Additional story... last summer saw a boat in the dock across the channel from mine that kept puking out water from the bilge outlet. Figured something wasn't right, so drove around and headed over to check it out. The guy had left his washdown pump on by accident. The wash hose had then split and was spraying all over the inside of the boat. Then the bilge was pumping it overboard. I headed to the office and we rounded the owner up. There probably wasn't any danger of sinking, because it likely would have quit pumping same time the battery powering the bilge ran down. But what if that bilge hadn't had an auto switch? Or what if it was a drain plug leak, or some other live well hose failure, or such, which eventually would have run the battery down. At least two batteries gives you a little longer chance for someone to see it.