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Some Boat Winterizing Basics

Your dealer knows the best techniques to ensure your Grady-White overwinters well. Start with water tank and engine and battery protection, plus adequate storage. Remember to stabilize your fuel supply. Most experts suggest you top off tanks and add the appropriate amount of stabilizer.


Outboard Engine(s)

  • Gauge the remaining fuel in the tank and treat it with the correct amount of a fuel stabilizer. Many experts suggest a full tank in part because a full tank leaves less room for any incidental condensation.
  • Flush the engine with fresh water using flush muffs or the flushing port usually found on the back of the engine.
  • Start the engine and with it running and the cowl removed, spray fogging solution into the air intakes on the front of the engine.
  • 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.

Fresh Water System

  • Completely drain the fresh water tank and water heater.
  • Isolate the 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 faucets including the shower and any wash-down areas until you see the antifreeze coming out.
  • Also put non-toxic antifreeze in the water heater.


  • 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 that will not harm your system and let sit for a few minutes.
  • 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.

Thanks to Boat US for these and many other great boat ownership tips.

You can see many more of our maintenance tips on winterizing and other topics on our website including our downloadable Quick Reference Maintenance Guide.

The best guide to maintenance for your Grady is your owner’s manual.