Relating to shore charging keep this in mind. The deeper you cycle your batteries, the fewer cycles you'll get over the battery's lifespan. And, its not a linear equation. At half cycles you'll get way more than double the number of deeper full cycles. Also, leaving a battery in a discharged state (even partial) accelerates the degradation. There's no memory effect on these type of batteries so there's no downside to an immediate recharge after a partial depletion whether its by your alternator or shore charger. The point is to get your batteries on a smart charger the minute you put your boat into storage each and every time. Things may look okay now but your battery(s) amp/hour capacity may look much different from the factory specs after a single season.
David
Earmark Marine