Re: Extension cords @ dock
Many marinas may offer 15A service on a standard 3 prong plug, others will require an adaptor. If the boat's not set up for 'shore power' the only concern I'd have about the 'extension cord' is that it's properly rated for marine use. The marina may not allow a generic home depot cord if they are paying attention. I think the cords need an UW approval (underwater) rating.
It may be nice to be able to plug in a battery charger too.....The other issue you may run into is having to pay for 30A service even though you'll not need that much.
Finally, if you've got a decent charging system you might want to change to 12Vdc fans and get away from AC altogether....
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)