The State of Electric Yachts

I want to introduce you to the current state of affairs with electric yachts, signal where the technology is at from the leading electric yachts companies, and I want to address just where our thinking is different.

May I introduce you to Jimmy Cornell and his Aventura yacht’s concept and special features. He has set a challenge to sail around the world on zero emissions. The choice of vessel was heavily weighted towards high performance and solar panel area. Jimmy partnered up with Oceanvolt who “have been working for the last 20 years on perfecting electric propulsion on pleasure craft”. The system is driven with electric motors on sail drives and quite large battery packs. Jimmy elected not to have a generator onboard and increased his battery capacity and solar panels to 1300W. He installed a servo propeller which “adjusts the pitch of the propeller blades automatically so that the power generation and power output are optimal. The servo prop is a feathering propeller designed “to get the minimum drag, it is highly efficient optimally in forward and reverse and in hydro-generation.” This system can generate 1kW of power at 7-8 Knots and up to 3kW at 12 knots.

One critique of his approach is that 1.5kW is not a big solar system. In good conditions, 4.5kW installed would cover a couple’s energy domestic use. The solar is scaled to his system not his consumption, therefore in the long term his amenities aboard are dependent on other sources of energy (most yachts have a generator). The team sets out to cross the Atlantic and they run out of electricity and despite the fact that they are sailing in constant 12 knots of wind the hydro-generations system being optimised for low drag, underperforms. Their situation became very dangerous, refrigeration shut off, no hot drinks, no autopilot, no hot food – for nearly two weeks. The extreme risk posed by the power shortage meant they “had to hand-steer the boat for quite some time just to have enough energy for critical systems”.

In the ocean, loss of power becomes a life threatening situation and that is something we need to avoid at all costs. With CMG we change the approach to focus on the propeller and have engineered a way we can increase the wind range of hydro-generation, if the propeller is optimised for hydro-generation, or more correctly, motor-sailing. The system can deliver 50kW kilowatts of charge or a 10x improvement however, the expanded wind range allows effective generation for many hours in easy sailing conditions. When cruising, picking a weather window allows 10-20 kW of continuous generation resulting in always arriving with full batteries and a lot of fresh water. If you’re near the variables and you see a squall – in that half an hour of wind – you would be able to add over a hundred kilometers of range. The fundamental difference between what is currently happening in the market and our approach is not magic, but a normally engineered propeller optimised for hydro-generation, it is a little bit larger than the servo prop however, it generates energy differently because we select a fixed speed for the boat to travel and turn excess power of the sails into electricity. For an efficient sailing yacht, the loss in speed is not such a harsh price to pay for the amount of energy that you can make available for comfortable living – it’s really that simple.

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