Here's the situation: I've recently come into a Northern 1/4 ton (Mirage 24, essentially) and I need to find a way to charge the battery. It will be sailed primarily on weekends during the summer, and the electrical demands are limited- a cabin light, nav lights, depth sounder, knot meter, and VHF radio.
There doesn't appear to be an alternator or charging circuit on the outboard (1992 Evinrude 8hp 2 stroke), and the previous owner used to charge the battery by taking it home and hooking it up to an automotive charger. I've got access to shore power, but no AC system on board.
My initial thought was using a portable automotive battery booster as needed, although I have no idea if this is the best approach. Another option may be solar, although deck space is limited and we don't exactly have the sunniest weather in these parts! Are there any other options I may be missing? Any suggestions for how to keep the battery full?
with the loads you outline, a 15 watt solar charger would likely keep up with use just fine. leave it on the cabin top when in use, when you go sailing simply stow it away in the quarter berth. keep a voltmeter on board so you can check state of charge occasionally, and if you find your charge is not keeping up, plug in your battery charger to top off the battery. yes, it is not marine rated, yes, it is not the reccommended choice, but for 4 or 5 SUPERVISED hours a week of use, it won't be an issue. Check with your marina, though, before use- some get pissy about seeing Motomaster battery chargers on boats.