they make an electronic control that will automatically sound your horn with appropriate fog or other signal with out having to push a button every few minutes. I know that is not what you asked but I keep looking at them at the boat show and would like one. I have not been grounded or caught in the fog to need one yet. just a thought, and thanks for the sound link.
That derelict boat was another dream for somebody else, don't let it be your nightmare and a waste of your life.