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Winterizing Your Boat

Updated: Jan 5, 2022

You've had a great season but the time has come to take care of the boat. The time and energy you spend now will get you back on the water faster come spring. A good maintenance program can save you time, effort and money. It is also important to remember that your insurance policy might not cover damage to your boat if there is evidence of lack of maintenance or neglect.

  So we start with the basics- the best place for your boat during winter is out of the water, under cover, in a climate-controlled storage area. If this isn't an option, consider shrink-wrapping your boat. This provides a great protective cover from everything from the elements to damaging rodents. If neither  is an option, Short make sure that your boat is well covered with a tarp or some other sturdy material and perhaps even moved into the garage or a friends barn.

Once your storage is settled, your first step should be making a list of all items that need to be accomplished. BoatU.S. provides a  Winter Worksheet  that can be a great checklist. Also check your owner's manual for both boat, engine and trolling motor for manufacturer recommendations. The following will serve as general outline of major focus areas.

Inboard Engine

Run the engine to warm it up and change the oil while it is warm. This assures impurities are drained away with the oil. Don't forget to also change the oil filter. Flush the engine with fresh water. Then circulate antifreeze through the manifold by using a pickup hose from the water pump to a bucket of antifreeze.

Start the engine and allow the antifreeze to circulate until water starts to exit the exhaust. This process will vary slightly depending on whether you have a raw water cooling system or an enclosed fresh water cooling system. You should also change the fluid in your transmission. Remove spark plugs and use fogging oil to spray into each cylinder. Wipe down the engine with a shop towel sprayed with a little fogging oil or WD-40.

Stern Drive

You should thoroughly inspect the stern drive and remove any debris from the lower unit.

Drain the gear case and check for excessive moisture in the oil. This could indicate leaking seals that need to be replaced. Clean the lower unit with soap and water. If your stern drive has a rubber boot, check it for cracks or pinholes. Grease all fittings and check fluid levels in hydraulic steering or lift pumps. Again, check your owner's manual for additional recommendations by the manufacturer.

Outboard Engine

Flush engine with clean water using flush muffs or a similar device attached to the water pickup. Let all water drain from the engine. Wash engine down with soap and water and rinse thoroughly. Disconnect fuel hose and run the engine until it stops. It is important to follow a step-by-step process to make sure that all fuel is drained from the carburator to prevent buildup of deposits from evaporated fuel. Use fogging oil in the cylinders to lubricate the cylinder walls and pistons. Apply water-resistant grease to the propeller shaft and threads. Change the gear oil in the lower unit. Lightly lubricate the exterior of the engine or polish it with a good wax.

Fuel Fill your fuel tank to avoid a buildup of condensation over the winter months. Add a fuel stabilizer by following the instructions on the product. Change the fuel filter and water separator.

Bilges Make sure the bilges are clean and dry. Use soap, hot water and a stiff brush to clean up any oil spills.

Once the bilges are clean, spray them with a moisture-displacing lubricant and add a little antifreeze to prevent any water from freezing.

Fresh Water System (if applicable) Completely drain the fresh water tank and hot water heater. Isolate the hot water heater by disconnecting the in and out lines and connect them together. Pump nontoxic antifreeze into the system and turn on all the faucets, including the shower and any wash-down areas, until you see the antifreeze coming out. Also put nontoxic antifreeze in the water heater.

Interior Once you have taken care of the system, you should remove any valuables, electronics, lines, , fire extinguishers, flares, fenders, etc. Over the winter, these items can be cleaned, checked and replaced, as necessary. Open all drawers and lockers and clean thoroughly. Turn cushions up on edge so that air is able to circulate around them or, better yet, bring them home to a climate-controlled area. Open and clean the refrigerator and freezer. To keep your boat dry and mildew-free, you might want to install a dehumidifier or use some of the commercially available odor and moisture absorber products.

Out-of-Water Storage Pressure wash the hull; clean barnacles off props and shafts, rudders, struts, and trim tabs. Clean all thru-hulls and strainers. Open all water drains. Check the hull for blisters and if you find any that should be attended to you might want to open them to drain over the winter.

While you're at it, why not give the hull a good wax job? It is probably best to remove the batteries from the boat and take them home and either put them on a trickle charger or charge them every 30 to 60 days.

Remember to consult your owner's manuals for manufacturer's recommendations on winterizing your boat and other systems. If you have not done a winterization job before or don't have an experienced friend to rely on, find a professional to do the job for you.


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