Un-balacing the board for safety reasons

For safety reasons, how about unbalancing the board, that is inserting a 1 kg extra weight on one side of the board ?

In case of fly-away (motor still running although the pilot is in the water), the board would either crash on side or run in circles due to lack of balance, i.e. returning to the pilot in the water…

Woud that extra 1kg be felt at all in normal piloting conditions ?

a 1kg weight should not be required:

  1. Failsafe should prevent this from happening

  2. The torque from the propeller would cause it to go in circles if it did runaway anyway.

Interesting point 2 …

[quote=“jakebarnhill1, post:2, topic:3419”]
torque from the propeller would cause it to go in circles
[/quote]. It doesn’t. Mine kept going perfectly straight and would be gone if Don didn’t catch it on his Jetfoiler. The safest option in my opinion is a magnet leash that cuts power, discussed in many posts here.

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For sure a magnetic leash is great, we actually bought one.

But Murphy’s law being what it is ( I have flown many RC planes and many RC drones, believe me, s…t happens), I would like to have one more safety system which would be totally mechanical.

Maybe by simply installing the batteries on side and not centered, that would be enough to unbalance the board, and not enough to disturb the surfer.


Thats surprising, did your duct have struts that countered the water rotation at that stage?

Did faulty failsafe cause it to runaway?

I have the same concern as you.
I have not yet foiled but I was thinking of using a retractable style kiting leash to stay attached while still safely away from the board doing crazy things.

I was thinking of getting this:

Just so we are clear, I have a simple magnetic reed switch that cuts the power to the ESC’s remote antenna but I am worried about that not being enough.


That was an early test without duct and without leash. Not recommended. Could have been a faulty failsafe, I never figured out what exactly happened. Board took off straight after a crash with around 5 mph speed. I had to open the battery box in the water and disconnect/reconnect power to reset everything before it would work again, also not recommended. I crashed a lot and also lost my gopro, but it was fun, this was the session here.


Hi JB - hijacking your conversation to add my 2c

Cutting the remote antenna was NOT enough for my setup to stop a runaway condition, despite programming in the fail-safe to the control system. Cutting the power to the receiver seems to work, and PM has outlined that he has this implemented. I don’t like it and am not convinced it will be reliable.

Consider having the disconnect leash cause a forced voltage to the ESC signal. This idea could be implemented in many ways.

I’ve not really concluded about how I will apply this to my build but I imagined that I would cause a leash disconnect to to de-energize a relay that would both open and close a circuit, with the latter bridging the earth and signal of the ESC input. One assumption here is signal=ground is a request to the ESC to not run the motor and works perfectly. I don’t know this to be true, yet.

The system may be made more reliable with the addition of some secondary circuit. My thinking is to come up with something to do that also triggered by the leash.

My most wacky idea for a secondary measure is a rudder - the idea to go in circles if the leash is pulled and the esc-cut/esc-ground feature of the leash does not work. Though, there are so many reasons not to do this. If implemented poorly you’ll have some unintended dismounts. Also really complicated to implement on the drive unit. I have an ulterior motive for this crazy idea though, I want a rudder setup for steering & attitude trim should my much anticipated foiling experience suggest it is worth it!

I would like to make another note about the reliability of the control system. My UBEC failed in testing and even with the signal-loss failsafe programmed in the motor went nuts. I highly recommend running the UBEC from a low voltage source (1 battery) or better yet in my view, a separate high capacity 6-12v battery that powers the receiver circuit directly. Two of these could be paired with an appropriate circuit to provide supply redundancy.

Currently I have:

  • Leash cutting the receiver power; intend to change this to force a specific voltage to the ESC signal (ideally bridging gnd and signal since that wouldn’t rely on any power supply)
  • NO UBEC 6V nominal 2AH receiver battery; am testing a fail-over circuit for the receiver as noted above

Totally. Even a cheap USB 5v lipstick power bank would work. But I guess that a common ground should be shared between the main batteries and the small separate one ?

Pingu hi,
Marine Safety De-Fault settings
You say you set the signal loss safety, is that the receiver setting?
You probably know this already!
Just in case
Most marine applications from ships gyroscopes to ESC’s are run a factory set De-fault of Full Power!
This is set this way to allow Emergency Evasion Tactics
This may or may not be an explanation for you over run