Winterize Boat (How to Prep Your Boat Ready for Winter) - Winterizemylife

Winterize Boat (How to Prep Your Boat Ready for Winter)

  • By: admin
  • Date: November 27, 2021
  • Time to read: 5 min.

When summer begins to fade into fall, and it’s time to take your boat out of the water, there are several things that need to be done before you put your boat away for the winter.

The freezing temperatures of winter turn water from a medium for fun in the sun into a boat’s biggest enemy.

Water left in boat systems, such as the engine, fuel, and plumbing systems, will expand as it freezes.

This can lead to damage that is expensive to repair, including corrosion, cracked engine blocks, busted pipes, and widespread mold.

Understanding how to winterize a boat helps to ensure that your boat will start up as easy as a summer breeze when the boating season comes back around.

Our step-by-step guide will cover all the necessary measures required to protect your boat throughout the off-season.

How to Winterize a Boat Step by Step

Follow our 10 step checklist to properly winterize your boat, or use this list to confirm that the winterizing professionals you hire are taking the necessary steps to protect your boat from the harsh winter elements.

  • Change the Engine Oil and Oil Filter

Leaving old oil in your boat’s engine over the winter exposes engine parts to moisture, which builds up in the oil over time. Changing the oil before storage helps prevent corrosion from the moisture and acids found in dirty oil.

A good time to change the oil is after running the boat on the water, ideally when you are taking the boat out for the last time of the season. This will stir up any impurities and heat the oil so that it drains more quickly and completely.

Once the dirty oil has been drained, replace it with fresh oil, and change the oil filter, while you’re at it.

  • Flush the Engine and Drain the Water

Draining water from your boat engine’s cooling system will prevent damage caused by freezing. First, use fresh water to flush the engine to remove dirt and grime.

Flush until the water runs clean, then remove the drain plugs so that all the water can drain from the engine. Check the water pump hose to make sure that there is no water left in it.

  • Stabilize the Fuel System

When fuel sits stagnant in your boat for two months or more, it will break down and gum up the inside of your engine. It is nearly impossible to empty all of the fuel out, so stabilizing your fuel is the best practice when winterizing your boat.

Add marine fuel stabilizer to the gas tank of your boat, then fill the tank with gas until it is full. Run the engine for a few minutes to distribute the treated fuel throughout the system.

A full tank of stabilized fuel will also prevent condensation, which can cause corrosion, and keep gaskets from drying out over the winter.

  • Fog the Engine for Corrosion Protection

Because oil doesn’t continuously coat engine parts when your boat is not running, special oil sprays are used to prevent internal engine corrosion, in a process called fogging.

Usually, fogging oil is sprayed into the engine air intake as it runs. As you continue to spray, the fuel line is disconnected so that the engine dies, and the internal parts are thoroughly coated. It is wise to check your owners manual for the recommended fogging procedure for your specific model of boat.

  • Flush the Engine Block With Antifreeze

If any water is left in your engine, it could cause damage, and even crack the engine block. Just to be on the safe side, you should flush your engine with antifreeze.

This is done by drawing antifreeze into your engine, through the engine’s water intake, as it runs.

  • Change the Gear Case Lubricant

Just like the oil in your boat’s engine, the gear case lubricant acquires moisture and grime over time. To prevent rust and corrosion from developing over the winter, you should drain old gear oil and replace it with a new lubricant.

Gearcase lubricant will be easier to change when the engine has just run, as the heat will help the dirty oil flow out more efficiently. If the oil is cloudy, or there are metal shavings in the oil, you should have your gear case looked at before storing your boat for the winter.

  • Remove the Battery for Storage

If you leave your battery in your boat over a long period of storage, it will likely die, which means you won’t be able to start your boat come spring.

Bringing your boat’s battery inside for the winter allows you to maintain it’s charge and protect it from the cold. Make sure the battery is fully charged before storing it for the best results.

  • Drain Freshwater Plumbing Systems and Add Antifreeze

As with any pipes, stagnant water that freezes inside boat plumbing can cause the pipes to crack and burst, Draining the water and treating plumbing with antifreeze will prevent this problem.

Check any other reservoirs and systems that hold water in your boat, and empty them out. This includes live wells, bilge pumps, and raw-water washdown pumps.

  • Clean the Interior and Remove Valuables

Cleaning up the interior of your boat before the cover goes on for the winter can help prevent the growth of mold and mildew, especially if you properly control excess moisture.

Vacuum carpeting and upholstery, wipe away surface grime and treat any mold or mildew so that it doesn’t spread. You should also wash the exterior of your boat to remove scum and algae buildup.

Be sure to inspect your boat for any damage, as you clean, and remove all valuables to prevent theft while the boat is unattended.

  • Cover the Boat

There are a few different cover options, including shrink-wrap and cloth covers. A good cover needs to keep rain and snow from getting into the boat while providing ventilation to allow any moisture inside of the boat to escape.

Moisture in a covered boat can cause mold, mildew, and corrosion to develop, making for a nasty surprise when you uncover your boat next season. This isn’t only bad for your health and your boat, it takes a lot of time and energy to clean up.

Make sure that the boat cover is properly vented, whichever type you use, and store your boat in a covered area, if possible.


Whether you winterize your boat on your own or hire professionals to do the job, knowing what is involved in the process means that you can make sure nothing is missed, for a less stressful start to the next boating season.

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