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Comment by dzhiurgis | Hacker News Reader

Charging these by marinas with solar shade seems obvious fit - it protects the boat from weather plus their batteries can balance grid as they are only used like 0.01% of time.

Question I have - do hydrofoils use ground effect to generate extra lift?

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Water is considerably different to air and there is no analogous effect for ground effect in water.

Edit: I realise now that you mean hydrofoil as in the boat rather than the submerged wing (it's confusing that they both have the same name). I don't think the ground effect from the boat's hull contributes much to the lift but it is something that the designers of the AC75 boats take into consideration https://www.sailmagazine.com/racing/36th-americas-cup-differ...

I think the OP is referring to ground effect above the water surface, as employed by for example eraknoplans (https://en.wikipedia.org/wiki/Lun-class_ekranoplan)

I would speculate no, as it seems a trade off between inherently stable and inefficient (standard v shaped hull) and inherently unstable, but more efficient (inverted v).

Ekranoplans have wings and aerodynamic control surfaces.

I also wonder (this may be the primary reason) if the speeds a hydroplane achieves are sufficient to generate much lift in air from something the size of a boat hull.

I’m guessing no because you have to travel pretty fast for an air wing to have an effect (~50-200mph), but you travel relatively slower for the hydrofoil to perform well (10-30mph). (These are very approximate numbers I made up from experience riding on different types of boats. They are not physical limits or anything like that!)

I think TeamNZ were talking about supercavitation for next foils so speeds can go well over 100km/h in next few years.

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