Re: Do I need a battery charger?
A mooring boat really benefits from solar or wind.
The key thing to understand is that as batteries approach a full charge they start charging more slowly. No matter how powerful your alternator is a lead acid battery needs several (perhaps many) hours of charging to hit 100%. The bottom line is that a boat with only the alternator rarely runs the engine long enough to make this happen.
The second thing to understand is that battery lifetime is heavily related to the state of charge. So a battery that spends most of it's life at 100% is going to last a lot longer than one sitting at 80%.
So solar is an excellent complement to the alternator on a mooring boat. The alternator can provide bulk charging and bring the battery to 80-85%, then the solar can top it off over a couple days.