
take a budget mystery 30a esc for a helicopter or plane, these are dirt cheap
i found it works fine with my basic pistol transmitter that i use for my boats

remove cover and cut 2 pieces of copper tubing

use thermal glue to stick copper tubing to metal heatsinks

after glue dries wrap up well in tape

i used a small bit of blue silicone to seal the gaps in the tape and make it water tight

make a loop using silicon tubing at one end
the boat in the video above is using this esc, it works fine, stays ice cool and is a fraction of the cost of an off the shelf water cooled esc