Mateo - "Not sure if 30kW electric propulsion equals 40hp in practice, perhaps more."
At the prop 40 hp = 30 KW. The real question is the losses in getting the power to the prop. A diesel engine has transmission losses typically in the 15 to 30% range so it typically has to produce 15 to 30% more power to actually get the rated number.
If diesel is used to generate electricity it is generally 60% efficient so it has 40% losses for production and then 15% resistance losses. That means in the end diesel directly powering the the prop is 70% efficient and if it goes through a generator it is 45% efficient.
Similarly if the electricity is coming from solar, there is a 40% loss going through the batteries, and another 15 percent loss going to the prop. Ideally the motor should be driven directly from the solar panels and then it becomes more efficient, but that requires 30KW worth of solar panels.
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Posted by: taladorwood@yahoo.com.au
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