.

The E1 Series has some serious resources, too.

There are nine teams in the league, with the likes of Tom Brady, Rafael Nadal, Didier Drogba, and Steve Aoki serving as team owners. There are also partnerships with other big name yacht makers like Sunseeker and Azimut. The series went through a developmental phase where swaths of engineers tweaked the 'Racebird' concept until it reached speed and handling capabilities beyond any other hydrofoil ever produced. The series travels the world to renowned waterfront cities -- places like Venice, Monaco, Doha, and Miami. It's trying to reimagine the future of boating, and people are starting to notice.

On the technical side, the Racebird uses a 150 kW motor (roughly equivalent to 200 hp) that pushes top speeds above 50 knots (57 mph). Their carbon fiber hulls and advanced battery systems make them ultra-lightweight, efficient, and extremely maneuverable -- a key feature for withstanding the G-forces of E1's tight courses. The E1 Racebird harkens back to the same base as the Chartwell Trifoiler, albeit with a little more 'juice' to work with.

The Chartwell design bears a noticeable difference in the design with the sponsons, but the reasoning comes from the differences in intended usage. One is intended to provide stability and comfort for public transport, the other is intended to improve banking and shoot around turns without losing speed. Similar in necessity, different in function.

The Racebird is smaller than the Chartwell design at 24 feet (7.3 m), but it wasn't designed to consider extra passengers, either. The Racebird seats two passengers -- a pilot and co-pilot -- while the TriFoiler is meant to host up to 40 passengers across its 78-foot (24 m) main deck. In short, the keen eyes of the boating world have picked up on the potential of the trimaran hydrofoil and decided to push its development forward. The E1 Series itself states on its website that "the technology developed for Racebirds may influence future commercial electric boats, paving the way for more sustainable marine transportation." There's also the matter of the top secret Mercury Marine outboards on the Racebirds. While it isn't confirmed, the unannounced appearance of Mercury Marine 'HVe' outboards at boat shows have a strikingly similar appearance to the 'E1-X' motor used in the E1 series, but neither Mercury Marine nor E1 has publicly disclosed the details. One might assume the HVe is the forthcoming public version of the highly secretive experimental racing motor.

(Editor's Note: we noticed these motors at the Vancouver International Boat Show in January, but there is still no word from Mercury about their existence. We asked the boat owner, but they were unable to discuss details. The motors are currently being tested on recreational platforms.)

So what does this all mean for the future of the hydrofoiling trimaran? No one has a crystal ball, and the boating world is famously turbulent, but some facts remain. The hydrofoil concept has been around since the early 1900s, so it stands to reason that its continuing reappearance is because its potential cannot be overlooked. Battery technology has also accelerated at a fever pitch as auto manufacturers, boatbuilders, and commercial enterprises have devoted resources to developing batteries that are more capable and longer lasting. Perhaps we've reached the point where hydrofoils, trimarans, and battery capability have ascended enough to make a once novel idea a realistic possibility. Maybe it’s time the trimaran steered us into the future. If you watch an E1 race, it's easy to see why the hydrofoil keeps coming back. It's amazing to see a boat snap around turns at 50 mph in a way that gas-powered boats simply can't do. Chartwell's design also proves that the trimaran hydrofoil might hold the potential to building commercial vessels beyond standard flatbottom hulls and gas-powered engines. Maybe the future is now.