I am replacing the battery in my 200 HP inboard/outboard boat ... if there is a big difference in price between "Marine" and "Auto" applications, what does this represent in content?

Is there a real difference for a given casing size? My is a size 24 (pretty standard auto size) and has 400 cold crank amp rating ... what is real issue if I simply replace it with an auto battery of the same output?

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George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg