Dual motor efoil for improved efficiency

efoils – Electric Hydrofoil Surfboards
1

Hi all,

so, I’ve been thinking about building a dual motor efoil with the following configuration:

  • One small motor on top of the mast (very close to the board) with a prop that is optimized for getting the board up to speed from zero
  • One small motor at the bottom with a prop that is optimized for foiling speeds. This motor can be much smaller than what we have to use today since it only needs to be powerful enough for foiling and not for getting the board out of the water

The motor at the top of the mast would be wired up with a sensor that detects if it is under water. As soon as the motor is out of the water, it would be switched off and only the bottom motor runs.

I think the main advantage would be that the motor and motor pod at the bottom can be smaller, which results in less drag and less battery usage.
Also, the prop can be optimized specifically for foiling speeds which will probably lead to additional efficiency improvements.

Thoughts?

t-dub

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2

Another dual motor possibility found on the Web:

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image

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3

That one is different though since it has both motors at the same height.
You would only get the efficiency improvements (discussed in the first post) if there’s one motor at the top and one at the bottom.

4

Never tried:
Another way to get the efficiency improvements would be to decrease the main wing surface by one third (800cm2) and to add a very small wing (400cm2, a kitefoil one) under the top motor.

5

As a Wingfoiler, what I m sure is efficiency will be far better with high aspect foil (aspect ratio >~ 9-10)

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