Winterizing a boat with one gallon of antifreeze

I wandered into the West Marine store to pick up some Starboard to use for making a permanent mount for the Thoosa electric motor throttle control and some propylene glycol antifreeze to winterize the boat. I got a little "sticker shock" from the price of the Propylene glycol antifreeze that is used to winterize on board water and engine systems. Almost five dollars a gallon! When I saw that I was glad I had converted to electric propulsion as I no longer need the extra three or four gallons to winterize the diesel engine. Knowing I had some left over Propylene glycol antifreeze from last year I opted to buy only one gallon. It turns out that is all I needed. This is good, very good. Good for the environment and good for the wallet.
Here is how I did it: