Winterizing Your Boat

Photo of winter boat storage ashoreBoats properly stored ashore and winterized are most likely to hit the water without damage and be ready for on-the-water fun come spring.

It's that time of year again. The leaves have started to change color, and the nights are getting longer and cooler. Before the mercury dips below freezing, you need to prepare your boat for the coming winter. At its most basic, winterizing means draining any water aboard or replacing it with enough of the right kind of antifreeze to protect against the lowest temperatures your boat might experience.

Fresh water expands in volume by about nine percent when it freezes and can push outwards with a force of tens of thousands of pounds per square inch. That expansion can crack an engine block, damage fiberglass, split hoses, or destroy a refrigeration system overnight. An analysis of ten years of freeze claims from the BoatUS Marine Insurance claim files found that more than three-quarters involved cracks in the engine block or the exhaust manifolds that occurred because water remained in the engine or cooling system during a hard freeze.

Those claims come from all over the country, not just from the states that get snow every year. Boaters in the frozen North know they need to winterize, so their freeze claims almost always involve a problem with how the boat was winterized. In the temperate South, the claim files include many more claims where the boat wasn't winterized at all, or where the boater was depending upon a heater to keep the engine from freezing and the electricity went out.

Most of those who don't winterize, or don't winterize properly, only find out something is wrong in the spring when brown froth starts spewing through a crack in the side of the engine block or what looks like chocolate milk appears on the dipstick. Repairing freeze damage takes time and all too often involves a complete engine replacement. By the time the boat is in working order, a good part of the boating season will have been lost. Winterizing most boats takes from an hour to a day. Unless you are located in Hawaii or the Florida Keys, we recommend winterizing your engine if you will be laying up the boat for even a few weeks to minimize the chances that a sudden freeze will put it out of commission next season.

While winter layup lists can run to several pages and take a month of Sundays to complete, many of those lists include maintenance and cosmetic items that, while nice, don't make it any more likely your boat will get through the winter unscathed. Even if we have the best of intentions in September when we put together our fall work list for the boat, life tends to get in the way, and all too often we find ourselves rushing to the boat the weekend before a hard freeze is forecast. At that point, all we have time for are the essentials that will protect our boat from damage.

In The Boater's Guide To Winterizing, you'll find the list of items that would have prevented more than 95 percent of the freeze claims handled by the BoatUS Marine Insurance Program in the past decade. Of course, every boat is different, and you'll want to add other items from the owner's manuals for your boat and the additional equipment it carries. The checklist can serve as the starting point for creating your own winterizing list that will maximize your boat's chances of coming through the winter without damage. 

— Published: September 2014

Seaworthy, the damage-avoidance newsletter, is brought to you by the BoatUS Marine Insurance Program. For an insurance quote, please call 1-800-283-2883 or apply online at BoatUS.com.