Cooling the ESC


Looks very neat, thanks for sharing


Looks great, but just be cautious those lipo packs expand (puff up) when they get hot, I have the same ones, and if you have ANYTHING near them with a point it could puncture the side of battery and cause an explosion. Looks like a tight fit in that battery box.


Is there a way to cool the esc/battery without water cooling? I want to build a sealed board so no leaks.
Using over kill esc (


I don’t think 300A is overkill if you want the electronics to run efficiently and cool. Anything smaller than 300A I feel will generate extra heat, waste energy, increase risk of fire/melting, and reduce the life of ESC. Drawing 80-135A is a ton of current and will get warm so watercooling is a must when ESC is stored in a sealed compartment. This ESC you show does not have water cooling and it will become an issue in my opinion.


What about using dynamic pressure as the water pump. Picture a pitot tube in the mast just above the motor pod, with a cooling tube that runs up to the parts that need cooling.

At low speeds (below take-off speed) the pressure required is very small since the water needs to be lifted only a few inches. At 11 mph, the pressure developed is about 1.8 psi or 50" of lift…plenty. Pressure increases as the square of velocity so cooling potential gets better with speed.

Pros: No moving parts, no electric power consumption, cooling increases with speed/power use.

Cons: plugging an issue?


I feel using water pressure from in the duct or nozzle would work better as there is a lot more pressure. I also like the idea of the water shooting out of the board in an area you can see to be sure its working as it should.

The same thing with the flow, the more power you consume the more water is used for cooling which is great. I like that no electronics are required for this cooling method, its what I am doing.


This creates many problems:
Clogs in Pipes
Erosion from salt


This method is used by many companies for colling motors etc… circulating water.
As always, users should flush and rinse efoil after use in salt water.
I do like the closed loop circulation system that Seadoo uses, but it requires a pump/electronics, though there are ways to do this without electronics…

What is your solution?


We have plenty of plumbing in our RV and its not that difficult. No issues whatsoever. Use good plastic tubes and those tube clips that you open with pliers. I would not recommend screw on hose clamps.


ya a boat ESC with water cooling is all of our solution… but you need water to cool it and that is what you said was the issue… how are water cooling it thats better than what we on the forum are doing?


I’m on this solution too, the less the better, on sea. But still I’ve to figure out how to run a plastic pipe from duct (Rice nozzle or whatever) all the way up to the board.
My mast clamp and propulsion system doesn’t have any room left and on the outside… doesn’t cause more drag?:thinking::thinking:
Do you have a photo or drawing?


Obviously, the best solution is inside the mast but if you don’t have room then maybe look at something flatter to shape to run up mast? If there is a section inside the mast that is separate, have tubing from duct into that area of the mast, and the mast section fills, then install nipple and hose coming out of mast near the board??

We have a design where the impeller nozzle that is 3d printed has the water inlet and area embedded within the 3D part and is accessible near the aluminum tube which is streamlined. But, we are planning on doing CNC aluminum parts with a lightly different design it looks like.


Hi, refugee from here, I was amazed to find the efoil branch, like many others I have been watching & enjoying @pacificmeister’s youtube channel.

Anyways yes esk8 loves the VESC (and it’s non copyrighted derivatives). In terms of cooling there is commercial options from a company called 3d Servitas based in Lithuania.

The owner is on ES -

His son is on esk8 builders and has worked with his father to design a case ystem for the Focbox which is probably the best price-point Vs quality VESC 4.12-based direct fet controller H/W out there right now, they have just completed a design and are making focbox controller boxes right now

No affliation, just a customer


So this Vesc thing is like an open source ESC? Like Arduino is for micro controllers?


Coming back to this topic, I’m still focussed on finding the right water pump for ESC cooling. My mast (RL-Board custom lenght mast) doesn’t have any chamber in front, so no way to use that as dynamic pressure intake. I’m left with the hose-thru-mast (near trailing edge chamber), and here it goes the “Which pump do I get?” struggling doubt.

Acquarium submersible centrifugal pump, quiet, powerful… not selfpriming.

Peristaltic type, noisy, extremely low water flow… selfpriming.

What you guys use to cool the ESC? Could it work a centrifugal model, if receives backflow of water from the outlet, before to start it when the board tail is still on water? Could it acts as a priming?


Yes, just the name (VESC) is licensed, so you see others use different names - FocBox, for example.


Yes it is. It’s pretty easy to modify the software and add custom applications running on the vesc.
BUT that’s usually unnecessary.
The computer software that comes with it is of really high quality. You can view all currents and voltages in real time while testing. And it has configurable current limits for everything and anything.
With standard cooling it’s only rated for 60A and 12S. Mine with a custom, isolated aluminium heatsink did not get above 40°C with 80A. Sadly I killed it on the test stand by my own foolery and have yet to repair it.


No way to use VESC right now. Current motors are 500kv and people running 12s. Also people running higher current.
We need to wait for a true 100kv without a gearbox and high power inrunner before we can consider focboxes/vesc4/etc.


I’m not sure I follow your thought here. How will a 100kv motor help here? I assume the amp draw will be similar to the existing motors (we do need this power).


500kv with 12s voltage results in a erpm higher than 60k.

Focboxes and VESC model ESCs have a 60k erpm limit. Anything above that generally results in a fried DRV chip.

In the eskate world, people tend to stay around 190kv for 10s-12s, or 260kv for 8s.

A 100kv motor (to replace a 500kv + 5:1 gearbox) would result in an erpm max within VESC limitations.

Power and current are another factor.

Modified Hiorth-build from Sweden