The Dutch build

I haven’t had experience with in runners yet, but you need lower timing for in runners from what I’ve read. I think your guess of 3 degrees wasn’t a bad guess. put it in water and give it lots of throttle, if it loses sync i.e. the motor stops or squeals to a halt, increase the timing until it doesn’t lose sync.

awesome work on the build!

The PWM rate is the rate at which the Fet switching is done I think an ESC guru could chime in here I don’t fully understand it.

from what I understand however a higher PWM rate is good for low inductance motors (usually smaller motors) so they run smoothly, with a high PWM rate the esc will run a little warmer due to more switching losses. With my outrunners 8KHZ works fine, at the current moment I’m running 10KHZ I couldn’t notice a difference.

maybe @PowerGlider @nickw1881 @Flo could chime in here and explain how it works more!

Hi fellow builders,
Hereby a little update:
I bought 2 other props; 7 7/8 x 7.5 honda 5hp prop

One lathed down to ±140mm

I still have the 7.25x5, I just lathed the hole to 12mm to fit on my new shaft.

I will still use my reisenauer 6:1
I will use my new Typhoon HET 700-98-670

Saturday I will test the 3 different props with different motortiming and measure the thrust and amperage. Hopefully make another run when everything looks safe :slight_smile:


btw, the motors could be bought rediculour cheap at

only 80dollar


Hi Thijs :slight_smile:

When reading about your motor specs, the shaft seems to be 8mm
But then you have a 6:1 Reisenauer…

So I guess you lathed down the motor shaft to 5 mm ?

Thank you

HI Phil, yes, Please see my reaction in this topic, how I lathed it down. Just took me 20 mins :smile:

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OK. Well that obviously worked !

Quick one : why not taping around the motor + reisenauer with metal tape ? That would make it somehow waterproof, while still cooling down ?

Well I tried that in my first design(with the blue motor), however there are some concerns:

  • How do you waterproof the front end of the motor (near the mast)?
    o Perhaps you could glue the front part in a mast clamp
  • The motor is not designed to distribute the forces trough the motor housing, my blue motor was made of very thin aluminium.
    o Perhaps other motors are constructed more beefy and have a stronger body
  • The Reisenauer only has a bearing, this bearing is not waterproof.
    o This is why you need some kind of housing around the reisenauer with a lip-seal.

Not sure if tape would work; don’t forget that you have about 0.1bar of water pressure under 1 m of water. Water will slip trough tiny gaps(capillary?) very easily! ‘somehow waterproof’ is not good enough :wink:

Thijs please one more question…

Where did you get that coupler which you screw on the Reisenauer ?

When looking at Reisenauer catalog, I see only a 10mm shaft and no coupler ?

Thanks again

This is just how it’s delivered. You can screw in a m10x1(fine metric!!!) Shaft.

I lathed a new shaft at the workshop at my work.

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I found these guys in the UK:


OK… See the way the Super chief is delivered… No coupler…

Unfortunately this wont fit in the m10x1 thread. You could use this and cut off the head cap:

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Will not fit , need to be m10x100 ( fine)

For the super chief with the polygone 6x7 shaft you can use this:

For the super chief round 6mm shaft , you can use a " classic" coupler

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Wat a succes Thijs, i m from the Netherlands as well. Any updates ? I learned a lot from this topic

Hi Louis, thanks! Are you foiling already? No updates means good news I guess.
Only my pinion came lose twice… the strongest loctite is just not strong enough!

I still use my lathed propellor, I believe it’s really efficient. I also bought 2 tiny longtailboat props in cambodia which I want to try out soon.

The hole is tapered. In the picture I put some epoxy around a 10mm shaft which I greased with Vaseline. Now it’s stuck however :sweat_smile:

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No flying yet :slight_smile: About 10 years ago I already made electric outboards etc.

Later a Lampuga kinda Jet surfboard. But so much power and battery needed with a Jet surfboard, now with foiling so much better.

I always thought we need to have prop rpm of about 2500 rpm, most outboard props were designed to stay around that rpm. I see many people here with about 4500 rpm prop speed, maybe with foiling we have so much less drag ? The torqeedo prop even is 1400 rpm. seems that slower rpm with more pitch better efficiency ? Well maybe this different with a hydrofoil.

I also see a small self priming pump, does that work good ?


Impressive! I d like to see that design.
Low rpm with high pitch asks for a high torque; something a small diameter motor cannot deliver. High torque draws a lot of amps or a large ratio reductor. It’s just a matter of the right balance.

The self priming pump works fine, though I would go for another type(window wiper type) as I always have to suck on the tube go get it started.

Btw maybe you, or someone else is interesting in an huge(2kwh)li ion prismatic battery pack? Its to heavy for my project after all… 20kg…
Including a Bluetooth 90amp bms(8-24s) it can go for 250eur.

Is it possible to share your mast clamp 3d files ? Thank’s

Have you been able to test your longtailboat propellers ?