New Zealand hydrofoil builder develops ‘the coolest electric motor’

Vessev is a New Zealand builder of hydrofoiling electric boats – ferries in particular – that has developed an internal closed-loop cooling system for their motors enabling better performance in tropical climates where water and air temperatures are a factor.

The ‘VS–Drive’ now powers the nine metre (30 ft) Vessev VS–9 “Kermadec“, a hydrofoiling tour boat that takes visitors on 40 minute trips around  Auckland’s Waitematā Harbour and the pristine waters of the nearby Huaraki Gulf. It carries 10 passengers at a cruising speed of 25 knots (29 mph / 46 kph) and is part of the transport company’s journey to have net-zero operations by 2040.

Vessev says the company has strong interest for their ferries from customers across three continents and that the motor will scale to other models in development, including 12 and 18-metre vessels, as well as their recreational boat, a Finalist in the 2025 Gussies International Electric Boat Awards.

Like many other electric drives, the VS–Drive is a pod motor, meaning the motor itself operates underneath the water surface and turns the propeller shaft directly rather than having a motor above the surface and using gears and cogs that reduce efficiency.

Being underwater means there is almost no noise, while another benefit of having it submerged is ‘passive cooling’. Some of the heat from the motor is transferred to the water just by moving through it. However, the larger the motor, or the faster it spins, the more difficult it is to disperse the heat. It becomes more difficult if the water itself is warm.

New Zealand hydrofoil drive cools to 50ºC / 106ºF

The engineers at Vessev have addressed this with an ‘active cooling’  system using a closed loop of coolant as part of a modular design that allows for easy maintenance. The motor has a continuous output of 65 kW (90hp) and peak power of 110 kW (150 HP). While it has a tolerance of 100 degree Celsius (212º F), it operates consistently below 50ºC / 106º F – which is cool enough to touch.

“The VS–Drive began as a clean-sheet design to overcome one of the trickiest challenges in electric marine propulsion: overheating,” said Max Olson, Vessev’s Chief Technology Officer. “The result is sustained high-torque output, and unparalleled performance in tropical climates.”

He added that the VS-Drive was among the company’s most game-changing features – which is a strong statement considering their overall goal was to create a 3,300 kg (7,275 lb) vessel that flies above the water on hydrofoil wings.

The main benefit of hydrofoiling in general is the reduction in the amount of energy needed to keep a boat moving through water at speed. Because the only things in the water are the wings, the pod motor and supporting struts, the resistance and friction is very close to zero. The energy use can be as much as 80% lower than that of a traditional planing boat.

That efficiency overcomes the range issue that concerns many people. Using less energy means the boat can cover the same distance at the same speed using a lighter, smaller battery. Another advantage is that the wake is insignificant, a bonus when travelling through no-wake zones or sensitive marine environments.

That is one of the benefits that appealed to the Finn Lough luxury eco resort in Northern Ireland, who will have a Vessev V-9 in operation to allow guests to explore the lough (lake) without disturbing its tranquility.

Vessev CEO Eric Laakmann said the Vessev-9 and VS–Drive are unlocking a new level of what’s possible for electric marine transport. “We’re excited to see operators around the world benefit from this propulsion technology across a range of applications.”

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