I was under the boat last week, and noticed the main transom zinc was almost gone. I told my diver who cleans my boat. Well, i went under today, and its gone - completely. How long should i wait, with no zinc? If it's another week, is therefore potential for galvanic action to start pitting my underwater metals? I am not happy with him, but wondering if if you have some time before any appreciable corrosion may occurr?