Seaworthy | From The BoatUS Insurance Files


Winterproof Your Boat

By Beth Leonard
Published: October/November 2013

Whether you live in Alaska or Alabama, these nine winterizing steps will get you back on the water faster come spring.

5. Clean up and clear the air. With all that stuff off the boat, cleaning is a whole lot easier. Scrub the decks and get rid of the ugly stains that bothered you all summer. Pull out the anchor rode and rinse it of mud and seaweed, then scrub out the anchor locker. Clean the black scum out of the corners of the lazarette and other deck lockers. Wash your lines in a big bucket with warm, soapy water (use a mild dish or laundry soap to prevent damage); dry them in the sun before stowing them again. Check your sails and canvas to see if they need cleaning or repair. Below, wipe out lockers and drawers, as well as wood and plastic cabin surfaces, with a 10 percent vinegar solution. Clean hatches, portlights, and see-through plastic curtains inside and out (use soapy water on plastics like Plexiglas, Lexan, or acrylic curtains rather than ammonia-based cleaners). Clean the cabin sole, then pull up the floorboards and clean out the bilge. You'll probably find a few things that went missing last summer while you're down there. To keep the boat mold-free and smelling fresh all winter, leave the interior doors and lockers open so air can circulate. If you're covering the boat and have a small, relatively protected portlight in the head or in the cockpit footwell, leave it open to increase the airflow. If your boat has suffered from mold in the past, put out some desiccant like DampRid.

6. Winterize your engine. Your engine manual will have detailed winterizing instructions. You'll find general recommendations for inboards, outboards, and sterndrives on our BoatUS winterizing web page. Empty small gasoline tanks if at all possible. Add fuel stabilizer to large, integral tanks and then top them off. Top off diesel fuel tanks to limit condensation. Change your engine oil and replace all filters. Check hoses, belts, and clamps; clean strainers. Open and close all thru-hulls. If the boat's in the water, leave them closed (except those on cockpit drains); if out of the water, leave them open. Top off the batteries, then disconnect them and clean the terminals. If the boat's in the water, reconnect them so they can operate the bilge pump and high-water alarms. If the boat's out of the water, you might want to take your batteries home and leave them on a trickle charger throughout the winter.

Photo of engine drain plugs
Photo: John Tiger
Some engines have multiple drain plugs — check your owner's manual to find them all.

7. Freeze-proof your boat. The expansion of water when it freezes can crack an engine block, damage fiberglass, split hoses, or destroy a refrigeration system. Where you can't drain water, you need to use enough of the right kind of antifreeze to protect against the lowest temperatures your boat might experience. Pump out the water tanks, drain the hot-water heater, sponge out bilge water that the bilge pump can't remove, and drain live wells. Run nontoxic antifreeze not just through the raw-water cooling system of an inboard engine — don't forget the raw-water strainer! — but also through any parts of the pressure-water system you can't drain, as well as heads and associated plumbing, ice makers, air conditioning pumps, sump pumps, and bilge pumps. On trailerable boats, make sure the drain plug is left out and the front of the trailer is raised slightly to assist with drainage.

8. Wax and shine. It may seem counterintuitive to wax your boat before laying it up instead of after, but the best way to protect your boat's gelcoat and to keep her shining like a mirror for many years is to do both. See "How To Make Your Fiberglass Gleam".

9. Cover the boat. A good boat cover keeps snow from accumulating on the decks, melt or rainwater from pooling and freezing in the cockpit, and air circulating above decks and below to minimize mold and mildew. It also protects the topsides and decks from pollution, bird calling cards, and the weather. A custom-made, heavy-duty canvas cover is the best solution, but also most expensive. Many owners build their own covers, and most yards will shrinkwrap boats for a fee. Whatever method you use, the cover must be adequately supported and tapered so that large amounts of snow will slide off rather than pile up. Make sure there are spacers to hold the cover off the topsides to improve ventilation and minimize damage to gelcoat and paint. Covers for boats over 30 feet or so should also have a couple of weatherproof vents to encourage air circulation.

It may sound like a lot of work, but if winter messes with your boat, you could lose half the boating season fixing a cracked engine block or dealing with a badly molded interior. These nine steps will increase the odds of an uneventful winter, and help you make a fast getaway come spring.End of story marker

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