My fishin buddy has a 1 year old 18' boat with a V-6 inboard/outboard on it. This is the third battery he's put in it because they're going bad. Other than the issue that something is causing them to go bad my question is, why would he need to replace it with a Marine battery. It's a v-6 with an alternator so it is virtually the same as a car. It's not like my canoe where i'm out all day, run the battery down and come home and charge it. Anyone have any input on why a marine battery is required in this boat?