How to Winterize a Boat for Storage

If you’re a year-round boater, completing a mid-season boat check is important for boating safety, performance, and longevity. But for many boat owners, the boating season begins to wind down when warmer days end. Knowing how to winterize and store your boat will help keep it in good condition through the cold months and well-prepared for the next boating season. Winterizing your boat at the end of the season is essential for boat owners who own inboard boats or boats with an enclosed propulsion system within the hull and for those who live in areas where the temperature drops below freezing.

Winter boat maintenance and preparedness don’t have to be hard. O’Reilly Auto Parts has compiled a helpful list of marine maintenance tips to help you get started on your boat’s winter storage preparation. Protect your boat until spring with this helpful winterizing guide.

No matter what type of engine your boat has, it’s important to inspect and change your boat’s engine oil and filter before storing it for the winter. Changing your boat's oil and oil filter before storing it for the winter prevents moisture and oil build-up, which can damage the boat's engine components. Changing your boat’s oil before winter also removes any water in the engine, which could freeze and cause corrosion during the winter. Different engines require different marine engine oils, filters, and procedures. For specific instructions on how to check and change your boat’s outboard engine oil and filter, refer to your boat’s owners manual. In addition to flushing and refilling your boat’s engine oil, it’s important to flush, drain, and refill other fluids, including coolant, hydraulic fluid, outdrive oil, and more for optimal performance. Steps for draining and refilling these fluids to normal operating levels can also be found in your boat's owners manual.

After replacing your oil and filter, it’s time to winterize your boat’s fuel tank. Part of winterizing your fuel tank is filling your tank up almost to the top. Leave some room in the tank in case the fuel expands as the temperatures drop. If you don’t drain your boat’s fuel tank before winter, it’s important to store your boat with an almost full tank of fuel to eliminate any excess air, which could cause condensation and corrosion damage. When refilling your boat with fuel, make sure you’re using ethanol-free fuel to limit the risk of degradation during storage. When you fill your tank up, add a marine fuel stabilizer to prevent the fuel from breaking down, evaporating, or oxidizing during winter. Adding a marine fuel stabilizer to your fuel tank is especially important if your boat has a carburetor instead of fuel injectors since unstabilized fuel left in a carburetor can oxidize more quickly during storage and lead to varnish buildup and other fuel system problems. After your boat is fueled up and you’ve added a fuel stabilizer, start the engine and let it run for a few minutes to distribute the fuel evenly before storage.

Before cold weather sets in, drain any water from livewells, hoses, and pumps. Livewells are water tanks typically found on pontoons and fishing boats to store live bait and caught fish. Livewells pump and circulate water from outside the boat into the tank, keeping the water oxygenated and fresh for any marine life kept in the livewell. Make sure to drain any water from other additional systems, such as raw water washdowns and bilge pumps to prevent water from freezing inside the system.

When winterizing your boat, ensure there’s no water left in the livewell or hoses. Water left in your boat’s hoses can freeze, causing the hose to crack or burst.

It’s also important to drain your boat's freshwater plumbing system. To do this, turn on the electric pumps and open the faucets to let the water drain completely and allow the pipes to bleed dry. After you’ve drained your boat’s plumbing system, add antifreeze to prevent any trapped water from freezing. Running antifreeze through the system removes any remaining water from the pumps and hoses, ensuring any water left in the system is protected against freezing during cold-weather storage.

In addition to frozen water, mildew formation is another concern when storing boats for the winter. Mildew is most common in damp, poorly ventilated places. Not only is mildew toxic to inhale, but it can also damage your boat's upholstery, painted surfaces, and vinyl. Propping open all storage compartments and hatches to allow adequate airflow is the best way to prevent mildew from forming on or in your boat. Before leaving your boat in winter storage, open hatches, ports, lockers, storage compartments, and seat basins to prevent mildew and keep your vessel ready to hit the water come warm weather.

Charging your boat's marine or deep-cycle batteries before winter greatly reduces the risk of the battery freezing in colder temperatures, ensuring your battery will be ready to use next boating season. If your battery is left with little or no charge during the winter, it is more likely to degrade and freeze. This can limit its ability to recharge next season when you’re ready to use your boat again. If the water in your marine battery freezes, the battery case can expand and cause leaks and cracks, which may lead to corrosion and reduced charging capacity. Adding distilled water to open-cell batteries and bringing batteries up to a full charge before cold weather arrives can help prevent your battery from freezing and helps ensure your battery will be ready to go next boating season. You can also use a battery maintainer to keep the battery charged throughout the winter and, if possible, the batteries can be removed from the boat and stored inside a more stable environment like a shop or garage.

Some boat manufacturers may recommend adding fogging oil to your engine when winterizing your boat. Fogging oil is a lubricant that protects marine engines against corrosion and moisture buildup during storage. This aerosol spray is applied to core engine components, such as the engine’s cylinders. This spray creates a protective coating that keeps moisture out and prevents rust formation, which keeps your boat's engine in top shape and ready to run next season. Fogging oil also protects against contaminants that can clog the engine and reduce starting performance, such as carbon deposits. Check your boat’s owners manual to see if applying fogging oil to your engine is a recommended winterizing step for your boat.

If you’re gearing up to prepare your boat for storage this winter, O’Reilly Auto Parts has the winterizing products and fluids you need to get the job done in no time. We carry replacement marine oil filters and oil, antifreeze, marine fuel stabilizers, fogging oil, Super Start Marine & Deep-Cycle Batteries, fuel pumps, drain hoses, and more for your boat. If you’re unsure which parts or fluids are right for your boat, our Professional Parts People can recommend the best products to winterize your boat and keep it in top condition for the next boating season. If you need to test or charge your boat’s batteries before storing them for the winter, O’Reilly Auto Parts also offers free battery testing and charging for boats, jet skis, and other marine batteries at all store locations. If you need to replace or upgrade your battery for next year, we can also help you find the marine battery you need to hit the water with peace of mind.