When your marine battery dies, it can be tempting to charge it with a regular charger. However, this is not recommended, as doing so can cause damage to the battery and the marine electronics in your boat.
Marine batteries are designed specifically for use in boats and other watercraft. As such, they require special charging equipment that is able to handle the unique demands of a marine environment. If you don't have a charger made for marine batteries, it may be time to visit a marine battery supply store for a new battery.