Winterization Tasks You Can Do

Posted: September 1, 2011

Here’s how to get your boat hibernation-ready on a shoestring budget.

By: Lenny Rudow

As the boating season draws to a close, it will soon be time to pack up Mom’s Mink for the winter, and chances are you’ve spent most of your boating budget on fuel. We feel your pain. If your winterization budget was consumed by summer fun, and having a yard winterize your boat is out of the question, fear not. This is a job most handy DIY guys or gals can do. Here’s how to make your larger trailerable cabin boat happy while it’s on the hard.

The head is a good place to start. Actually, it’s a lousy place to start — probably everyone’s least favorite part of the boat to maintain — but it has to be done, unless you want burst pipes and leaky fittings to drip raw sewage next spring.

If you have a portable head, the entire job can be completed by emptying it, washing it and stowing it in the garage or shed. The rest of us have to do a bit more work. Start the process by pumping the holding tank dry. Then flush the system with fresh water and pump it dry — twice. Next, you have to get some antifreeze into the lines. (Check your owner’s manual for which type of antifreeze is best; certain varieties may damage the system.) The easiest way is usually to remove the raw-water intake hose from the seacock, put it into a jug or bucket full of antifreeze and run (or pump) the head until the antifreeze gets sucked all the way through the system and into the holding tank.

Freshwater systems will also need a healthy dose of antifreeze, but in this case it’s imperative you pay close attention to the type. Common ethyl glycol antifreeze formulated for your car’s radiator (the green stuff) is highly toxic and should never be used in a freshwater system. Choose a propylene glycol formula (pink in color) that is non-toxic and provides “burst protection” to minus 50 degrees Fahrenheit. 

Drain the system by opening up the fill and all the faucets and hoses, and let them run until they sputter with air. Then close all the faucets and hoses except the one farthest from the freshwater tank. Pour antifreeze into the inlet until some runs out of the single open faucet. Then close it and open the next outlet in line (closer to the tank). Continue opening and closing each faucet and hose as you work your way closer and closer to the freshwater tank, until all the faucets have been observed running antifreeze.

For an extra dose of freeze-free security, inspect all of the system’s drain hoses for droops or loops. If you find any, lift them above the drain’s level, so any trapped water runs out. Then add a dose of antifreeze to them by pouring it down the drains.

Raw-water washdowns need protection, too. After running them dry, remove the hoses from the threaded fittings, so no water remains trapped inside. Then pull the intake hose off the seacock, put the hose into the antifreeze and pump it through the system.

Macerated fishboxes are often forgotten during winterization, and that’s one of the reasons fishbox macerator pumps seem to have a short life span. Don’t forget that in addition to the fish slime, they sucked through icy water, so freeze damage is a distinct possibility. Prevent it by pouring non-toxic antifreeze down the drain while the pump runs — and don’t stop until antifreeze comes out of the drain’s through-hull fitting.

The hull itself needs to be winterized, too. The first step is easy: Pull the plug(s) and drain any bilge water. If there are any areas in the hull that you know trap water — corners where bulkheads and stringers meet, transducer pockets or sumps — soak up any standing water with a rag, then pour some antifreeze directly into the area.

Now that all of the water’s out, it’s time to make sure it stays out. Shrinkwrapping the boat is a solid (more expensive) option, but the old standby polyethylene tarp will do the trick. (Canvas is stronger but more expensive than a tarp.) Avoid “economy” tarps that are 5 to 6 ml thick in favor of heavier-duty 11 to 12 ml tarps, and make sure they have reinforced grommets every 18 inches to 2 feet. 

You need to make 100 percent sure that water won’t pool on the tarp and snow won’t make it sag, or it’s sure to rip or collapse at some point. Depending on the type and shape of your boat, you may be able to put the tarp directly over it, or you may need to construct a frame to form a tent over the deck. In either case, make sure the boat’s windshield, the aluminum Bimini frame or a lightly built T-top isn’t going to bear the brunt of the weight. (Note: Bimini frames are best removed and stored indoors for the winter.)

Put the tarp over the boat and secure it with lots and lots of tension, which can be created by running lines back and forth under the boat or hanging milk jugs filled with sand from the grommets. Now, go back inside the boat and look for sharp edges or accessories that may wear holes in the tarp. VHF antenna mounts, windshield corners, points or corners on railings, and T-top rocket launchers are common problem spots. Cover these with a piece of carpet remnant or a thick rag held in place with duct tape. And if your boat has outboards, make sure you cover the cowls (a soft blanket or shaggy mat works well), or the tarp will wear away the outboard’s shiny finish as it shifts in the breeze.

Covering your boat with a tarp doesn’t mean you’re done. It requires some spot-checking through the winter. After a heavy snowstorm, knock off any clinging white stuff and readjust the lines if necessary to keep the cover taut. And remember that poly tarps are pretty unreliable if the wind blows more than 40 or 50 knots; after heavy winds, make sure you check it out — and ensure that your boat’s winter slumber can continue in peace. 

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