My new to me '02 353 has What looks like almost brand new Napa Marine starting batteries, 550cca, seems too small to me. Thoughts?

A "starting" battery is probably not the best choice for your boat and 550CCA may be a little small. I assume they are group 27's. If new you are most likely ok in terms of starting and so on, you'll just need to be carefull in terms of stereo and other electronic use. I have the NAPA marine in the Fountain, not positive but think they are a combo type vs the deep cycle. I'll check later and let you know. The NAPA's are made by one of the majors, and have worked fine for me, had them in the Velocity as well. Sister & brother-in-law own the local NAPA, price is always real good.

P.S. You should remove the ? from the Got Boat.

I had a napa and they are dual type, like ragged said those are OK for starting but the bigger the better for your stereo and electronics

Regardless of Group Size....1000MCA/750CCA (wet-cell starting battery). This pretty much holds true for any fuel-injected MerCruiser (incl Racing).

Note: If they are Group 27's then you'll have to get Interstate Batteries, to match that spec.

5PM,

Checked mine today = NAPA Premium Marine Dual Purpose, 770 Cranking Amps, Reserve Capacity 150. Put these in last year because one of the batteries was not taking full charge, they have worked fine for me, but don't have a lot of accys, and just standard stereo etc, not the mega waaaaaatttttttt system like RIP and the Senator.