Here are a few more winterizing mistakes that my yard or I have made:
Not running antifreeze through toilet intake hose (pouring it into bowl will freeze the raw water pump).
Not draining mufflers or running enough antifreeze through mufflers
Not adding antifreeze to shower sump
Leaving drain plugs in hull (I had hundreds of gallons of water trapped in the bilge)
Leaving the fridge closed (mold and mildew)
Peter
1981 32' sedan bridge
twin Chrysler 360 cu. in. 250 hp engines
Raw water cooled
Nimbus II
Home port: New Buffalo, MI