Proper winterization prevents freeze damage that can cost thousands to repair. Here's the complete checklist.
Gas inboard/sterndrive: Run engine with fresh water flush. Drain cooling system. Fog engine with fogging oil through carburetor or throttle body. Change oil and filter. Add fuel stabilizer to a full tank. Run engine briefly to circulate.
Diesel inboard: Change oil and filter. Change fuel filters. Fill fuel tank completely (prevents condensation). Add biocide. Run engine to circulate. Change coolant if needed.
Outboard: Flush with fresh water. Fog cylinders. Drain or stabilize fuel. Disconnect battery. Trim down to drain lower unit. Change lower unit oil.
Drain all freshwater tanks, hot water heater, and lines. Pump non-toxic antifreeze (propylene glycol, NOT automotive) through all faucets, shower, and head until pink fluid appears at each outlet. Don't forget the raw water washdown.
Fully charge all batteries. Disconnect negative terminals. Store batteries in a cool, dry place (not freezing). Connect to a maintenance charger if possible. Clean terminals and apply anti-corrosion grease.
Shrink wrap (professional, $12-20/ft) or a quality fitted cover. Ensure ventilation to prevent mold. Remove all food, beverages, and anything that can freeze and burst. Leave cabinets and lockers open for air circulation.
Get a personalized winterization and commissioning checklist at informedboating.com.
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