Cooling the ESC


I use a stainless steel Cable gland

I don’t have a picture of the box into the board, I’ll take it ASAP
but I have this one when I started the installation



Got it, the glands are mounted inward


Clever mounting:)!!!


Whilst there may be some technical challenges in mounting, has anyone considered mounting a waterproof ESC in the mast? The aluminium has excellent thermal conductivity and being exposed to moving air and water, would allow heat dissipation. Would also allow any fires to be contained.


It is good idea and I believe this is the way to go. The issue is to find an appropriate mast the ESC will be able to fit in there and most important to have good surface connection (which is square type) to the mast profile. Quite challenging to achieve. I will definitely go in that direction once I will choose the hydrofoil to start with.


That’s where I’m headed. You have to add an airfoil shape to your aluminium heatsink however. Be careful with raw aluminium in seawater, I will ride on a lake.


@smarm mounting the ESC in the mast certainly looks like a good idea with some advantages

  • good cooling
  • compact build with removable mast (maybe)

However there is one very important point when running a brushless setup: the wires between battery and ESC should be short (maybe not longer than 20cm to 30cm). If they are longer, this must be compensated with capacitors close to the ESC.

Otherwise there is a risk that voltage spikes damage the ESC.

So pay attention where you plan to put the batteries.


I was thinking that we could mount thr ESC in a small aluminium box and mount that inside the board with some space around it for water to pool. Water will remain around the box naturally like a puddle.


Interesting. Thanks for picking this up, yet another hurdle to the ideal solution

For those interested in reading a little bit more of the science behind this, there’s a great thread here:


So I think based on the above information, I’m going to try and KISS for the first version of the board; however feel I might have to introduce water cooling based on the Australia ambient temps as we enter summer here (bit different to Norway!!!)

I’ll use a 12V peristaltic pump for active flow, but I’m still undecided to try for a closed radiator type system, or an open system with water intake from pipes in the mast (which will be it’s own headache)

Any thoughts?


I like KISS and want to put my esc in a small, sealed alu box. Then fill the aluminum box with oil. This should cool the esc.
Cooling the aluminum box should be easy.

I’ve also decided to go with a vesc (focbox). They are rated up to 60amps constant. And in contrast to other esc they shut down gracefully when overheated and don’t just burn up. Tested this many times.

Note that I’m far away from testing. In fact going skiing tomorrow.


I had a similar idea. Placing the escs (two engine setup) in the waterproofed mast and filling it with a synthetic oil used in transformer rectifier units. Preliminary I am planning to reduce the mast volume with a filler to reduce overall weight.


My ESC will be mounted in the Aluminium Box. The heat sink will be pressed against the bottom. I did not decide for an ESC yet, but I hope it wil have a flat mounting surface.

The box will be surrounded by water. There is a spacer undenath, so water can flow. The channel on the right drains any excess through the board. So in theroy, the lid seem will not be submerged. I probably seal the seem with tape as well.

  • ESC is separated from the Batteries
  • ESC is cooled
  • ESC is in a metal box
  • Box is removable.


Nice, but I would recommend you placing the battery compartment further back. Bad experience with front heavy E-foil. But that is just my opinion.


Anyone else got an opinion on this? I have no idea where my foot placement will be. The Battery compartment will stick 60mm out of the board. It can withstand my weight, but stepping on it might make it difficult to ride?


I was thinking of placing the esc in a sealed aluminum box. The bottom of the box would be made from a heat sink with fins. The box would be mounted and sunk into the bottom of the board just ahead of, or just behind the mast with the fins facing downward.


Hi Max, I would try to find positions so that you neither step on ESC box or battery box while riding. I looks to me like right now that your front food would likely need to be on the battery box and the back foot might be on the ESC box. All depends on your wing setup of course, just judging from where I stand. My battery is in between the feet and I never feel the need to step close or on it.


In my personal opinion, the position of your battery is perfect, if you look at the rest of efoils, the tendency is always to ride forward on the board due to the backward weigh. I think is better more weight near of the nose and can put the receiver without signal loss problems there too.
If you have a problem with the battery that is burning, probably you can save the rest of the electronic.


I can stand on the ESC box. The gaps in front and behind it will get covered by a plate. Now I am not sure where to place things : ) I can still move the mast back and forth by 70mm.



I tried my new remote today so I took some pictures of the box


DIY remote waterproof JeffM => STL files