Flipsky 100kv flier esc Holland build

After almost 15 years of playing around with electric outboards, jetsurfboards, winches, electric surfboards, fast Ebikes and other projects, reading and posting for years at the endless sphere forum I today had my best ride ever on my homemade electric hydrofoil :slight_smile:

No leaks, no burning stuff, nothing broken, no slow riding with 10kw input power but playing around for a long time with just 1300 watt.

I did cut a surfboard in a 165cm piece at the almost no rocker area.

A boat hatch with the sealing replaced by alieexpress silicone tube, works great, no leaks. Inside the board, so not on top, so the board is almost flat at the surface.

LG Chem 15ah lion pouch battery from opel ampera ( chevy volt ) in 11s 30ah pack.

Gong Pro L wing 65cm mast.

65161 flipsky 100kv motor, filled with Corrosion X

Flier 500A esc. Firmware boat 24s v31a with starting power at 95%. Timing at 5
Starting is a bit up and down I hope we can solve this.

Prop, standard cheap aluminium prop from alieexpress, 7/12 diameter with 7 pitch

Bad weather filmed with bad camera:

Top speed was about 25 kmh non foiling. and 1300 watt flying cruising speed at about 20 kmh.

Build inside the board a display, alieexpress waterproof encloser, with Big screen GPS 2x temp reading, Battery level indicator, and a meter for Watt hour, powerconsumption Voltage etc.

I was suprised today to see that it only took 1300 watt for cruising in rough conditions. Maybe I try an 8 pitch prop later and I wonder what a flying rodeo prop would do, they are also 7 pitch I think and they say they are even more efficient compared to the cheap chinese alu props.
I think lower rpm with high pitch prop is more efficient then low pitch with high rpm. Maybe I am wrong about this?

When accelerating I see about 3000 watt. I did not use the watercooling, the 500A has a big alu plate and keeps cool. The motor is very silent and is really powerful. Accelerating is real fun !

No load amp is now only 3.3a at 42v with full throttle with the big alu prop mounted blowing some wind.
I think the sealings, bearings and corrosion x is now all in place and the motor runs really smooth.

For safety reason I wanted to make sure that I have a good deadman switch, in other projects I used a magnet switch at the ESC powerline, or at the ESC signal line, but in those cases the motor kept on running for about a second. And a second of power can be dangerous, the board can ride away fast or you hit a running prop.

So what I did is installing a 80v to 12v converter parallel with the main power wires, from there is a magnetic switch at the surfboard that will switch on 2 x small relay, and they will power the GPS Speedometer, Battery level indicator, the watt data meter a 12v to 5v converter as a BEC for the receiver, and it will power the 12v waterpump, it will power it will power the 500A Esc by the precharge resistor and it will power a time delayed relay which is set at 2 seconds, ( bought for a buck at alieexpress ) after these 2 seconds the Capacitors of the Esc are charged and it will turn on a heavy 200A relay that will power the big 500A esc by the main power wires, so now there is no spark seen in the 200A relay and can not be welded together inside the relay.

Long story, but I just want to share it with you, I did not see a more simple solution for a 100% sure all power is OFF.

When I fall of my board there is no power anywhere, only at the small 80v to 12v converter that will almost drain nothing from the battery. It works really good.

Ofcourse I want to do things like a good paint job with rubber deck etc.
But I also wonder why it is so hard to ride, last summer I efoiled with an F one 850cm wing, that was to unstable, now I have this Gong Pro L with 1350cm2 and it is much better but not like cruising along in corners, maybe need more practice or bigger wing ?

I have noticed when kitesurfing with Fone Ic6 foil 850cm2 compared to the Fone ic6 foil 850cm2 version 2 that the version 2 has a longer fuselage and I think therefore much more stable. I hope Gong will provide a longe fusulage too.

Also, when foiling the board will fall over, the board is so heavy like it is top heavy and wants to fall over.
When kitefoiling you have lighter board and a kite to hold on.

I mounted my foil mast 33cm ( middel foil ) from the back, If I would mount it more to the back does this have effect in stability or does it only change the position of standing ?


I am glad that we are starting to here good things about this 65161 flipsky motor.

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Good job! Looks great.

I am not familiar with gong foils but, is it possible you have the rear wing on upside down? This could be causing the difficulty you are referring to.

Did you have to modify that prop to fit this motor, or was it just bolt on? Can you provide a link to the prop you used?


yes it looks like the rear wing must face the other way

Yes, you guys are right. My kite foil Fone is the back wing facing up. So I thought I had it right. Now I’m really curious about if it will be more stable or not.

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This prop. Just drilled it up with hand drill to 12mm. Then with a dremel I cut off a piece so I can lock it to the shaft.

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Thx for the prop link!

Flip the rear wing. You will be surprised how much more stable it will be. I could tell just by watching the video of you kneeling on the board that something was not correct with the wings.

Let us know how it rides.

I have a crazy work month. But, I’ll be back at shaping my board next month. I’m currently building a vacuum pump for vacuum bagging my epoxy work.


That prop looks way to big for this motor. I’am suprised that it only took 3000watt. I have the flipsky 120kv and will try with a 7x5 prop cutted down to 130mm diameter. Do you know what rpm you get right now?

I think this is 190mm diameter. 7.1/4

I think rpm is about 3800rpm. Torqeedo outboard are really efficient and they go for only 1300rpm with a really big propeller. Maybe that is different? Because they power a boat? Waterwolf electric surfboard also use this big propeller I think.
I can cut it down and see if it works. With a 5 pitch prop that I cut down I almost got no speed anymore. I think because of the variable pitch or to much slip because of the smaller diameter

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You tested this prop and it worked great. Based on your video I am buying this prop.

Don’t cut this prop! If anything get another prop to play with.

You can’t just focus on diameter and pitch. Because the blade area plays a really big role. This prop you are using has much less blade area then the FR prop. So that is why the diameter of 7 1/4" with 7" pitch isn’t too much. Also, it’s a plastic prop blade right? The blades probably flex under load, and decrease the pitch.

That is a very good working prop you got there!



Just ordered one of these props! Excited to give it a shot and compare it against my solas on my 120kv flipsky

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Great. Im curious about the results.

Do some of you know a good solution for this ugly cutting? Micro balloons with epoxy? And then shape it by hand maybe ? I want it to make it nice and rounded if possible.

You could try using an epoxy filler applied evenly with a spatula and then the final sanding.

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I’d use an angle grinder with a flapper wheel.

It’ll smooth that out in less then a minute!

But, lots of dust. Use a good mask. Shop vacuum up the dust.


3800rpm with 7inch pitch would theoretically give you a top speed of:

3800 x 60 x 7 x 2,54 / 100 / 1000 = 40,5km/h
If your top speed is 25km/h now, you have a lot of prop slip or your rpm is lower than expected?

Ofcourse there will always be prop slip but 10 - 15% is more likely.

I’m not saying this prop won’t work because it does, but I’m not sure if it is realy that efficient.

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Well. Non foiling with the rear wing upside down I saw 25 kmh. I see without load about 4000rpm. I estimated 3800rpm with foiling. Maybe this is wrong and I have only 3200 rpm. I don’t know. Will do more testing soon

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I thought that video was excellent speed with board still on water surface. Prop looked like it was working really good to me. And the price is right!

I’m looking forward to more testing!


I reach 37km/h on the surface with my first geared setup. I hope to atleast reach the same speed with the flipsky 120kv. I will run it at 14s. Can’t wait to test it but that will be in spring / summer, cause I can’t handle the cold :frowning:

Just tried out that 7.5x7 alibaba prop that @Louis has! MUCH more power than the solas I was running before! I couldnt even get to full throttle while on the foil. It was too fast. Fast but comfortable cruise speed was around 66% throttle and about 3000RPM. The only negative thing I can say about it is now my board/motor makes a strange squealing sound. The sound goes away at higher rpms. Not really sure what it is. Nothing is rubbing or anything. No current draw data yet but I rode longer than I ever have before so im guessing this prop is more efficient than the solas prop too.

Great find Louis!



It’s squealing because you have strapped a giant piece of rubber around your mast! That will make it much less efficient!

I’m still waiting for mine to arrive from China. But, this is great to hear! Looks like we found a prop that works good and is easy to modify to fit our motor shaft.

Why do you have your wires run externally? What type of mast is that? Won’t fit internally? That is a lot of drag.