As the boating season draws to a close for most of the Northern Hemisphere and colder months approach, it’s inevitably time to prepare your boat for winter. Winterizing your boat is essential to protect it from the elements and ensure it's in top condition when spring rolls around. Whether you're learning how to winterize an outboard engine, store a boat for winter, or prepare plumbing systems for freezing temperatures, this guide will walk you through every step.

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Above: A few sailboats remain moored out on the water in late fall. Photo by Marta Wave.


Should You Take Your Boat Out of the Water for Winter?


The first decision when winterizing your boat is whether to store it in or out of the water. If you’re trailering a small boat, the choice is simple, but larger boats may pose a dilemma. Hauling your boat out of the water for the winter prevents potential freeze damage and reduces the risk of sinking, but it comes with associated costs. Learn more about the risks and benefits by reading In the Water Winter Boat Storage.

Boat In Winter Covered In Snow On Dock

Above: A small boat covered in snow sitting on a dock upside down in the winter. Photo by M. Ivserg via Pond5.


The Best Way to Cover Your Boat


No matter where you store your boat, covering it properly is crucial. Your options include plastic tarps, canvas covers, and fitted covers. While DIY methods can save money, hiring professionals for a custom-fitted canvas or shrink-wrap cover may offer superior protection against snow, ice, and UV rays. For more detailed advice, read How to Cover a Boat and Should You Shrink Wrap Your Boat?.


Winterizing Water Systems


To prevent freeze damage to water systems, potable antifreeze must be flushed through all onboard plumbing, including faucets, showers, and washdown systems. Use propylene glycol antifreeze (the "pink stuff") to ensure safety. Check out our detailed instructions on winterizing freshwater and raw-water systems for further guidance.

Sanitation and Air Conditioning Systems


Marine sanitation systems and air conditioning units require special care during winterization. Pump antifreeze through all components, including the heads and air conditioning systems, to avoid freeze damage. Consult manufacturer recommendations when in doubt.

How to Winterize an Outboard Engine


Winterizing your outboard is a key step in boat winterization. Tasks include changing the lower unit oil, flushing the cooling system, and fogging the engine if it will be idle for extended periods. Watch our video guides for step-by-step instructions: How to Change Lower Unit Oil and How to Winterize a Four-Stroke Outboard.

How to Winterize Inboard Engines and Stern Drives


Inboard engines and stern drives require careful winterization to prevent freeze damage in the cooling system. Running antifreeze through the engine block and exhaust system, along with changing the engine oil and gear lube, are essential steps. Watch our video on How to Winterize Your Stern Drive and Pressure Water System for more details.

Fuel Systems


Proper fuel treatment is essential to avoid issues like condensation and ethanol-related damage. Adding a fuel stabilizer and changing filters are necessary steps to protect your fuel system during winter. Read Winterizing Your Boat's Fuel Tank for expert advice on fuel storage.

Batteries


Disconnect your boat's batteries and keep them on a trickle charge to prolong their lifespan during the off-season. If you don't have a solar or electrical hook-up, store your batteries indoors and use a charger designed for your battery type. More tips are available in our Basic Boat Battery Check-Up and Maintenance guide.

Final Winterizing Tips


After completing the major winterization tasks, don’t forget to clean your boat thoroughly, remove sensitive equipment, and check all stowage compartments for items that could freeze and cause damage. For a detailed checklist of last-minute tasks, refer to the final section of our guide.

Editor's Note: This article was originally published in 2015 and was last updated in October 2024. 

Written by: Gary Reich
Gary Reich is a Chesapeake Bay-based freelance writer and photojournalist with over 25 years of experience in the marine industry. He is the former editor of PropTalk Magazine and was the managing editor of the Waterway Guide. His writing and photography have been published in PassageMaker Magazine, Soundings, Fly Fishing in Salt Waters, Yachting Magazine, and Lakeland Boating, among others.