Candela’s New Electric Pod Drive

Swedish electric boat manufacturer Candela has launched a C-Pod electric boat motor and it claims the new model is “four times more efficient than the best electric outboards.”

The motor is actually in a torpedo-like housing that is below the waterline and it drives the contra-rotating propellers directly. This eliminates the need for gears and other linkage found in most propulsion systems and there is no parasitic power loss.

Constant Cooling

Having the motor operating below the surface also helps cool the unit and it doesn’t need to have any water pass through it, which does away with corrosion concerns.

“The first obstacle toward a very small high-power motor is heat,” said Gustav Hasselkog, Candela founder and CEO. “You can take any motor and give it three times more electricity than it is rated for. It will work. But only for a few seconds. Then it melts. With Candela C-Pod, we have almost unlimited cooling power — we just need to get heat from the coils to the surrounding water flow.”

Hasselkog explained that the engineering challenge was to make the electric motor compact enough because they need to have a small diameter to create minimal drag. Candela opted to increase the rpm and lower the torque to boost the C-Pod’s power density. The solution was to split the thrust needed between the two propellers. This allows for smaller-diameter props spinning at higher rpm, which suits the motor’s underwater position. The C-Pod’s weight is listed at 57.32 lbs. (26 kg).

Real-World Use

The first vessel the C-Pod is being used on is a P-12 electric water taxi that carries 12 people. For this application, the engine is developing 50 kW and can reportedly push the boat at 30 knots. The next boat will be a twin-engine installation on a P-30 ferry.