I assume this works similar in premise to how someone can generate forward momentum by pumping a hydrofoil surfboard like this https://youtu.be/3Ksamgpu2S0
But it looks like this boat isn't using a foil, but rather hydraulic pump based electrical generators inside the boat. The article is short on details on how the design works. They do link to two other foil based propulsion boats though:
It's not clear from this article how the trimaran works, but you can see in the photos that there is a gap at the top of the outboard hulls. So I suspect it's the relative motion between the outboard hulls and the inboard one which is converted to hydraulic power - makes sense, it will be a short movement with a huge force behind it. That is then fed to a generator, electrical storage and propulsion unit.
Hydrofoils have a very high lift drag ratio. You also have to remember the wetted area of the hull produces significant drag too. Lifting most or all of the hull out out of the water can enable dramatically higher speeds, at the cost of stability and complexity. The biggest America's Cup catamarans were roughly the scale of a 7 story apartment building, but were capable of lifting their entire mass on a foil the size of an ironing board. Because of the density of water, foils can generate a lot of force as lift.
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When I see a wave foil I wonder how that doesn't make more drag than power...is this similar or something different?
I assume this works similar in premise to how someone can generate forward momentum by pumping a hydrofoil surfboard like this https://youtu.be/3Ksamgpu2S0
But it looks like this boat isn't using a foil, but rather hydraulic pump based electrical generators inside the boat. The article is short on details on how the design works. They do link to two other foil based propulsion boats though:
https://www.popsci.com/gear-gadgets/article/2008-02/wave-run...
https://newatlas.com/autonaut-autonomous-unmanned-surface-ve...
What sort of wave foil do you mean?
It's not clear from this article how the trimaran works, but you can see in the photos that there is a gap at the top of the outboard hulls. So I suspect it's the relative motion between the outboard hulls and the inboard one which is converted to hydraulic power - makes sense, it will be a short movement with a huge force behind it. That is then fed to a generator, electrical storage and propulsion unit.
Most seem to involve a wing or fin extending out from the hull in some way.
That seems like it would introduce drag and greatly limit speed.
Hydrofoils have a very high lift drag ratio. You also have to remember the wetted area of the hull produces significant drag too. Lifting most or all of the hull out out of the water can enable dramatically higher speeds, at the cost of stability and complexity. The biggest America's Cup catamarans were roughly the scale of a 7 story apartment building, but were capable of lifting their entire mass on a foil the size of an ironing board. Because of the density of water, foils can generate a lot of force as lift.
Oh this kind of thing? https://wavefoil.com/
I'm assuming they've tested it and it's not entirely fraudulen and does in fact give more speed than drag?
I'm not really sure the existence of a thing really indicates efficiency or usefulness, that's not a high bar.