Although some of the plugs on engine blocks twist open, it is best to remove them completely and keep them out during storage to prevent accumulation of condensation. Remove the hoses from the raw water pump and blow through them to remove all water. Be sure that water in the transmission cooler is also removed at this time. Lowering the trailer tongue will help water flow out of the back of the engine. Place all plugs, hoses, clamps and parts that you intend to leave out during storage in a plastic bag and tie it to the steering wheel to insure that you'll know where to find them in the spring and will not start the boat without reinstalling them.
Battery Remove the battery and clean terminals.
Check the charge and replenish with a trickle charger if necessary. Store the battery in a cool, dry place where it will not be subjected to freezing temperatures. Periodically check the condition of the battery and replenish with a trickle charger as needed. Always use cation when working with or storing batteries as they naturally produce explosive gases and contain caustic acid. Be sure to work the wheel and control lever back and forth to coat the entire system.