Thank you for all of the input.
We managed to get back down to the boat and alas the problem has had the nerve not to self-correct (and since the boat next door was no longer plugged in we'll have a hard time continuing to blame it on them). When we briefly tried plugging our boat in again (she was left not plugged in), we found that not only did the reverse polarity indicator light up but also that we had no power at any of our 120V outlets. Attempting to throw and reset the circuit breaker and the GFI outlets had no effect. I'll explore further with the marina any changes they have made, but any answers to a couple more questions would be greatly appreciated:
1) What impact could it have on a boat if the marina wiring (30A) was changed so that when the boat was plugged in the ground, neutral, and hot wires got switched (e.g., if hot went to the neutral or ground wire on the boat)? Could these switched wires have taken out my 120V system (from what I could find there were no obvious burn marks, triggered breakers, etc.) and how?
2) Given all that can happen, is it the best policy to always leave one's boat connected to shorepower?
Last edited by oft; 06-07-2007 at 11:25 PM.