How to Winterize a Boat

By following some of the below suggestions, you should be in good shape for the winter. Do not, however, neglect 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 experience friend to rely on, seek out a professional to do the job for you.

Outboard Engine(s)

• Gauge the remaining fuel in the tank and treat it with the correct amount of a fuel stabilizer
• Flush the engine with fresh water using flush muffs or the flushing port usually on the back of the engine
• If a 2 stroke, start the engine and with it running and the cowl removed, spray fogging solution into the air intakes on the front of the engine
• If a 2 stroke, while it’s still running, remove the fuel line from the engine and continue spraying fogging solution until the engine dies. It is important to run the engine with the fuel line removed to burn all fuel from the carburetors to prevent build-up of deposits from evaporated fuel
• Apply water resistant grease to propeller shaft and threads
• Change the gear oil in the lower unit
• Lightly lubricate the exterior of the engine or polish with a good wax
• Wash the engine down with soap and water, and rinse thoroughly
• Always tilt the engine to the down position if stored outside in the weather to allow rain water to drain from the exhaust port so it will not freeze and possibly damage the gear case.

Protecting Internal Engine Components

• Please remember, always refer to your manual for maintenance spark plug inspection and replacement to use the correct procedure for removing spark plugs.
• Change the engine oil and filter
• Remove the spark plugs
• Spray approximately 30 ml (1 fl. oz) of Storage Seal Trust Inhibitor into each spark plug hole.
• For 2 stroke engines, actuate key/push button start to crank the engine through one start cycle, which will distribute the storage seal throughout the cylinders.
• Install the spark plugs.

Interior

• Once you have taken care of the system, you should remove any valuables, electronics, lines, PFD, 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 can 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 such as “No Damp,” “Damp Away,” or “Sportsman’s Mate.”

Exterior

• Paint should be touched up and corrosion guard sprayed onto components for proper protection.

Out-of-Water Storage

• Pressure wash hull, clean barnacles off props and shafts, rudders, struts, and trim tabs
• Clean all thru-hulls and strainers
• Open seacocks to allow any water to drain
• Check the hull for blisters and if you find any that should be attended make a note to tell your service manager Now is a great time to give the hull a good wax job
• Remove, check, and charge your battery in a cool, dry location. Always follow battery manufacturers recommendations.

In-water Storage

• Close all seacocks and check rudder shafts and stuffing boxes for leaks; tighten or repack as necessary
• Check your battery to make sure it is fully charged, clean terminals, add water if necessary, and make sure your charging system is working
• Check bilge pumps to ensure they are working and that float switches properly activate the pumps and that they are not hindered by debris
• Monitor your boat regularly to avoid leaks, or animal infestations
• If your mooring area is likely to freeze, be sure to suspend water agitators below it to bring warmer water to the surface so it’s not iced in

Fuel

• Some manufacturers suggest filling your fuel tanks and adding stabilizer to the fuel. Fuel tanks leave less room for condensation to form.
• Other manufacturers, noting that ethanol may spoil over the winter no matter what you do to it, suggest just adding fuel stabilizer. If the fuel is spoiled over the winter, there is less to drain and dispose of.
• Additionally, adding fuel stabilizer prior to the season end can assist with the stabilizer making its way through the injectors and other components.
• Please refer to your owner’s manual for specific information on your make and model
• Change the fuel filters and water separators.

Bilges

• Use soap, hot water, and a stiff brush to clean up any oil spills
• Once the bilges are clean, spray with a moisture displacing lubricant
• Add a little antifreeze to prevent any water from freezing

Fresh Water System

• 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 a non-toxic antifreeze into the system and turn on all the facets including the shower and any wash-down areas until you see the antifreeze coming out
• Also put non-toxic antifreeze in the water heater

Head

• Pump out the holding tank at an approved facility
• While pumping, add fresh water to the bowl and flush several times
• Use Vanish crystals or whatever your owner’s manual recommends
• Add fresh water and pump out again
• Add antifreeze and pump through hoses, holding tank, y-valve, macerator, and discharge hose
• Again, check your owner’s manual to make sure that an alcohol-based antifreeze won’t damage your system

Please remember this is a general checklist to get your boat winter ready. Always refer to your boat, engine, and battery manufacturer’s manuals prior to starting any work.

For your convenience, here's a downloadable, printable copy of this checklist. Follow these steps, and when spring comes around, read our tips on how to de-winterize your boat.

If you're a Lowe Boat owner and need more information, see our list of frequently asked questions, or contact your local dealer.