DIY Winterization Checklist

Don’t be fooled by the lingering nice weather. Winter is here and the time to get your boat tucked away for the cold months ahead is NOW.

If you decide to DIY this season, here are our top winterization tips to ensure your boat is put away properly

Freshwater Systems

You can’t leave any water in the system untreated, or it might freeze, expand and crack or burst whatever is trying to contain it (tank, fitting, pipe, etc.). Drain the tank. You can do this by simply turning on all the water spigots until your tank runs dry, or by using a portable pump of some sort. Pour in nontoxic antifreeze (available at marine supply stores and hardware stores) until the pink antifreeze runs out and you’re sure no more untreated water remains. You just want the antifreeze to have gone through — there is no need to keep the tanks filled with antifreeze solution. In fact, doing so creates a tedious purging chore in the spring.

Shower and Sinks

Turn on the sink or shower pump and open the faucet valve. When the antifreeze comes out the faucet, close the valve. Sinks and showers must also be cleaned, washed and dried; pour a small amount of antifreeze down the drains when finished. Don’t forget about your transom shower if you have one.


The contents of the head and holding tank must be pumped out at an approved pumping station. As it’s being pumped, pour toilet cleaner (check your owner’s manual for approved cleaners) into the bowl and let the cleaner sit for a few minutes. Then, flush and give it a final rinse and pour antifreeze through the bowl, macerator pump, holding tank, Y-valve and discharge hose.

Water Heater

You don’t want to leave your water heater filled with antifreeze over the winter. Simply drain it and then flush with antifreeze until you see pink antifreeze come out the drain or portable pump discharge. But you need to flush antifreeze through the other water system components; to avoid needing enough antifreeze to fill the water heater, savvy boaters make a bypass hose consisting of a length of hose and standard NPT fittings. Connect one side of the bypass to the heater’s cold supply and the other end to the hot return line on the domestic water side of the heater.

Raw-Water Systems

If you have a saltwater washdown, anchor washdown or live well, this should be winterized as well. Disconnect the intake at the seacock (close the seacock if in the water). Next, jam the now loose end of the intake into a jug or container of antifreeze. Turn on the pump, open the valve, and leave it open until antifreeze runs out.


The bilge should be thoroughly cleaned and scrubbed of all oil and dirt. Use a biodegradable cleaner (Simple Green works well) and thoroughly dry the area before layup. Just before storage, add a little antifreeze in the lowest part to prevent any water or condensation from freezing.

Department of the Interior

Interior killers are mold and critters. To keep mold at bay, remove all personal items from storage (life jackets, anchors, fire extinguishers, etc.) and air-dry them; then store them in your garage or basement. Inspect them and replace as needed over the winter months. Alternatively, if there’s no room at home, hang them throughout the boat so they’re not sitting and can’t collect moisture. Vacuum and air-dry all inner compartments, drawers and lockers — especially carpeted areas. Don’t replace covers and cushions tightly; leave them off or place them on loosely to promote air circulation. Put moisture absorbers such as Damp-Rid or similar products in these areas, and if necessary invest in a small circulation fan, especially if the boat will be shrink-wrapped. Don’t forget to turn off, defrost and remove all food from fridge & freezers.  Prop the doors open to improve circulation

Fuel System

Fill the tanks almost full to prevent condensation. Fuel should be treated with a fuel conditioner (Star Tron, Sta-Bil, etc.). Read the instructions of the product you’re adding and add a bit more. The engine must be run long enough (usually at least 10 minutes, some maybe more) to get the treated fuel into the intake and engine before final shutdown. In fact, if you can, add the winterizing dose of fuel stabilizer to the tank during or just before the last trip of the year to really ensure it’s throughout the system. Change the water-separating filter and any additional in-line filters as well.


All flooded electrolyte (non-AGM) battery cells must be topped off with distilled water, and then the battery must be fully charged so the water won’t freeze. The terminals should be cleaned: Baking soda works well. Coat the terminals and exposed wire/cable ends with dielectric grease. If possible, remove the batteries from the boat and store them in a cool, dry room. Ensure that all battery switches and breakers are off so nothing can feed back and/or surge.

Hull and Deck

The boat should receive a thorough cleaning and wax coating. The bottom, if fouled with marine growth, should be cleaned completely before storage. It will be much harder to clean in the spring if left dirty over the winter. Inspect your hull for cracks or damage otherwise unnoticed while the boat was in the water. Inspect the running gear. Change your zincs so your boat will be ready for spring.

Tops, Biminis, Covers, Side Curtains

Winter winds kick into high gear and added weight from heavy rain and snow can put a beating on soft goods, aging them prematurely or ruining them completely. Remove all canvas, sails and cushions and make sure they’re clean and dry before storing them for the winter. 

To cover or not to cover?

A good cover keeps leaves and debris from clogging drains, snow from accumulating in the cockpit and from pooling water that can lead to delamination and freeze damage. If your boat will be stored inside, use the mooring or trailering cover to protect it from dust, dirt and animals. If you shrinkwrap, have vents installed the entire length of the cover so moisture can escape and prevent mildew from growing.

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