I did an bpat session on a Armstrong 140L 6'5 board and it was pretty discouraging. The foil was all over the place in the prop wash making it just about impossible to get any stability trying to stand up. The board was also a bit of a sinker for me. They said the wing would after some stability and lift making it easier, so we'll see. Next lesson will be with a wing. Not sure how it will go on a board that I can barely kneel on.
Trent hink wrote: ↑Sun Aug 14, 2022 9:44 pm
I'm a bit surprised nobody has come up with a gasoline-powered one yet.
I'd be a buyer. There are water cooled motors available in the RC boat industry.
https://www.bonzisports.com/product/zen ... ro-wt1048/
This one is 30cc, 3.7HP at 13000rpm. It would need to be geared down, but gearing down would increase torque and mitigate any drive train losses. Should be able to get plenty of power to the prop for an efoil. These motors have centrifugal clutches so at idle the prop would not spin. You would probably need a 3:1 reduction. Could do that in a planetary gearbox attached to the motor mounted vertically with a 1:1 right angle drive down at the prop. A flexible driveshaft might work also. Imagine a front mounted mast at about a 45 degree angle or whatever it needs to get the foil at the proper depth and fore/aft position. Motor would mount up front angled in line with the mast. The flex shaft would go from the motor gearbox down the mast and make a 45 to the prop. Not much torque there so a string trimmer shaft should work. I made a kayak motor once using a sting trimmer and it worked quite well.
For the guys that want to zen out on a silent ride, this isn't for them.
I'd have to build the board for this. I can't see retrofitting an existing board like you can do with an electric setup, Like Foil Drive. For that reason, electric is easier because the motor can be mounted underwater. I've looked into this as well. Motor and ESC can be had for about $300. A 6S 20AH LiPo battery is about 200. For an 18S system you would need 3 batteries in series. To double capacity you would parallel 3 more (total of 6 batteries for 40AH capacity) This is about the capacity of the Lift full range battery. Advantage here is that if you get a dead cell in one of the batteries, you toss it and buy another $200 battery. Another plus is that there would no on-board BMS. You use an RC LiPo balance charger and charge each 6S pack alone. I have a 4 station charger that will do four 20AH packs at a time. This could be mounted just like a Foil Drive or you could built a board, or cut open an existing board, and hide the electronics inside.