If a boat is stored under cover for the winter, it will remain cleaner and be less exposed to the weather. It should not be sealed up tight but should be well ventilated to prevent mildew and rot.
Small boats that are stored outside should be turned upside down so they do not fill with snow or rain and should be raised off the ground on blocks to allow for drainage.
Here is a basic checklist that will vary depending on the type of boat:
• Oil filter changed.
• No oil leaks found after oil and filter changed.
• Fresh-water cooling system: antifreeze coolant solution checked.
• Fresh-water cooling system: petcocks free of sediment.
• Fuel conditioner-stabilizer added to fuel tank and fuel tank filled with fuel.
• Fuel filters and sediment bowls cleaned and/or elements changed.
• Carburetor filled with mixture of 50 percent fuel conditioner and 50 percent fuel.
• Engine fogged through carburetor with rust-preventive oil.
• Raw-water cooling system flushed out with fresh water.
• Raw-water cooling system drained (all petcocks opened and all hoses drained).
• Raw-water pump impeller removed for storage.
• Raw-water cooling system filled with anti-freeze coolant solution.
• Distributor cap, rotor, and spark plug wires wiped clean and sprayed with moisture inhibitor.
• Tension relieved on all drive belts.
• Flame arrestor cleaned, reinstalled, and sealed shut with plastic film and tape.
• Spark plugs cleaned, excess fogging oil purged from cylinders, and spark plugs reinstalled.
• Exhaust openings sealed shut.
• Batteries removed for storage where they can be kept charged.
• All surfaces on engine and its accessories wiped clean, paint touched up, and bare surfaces coated with rust inhibitor.
• All moisture-holding items removed from engine compartment.
• Engine compartment hatches left slightly ajar for air circulation.
• Reverse-gear transmission, V-drive, or stern-drive unit serviced in accordance with manufacturer’s recommendation.
• Straight inboard or V-drive propeller-shaft packing nut loosened.
• All water that could freeze and break thru-hull. Sea-cocks must be removed.
Note: always follow the engine manufacturer’s advice for winterizing. Do not drain antifreeze on the ground. Protect the environment.
Sourced from the CPS Boat and Engine Maintenance Course. For more info on Boat Maintenance register for a class near you.
Here is a video tip for Winterizing an Outboard Engine: