Windy2, do you have a direct drive? If so, what size battery did you get? My boat is still in storage (gotta get it out, but it's still more like winter than summer around here) so I can't measure how much space I've got to work with.
I called a few stores to see if the Optima that I think is the right size is in stock. The prices varied from $180 at a national chain to $115 at a local mom and pop for the exact same battery. Kinda surprising how much the price varies.