Shore power receptacle on 3207

[iceman3500]

Just got the tub in the water this week. Going to park it at my one of my buddy's docks. He has shore power to the dock but with a regular 120v/15a plug. Which shore power receptacle is the one I should use to just run the fridge, charger, etc: the one closest to the bow or the one closest to the stern? I tried both tonight but as soon as as I plugged it in, the GFI at the house power tripped. I was using a 30a to 15a adapter and then a regular extension cord. I'm not sure how tight the plug should be going into the boat; there was a little wiggle room there but I got the threaded coupler on without trouble. It was raining out but I tested the power with a regular 120v load and it worked fine. As soon as I put the shore power adapter on and tried to plug it in, the GFI would trip. I had the switch on my power panel to shore power. What do you do with the battery switch while on shore power; on/off? Sorry for what are probably simple questions to most of you, but I'm learning as I'm going. Should have paid more attention in shop class 35 years ago instead of dreaming about drinking whiskey and making love all the time. Any input is appreciated.
Iceman

[waybomb]

If it's raining and you are using a standard 115/15a receptacle and extension cord, could be water getting into the connection. Doesn't take much.

I am guessing the connector at the bow and the stern are both connected to the same place inside. The bow connector is probably when docking bow first, and the stern connector for backing in.

Many of your accessories are 12vdc, like lighting, stereo, various pumps, etc, so for the most part, at least have one or the other "on". Leave the charger on to keep the house battery charged.

[iceman3500]

The receptacles are side by side on the starboard side just outside the electrical panel. One guy explained that one of them ran the heat and a/c through the shore power, the other ran the rest of the shore powered electrical. I don't know which is which and I only need the one.

[AaHubb]

If we assume the boat is wired correctly then I would suspect the shorepower or 30~15a adapter has neutral and ground reversed. A GFCI trips when there is an imbalance between current in and current out on the ac supply (some current leaking to ground). One test is to turn off all breakers on your ac panel, plug in the shorepower then turn on the breakers one at a time till the gfci trips. If the gfci trips when first connected the problem is most likely in the shorepower wiring. If a certain breaker causes the trip then the problem is in the equipment on that circuit.
Good luck, these kinds of problems can be a bear to find.