4 Boat Winterizing Mistakes that Could Sink Your Ship (With Tips to Avoid Them)

boat winterizing mistakes
Aovid boat winterizing mistakes to that could cost you your boat. Photo courtesy of BoatUS

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Common boat winterizing myths or mistakes that can cost you big in repairs, or even destroy your boat

If you live in a boating climate where the temperature drops below freezing in the winter, then winterizing is one of the most important things you should do with your boat maintenance each year.

Despite whatever wive’s tales or myths you have heard about saving you time or money in your winterizing routine, there are no short-cuts if you want to do it right and avoid damaging your boat.

Boat Owners Association of The United States (BoatUS) helps to set the record straight by sharing their experiences seeing “boat winterization gone wrong”. And as one of the biggest providers of boat insurance programs they have seen it all… the good, the bad and the ugly when it comes to mistakes that will cost boaters their boat.

Mistake #1: Not Filling the Tank with Fuel

If a boat has a built-in gas tank, it’s recommended to leave the tank as full as possible over the winter with a smidgen of room for fuel expansion.

Leaving the tank nearly full limits the amount of moisture that can potentially condense inside on the tank’s walls as outside temperatures fluctuate, preventing phase separation of ethanol (E10) fuel. Note one caveat: If your boat is stored in a rack system or indoor storage, check with the marina. They may require you to empty the tank to minimize the risk of fire.

TIP: Never plug a fuel vent. Ever.

Mistake #2: Adding Fuel Stabilizers to “Fix” Gas Issues

Some boaters think that come springtime, any phase-separated gasoline in the tank can be fixed by adding a fuel stabilizer or additive. But that is a myth – once gasoline phase separates, that’s it. Kaput. End of story. The only solution is to have a pro remove the contaminated fuel and water mixture and start anew — a difficult, hazardous and costly task for boats with built-in fuel tanks. However, it’s critical to use a fuel stabilizer each fall to help keep fuel fresh over the winter, keep corrosion at bay and to help prevent the onset of phase separation.

TIP: Put the stabilizer in before you nearly fill the tank for its long winter nap. This will allow stabilizer to fully course through the fuel system as you run the engine when filling with anti-freeze.

Mistake #3: Not Anticipating a Winter Freeze

BoatUS notes that while there are quite a few claims from the colder climates, many boat insurance freeze damage claims also come from southern, temperate states hit by an unexpected freeze or when space heaters fail due to sudden storm power loss. In the northern climes, storm power outages also are to blame for engine block freeze related claims, however, both areas of the country have their fair share of winter freeze claims due to one reason: the failure to follow winterizing procedures.

TIP: Don’t let your buddy do the job – it’s a common refrain BoatUS claims staff hears every spring after a cracked block is discovered. Having your marina winterize your boat and systems may offer better protection if there is an issue come springtime. Another option is adding ice and freeze insurance to your boat insurance – most insurers do not charge much for it, but there are deadlines to purchase.

Mistake #4: Using a Space Heater to “Winterize” Boats

It’s never okay to “winterize” the boat by leaving a space heater running onboard. In addition to the sudden power outage problem, every winter BoatUS sees fires from heaters, plugs and cords, and from heaters that were left running on unattended boats.

According to BoatUS, the boat shown above was “winterized” by placing a space heater in the engine room. While afloat in the slip, it caught fire when the extension cord used to power the heater shorted.

Unless you live in Hawaii or the Florida Keys, BoatUS recommends winterizing your engine if you will be laying up the boat for even a few weeks to lessen the chances of sudden freeze damage.

TIP: Save time and make winterizing easier by installing an engine flushing system — typically a simple valve with a connection for a garden hose along with an anti-freeze pick-up hose/strainer — on your engine.

guide winterizing boatMore Boat Winterization Tips

While water may be your life in the summer, water is an enemy to your boat engines in the wintertime.

For more tips on the proper way to do boat winterization (including marine products you should use, engine care and winter storage tips), be sure to check out “The Boater’s Guide to Winterizing“, a free how-to guide compiled by BoatUS.


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Diane Seltzer

View posts by Diane Seltzer
Diane is the founder of MyBoatLife.com as well as the boating lifestyle site for kids BoaterKids.com. Active in the boating industry, Diane has also led the marketing for multiple recreational boating businesses and startups.
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