The season's winding down, the water's getting cold, and it's time to think about putting your boat to bed for winter. Winterizing might not be the most exciting task, but doing it right protects your investment and means a smooth, stress-free launch in the spring. Here's how to do it properly.
1. Change the Engine Oil and Filter
Old oil is acidic and will corrode engine internals over a long storage period. Change the oil and filter before laying up — not in spring when the damage is already done. Run the engine briefly after the change to distribute the fresh oil through the system.
2. Flush and Fog the Engine
For outboards and sterndrives, flush the engine with fresh water to remove salt, sand, and debris. Then, with the engine running, spray fogging oil into the carburetor(s) or intake until the engine smokes and stalls — this coats internal surfaces with a protective film. For inboards, flush the raw water cooling system and consider adding antifreeze to the coolant circuit.
3. Stabilize the Fuel
Ethanol-blended fuel (E10) absorbs moisture and degrades quickly. Add a quality marine fuel stabilizer to a full tank, then run the engine long enough to get treated fuel through the entire system — carbs, injectors, fuel lines. A full tank also minimizes condensation inside the tank over winter.
4. Protect the Cooling System
For raw-water-cooled engines, drain all water from the block, manifolds, and heat exchanger — any water left can freeze and crack expensive castings. Use non-toxic marine antifreeze (pink, propylene glycol-based) to flush through the system as a final step. Don't use automotive antifreeze — it's toxic to marine environments.
5. Remove and Store the Battery
Cold kills batteries. Remove your battery (or batteries), clean the terminals, and store them somewhere above freezing. Connect them to a quality smart charger/maintainer over winter — a trickle charger will keep them topped up and healthy. You'll thank yourself come spring.
6. Flush and Winterize the Freshwater System
If your boat has a freshwater system, drain it completely and blow out the lines with compressed air, or run non-toxic antifreeze through the pump, lines, and fixtures. Don't forget the head, shower sump, and water heater if equipped.
7. Clean, Wax, and Cover
Clean the hull, deck, and interior thoroughly before storage — mold, mildew, and stains are much harder to deal with in spring. Apply a coat of wax to the hull and any exposed fiberglass. Use a quality boat cover or shrink wrap to protect against UV, debris, and precipitation. Leave vents open for airflow to prevent mildew.
8. Don't Forget the Trailer
If you store on a trailer, check tire pressure and condition, grease the wheel bearings, inspect the bunks or rollers, and make sure the lights are working. Repack the bearings if it's been a while — trailer bearing failure is one of the most common (and avoidable) boating headaches.
A thorough winterization now means a happy commissioning in spring. Take the time to do it right and your boat — and your wallet — will be in great shape when the warm weather returns. ❄️🛥️