How to Winterize a BoatSnow filled boat 

With winter in full swing, did you remember to winterize your boat? Whether your boat has an outboard, inboard, or stern drive gas engine, the following nine steps will assure quick, easy startups when the snow melts and warm weather returns this coming spring. 

01 Replace Engine Oil

Old oil contains moisture and acids that can pit bearings and other engine parts while in storage. This makes draining and replacing it a top priority in the offseason. To do this, begin by warming up the engine, while in water, so most of the dirty oil containing all of the impurities will flush out more easily.

Next, after draining the used oil, replace it with high-quality oil and filters as recommended by your engine’s manufacturer. It's also recommended that the oil and filter in 4-stroke outboard motors are changed before storing for the winter.

02 Flush and Drain Cooling Water

To stop the damage from expanding water when it freezes, you must drain the water from your engine.

For inboard and sterndrive engines: Begin by flushing the engine with clean water using water muffs or a similar device to connect a garden hose to your cooling system. (Never run a marine engine without water). Then flush until the engine reaches its normal operating temperature.

Next, remove all drain plugs. These parts are typically found in the engine block and manifold. You may need to remove the water pump hose as well to drain the leftover water.

For outboard engine maintenance: Begin by making sure all drain holes are open. Then after starting the engine, clean the cooling system by flushing it with fresh water. This typically only takes a few minutes. (Use water muffs or a similar device connected to a garden hose.)

03 Stabilize Fuel

Fuel can deteriorate in as few as 60 days, causing plaque and varnish to build up in the engine. This results in hard starting, poor performance, and lessens the lifespan of the engine.

The quickest way to counter these problems is by adding a high-quality marine fuel stabilizer to prevent fuel deterioration.

After adding the proper amount of stabilizer, fill the tank with fresh fuel to prevent condensation that can lead to internal corrosion. Next, run the engine for a few minutes to mix the treated gas throughout the system—either while your boat is in water or while using water muffs or a similar device designed to run the engine with a garden hose.

Remember that draining gasoline does not stop all varnish formation in engines, as there is always a bit of fuel left behind. Gaskets can also dry out and break while in storage causing leaks in the spring.

04 Protect Internal Engine Components

While in storage, engine oil drains away. This exposes internal engine components to the elements in winter and can lead to cylinder scruffing due to corrosion and metal-to-metal contact come spring.

These issues are easily avoided by using a fogging oil spray. This type of aerosol is formulated to seep deep into the engine and coat parts with a protective layer of anti-corrosive compound.

05 Replace Gear Oil

Draining the lower unit of used gear oil and replacing it with a fresh supply is of utmost importance. When changing the gear oil, also check for moisture. If water comes out first or if milky or lumpy oil is present, your boat may be experiencing moisture contamination. This indicates that your boat may require new seals before next season.

06 Grease and Lubricate

Find all your engine’s grease fittings by checking the owner's manual. Then use a marine-grade lubricant to protect against rust, corrosion, and oxidation while in storage.

07 Remove Valuables

Marinas receive light traffic during the winter, which increases the risk of break-ins. Make sure that all valuables, including expensive electronics, are removed. It may be worth considering insuring your boat, even while it’s not on the water.

08 Clean and Wax

09 Cover

The best place to store a boat is in dry storage, but this can be quite pricey. At a minimum, cover your boat with a strong, durable cover. Another option is to shrink wrap your boat, but this tends to add to the workload come spring.​

Bedford Regional Water Authority
1723 Falling Creek Road • Bedford • VA 24523

How to Winterize a Boat