Does it make sense potting the ESC and the receiver for the remote control or not?
I see the advantage in the waterproofness and shock resistance.
BUT: What about temperature dissipation? In addition, you can no longer reprogram the ESC once it is cast. Or is it possible to not pot the USB port for further programming? (Shed all the ESC, but let the USB free?
AND: Can you also put potting compound in the receiver for the remote control or will you no longer have reception?
This all depends on the specifics of your ESC and remote, but…
The heat from your ESC needs to be dissipated. If you pot over the heat generating parts then it will overheat and smoke. You can pot it but just make sure that the heat can escape from the hot bits (use masking tape or wax or mold release etc while potting to keep them uncovered). Typically the FETs are where the heat is generated in an ESC, but there may be other components in the ESC that need cooling too. Your ESC should have heat sinks attached from the manufacturer. These should be given a way to get cooled. eg. outside air or water flow, or thermally connected to outside air/water via an externally waterproofed heatsink.
For your remote, it should be safe to pot completely depending on the potting compound you use. Epoxy is transparent to radio frequency transmissions. I think most potting compound should also be, but your spec on the product you use will possibly state that.
For my build I am potting pretty much everything I can, and only leaving stuff exposed that I will need to access in the foreseeable future. You should definitely leave your USB port available I think if it is the only route to change your configuration or update firmware etc. You can probably keep it coated it in TefGel or similar to reduce the risk of water ingress and corrosion.
I would say that esc potting isn’t needed in a normal efoil so i wouldn’t do it. Make your box waterproof and use double protections for water, like outside waterproof box + inside splashproof box, keep the esc mounted with distance to any walls that will lead water to it, add some sponge material in the bottom for any small leakages.
If you’re doing a foildrive below board thingy then i would consider potting. It’s a totally different use case with long term immersion in water, flowing water and pressure against the enclosure.
I’ve potted my receivers to get that double protection since they had exposed pcb’s
I’m doing this now. For pcb without heat I landed on soft potting silicone inside a 3d printed case (too soft for mechanical forces) for ESC I’m doing natural cure silicone in printed case (same reason) but leaving both heatsinks exposed and glued to alu case afterwards, with heatsink paste. This allows servicing, in theory. You can use heatglue also but it’s a mess to remove imo.
insert a rubber plug into the USB port then cover with vasoline. after potting remove the vasoline then add silicon to cover the plug. Break it out when you want to access it then after replug and reapply silicon to reseal it.
I have not actually reached that point in my build. For my transmitter though, I have used a ESP32 microcontroller in a customized bremote based 3d printed model (thanks @ludwig_bre!). When I potted that, I made an extension out of a sacrificed USB cable, plugged that into the board and soldered a new female plug end onto the chopped extension. Then I potted over the plugged in one using UV activated resin. The exposed plug is inside a cavity in the transmitter that is waterproofed using a screw cap and o-ring and RTV silicone.
I have not field tested this though, so will see once i complete whether this will be effective long term.
The ideas @gazlinux proposes above sound excellent.
