Unless you live in a four-season boating location, most of us will have to do at least some of the items covered below in order to properly prepare for winter. This will not be an end-all-be-all list, but it will get you started in the right direction.

Initial Considerations

  • Should you haul it out or to leave it in the water?
    • How cold does it get where you are at?
    • Is there snow in the winter? Ice? How much?
  • Use of a cover
    • Will a store-bought cover suffice for your winters?
    • Plastic Tarp?
    • Canvas?
    • Should you shrink wrap?
  • Plumbing
    • Do you need to use antifreeze for your freshwater system?
  • Air Conditioning
    • Raw water intakes
  • Sanitation system
    • Raw water intakes
    • Fresh water intakes

The above list is just to get you thinking in the right direction. What you decide to do depends a lot on your location. Do your research and act accordingly.

Engine WinterizationWinterizing Your Boat

The winterization process for your engine depends on what type of engine you have. Let’s review checklists for both outboard and stern drive models.

Outboard Engine Winterization

  • Perform Freshwater flush.
  • Change the lower unit oil. This ensures no water is in the system.
  • Add fuel stabilizer and run motor about 10 minutes.
  • Tilt motor up and down a few times to ensure every drop of water is out.
  • Store in down position.

Stern Drive Winterization

  • Remove all water from the block then add antifreeze.
  • Remove and Replace (R&R) lower unit oil. Add fresh oil to ensure there is no water in there.
  • Fog the motor. Get motor running up to running temps, remove spark arrester then spray fogging oil directly into the carburetor.

Fuel systems

Stabilize, stabilize, stabilize. With the addition of ethanol in our gasoline, no engine is safe. Use a stabilizer that neutralizes the effects of added ethanol.  If you run a diesel, use a diesel additive that contains a biocide.


  • Smaller Boats
    • If you can, remove the batteries, take them home and put them on a trickle charger.
    • If you can’t remove the batteries:
      • Top off your wet cell batteries.
      • Ensure battery connections are tight and clean (this means no corrosion).
      • Hook them up to a float charger or a smart charger.

General Precautions

  • Thru-hulls
    • If left in the water, all thru hulls must be protected
      • Close all seacocks.
      • Close gate valves.
      • If thru hulls cannot be closed and they are below the water line, your boat is a candidate for being stored ashore.
    • Exhaust Ports
      • Plug exhaust ports if your boat is stored in the water. Remember that snow adds weight which in turn forces your stern lower and places the ports below the water line.
    • Bilge Pumps (That Sinking Feeling)
      • If your bilge pump runs, that means you are slowly sinking. Your pump is just ahead of the curve. Stop leaks before the winter. Don’t count on the pump to keep your boat afloat.
      • Ensure bilge is clean and free of debris.
    • Drain Plugs
      • If your boat is out of the water, then the drain plug is out too. Always. Otherwise you will turn your boat into a tub.
      • Consider a one-way plug – great for hurricane and flood prone areas.
    • Docks and Dock lines
      • Prep for strong winds and heavier surge.
      • Use nylon – it stretches.
      • Use chafe guards to protect chafing points such as in chocks, guides and other contact points.
    • Fenders
      • Add more if needed.
      • Adjust current fenders.
    • Steering Wheel/Tiller
      • Tie off.
    • Below Decks
      • Open all lockers.
      • Remove all items from fridge/freezer and leave doors ajar.
      • Secure all ports and hatches.
      • Leave all breakers off except for bilge, battery charger and alarms.

The Take-Away

This is a high-level overview of just some of the things to consider this winter. Your boat, what you do with it – whether you leave it in the water or on the hard – and your location will dictate your own personal winterization techniques.

Improper winterizations have led to countless incidents that include sinking, fires, frozen cracked blocks and frozen cracked lower units along with all the things that can go wrong topside. Taking this seriously and covering all the bases will ensure you can get back on the water next spring with little to no damage.


*Yachts360 provides the information in this post as a general guide. Please check with your local marina and/or mechanic on specific winterization techniques for your personal vessel.