First, depending on what you want, you may not need an inverter. Do you just want AC at dockside? If so, that's simpler and cheaper. (And I consider it a safety feature that I can only run the blender to make margaritas while docked!)
I did that myself, largely with parts from eBay. Components I used:
* 30A shorepower receptacle
* 30A 50 foot shorepower cord
* AC panel
* Galvanic isolator
* Xantrex TrueCharge 20 battery charger
* GFCI outlet and enclosure
* Marine rated cable (don't skimp here!), and a pair of inline fuse holders and fuses for the connection from the battery charger to the batteries
* Blender for margaritas (most important part!)
I mounted the shorepower outlet on the inboard side of the port lazarette near the Whale Gusher. I used 3 conductor 10 gauge cable to take the AC back to the panel. I mounted the AC panel facing the port quarterberth (which I don't think you have, judging from your hull number?) as I wanted it near where the power was needed, and I like keeping it distant from the main DC wiring.
Household wiring is very different than boat wiring. At the panel, both the neutral and hot wires run through 30A breakers before going to the neutral bus and hot bus, respectively. The breakers are ganged together. This is done because it is all too possible that a dock outlet could be wired with reverse polarity, in which case a short between neutral and ground would be catastrophic were the neutral not breakered. But the AC ground is not breakered so there is always a path back to ground in the case of a short.
Most AC panels will have a reverse polarity light. Mine also has a voltage breaker that trips off the main if too much voltage develops between ground and neutral, protecting me automatically against reversed polarity.
The AC ground is a much more difficult topic, as different people have different views on what to do with it. One line of thought is that AC ground should be kept separate from the boat's DC system. I don't like this. If AC ever shorted into the DC system, there would be no path to ground to trip anything, and worse, all the underwater metal on the boat (which SHOULD be bonded to DC negative and the zincs) would become hot, posing a risk to swimmers, and likely causing massive, rapid corrosion of the underwater metal.
So the solution to that is to bond the AC ground to DC negative at the battery. But this poses a corrosion hazard as well, so what is then done is that a galvanic isolator must be installed inline to the AC ground before it reaches the boat's panel or anything else, and especially before it is bonded to the boat's DC negative. I built one myself using two bridge rectifiers and the heatsink from a very large Pentium.
From there, it's just three wires from the AC panel to the battery charger, and another three wires to the GFCI outlet(s) installed.
The charger will need one negative and two positive wires to the batteries; all should be pretty big (10 gauge or possibly 8 gauge for a 20A charger?), and the positive wires should be fused. I mounted the charger in the cabinet under the sink, in the thin strip of fiberglass to the left of the door, above the foot pump for the sink. As I store batteries off the boat in the winter, the charger can be removed quickly, and just this year I finally got around to wiring a male and female marine grade plug to make removing it easier.
For outlets, I just installed one on my boat, near the galley by the sink foot pump; it's right where I would operate that blender.
Enjoy your margaritas!
Ryan Pierce
Tesara, #337
