UK axial-flux motors power clean outboard motors for boats

Published: 22 December, 2022

A Dutch offshoot of the UK axial-flux motor developer Saietta is about to start production of an electrically powered outboard motor for boats that, it believes, will pose a significant challenge to traditional outboard engines, especially as emissions legislation drives a move towards electric power. In Amsterdam, for example, all new vessels will have to be electrically powered by 2025, and it is predicted that 74% of outboard motor sales in Europe will be electric by 2030.

The electric outboard motor, being built by the Saietta spin-off called Propel, is based on a 10kW “pancake” axial-flux motor – the equivalent of a 25hp traditional outboard engine – with a controller mounted on top. The 47kg outboard machine uses a modified version of Saietta’s AFT140i motor and integrated controller which has been developed over the past five years at its Light Duty eDrive business at Silverstone, UK. The motor drives a 12.8-inch propeller which spins at up to 1,440 rpm, with a claimed 62.1% conversion efficiency of motor torque to the forward drive of the vessel.

The motor is started with the flick of a switch. A colour display on the tiller or remote controller provides information about the machine’s operation. The motor, controller and electronics are located above the waterline, simplifying access and reducing drag compared to rival products which have motors and gearboxes in bulky housings below the waterline.

Series production of the outboard machines will start soon at a new assembly line in the Dutch city of Apeldoorn. Prices are expected to start at €5,900 (£5,144).

“Once you experience the Propel way, you will never want to go back to noisy and smelly petrol motors,” declares Saietta CEO, Wicher Kist. “I have been testing the advanced prototypes on the water and this product is in a different league to other electric outboard motors in terms of its refinement, power delivery and user experience.

"Leisure boat owners and operators will soon have no option but to switch to electric motors as cities implement new rules to clean up their waterways,” adds Propel’s managing director and chief technology officer, Sander van Dijk.

The pancake motor and its controller are housed above the waterline, offering advantages over other designs

European boating enthusiasts buy 200,000 outboard motors for leisure purposes every year, generating sales worth $900m.

The 10kW Propel S1 outboard motor will be supplemented over the coming year by 7kW and 13kW variants. The company will also be selling modular 48V battery packs in 6.6, 10.2 and 13.6kWh capacities.

The S1 outboard motors join Propel’s existing D1 inboard electric motor which was launched last summer to replace ageing diesel engines.

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