Protect Your Boat’s Deck From Ice Damage This Winter


It is the first day of fall, and that means winter is right around the corner, which is no fun sailors who live in the northern slice of the planet, unless, of course, youre an ice-boater or frost-biter-in which case, Im happy for you (spoken like a true Floridian). Of all the many evils that winter visits upon our boats-mold, mildew, snow, ice-one of the most insidious is also invisible. Im talking about the water, soon to become ice, that could be trapped in the core of your deck.

If you had niggling leaks at your mast, your forward hatch, or deck hardware this summer, those niggles can become nightmares when freezing temperatures begin to do their sledgehammer work upon our boats-as well as our psyche. Most decks these days are sandwich cores, which have a stiffening material, usually foam or balsa, or plywood, sandwiched between two fiberglass skins. (For a more in-depth picture of the pros and cons this construction process, check out our report on core construction.) For the moment, however, all you need to know is this: Once water enters the core of your deck through a small leak, it can often spread unnoticed. Bring on winter, and its freezing and thawing cycles, and the core begins to break down, and our light, stiff deck starts turning to Jell-O.

The freeze-thaw cycle can also break the bond between the fiberglass and the core, further weakening the deck structure and introducing new problems. In a worst-case scenario, you return to your boat in the spring and find bubbles, bulges, and cracked gelcoat or fiberglass where water has pooled and frozen, pushing your deck’s outer skin upward.

Bottom line is this: Of all the fall maintenance fun (don’t call them chores) youve got to deal with in the weeks ahead, take some time to address the leaks. Much of what youll need to carry out your own leak-repair project is right here in our archives. Our most recent report on caulks and sealants can help you find the right sealant for the job. Owners of teak decks will want to consider our tests of teak sealants. For a good do-it-yourselfer perspective on sealants and caulks, checkout PS contributor Scott Rosenthals account of his seasonal assault on leaks aboard his boat Willow.

Better yet, if you want to prevent leaks to begin with, follow the time-tested technique for sealing through-deck penetrations to prevent leaks from reaching the core when you add or re-install deck hardware. Although not a complete remedy against the scourge of winter, our boat winter-cover project can cut down on the damage done. This last article is available to non-subscribers as well. (Pass it on!)

Darrell Nicholson
Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 50 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him at