UK-based Hybrid Marine International has developed a twin, compact e-motor installation using the latest in highly efficient salient pole electric motors.
Launching at Seawork was the latest innovation from UK-based Hybrid Marine International, with an example of the converted engine on display. Responding to the surge in hybrid sales, the company partnered with EP Barrus to co-develop a system for Yanmar engines. The new installation, which can be retrofitted, uses twin 15kW electric propulsion motors that are also highly efficient as 10kW engine-driven generators.
"This is the result of 24 years of evolution. We have managed to double the charging capability for the same weight and increased the electric drive output by 50% within the same footprint. Our previous motors were liquid cooled, which on a seagoing boat needed dedicated inlets, outlets, pumps and heat exchangers. But with this new design we’ve gone for an air-cooled motor. We found a salient pole design that is incredibly efficient, and by placing a shroud around each motor, and using laminar flow techniques, have achieved excellent cooling just from a blower."
Advanced Hydro Regeneration Under Sail
Salient pole ‘synchronous’ motors are often – a little confusingly – described as hybrid motors, as they use a combination of permanent magnets and field induction coils. This gives the motor a much greater range of operational revolutions, especially the ability to create power at low speeds, which is ideal for hydro regeneration under sail.
"This type of hybrid motor has been optimised for energy recovery from a free-wheeling propeller. The owners of sailing boats don’t want too much propeller drag when not actually regenerating, so they opt for folding or feathering propellers. However, these props are prone to surge effects in a seaway, so we have developed advanced algorithms that detect these surges and ensure the charging remains constant, without sudden spikes."
The cooling shrouds have been optimised with the help of a physics graduate, who was tasked with making the air flow as efficient as possible. “Actually, due to the design of the electric motors, there is very little waste heat anyway,” Hawksley said. “What is created is drawn back into the engine.”
Real-World Application: Commercial & Sailing Catamarans
The first example of the new engine is destined for a whale-watching vessel in the North Pacific, where the 150hp diesel engine will get tourists to the location quickly, and the 40hp electric drive will gently – and almost silently – enable them to follow any whales they find. The vessel is also equipped with sails and will renew as much energy as possible in suitable sailing conditions.
“The electric drives also offer a boost mode,” Hawksley noted. “This can prove useful if the boat is stationary and needs a quick burst of power to get it moving.”
Hybrid Marine has seen a significant increase in sales as sailors move away from a combination of separate systems (such as LPG for cooking) and demand the creature comforts of home without constant diesel generator use. The largest growth in hybrid installations has been seen in sailing catamarans, and this new system enables boatbuilders to provide a significantly more powerful and efficient system for much less weight and space.