How to Winterize Your Boat Before Storing It

When preparing your boat for winter storage, one of the most important decisions is choosing the right storage option. The type of storage you select — whether indoor or outdoor, at home or in a self-storage facility — has an impact on the winterization process. Below is a breakdown of the different storage options and how they affect the steps you need to take to ensure your boat remains in top condition throughout the winter months.

Indoor Storage

Indoor storage offers the highest level of protection for your boat during the winter. Heated, climate-controlled storage facilities provide the best protection against freezing temperatures — you can cut down on the amount of antifreeze you need and worry less about moisture damage. On the other hand, unheated indoor storage protects your boat from rain, snow, wind and debris, but you’ll still need to perform a full winterization, including draining water systems and adding antifreeze to prevent freezing.

Outdoor Storage

Whether you’re parking in your driveway or self-storage facility, invest in a simple tarp, a custom boat cover or a covered parking space to protect your boat from snow, ice and UV rays. Without one, your boat will be exposed to all weather conditions, making it crucial to follow all winterization steps meticulously. Many storage facilities offer covered parking spots that offer protection from the elements and gated entry to ensure your boat is secure.

Cleaning and prepping the inside of your boat is an important first step in winterizing. Proper care and maintenance will protect the interior — including seat cushions, wood and other materials — from mold and mildew that may develop over the winter. Here are some things to consider as you’re cleaning your boat:

• Bag up and remove pillows, blankets, bedding, clothing and removable seat cushions, and prepare them for winter storage.
• Remove all gear and equipment — including fishing rods, life jackets and tackle boxes — and pack them up for storage.
• Empty out storage compartments, lockers and closets.
• Clean out and defrost the refrigerator and freezer.
• Spray vinyl seats and covers with mildew spray.
• Deep clean any appliances, carpets and floors. 
• Apply a coat of protective wax to all exposed surfaces.

Any water left in the freshwater or raw water plumbing systems may freeze during the winter, causing cracked pipes and other major damage. It's important to drain all the hoses and pipes, flush them well and refill them with antifreeze. 

Here’s a step-by-step guide on winterizing your boat’s plumbing system:

• Completely drain all holding tanks. You can do this using a water pump or simply open all the faucets and let them flow until there is no water dripping from them. 
• Drain the water heater, then install a bypass hose, which connects your cold water tank to the hot water faucet. After you install the hose, then fill it with antifreeze.
• Remove any water filters.
• Close all the water taps.
• Refill the plumbing system with propylene glycol antifreeze.

Any water left in the freshwater or raw water plumbing systems may freeze during the winter, causing cracked pipes and other major damage. It's important to drain all the hoses and pipes, flush them well and refill them with antifreeze. 

Here’s a step-by-step guide on winterizing your boat’s plumbing system:

• Completely drain all holding tanks. You can do this using a water pump or simply open all the faucets and let them flow until there is no water dripping from them. 
• Drain the water heater, then install a bypass hose, which connects your cold water tank to the hot water faucet. After you install the hose, then fill it with antifreeze.
• Remove any water filters.
• Close all the water taps.
• Refill the plumbing system with propylene glycol antifreeze.

No matter what type of engine your boat has, it needs special attention before the winter cold sets in. While all engines need to be drained, cleaned and refilled, the details differ significantly. Always check the documentation for your motor and follow the manufacturer's instructions on cleaning, caring for and maintaining the motor for your specific boat. The following tips are meant to be a general overview of the process.

How to Winterize an Outboard Motor

1. Change the lower unit oil.
2. Flush the cooling system with fresh water while the engine is tilted down.
3. For four-stroke engines, change the oil and oil filter, as well as the fuel filter and air filter.
4. Fog the engine with fogging oil to protect it from corrosion.

How to Winterize an Inboard Motor

1. Change the engine oil and filter while the engine is still warm. 
2. Fill a 5-gallon bucket with propylene glycol, ensuring you’re using antifreeze rated for engine use.
3. Remove the raw water intake hose from the closed seacock intake and drop it into the bucket of antifreeze.
4. Run the engine until antifreeze is flowing from the exhaust.
5. Fog the engine with fogging oil.

How to Winterize a Sterndrive Engine

1. Inspect the sterndrive for cracks, damage and marine pests.
2. Drain any water from the drive.
3. Fill the engine with antifreeze.
4. Drain and replace the gear lube in the lower-unit drive.
5. Check the propeller shaft for damage.
6. Check the bilge pump operation.
7. Check all the fluid levels. Top them off if necessary.
8. Plug the exhaust ports to keep out pests and weather.

Some manufacturers recommend draining the fuel tank before winter storage, while others suggest that the fuel tank should be full. Always follow the manufacturer's recommendations. Regardless, be sure to treat the fuel with a stabilizing additive to prevent separation and change the water separators and fuel filters.

Your battery also needs special treatment before you tuck your boat in for the winter to avoid battery freeze and ensure that it will charge in the spring. You’ll want to inspect the battery for signs of corrosion or wear and clean or replace it if necessary. Then you’ll want to follow these steps:

1. Charge the battery to full power.
2. Disconnect the terminals.
3. Remove the batteries.
4. Store them in a cool, dry place where they won't freeze.
5. Ideally, charge your batteries once a month or put them on a trickle charger.

There are many different options for covering your boat, each with its own pros and cons. Plastic covers are the most affordable option, but they’re less durable and need to be replaced after a couple of seasons. Canvas covers are more durable but cost a bit more. Custom-fitted covers provide the best protection but are also a more expensive option. 

Finally, many boat owners will opt to have their boats shrink-wrapped for storage. While it's the priciest option, shrink-wrapping provides the best possible seal to keep out weather, water and UV rays that can damage your boat during the off-season.

Properly winterizing your boat only takes a weekend out of your schedule, but will save you lots of time, expense and labor when it's time to recommission your watercraft in the spring. To learn more about boat storage and amenities that SmartStop offers, check out our boat storage options.