Winterizing Your Family Boat

As winter draws near and another boating season comes to an end, it’s important to properly prepare your yacht or other type of boat so it’s as good as new once spring rolls around. Incorrect winter storage can lead to costly damage, so always remember to winterize your boat’s engine and body and store it properly.

Winterizing the Engine

Flush the Engine

When a boat sits for a long time, oil, dirt, and other engine contaminants settle to the bottom. To prevent this, flush the engine with fresh water, either manually, by attaching a hose to a set of boat “earmuffs” and then attaching them to the water intake valves (for older engine models), or automatically, by hooking a hose directly to the motor (for newer models).

Drain the Engine Block or Flush with Antifreeze

Next, drain the engine block completely or flush it with antifreeze. Propylene glycol-based antifreezes are more environmentally friendly than ethylene glycol-based ones and might also be better for your engine. The flushing method depends on whether you have an inboard or outboard motor. For inboard yacht and boat motors, place the water intake hose into a bucket filled with antifreeze. The amount of antifreeze needed varies by boat model and type, but 5 gallons is a good starting estimate. Allow the motor to idle, and stop after you have seen antifreeze coming out of the exhaust outlet for at least 30 seconds. Remember to replace the intake hose in the seacock. Purchase an antifreeze kit if you have an outboard motor and connect it to the water intake valve after flushing the engine with water. You are finished with the antifreeze flush when the motor has run long enough for the entire antifreeze kit tank to empty.

Change the Oil

In addition to flushing the engine and engine block, change the engine, transmission, gear oil, and replace the oil filter. Always properly dispose of used oil  at a recycling facility. Apply fogging oil to spark plugs, engine cylinders, and carburetor intakes to prevent corrosion.

Taking Care of the Battery

When storing your boat in dry storage, remove the battery, charge it fully, and store it separately to prevent corrosion and theft. Keep an eye on battery charge and water levels during dry storage. When storing your boat in water, the battery should stay connected and onboard so the bilge pump has power if needed.

Winterizing the Fuel Tank

You can always drain the fuel tank and supply lines to winterize your boat. If you plan on leaving fuel in your boat over the winter, stabilize it to prevent fuel degradation, erosion, or clogging. Fill the fuel tank with regular gas to approximately 95% capacity. Then, add a stabilizer and run the engine for 10 to 20 minutes to evenly distribute it within the gas. It’s also a good idea to replace the fuel filter and water separator, turn off all fuel valves, and seal any exterior exhaust ports off with duct tape to limit condensation.

Protecting the Body

Clean barnacles, dirt, and scum off the bottom and sides of your boat, paying particular attention to invasive species. Pressure washing is effective, but make sure you know the boat pressure-washing laws in your area. Apply boat wax or polish after cleaning to prevent new buildup. Inspect your hull for fractures and blisters. Have cracks evaluated by a professional; pop blisters yourself, drain them of water, and patch them using an epoxy-based filler. Check your propeller for damage and perform any needed repairs. If your boat has a marine head, empty the tank at a disposal facility and then flush the bowl with fresh water and cleaner. Rinse with fresh water and add antifreeze. Wipe down interior surfaces, vacuum any carpet, and treat any vinyl with vinyl cleaner. You can install a dehumidifier (either store-bought or homemade using calcium chloride) in interior storage to help prevent mold and mildew buildup. Clean all bilges, remove drain plugs, and drain any leftover water.

Storing Your Boat

Explore your options for boat storage so you can make an informed decision.

Dry Storage

If you choose dry storage, invest in a boat cover to protect your boat from the elements, whether you choose to store it indoors or outdoors. For outdoor storage, an 8-to-10-ounce cotton cover is recommended. Make sure the cover fits your boat properly, stretching tight to ensure water runoff. If you will be storing your boat outdoors in extreme conditions, you may want to consider shrink-wrapping it instead of using a standard cover. Shrink-wrapping offers waterproof protection and is able to withstand large accumulations of snow. If you have a boat trailer, make sure to put it on blocks to take pressure off the wheels.

Wet Storage

Wet storage offers more protection from extreme freezing but can also cause blistering and be more expensive than dry storage. In colder climates, wet storage isn’t available due to freezing.

• How to Drain the Engine Block or Flush it With Antifreeze (PDF)
• Step-by-Step for Fuel Stabilization
• General Tips for Winterizing Your Boat
• Basic Checklist for Winterizing Your Boat
• In-Depth Winterization Checklist
• Boat Storage Options
• Checklist for Boat Storage
• Keeping Your Boat Fungus-Free in Storage