A friend with a Spencer 35 and I (CS27) were discussing whether to bond through hulls or not. The concensus seems to be not to and I agree. In our research we came across info on galvanic isolators. After some reading we found that the green ground wire of an ac system on board should be connected to the boat's negative ground - negative bus and ultimately the engine ground. His boat doesn't have this connection and neither does mine. The ac system on my boat was by all accounts professionally installed with Blue Seas ac panel and tinned marine wire etc. All ac outlets are gcfi - 3 with a 15 amp breaker for each one. The shore charger is on its own breaker. The main breaker is the familiar double to break both hot and neutral and show reverse polarity. My friends Spencer 35 has a more basic system with a household box and no main double breaker but he does have gcfi outlets. Everything that we read explains ABYC regulation of grounding the ac green and goes on to explain the need for the galvanic isolator. My question is what is wrong with not grounding the green to the engine block and using gcfi outlets. It obviously works and has for many years. In my reading it seems that by connecting ac ground to the engine block and therefore to the dc ground you are inviting more electrolysis issues. What does everybody else think of this?