Although we live in the southern regions, that doesn’t mean we are not prone to freezing temperatures. When you’re being faced with freezing weather, its important to understand what goes into winterize a boat. The steps are very straightforward and do not require a significant amount of time but can save a substantial amount of money in repairs. 

Why Should A Boat Be Winterized?

A boat should be winterized to avoid batteries and engines from freezing up and cracking. I have had the opportunity to winterize boats before the onset of harsh conditions. Take it from me cracked engine blocks and batteries are easily avoidable by following simple procedures. 

Outboard Engine Preparation To Winterize A Boat

Products needed from a local auto part store

  1. Fuel Stabilizer
  2. Engine Fogger Spray

Start by stabilizing the fuel. How does a fuel stabilizer help? Fuel that sits for extended periods can become sticky. The stickiness will gum up the engine. Additionally, it aids in reducing evaporation and repels water.

Measure and add the appropriate amount of stabilizer to the gas tank. In your driveway, attach a garden hose and fire up the engine. Run the motor for five to ten minutes; this will be enough time for the stabilizer to make it into the engine. 

Have the fogger spray handy. What does an engine fogger do? Fogging spray is a lightweight oil that coats the inner parts of the engine. This coating prevents moisture buildup, which in turn causes corrosion and rust. To apply the spray, disconnect the fuel line and run the motor.

As the engine begins to sputter from lack of fuel, spray the oil into the fuel line for a full coating. Once the engine dies, remove the spark plugs and spray fogging oil into each cylinder. 

With the garden hose still connected, thoroughly rinse the inner cooling system. Do this for about two to three minutes. Once this is complete, tilt the engine all the way down so that the water completely drains out. I highly recommend making sure that all of the water has drained. Undrained water may lead to internal cracking of the engine.

The lower unit is also susceptible to freezing weather damage. Drain the gear oil in the lower unit and replace it with fresh oil. Water can be found in the lower unit, thus causing it to freeze, expand, and damage the lower unit. Should the oil be milky during the draining process the engine is likely to have a more serious problem and requires a mechanic.

Inboard and Inboard Outboard Motor Preparation To Winterize A Boat

The routine is very similar to an outboard, except for a couple of steps.

Follow the same procedures for the gear oil.

Apply stabilizer to the fuel tank and run the engine. 

Fog the fuel line while its running and then coat the cylinders with spray.

The key difference between inboard engines and outboards is preparing the cooling system. The process is simple.

  1. Remove the hose that connects to the raw water intake.
  2. Have a five-gallon bucket full of antifreeze.
  3. Place the hose in the antifreeze and run the engine.
  4. Run the engine until the antifreeze is running out of the exhaust. 

Battery Preparation

Pull all of the onboard batteries out of the boat but remember to label the connections to reconnect in the spring. 

Move the batteries to your basement or an area that they will not freeze.

Attach a trickle charger that is rated to the type of batteries you have. Keep them charging all winter long. 

Winter Storage For A Boat

Depending on where the boat will be stored, the process can be slightly different. If possible, keep the vessel in a garage or indoor storage facility.

Thoroughly clean both the interior and exterior of the vessel. Dirt and grime left on surfaces can lead to permanent staying if it remains for extended periods.

Remove all valuables such as fishing equipment and electronics if the boat will not be at your home.

Lock the hitch and place blocks by the wheels to avoid the trailer from moving. 

Cover your boat with the fitted fabric it came with. If it does not have a cover, purchase a tarp large enough to enclose the vessel fully. 

Shrinkwrapping is another excellent option. Shrinkwrap will eliminate dirt and debris from entering through the winter months. Call your local marinas to see who offers this service. The cost typically comes at a per foot rate. 

Use this out of service time to inspect the trailer. Tires, bearings, lights, etc. can all be worked on during this time. I utilized out of service time to pull and replace bearings every other year to ensure I would not have any issues during prime boating season.


Take it from me, the task may sound daunting, but in all reality, it is actually quite simple. Don’t be the dummy who was too lazy to take care of it. When the next season starts, you may be shelling out thousands of dollars in avoidable expenses. Now your budget for new boating toys, electronics, and fishing gear is wiped away. Ask a friend who you boated with all summer long for a lending hand; the work will be quick between the two of you.