Winterizing Checklist

Portable Water System

  • Drain water from all freshwater system lines and pumps.
  • Inspect pump impellers for wear and lightly lubricate with Teflon-based grease.
  • Inspect hoses for signs of softening, cracking, bulging, leaks or pinholes and replace, if necessary, before filling lines.
  • Inspect hose clamps and replace as necessary.
  • Fill all plumbing system lines with non-toxic propylene glycol-based antifreeze.
  • Before recommissioning your vessel, add water freshener/purifier tabs to the freshwater tank to remove residual odors and condition newly added water.

Marine Sanitation Systems

  • Empty waste holding tank at an approved pumpout facility.
  • Rinse holding tank thoroughly to remove residual waste.
  • Pump antifreeze through bowl.
  • Lubricate gaskets and seacocks.
  • Check hoses for calcification and signs of wear. Replace damaged hoses if necessary.
  • Wash out vented loops.
  • Fill discharge and intake hoses with antifreeze.
  • Add antifreeze to holding tank to prevent freezing of residual waste.


  • Completely clean and drain bilge.
  • Inspect and lubricate all seacocks.
  • Clean out refrigerator, ice box, and freezer. Block door open and leave an open box of baking soda inside to absorb odors.
  • Remove cushions and curtains to store ashore.
  • Check and clean all storage compartments.
  • Secure all hatches and ports.
  • Place an appropriate number of dehumidifying devices or a thermostatically controlled heater in safe areas away from combustible materials.
  • Check to make sure ventilators are operating properly.

Engine Winterizing (always refer to your owners manual)

Fuel Treatment
 Treat your boat's fuel with a stabilizer. After adding it to the fuel, run the engine for 10 minutes or so to be sure stabilized fuel circulates throughout the engine. If you don't stabilize the fuel, carburetors and fuel injectors can be clogged with varnish deposits that ruin fuel systems.

Change the Oil
 Change engine oil to eliminate moisture and prevent corrosion. If you don't, moisture can cause excessive wear, which can lead to loss of power, poor fuel economy and possible engine failure.

Fog the Engine Cylinders
 Aerosol fogging solutions coat the inside of the engine to protect it until spring. Each engine manufacturer makes proprietary products they promote as ideal for their engines. Hook "ear muffs" and a garden hose to the engine, start it, and then spray the fogging-solution lubricant directly into the air intake until it's gone. If you don't fog the engine cylinders, corrosion can form inside the engine, covering the cylinders, pistons and rings with a patina of abrasive crud.

Drain the Engine (for inboards and stern-drives)
 Locate and open the petcocks (some engines have bronze plugs similar to bilge plugs) underneath the manifolds and on the sides of the engine block. Remove the water-pump hose from the bottom of the water pump to let it drain completely. If you don't drain the engine, water in the cooling chambers can freeze, expand and crack the engine block and manifolds. Tip: Newer MerCruiser and Volvo stern-drives have handy drainage systems with one drain plug near the front of the engine. Outboards self-drain and never require this step. Once this is complete, filling the block, manifolds, and water cooled components with biodegradable antifreeze is a wise step.

Drain the Gear-Case Lubricant (and recycle it)
 Clear, amber-colored lubricant means your gear-case seals are in good shape. Milky and sometimes lumpy oil means the seals need to be replaced. Tip: The time to do this is in the fall when marine mechanics are less busy and sometimes willing to offer special prices for winter work. No matter what condition you feel the lubricant is in, it should always be changed at least once a season and while winterizing is the best time due to any water in the drive could freeze and do damage.


At least disconnect your battery(s) or remove them to store in a safe environment and charge periodically according to the manufacture's specifications.