Electrical acumen? Me? Heh-heh.
This is the way the boat came out of the box. So, I'm working through everything now trying to figure out what's what. I can do the basics of electrical work - but I don't know anything about the design or mathematics of a system. So your advice, drawings, and help is welcome. Just judging by the above responses, it's a world with a lot of different opinions.
The PO was apparently an electrically accumened dude who added the charging relay, and what he assured me is a 200a alternator, and the Xantrex.
To your specific questions:
What is the HP and no of cylinders of your engine? The group 24 I have is over-kill for my 35HP Universal starting battery.
Yanmar 4JHE (4-cyl, 40-horse)
With such a small house bank, I am guesing you have a 40 Amp alternator.
Again - Previous Dude says 200a GM alternator that he put in himself.
I suspect that you have a major electrical upgrade ahead of you. Do an energy budget. You might not have enough amps in your system for an overnight passage without over taxing you system. I'll try to dig up my drawing and show you what is going on in my boat.
Major upgrade for the system or the batteries? I've already converted all fixtures to LED (except nav lights). But I am concerned about the draw of the radar, etc. Like you, my main concern is that the house power is solid.