I spoke to a battery company and found out that Optima was bought out a few years ago. When they got bought out the quality of their batteries began to suffer greatly! If you have some older Optimas then you probably have a good battery, but the newer ones are "crap" (according to the battery companies). This company used to stock them and recommend them to customers. After the Optima buy out they said the quality was crap and they finally stopped stocking and selling them.

IMO... Go with an Absorbent Glass Matt (AGM) battery. They are better designed to withstand the beating of running accross the water, and they "gas off" less than a standard lead acid battery. If you keep your batteries in the same compartment with the stereo equipment that means you don't have to worry so much about the hydrogen sulfide gas eating your expensive electronics. AGM batteries are also sealed and in a "gel" state so if you crack the case you don't have to worry about battery acid going every where. You can also mount them upside down if you chose and don't have to worry about them leaking. AGM will cost you more than a standard battery, but IMO it's worth the money.

The only thing you have to decide is what size you want.... 24, 27, 31?