Propulsion System - Motors, Gears, etc


@MaxMaker I was happy with the all up cost. So the shipping cost didn’t bother me. It’s still a great deal.


Looks good. Did you have to order the pinion separately? does the 390kv motor have a 10mm shaft? and what is the diameter of the inside of the pinion? Looking at ordering one of these too. Cheers


Pinion and Adapter Flange ordered seperately yes.
10mm Shaft on the 390kv yes.
Only 6mm inside the pinion.


Speed test with large foil, got 28(27.85)km/h (3/4 throttle, cant handle the lift in full throttle). pretty confident we will be able to ready 20knots with a slightly smaller foil, maybe more with some more improvements on duct/prop design.


Hi @NoWind, how are you going to put the pinion on the motor shaft? Lathing the shaft of any other ideas? I’m thinking in this direction too, but the shaft fitting problem is still to be solved…


I turned down the shaft on mine – worked out well. Picture in this post.


Hiorth, Nice work!

Could you explain what you mean by " ,can’t handle the lift in full throttle" please?

I’m wondering if it is a problem of too much decalage?


Your iride time was 32mins. Was the batteries flat, or could you go for longer.
What battery setup are you running ?


We use a sup foil, made for surfing (low speed) the foil come out of the water if we give full throttle due to too much lift. But super stable and easy to learn/foil in low speed, which also makes the setup very efficient (operates in the optimal range for the duct).

We have 2x100006smah lasts for 13-15minutes. Will soon have 2x 2.1kwh built with 18650 cells ^^ should give more than 60 min ride per battery.


I think i will turn it down on a lathe.
Will be easier then build some coupler which also will increase the total length.


Perhaps you should adjust trust angle of the motor in order to avoid excess lift. We use to do so with air plane to compensate thé blade torque and upward lift.


@NoWind I’m getting a very similar Chinese brand gearbox which looks similar to yours. Have a SSS 360kV motor which also has 10mm output shaft. My concern is how to couple the gearbox to motor to ensure shaft and gearbox centre are absolute centric.
Does the gearbox flange you have fit the SSS? Where did you get this from?


stumbled on this tonight, might be useful,. still waiting for more parts…got a lower unit from a johnson 5hp outboard yesterday, with a 9.5 inch x 6inch pitch propeller, might give it a test,


Hey @g.gregory8
Interresting with this transfer gear, never see this before!
Reisenauer itself talking about lasermelting the gear to the shaft for high output…
I have made such great expierences with Loctide 603 that i will try to glue it first… maybe it will not work that good as in my eboards because the shaft diameter is smaller … but i will check first

Yes @reisenauer got a fitting coupler for the SSS… You can only use 3 of 6 Mounting Holes of the SSS
It got a “fine tread” which will fit to the Gearbox :

Its the red part sitting on the SSS



Can you please provide the link of this Chinese gearbox? Thanks!


@Antonbit Here’s the link. Although being an unknown quality I wouldn’t recommend at this stage. I was miss informed at the start regarding input type and shaft sizes, although they have been helpful. Hopefully it works out, I haven’t received yet.


yep, it looks like an optimal way, I was a bit afraid of it, but @moggieuk pictures helped a lot, turning it down then, thanks


Hi David,
have you heard back from Alien Power about the 50-100 KV brushless inrunner yet?


I emailed Bruno a few days ago about it… this is what he said

Hi. Yes. The motors is been modified because were lack of power. Now it will be 9 poles instead of 6 and y winding configuration with 0.38mm copper. I guess we will have them in 2 weeks


No idea what it means. Sounds amazing though. 2 weeks? Better get my board cut!