[C320-list] Starting Battery

[Donald Lawson]

I plan to purchase a spare starting battery, as added insurance for an upcoming offshore trip. I intend to install it permanently this winter as described in the C320 website.  I used a group 24 on my old 2GM20 to start.  Is this acceptable or should I use a group 27? Anything bigger is overkill nor do I expect to purchase it from West Marine. Any recommendations?
Don L. #1005