My complete built. will not go up on foil


Welcome to my build! 2 years ago I set out to build an E-Foil. Bring my past experience form building an electric skateboard has helped a little bit, but to be honest I have learned a lot more since then. I owe a thank you to this community! A lot of my google searching lead me back to this forum again and again. You all are awesome!

I am in United States, Minnesota. Riding on the lakes so flat water and some boat wakes :slight_smile:

This is my first post as I felt the need to do my own homework and research be for asking questions. But now I am at a stuck point and could really use some help. I have taken my board out 7 times making minor adjustments and each time it has gotten better.

Problem is the board will not go up on foil but it does plain. I logged data on my Garmin watch and get to 6mph (Plane-ing out)

what I am noticing:

  1. It wants to go up on foil but feels unstable.
  2. I feel like I am at the top of my throttle/rpm
  3. The nose does not lift hard against me. I am actually very far back on the board but not dragging legs feet. I am keeling on the board at this point plane-ing out
  4. I feel this speed is sufficient to go up on foil. (please let me know if I am incorrect.)

Please check my build specs and I will do my best to answer all questions.
Photos will come as soon as the forum allows me to add them. For now Please see my instagram Koolwelds for pictures.

Complete weight with batter 60lbs
battery is 20lbs
I am 160 dry have ridden both with and without wet suit.

5’ home built board foam core and fiberglass/carbon lay-up
5’ long
24’" wide
majority of the board is 4" thick
Did some rough math factoring in board shape board it is a least 70 Liters

Complete wing kit with a 1500 wing from Clear Water Foils 1500 Surf Hydrofoil Kit | How to Build a Hydrofoil – Clearwater Hydrofoils
(I do not have many specs on the wing)

  • 29" (73 cm) mast
  • 1500 cm^2 front wing measures 40" wide
  • 17" (43 cm) stabilizer (both top and bottom are slightly rounded no flat)
  • 5.5 (2.5 kg) finished
  • 90mm mount holes (industry standard)
  • Wood frame and stabilizer + eps wing core

Flipsky Motor 65161 120KV

Flipsky water proof remote

FR 2 blade pro 7in pitch

Swordfish Pro+ 300A
Input Voltage: 4S-15S Lipo Cells
Continuous Current (Surge): 300A (380A)

Battery: (built by me)
14S8P Samsung 40T 21700 4000mAh 35A Battery (40T3)

12v water pump to cool ESC

Foil and Mast position
Foil is fixed to fuselage at 0 degree rake ( was made to come off but cannot get it off. :expressionless:
I have ridden with stabilizer at 0 degree and now at possibly 2 degrees down with a washer. I believe this is helping.

Mast has been tested at two positions:
5" between rear of board and mast trailing edge. I noticed that on plane I am kneeling on the back of the board to keep the nose up. If I move forward nose goes down seams opposite of problem from others

I have now ridden it with
11" between rear of board and mast trailing edge. But still can’t get it to go up on foil.

Please any thought into what I need to change to get my board up on foil. I have considered getting one of the Slingshot Hover Glide complete kits but I want to make and educated decision.


Welcome :grinning:

You have provided lots of info but very little about the board you are using such as length, width, volume, will the board float your full body weight when it’s not moving?

Sounds like a limit setting to me but there are lots of people better qualified here that can guide you about that.

Imho - 6mph or 10km/h is not fast enough to foil unless you have a lot of experience and even then it wouldn’t likely be stable. Need to go faster😎

How many watts / Amps are you drawing when you try and get up on the foil? What have you set up in you VESC?

You usually need to increase the motor current from what the vesc tool wizard auto detects, around 200amps seems to make the 65161 run pretty well, and set battery current to 100amps.

honestly I did cut some corners on the board. I looked at the specs of production boards and took rough dimensions then started shaping.

5’ long
24’" wide
majority of the board is 4" thick
Did some rough math factoring in board shape board is a least 70 Liters
full body weight not moving it floats okay.
at 6mph board is plane-ing feels like very little water contact/drag on bottom of board.
at this stage in the ride it feels unpredictable and sensitive for adjusting weight front and back. It could go faster, but board control diminishes.
I have ridden a production board and it was easy to get up on foil. felt very natural.

I went with a Swordfish Pro+ 300A ESC. which I am regretting a little bit. It does not have all the programming options like VESC. It does minor data logging so I will see if I can get max motor amps draw. Or record an amp clamp on a motor lead. It does not have battery amps settings I think the ESC pulls what is wants from the battery.

I suspect its just current limits. Try 150amp battery limit. You have a good motor and lots of battery. You should be planing at 15mph and then the foil will just pop up.

Your system seems mostly ok, unknowns are board, esc, wing, start technique.

I guess it’s not the start technique, since you tried before, and board seems reasonable from the basic dimensions.

A film with some starts could help pin down the issue.

Normally all beginners have issues with the board nose lifting too much, that you don’t get high lift sounds strange. Could the stab be wrong side up? Otherwise it surely is too little thrust.

I guess most likely issue are ESC, ESC settings or remote.

Photo upload.

Video to come soon. Thank you all all for checking out my build and providing advice to get my board on foil! This has been a fun project and this is a great community on Foil.Zone!

Going to test and try to get motor current data today.

Hello, this is my first time responding on this site. I also live in Minnesota, ride a flite board efoil and wing foil a lot. I have a lot of aerodynamic experience which translates to the foils most of the time. It appears to me that your stabilizer is lifting instead of pushing down on the fuselage, hence the trouble trying to get the nose of the board to come up. It could be upside down as someone else pointed out. I also have a speed read out on my flite board and I think 4 to 5 mph is way too slow to foil with any stability. I’m usually riding at 15 to 17 mph with an 1100 foil, probably minimum would be about 10 mph. My efoil has shims to adjust the stabilizer incidence angle and it doesn’t take much change in incidence to make a big change in how the board handles. If you want to communicate via phone, I could give you my number. Where in Minnesota are you located?

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Man your response has put a smile on my face! It is great that this community is all over the world but I know only one other person in Minnesota that had an E-foil (only one I’ve ever ridden) but he has moved out of the country. I have been hoping to meet other local riders and people that want to build.

I am in Golden Valley, Minnesota. I would really like to talk with you.

Yes the stabilizer was mentioned earlier as possibly upside down. This specific stabilizer has a mirrored profile top and bottom (not sure if this is a good design or not). It technically does have a top, as there is a grove to align it to the fuselage.

It was a cnc’d piece of wood that I fiberglassed up. I have installed a single washer under the forward mounting screw. Now the stabilizer is angled down slightly. maybe I need more angle?

So I have a new update on the board test ride. On Thursday 24th,
I tracked once again speed with my garmin watch and I could hit 9-10mph several times and 11.4mph once but it feels very unstable. I would also start getting the board on foil at this point. A few times I actually had the complete board out of the water! man was that a blast.

I also recoded current draw from one motor lead with an AC amp clamp meter. I recorded current meter’s screen with a go pro. (all of this was inside the hatch) sometimes you gotta get creative lol.
so @ 9mph I would creep up to 60 amp and 70 like twice all with board coming up on foil slightly. The times I got the board completely out of the water was a full send, but I lose a lot of control at this speed.

Stability aside that’s slow to get foiling. Are you standing up or kneeling? If you just kneel and put weight forward to prevent foiling you should be able to go full throttle on remote without falling off. Have you tried that? If you can’t go faster than 10-11mph you will need to change something.

If the ride like that is too wild just remove the foil ( leave mast on) and try it again

Use a Voltmeter and tell us what you get straight from the battery?

I am riding on both knees and hand kind of up front. I have made a few attempts to get one foot forward and down on one knee. but it has been about 2 year since riding a production board( which I got it up on foil effortlessly) so I may be doing something wrong.

I will make more attempt and getting a foot forward. The wing is meant to come off but last I tried, I left it alone because I thought I was gonna break it. I will see what I can do. I’m assuming you want to see voltage sag under load? Thank you for your advice!

Not concerned about V sag, just curious what the fully charged V reading is.

I’m also trying to understand how fast your board can go flat out without foiling. I suggested being on knees and keeping the board on the water because that’s a safer way to find out what top speed is.

My battery config fresh puts out 48V and I can do about 19mph which is lots fast enough to foil but going half that is iffy for stable flight.

9-10mph should be enough to get on foil with a wing this big - and you wrote that you were getting on foil, which is good.
60-70A (I assume battery current, not motor current) seems low - with my boards I easily peak at 110-120A while starting with a very similar battery configuration as yours (Samsung 40T 14S6P). This is especially true as your cable outside the mast will add a lot of drag, so try to set a higher current limit as said before.
If all this doesn’t help, I suspect you need a new set of wings…

Just a note: an ac clamp meter cannot measure motor current since the update frequency of the esc is too high for accurate measurement (and if it’s a FOC esc it delivers current to all phases, not only two)

The battery current might be 60A during starts even with higher setting, that depends on motor kV, prop AND settings

Agreed. But my 110-120A are for the same motor with smaller prop albeit different ESC (Flipsky 75/200).
That’s why I say that 60A seems very low to me - especially given the additional drag in Koolwelds setup.

If the prop is too big and esc does current limiting as it should then the battery current will actually go down with a big prop when compared to a smaller prop - this is really counterintuitive but comes from that the large prop cannot be driven to the same rpm.


Thanks for letting me know about the issue with trying to use an ac clamp meter. I did not know that. My ESC does have a little program box that will show data recoding. I’ve not been able to see data. I don’t know if I am riding to long. so I plan to do a short ride then check and see if it shows logged data.

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Im surprised nobody pointed out the most obvious reason: DRAG! Taping cables outside mast is a big no for efoils, search “100 kg” and you will find my thread on this issue. That foil looks pretty draggy too. Since you invested this much you might as well buy a Gong or similar to get some decent performance.


I missed this on the pics, i agree.

I made a video a while ago that shows the cavitation i got on my mast just from some layers of tape covering the cable hole i used before:

It’s pretty massive just from a small flaw.