Well, you open up a dogs breakfast of issues when you talk about grounding to the DC system.
Ignoring that issue, generators are considered a power source by NEC, duh, right;-). So the neutral and the ground point are one and the same. Connect the white neutral and the green ground wire to the same terminal.
If it is a NextGen, download their installation manual at http://www.nextgenerationpower.com/I...rt/UCM1-35.pdf
. Even if it is not a NextGen the AC end is probably the same- a Markon.
A couple of safety issues:
There must be a breaker (30 amp typically) within a few feet of the generator. On the Nextgen, it is to the left of the hot terminal. Hopefully your generator has one in a similar location. If not you need to add one.
This is a personal safety as well as a system protection breaker. Anyone working on the generator should trip the breaker to make sure he is not being back fed AC. Should never happen, but....
You had a generator in the boat before, but it was not grounded? Wow!!!!
Well, anyway, you need either a transfer switch (typically a rotary switch like Newmar's) or separate shore and generator breakers with a lock out bar that will only let one be hot at a time.
This switch should be at the main AC panel or if it is shore and genset breakers, it will be part of that panel. It makes sure that only one source of AC can feed the system at a time. If two sources feed at the same time, one will be fried- guess which one?
If you don't totally understand these instructions and the reason behind them, then you probably should get someone more qualified to help you with this installation.