I agree with Steve. I did the same thing but
added a "T" fitting above the valve that went to another valve for the ice box.I don't open the ice box valve except when there is water in the ice box which is bottled water and soda storage. In fact,I did not open the ice box valve last winter and the little amount of water in the line froze and cracked the second ball valve.I now have a stainless ball valve that I will open this winter because it is now on the check list.The way I found out that it was damaged was, after launching the boat, I decided to make sure there was no water in the ice box line. When I opened the valve, lake water started squirting out of the side of the valve. The "Tee" is below the water line.Use bronze valves and check them prior to and after every launch to make sure they are free and in good shape.r.w.landau