Curt, as JK said, go with the four Duracell golf cart batteries. Replace the OEM dumb charger with a smart charger. Take the lid off the battery compartment for easy access. You will need to change up the bracing a bit. Be advised the conduit for the charger wire under the rear bunk splits under the bunk (at least on my boat) you will need to feed the charger wire, then lift up the bunk and pass the wire into the conduit that runs under the deck next to the head and into the battery compartment. The wire on my charger wasn't long enough. The hardest part about swapping out the batteries is lifting those 4Ds and getting them off the boat. They are unbelievably heavy. I made a template of the batters, went to the local West Marine, used their heavy duty crimpers, and made the connection cables in the store. They folks in the store were most helpful! You will be very glad you did this mod. I am not a mechanic and managed the whole thing in an afternoon. A person who knows what they are doing (not me) could do it in less than two hours. Serious cruisers may add an engine starting battery, separate from the four golf cart batteries. That is the ultimate way to go, but I've not had an issue with my casual cruising. The only big draw on my boat is the refrigerator. All interior and exterior lights are LEDs.