Jim:

Ah, I now understand that you have an outboard engine and no refrigeration,
etc. As Jeff noted, the O/B alternator should keep up with all of your DC
needs while running. Then all you have to consider is what you use while at
anchor. This should be fairly small- cabin lights, radio and anchor light.
This will total about 20-30 amphours per day for several hours of cabin
lights and the anchor light all night.

This much power usage can be replaced with a single 100 watt solar panel on
a good sunny day. You could wire this panel into your boat's electrical
system through a cigarette lighter outlet without a controller if you are
careful to unplug it after you are done cruising and are back at the dock.

And some of your usage will be replaced by the O/B alternator if you move
from anchorage to anchorage. You might get by with as little as a 50 watt
solar panel if you start with fully charged batteries and are only out for
2-3 days at a time.

If that is your usage pattern, it might be cheaper still to install two 6v
golf cart batteries to add 220 amphours of capacity to bring you up to 300
amphours or so. With this much capacity, and your limited usage, you
wouldn't need to recharge at all for 4-5 days. Batteries are cheaper than
solar panels or generators if you can recharge them back at the dock.

David