I have a 44' standard class house boat reserved for Lake Powell. I
want to be able to recharge a deep cycle marine battery (group 27) for
a trolling motor.
I am especially concerned about overloading any aspect of the boats
electrical system or breakers. I would only connect the battery for
charging when motoring.

Should I
a) use a 12V to 110VAC inverter and a 110V battery charger connected
directly to one of the house boat batteries - this seems inefficent.
b) connect the battery in parallel with one of the house boat
batteries - is this too much of a load?

Thanks, james