Interesting that you duty cycle is locked in around 90% the entire time, is that the VESC limit? Are you basically holding the throttle all the way down the entire time there? Maybe this is a bit too fast for the 2-blade prop. Does the current drop at all if you hold a steady 20kph?
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If your friend has a compatible Gong mast perhaps you could put his foil on your board to see if that makes a difference
Troubleshooting 101. Change one thing at a time, observe and compare. 
Our builds are identical to the hair (except for board and wings, but the board does not make a difference when foiling). He has the same problem concerning high power demand as me. I could change the wing over to my mast, but I already know the result. It would not change anything.
I don’t hold the remote down all the time, I only use about 20% throttle (that’s on the flipsky vx3 throttle scale). I too found it weird that the duty cycle is at about 90%. When giving more throttle the foil does not go a lot faster as well, which validates the reading.
Max speed is at about 32km/h, which seems slow compared to others but that might be because we use a two-bladed prop which usually is slower but more efficient.
Maybe that’s where the problem lies? What could be a cause for such a high duty cycle?
Yes, the current does drop when holding a steady 20kp/h, but is still way too high. Then I usually use about 2500w instead of 3000w.
We also always turn on cruise control when foiling, that why the duty seems locked. But I am sure it is way too high.
Maybe the motor also simutlaneously tries to brake, and thus eats a lot of power?
Nothing wrong with your riding 
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The data looks to me like the prop has too little blade area.
With 120kV motor and 14s battery on a 5" prop (assumed, what is the pitch of the prop if you know?) you should have 40kmh at 90% duty cycle
Your setup has 40% slip, that’s what makes it that inefficient
I can send you a 3D printed prop of my own if you’d like to try this. Or the STL so you can print yourself, for free of course)
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I don’t know the props pitch. What exactly do you mean with “slip”?
I would be glad to print and test your prop. What material should I print it out of? PLA is okay for testing or should I use PETG or Polycarbonate or Nylon-carbon? I have all of these filament types at home…
Now, after you mention it, I noticed that I designed the adapter plate not quite well. I of course should have designed it in such a way, that the mast plate sits flush with the board, like in your set up 
That’s why this forum is nice, everybody adds their mustard (German saying 
) and I can learn from it!
I don’t know that your approach is really any different than mine in function.
If it is solid aluminum then to me it’s the same as mine other than it makes the distance from bottom of board to motor a bit longer. Your mast is 95 plus whatever thickness that is and mine is 85 which I suppose could allow more flex but I’m not sure anyone but pro-level riders would notice that and I’m definitely not at that level😀
What can make a difference in ride “quality” is any “wobble” in the mast structure. I even epoxy the mast base to the mast to absolutely eliminate any play at that joint.
Yeah, functionwise it is the same. It just is not as “water dynamic” when not foiling. But the are here to foil and thus it should not concern me.
there are some things to explain at least parts of the higher consumption.
Power is proportional to drag and drag is proportional to wet area. You have a poor looking duct, this:
Also:
- a long mast that you ride quite deep in the water
- a motor with 10% larger area
- a mast clamp that is larger than necessary.
Probably there is cavitation from the duct also, as it looks quite rough on the pic.
Get rid of the duct as a first thing, ride as high as you can, it makes a difference. I’d also try another prop, like the one Ludwig mentioned.
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It’s very clearly a drag issue and most likely the duct as the main culprit. Your bin test and the amount of slip you get proves that.
Slip is the difference between actual and theoretical travel resulting from a necessary propeller blade angle of attack . For a system with a lot of drag, you will see a much higher slip. Example when I run my setups without ducts I get about 10% slip.
Hey!
I printed the Prop that @ludwig_bre send me. Here is my new Log: Vetr.at Log View
The current draw is half of what it was before! So You guys were right, the duct played a huge role and I had the wrong prop.
Thanks a lot for all the help, I could not believe that drag plays such a big role, but you have thought me better…
This is how it looks now. The print quality of the prop is not good, I will have to reprint it with an 0,2mm nozzle and a smaller layer height and probably also out of PETG or PC instead of PLA.
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Well that’s good news that it’s working better for you!!
I’m not sure how similar the shaft of your motor compared to the Flipsky 65161 motor but you might also want to consider a Fliteboard prop.
Minor modification and not very expensive. Might be nice to experiment with a three blade as well.
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Nice! Glad it’s working for you. I was curious how the prop change would affect things. The consumption numbers look much better on your log file.
The flite prop is also injection molded (I think) and much smoother, sharper, and stronger than most 3D printed props. You may end up with even lower consumption numbers
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Yeah, I also thought about getting the prop from Fliteboard. Maybe the end speed would be closer to 40kph than as well (although 30kph is plenty fast already). My friend considers buying the impact vest from them, I will probably throw in a prop (or two) into that order.
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Could I trouble you for the STL file you mentioned here? I’d like to give it a try!
I did not print nor design this Prop. I bought it from someone here in Germany. He printed it and coated it with some kind of resin. The Prop was actually pretty well printed and somewhat durable, but is not as efficient nor fast as the Flite-Prop. I was not able to get similar results nor strength with my Bambu X1C, (printed different prop) not even with a 0,15mm nozzle.
So, sorry, I don’t have a print-file…