Candela C-POD - the "most efficient boat motor ever"
Candela, the Swedish electric boat builder from Stockholm, has introduced what it describes as the most efficient boat motor ever – the Candela C-POD electric pod drive. Unlike most boat engines, which transfer thrust to the propeller through a complicated set of shafts, bearings and gears, the Candela C-POD gets rid of the gears altogether.
Two ultra-compact yet powerful electric motors are mounted under the water in a torpedo-like socket, directly driving the propellers. Each motor is coupled directly to a propeller, which minimises friction losses. Contra rotating propellers add the benefit of very high propeller efficiency.
“The engineering challenge was to make the electric motors compact enough,” says Gustav Hasselskog, Candela’s founder and CEO. “Being submerged, they have to have a very small diameter in order to cause minimal drag.”
By placing the motors under the water, Candela also solved the problem all electric motors face: heat. The Candela C-POD engineers designed the slim pod drive to be directly and efficiently cooled by the flow of seawater, thereby enabling higher operating temperatures and extracting more power from the motors.
“The first obstacle towards a very small high-power motor is heat,” says Hasselskog. “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.”
Another benefit is silence. The Candela C-POD has no gears and is therefore completely quiet, even at 30kt. Freed from gears and with very few moving parts, the Candela C-POD will also last several thousand hours without any maintenance whatsoever.
The Candela C-POD was born from the unique requirements Candela places on electric drive trains. The company’s electric hydrofoil craft fly above the water on foils and consume 80% less power than traditional powerboats. Making a more efficient motor directly translates to huge gains in range. The Candela C-POD will be fitted to the Candela P-30 electric shuttle ferry, the Candela P-12 water taxi as well as future leisure boats. Developing 50kW for take-off, a single Candela C-POD has enough thrust to propel Candela’s 28ft, 12-person water taxi, the Candela P-12, at a speed of 30kt. For the company’s bigger 30-person shuttle ferry, the Candela P-30, two Candela C-PODs will provide the same speed.
Source: IBI News