Thanks for the suggestion. I took it out to test it in salt water today and had several problems with it. First off the motors seemed to stop responding or failed to spin up when in the water. If I lifted it out, the motors would spin and if I dropped it in the water it would keep spinning, however if I stopped the motors and tried to start them spinning again they often wouldn’t start.
They spin freely when off, so I don’t know what is going on. I put it back on the bench and they seem to be operating ok. I tried recalibrating them again. I found one motor would not not start up. So if I did the ESC calibration (turn on only the one motor with button pressed to get the beeping, then press once and flip the setting to +1, press again, -1, wait) the starboard motor never starts spinning unlike the Port or vertical motors.
When operating them on the bench the starboard motor emits a short beep sound too.
Any more thoughts on where to go from here?