Winter is coming, and if you live in a region where temperatures drop, it’s time to winterize your boat. Even if you’re lucky enough to boat year-round in places like South Florida, where winter is more of a rumor than a reality, proper storage is essential to keep your boat in prime condition. If you keep your boat in a hard freeze zone like Chicago or New Jersey, the need to winterize your boat is a given. And for those in regions with unpredictable cold snaps — such as the Carolinas, Chesapeake Bay, or Northern California — winterizing is the best way to avoid costly damage and ensure a hassle-free return to the water in the spring.
This article is a general introduction to the products used and the practices employed in the winterization process.
- The Risks of Not Winterizing
- Antifreeze: Your Ally Against Jack Frost
- Virgin Antifreeze is Best
- Selecting Antifreeze Based on Value
- Typical Winterizing Tasks
- Winterizing FAQs
- Related Articles
The Risks of Not Winterizing
Left unprotected, cold temperatures can cause water in the engine, the freshwater tank, sanitation, or other systems to freeze, which can cause expensive damage to system components and connections. Freezing temperatures also cause fuel and oil chemistry to change, which can adversely affect engine performance. In addition, inactivity can cause the engine’s internal surfaces to rust.
Here are some of the maladies that can befall an unprotected boat during storage:
- Corrosion can occur on internal engine surfaces during storage once engine oil stops circulating and drains away into the pan. Fogging oils help prevent corrosion by forming a protective shield on internal engine components such as pistons, rings, and cylinder walls. These additives are sprayed into the engine prior to storage. Crankcase oil stabilizers perform a similar function but are poured into the crankcase instead of sprayed directly onto the cylinder walls.
- Varnish and gum form in fuel when it is left in fuel systems for long periods of time, especially in winter. Fuel stabilizers can help keep gum and varnish from forming. These additives are poured into the fuel tank prior to storage.
- Freeze damage can occur anywhere in the engine cooling system or potable water system. Because it is difficult to make each system completely clean and dry, antifreeze is used in these systems to prevent the water that remains from freezing. By pumping antifreeze through a water system in the fall, boaters can keep the hoses, pumps, tanks, and other plumbing from freezing in the winter.
Antifreeze: Your Ally Against Jack Frost
Antifreeze is an additive which, when added to water, lowers the freezing point of the water molecules. The freeze-proof ingredient in antifreeze is either ethylene glycol or propylene glycol. Ethylene glycol makes a good antifreeze/coolant but is a deadly poison, which makes it dangerous to pets and wildlife and makes disposal problematic. Propylene glycol (PG) is odorless, tasteless, biodegradable, and non-toxic. It’s as effective in freeze protection but is more expensive to produce.
There are three main types of marine antifreeze: potable water system, engine winterizing, and engine antifreeze/coolant, which vary according to the additives in them.
Engine system antifreeze/coolant should never be used in potable water systems, due to the potential presence of toxic ingredients.
Virgin Antifreeze is Best
It’s common to recycle PG that is used in aircraft de-icing and to sell it for use as marine and automotive antifreeze. Due to the contaminants that may be present, we recommend that you buy virgin PG products that have not been collected off the tarmac of an airport. While virgin PG products cost more, they are worth it — especially if they are to be used to winterize drinking water systems.
Selecting Antifreeze Based on Value
The main thing you are paying for is the amount of PG in the product. PG levels vary from around 25% to 95%. More PG in the product means you have to use less to achieve a certain level of freeze protection. Products that advertise protection to -50°F may require that you use 100% of their product to reach this level of protection, while other products can be diluted 1:3 with water and still hit -50°F. In other words, you need to know the recommended dilution of the product to reach a desired level of protection, as well as the price, to make a value comparison.
Typical Winterizing Tasks
The following tasks are typical to what boat owners do to winterize a boat. The actual tasks required will vary according to how your boat is equipped. We suggest you create a winterization checklist based on your boat’s owner’s manual. For specific step-by-step procedures, see the related articles at the end of this page.
Start with a Clean Boat: A clean boat will fare better during periods of inactivity and reduce the prep work required when it’s time to use it again. Thoroughly clean and wax the hull, deck, and all hardware and trim. Check fiberglass and gelcoat for damage and make necessary repairs. Clean windshields and any fabrics such as canvas covers, Isinglass, and Bimini tops. Dry canvas completely before storing it neatly, preferably indoors.
Flush Your Engine’s Cooling System: Giving your engine’s cooling system a good freshwater flush to remove dirt and debris, followed by treating the system with antifreeze, is essential to protecting your outboard, inboard, or sterndrive engine against freeze damage. West Marine offers a number of Antifreeze Winterization Kits to make this process easy, including our Engine Winterizing Kit and Camco’s Inboard/Outboard Winterizing Kit.
Protect Potable Water, Sanitation, and AC Systems: If left unprotected, all of these systems can suffer freeze damage. Treating them with PG antifreeze is the best way to ensure against unwanted surprises come spring.
Install a Water Heater Bypass Kit: If your boat has a water heater, installing a water heater bypass kit gives you the ability to isolate the hot water heater from the rest of the freshwater system so it can be emptied independently. This prevents you from having to fill the hot water heater with antifreeze, which is costly but unavoidable without this device.
Treat the Fuel System: Fill the fuel tank with fresh fuel to prevent condensation buildup during storage. Replace the fuel filter or install a water-separating fuel filter if you don’t have one. Treat your fuel system with a fuel stabilizer following the manufacturer’s instructions to prevent gum and varnish buildup. After adding the stabilizer, run the engine for a few minutes to circulate it through the system.
Fog Your Engine: To prevent rust and corrosion during storage, spray fogging oil into the engine where it will coat cylinder walls and other surfaces. Fogging oil forms a protective barrier without leaving residue or causing excess smoke when the engine is restarted.
Change the Engine Oil and Gear Lube: Change the oil and filter in inboard engines and four-stroke outboards. Run your engine up to normal operating temperature first, since warm oil drains more completely. Drain and refill the outdrive gear case or outboard lower unit to avoid damage from water and impurities freezing inside. Look for signs of water intrusion in the gear oil — a milky appearance indicates a failed seal that should be repaired before spring.
Lubricate Bearings, Fittings, and Hardware: Lubricate all fittings on the sterndrive, steering system, and engine trim mechanism. Use a moisture-displacing lubricant on hinges, latches, and metal parts. Inspect and grease wheel bearings on trailer boats and apply water-resistant grease to the propeller shaft.
Thoroughly Inspect Your Boat: Take the opportunity to inspect potential problem areas. Look for signs of corrosion, wear, and rough operation in steering and control systems. Inspect fuel lines, hoses, and wiring for any damage or leaks. Tighten hose clamps and check engine belts for wear. Replace parts showing excessive wear or corrosion, including sacrificial zinc anodes.
Prevent Moisture Damage: Remove any standing water and debris from bilge compartments, lockers, and storage areas. Clean these thoroughly and use moisture absorbers to prevent mold and mildew. Clean and dry cushions and store them upright to promote air circulation.
Remove Unnecessary Gear: Take off any gear that doesn’t need to remain on the boat during winter — life jackets, ropes, and electronics. Store these items indoors to avoid dirt, moisture damage, and theft. Remove the marine battery, clean its terminals, and store it in a cool, dry place. Check and recharge the battery periodically during the off-season.
Cover Your Boat and Check it Often: For the best protection, store your boat in a climate-controlled space. If that’s not possible, use a high-quality cover. In harsh climates, professional shrink-wrapping offers the best protection, but a custom-fitted cover can work well too. Make sure the cover is secure and check it regularly for snow, debris, and water buildup.
Winterizing FAQs
Why is winterizing my boat important?
If you keep your boat in an area subject to a hard freeze or even an occasional cold snap, winterizing helps protect your boat’s engine, plumbing, and other systems from damage caused by freezing temperatures, corrosion, and inactivity. It helps ensure your boat is in top shape when you bring it back to life in the spring.
Do I need to winterize my boat if I live in a warm climate?
If you live in a mild climate like South Florida, where freezing temperatures are rare, full winterization may not be necessary. However, it’s still important to protect your boat against humidity, mold, and general wear during periods of inactivity.
What can happen if I don’t winterize my boat?
Skipping winterization can lead to expensive repairs. Water left in your engine or plumbing can freeze and expand, causing cracks and leaks. Fuel can degrade, forming varnish and gum that clog the system, and internal parts can corrode due to condensation.
How do I prevent my engine from freezing?
Run antifreeze through the engine’s cooling system and use fogging oil to coat and protect internal surfaces from corrosion. See the specific guides for your engine type in the related articles below.
What kind of antifreeze should I use?
For potable water systems, use propylene glycol (PG)-based antifreeze rated for drinking water systems. Never use ethylene glycol antifreeze in potable water systems — it is toxic. For engine cooling systems, use engine-specific antifreeze/coolant. Always use virgin PG antifreeze to ensure it is free from contaminants.
Can I use recycled antifreeze?
Recycled antifreeze is available but may contain contaminants from prior use. Virgin antifreeze costs more but provides peace of mind, especially for potable water systems where safety is a top concern.
What is fogging oil, and why do I need it?
Fogging oil is sprayed into your engine’s intake to prevent rust and corrosion on internal metal surfaces during storage. It protects cylinder walls, pistons, and rings during long periods of inactivity.
Should I cover my boat during winter storage?
Yes. Covering your boat protects it from moisture, dirt, and debris. Shrink-wrap provides the best protection against rain and snow. Canvas covers or tarps can also work well, provided you monitor them closely for snow and water accumulation.
How can I prevent mold and mildew during storage?
Controlling moisture is essential. Make sure your boat’s bilge is completely dry before storage. Use dehumidifier crystals to absorb excess moisture. If you shrink-wrap your boat, ensure the cover has self-adhesive vents to promote airflow. Low-wattage air dryers placed in enclosed areas help control moisture in larger cabins.
What are de-icers, and do I need one?
De-icers are small motors that circulate water to prevent ice formation around your boat. If you store your boat in the water during winter, a de-icer helps avoid hull and dock damage caused by ice forming around the hull.
Conclusion
When the geese fly south, it’s your cue to winterize your boat. By protecting its engine and systems with antifreeze, fogging the engine to prevent rust, and treating your fuel system, you’ll ensure your boat is ready for a hassle-free start to boating season in the spring.
We’re Here to Help
Whether you’re getting your boat ready for winter or gearing up for spring adventures, West Marine is here to support you. Find your nearest store for expert advice, winterization products, and hands-on help.