ELECTRIC AVENUE

Performance boats are among those leading the electric propulsion charge, with many teams recognising potential for tangible benefits on the racecourse.

- RUPERT HOLMES

The electric propulsion sector is developing rapidly, with volumes increasing, more players entering the market – there were 27 at the METStrade marine equipment show in Amsterdam last year – and prices set to continue falling. This is particularly true for lithium-ion batteries developed for automotive use, where the current trend for a doubling of capacity roughly every three years, while maintaining a power pack of the same physical size and cost, shows no sign of slowing.

The past couple of years have seen progressively more race boats turning to electrical power, including IMOCA 60s, such as Alex Thomson’s Hugo Boss; Fast40s, including Niklas Zennstrom’s Ràn; the ClubSwan 36; plus smaller keelboats and even RIBs, such as the new RS Pulse 58 (see boxout). Equally, Pogo’s Loxo 32E shows there’s also an appetite for very efficient electric motorboats.

BLISTERING TORQUE

While an electric motor will drive the propeller in forward or reverse gear just like a conventional internal combustion engine, there are further important advantages to electric units. These stem from the inherent differences in torque characteristics between the two different types of motor.

Internal combustion engines produce peak torque around a narrow band at moderately high revs. There is therefore a lag between engaging gear and achieving maximum thrust. However, electric motors have a much flatter torque curve, delivering ample power at any engine speed. As a result their low-speed performance is exceptional, which helps when powering into a head sea and when manoeuvring a yacht in tight spaces.

In addition this means electric motors can run more efficient propeller shapes – a significant advantage given power lost at the propeller can range between 30 and 80 per cent.