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Winterproof Your Boat


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

Photo: John Tiger

Yes, you read that right — Alabama. That’s where BoatUS Marine Insurance’s second most expensive ice/freeze claim came from last year. In that claim, water left in the engines of a 21-foot jet boat froze and cracked the blocks. In fact, 40 percent of the ice/freezing claims in the past year came from nine states we don’t normally associate with freezing weather, including California, Texas, Georgia, and Tennessee. Even if you keep your boat in an area with a moderate winter climate, you need to put it to bed properly. The nine steps that follow will ensure that your pride and joy has a good winter’s rest — and is shipshape and ready to hit the water as soon as spring arrives.

1. Create your personalized winterizing checklist.

Start with our “Boater’s Guide to Winterizing” PDF. Review our in-depth information on winterizing and add to the winterizing checklist any additional notes that apply to your boat. Then go through your owner’s manuals to find the specific winterizing to-dos for all your equipment. Don’t just pull out your engine manual. You’ll need to add to-do items for everything from deck-washdown pumps to refrigeration, and your boat owner’s manual may include other items as well. By the time you’re finished, you’ll have a comprehensive checklist tailored specifically to your boat.

2. Put together your winter refit list.

Take your boat out for one last spin and try to remember all those little things that bothered you over the summer. Did a leak soak a cushion down below? Maybe you have some deck fittings or a hatch that needs rebedding. Was your depth sounder unreliable? The electrical connections may need cleaning and resealing. Your winter refit list gives your nearest and dearest a handy holiday shopping list, and gives you a great excuse to spend time messing about the boatyard. Instead of thinking, “Darn, I meant to fix that over the winter. …” as you step aboard in the spring, you can revel in the sense of satisfaction that comes when you scratch that last item off your to-do list. Just don’t expect that feeling to last — it is a boat, after all.

3. Tuck your boat in.

You may choose to leave your boat in the water, tied snugly into her berth at the dock, or on the hard, either blocked up in a hardstand area or on a trailer. Whichever option you choose, make sure she’s set up well to handle the strong winds that often accompany winter storms, as well as the possibility of freezing temperatures and large amounts of snow. If you’re leaving your boat in the water, your lines need to be protected against chafe and set up to keep the boat away from the dock. If the boat will be blocked up on the hard, check that the jackstands have been placed on firm ground to take the boat’s weight evenly, and are chained together so one cannot slide out from under the hull. If you’re storing the boat on a trailer, taking the wheels off and storing them in the garage will keep the tires in good shape for next summer while discouraging thieves.

4. Clean out.

Once you’ve secured the boat in her winter berth, it’s time to get her shipshape to minimize the unpleasant surprises come spring. To keep furry guests in search of a winter meal ticket from coming aboard, empty the icebox and all food storage areas. Don’t forget the metal and plastic containers holding liquids, which can burst in freezing temperatures. Wash dishes, pots, pans, linens, blankets, curtains, and rugs. Store fabrics at home along with cushions and pillows to keep them fresh and mold-free. Take electronics home. Not only will that prevent theft, but large swings in temperature can damage those pricey screens. Send your fire extinguishers to be inspected, and take the batteries out of anything you’ll be leaving aboard like clocks and flashlights. You’ll avoid a battery leak over the winter, and start with fresh batteries 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.

Some engines have multiple drain plugs — check your owner’s manual to find them all. (Photo: John Tiger)

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.

Beth Leonard

Contributor, BoatUS Magazine