DIY Boat Winterizing

Published: Sunday, August 29, 2021
By: Dan Armitage

For the first time in two decades, I find myself owning a sterndrive-powered deck boat—sterndrive being the operative word. My last “I/O” was at the stern of a Sea Ray Weekender and the boatyard where I kept it docked at on Lake Erie would handle the winterizing. This time around, properly putting the trailered deck boat rig to bed for the winter is on me.

Here in the Great Lakes, where winter gives us several months of frigid weather, it is those freezing temperatures that are the biggest threat to boats and motors alike and also what makes winterizing an annual task.

Basically, “winterizing” means storing your boat properly, making sure engines and drives are protected, and rendering the boat’s plumbing system freeze-proof. To start, the safest place to store a boat any time of year is on land, eliminating the chance that it will sink due to a battery of threats. Cradles, jack stands, rack storage, and trailers are all off-season storage options. Bigger boats are typically stored ashore in cradles or on jack stands. Trailerable craft, such as my 20 foot Sun Chaser deck boat, are usually left on the trailer over the winter.

If using jacks, assure that the stands rest on cement or plywood so they can't sink, and that the stands are tethered together so they can't slip away from the boat. If you store your boat on a trailer, take the load off the tires by blocking up the hull, cover the tires to protect them from damaging UV rays of the sun, and angle the boat bow-high to allow any water to drain through the deck scuppers or garboard. In any case of a boat being stored outside in the Great Lakes, a properly fitted winter cover with secure support to allow it to shed snow is critical.

The key to winterizing is getting water out of places where it will cause damage when it freezes. When water freezes, it expands by nearly 10 percent in size, creating enough pressure to crack an engine block, destroy an exhaust manifold, total a toilet, or ruin a refrigerator. Drain or treat with RV-style antifreeze everything that could hold H2O over the offseason.

Most boat engines use raw water for some parts of the cooling system, and the water must either be drained or replaced with antifreeze. Outboards can usually be drained simply by tilting the engine all the way down, but for inboards and sterndrives like mine, the preferred method is to circulate antifreeze throughout the cooling system. To do so, antifreeze is drawn into the engine's raw-water intake, replacing the water. You can use a bucket and hose to do so, but there are systems available that make the task easier.

The latter was my biggest challenge, going from an outboard to a sterndrive-powered craft. That and checking the power-steering fluid levels... and the acrobatics required to remove and replace my engine’s oil drain plug way, way down in the bilge.

Some bullet points for DIY winterizing:

Fill the gasoline tank to no more than 90% capacity to allow for expansion and treat the fuel with stabilizer, or completely drain the tank to avoid condensation, ethanol issues, and stale gas at the start of next season.
Fog the cylinders of gasoline engines to protect against internal rust.
Change the oil in the engine and sterndrive or lower unit before putting the boat away for the season to prevent old, acidic oil from damaging internal parts.
Flush outboards and tilt them to the lowest position to prevent water from pooling inside and freezing.
Remove batteries and place them on a marine-grade trickle charger indoors in a well-ventilated area.
If critters are a potential problem, ward them off by placing aluminum pie pans filled with mothballs, commercial rodent repellent, or Irish Spring soap bars or shavings in critical areas aboard.
Visit your boat on a regular basis during the off-season to check that everything is ship-shape.

About the Author
Dan Armitage is a popular Great Lakes-based outdoor writer and host of the Buckeye Sportsman show (buckeyesportsman.com), syndicated weekly on 30 radio stations across Ohio. Dan is a certified Passport to Fishing instructor and leads kids fishing programs at Midwest boat and sport shows, and is a licensed Captain with a Master rating from the US Coast Guard.

A version of this article appeared in the Fall Issue (September/October) 2021 of Great Lakes Scuttlebutt magazine.

tags: Do It Yourself (DIY), Winterization