My marina has a GFCI breaker on my pedestal at the dock and the only thing that trips it is the main salon Cruisair A/C. On the Ocean Yachts the sea water pump and the main salon A/C are on the same breaker. I checked the connections at the pump and even disconnected the pump but the pedestal breaker trips immediately every time the salon A/C & Pump breaker on my panel is turned on. I spoke with a ABYC certified technician who is "too busy to spend 2 days troubleshooting GFCI problems" because it could be a myriad of issues on a 30 year old boat. He did mention that once those breakers trip a couple times they are more sensitive to not only ground faults but also amperage, meaning that the startup amperage draw on the A/C could be enough to cause the problem. I looked at the Micro-Air Smart-Start soft start that lowers the start up draw but I would need one for each of my 3 units, but am considering one just to see if it eliminates the issue. My problem could be something totally unrelated to the A/C. I've read that bad A/C control boards or pump relays can cause GFCI issues.