VESSEL REVIEW | Zero – Swedish-designed electric commuter hydrofoil prototype

Swedish manufacturer Candela Speed Boat has commenced trial sailings of a new high-speed ferry prototype.

The pre-production vessel named Zero was built to be capable of achieving high transit speeds using a combination of hydrofoil technology and all-electric propulsion. The design is DNV-classed and can handle significant wave heights of up to two metres. In rough weather conditions, the vessel will instead operate as a normal planing catamaran.

The ferry has a length of 11.99 metres, a beam of 4.5 metres, a displacement of 9.5 tonnes, and seating for up to 30 passengers plus bicycles, wheelchairs, and prams in standard commuter configuration. The vessel was also designed to permit operation even by only one crewmember, resulting in a lighter displacement and allowing owners to reduce costs.

A 252kWh battery pack supplies power to two Candela pod thrusters to deliver a top speed of 30 knots and a range of over 40 nautical miles at a service speed of 27 knots. The thrusters also make the vessel highly manoeuvrable, with sideways "crabbing" possible to allow berthing and unberthing in restrictive harbour waters.

Three carbon fibre foils are fitted beneath the hull to reduce energy consumption by as much as 80 per cent compared to regular fast vessels. Once the vessel becomes airborne, its digital flight control system adjusts the foils' angles based on various sensors, ensuring a smoother voyage and eliminating occupant fatigue. Candela said the control system can make adjustments to the foils at a rate of 100 times per second.

The foils' carbon fibre durable construction ensures that impact caused by small surface debris will not result in damage. Hitting larger objects such as logs will result in the foil breaking at a designated breaking point, which is positioned to maximise protection of the hull from impact.

Other notable features include an extendable automatic bow ramp that can be adjusted to quay heights ranging from 0.2 to two metres. This allows the vessel to embark and disembark at existing jetties without the need for additional specialised infrastructure.

Candela has commenced construction of the new ferries at its Stockholm facilities. The second vessel in the series, which is set to join Stockholm's public transport system by 2024, will transport citizens between the island suburb of Ekerö and the city centre. This electric vessel that promises minimal wake production has secured a speed exemption in the city, reducing commuting times from 55 minutes to just 25 minutes and making it a faster alternative to subway trains and buses that serve the same routes.

In addition to the 30-passenger ferry, variants of the hydrofoil vessel will include a 20-passenger boat with all-business class seating and a 12-passenger private leisure and commercial craft with a bespoke interior.