Has anyone tried a gas powered build?

Just curious if anyone has considered a gas powered board. You can get a 13hp (about 10,000w) engine for about $350, and then you wouldn’t need to get: a battery ($400-1000), a motor ($200-1500), a charger ($???] or an ESC ($200+).

It would definitely be louder, and a different experience. It would likely stick out of your board, and waterproofing it could be interesting, but it could potentially be WAY cheaper…

Difficult to run underwater. You would need some sort of transmission from the board down to the propeller like kardan, chain or belt. That would end up in a heavy construction.

It’s possible but would be a noisy as hell! I think that’s one of the beauties of the electric build. Everyone is amazed at how quiet they are.

Then there is “water transmission”… the Bruce Creation jetsurf convertible to jetfoil : replacing the electric engine inside the board to vacuum water up along the mast from its bottom inlet and expelling it from the rear of the board. Not sure about the efficiency though.

2020 Bruce Creat Water Inlet sm

That would be in gfoil.builders.
I know. That was bad.

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World premiere: if the gas (petrol) version sees the light of day, it will be thanks to the electric version :wink:

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There are a lot of pros and cons that I see.

Pros:

  • Higher torque
  • Way cheaper
  • Faster
  • Simpler (your drive-terrain would consist of: the engine, a drive shaft, a 90 degree gear, and a propeller)
  • Don’t have to worry about battery fires

Cons:

  • Would weigh more
  • The motor would have to stick out of your board (though a lot of people leave their electronics boxes out of the board anyway)
  • Would be really noisy
  • Would vibrate your board the whole time
  • Board would need some reinforcements to mount the motor too
  • You’d need some fancy valves that close when you crash to prevent the engine from being flooded

Honestly, in my opinion electric is definitely the way to go, but was just curious if anyone had tried to go that route!

This little 2-stroke outboard had the cylinder under water :wink:!

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I am considering to build one using a Honda grass cutter engine (which weighs less than 9kg). There are some issues to be addressed like:

  1. Drive system: 3 choices - Belt driven OR flexi drive rod + gear combination (like we have in grass cutters) OR hard drive rod + gear. I think belt driven is best (Serpentine Belt) Ofcourse mast thickness will increase.
  2. Exhaust - How will the it come out of inside chamber
  3. Air intake - How to manage water seeping issue
  4. Making it wireless - A bluetooth system with servo motors to pull trigger

The reason why i am looking for this is cost! and it matters! especially when u see lot of e-foil owners spending handsome money on parts post purchase. Despite being so pricey it still cant work for 5 years without making a dent in pocket.
I think this can work. Let me make it clear i am tax guy no formal degrees in science, engineering and i may sound illogical but i am okay with it. And i do care about environment. But honestly in my country we burn coal to generate electricity! Period!

The grass cutter is a great idea.
How much power does it has?
Maybe a powerful chainsaw could work too.

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I would keep it simple. Use a lower gear of a small outboard motor 2-3 hp range, its very simple to attach a shaft and a motor to it. The lower gear can be integrated to the the mast. The shaft is very thin on those, can go inside the mast. Small outboards have usually roughly 1/2 gearing, that is actually required to make a small gas engine work. Torgue is also an issue on those.

Actually think this would work well on an e foil, no more leaks and all electric parts on top of water.

Have been doing some testing on gas engine on surfboard and have noted that also a 3.5 hp ( 75cc 2 stroke ) outboard is sensitive to lack of torque. My tohatsu 3.5 really struggle with the Yamaha clone propeller with 8 pitch , same problem as the 65161 type motors also have. The problem is the diameter, not the pitch as such.

The critical moment would be to get it to fly, you would need low pitch propeller otherwise engine might stall. My gut feeling is that a Honda GX 50 might do the job with the right propeller and gearing, not sure a gx35 would be enough.

A Norwegian girl has foiled with a 4hp outboard engine

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Simplicity at its best, brilliant! Thanks for posting. Of course not competing with an efoil, but very cleverly executed idea. Think Kotaro Horiuchi made a working foil powered by a 2hp honda 4 stroke, but that was a foiling boat so the lift of probably easier.