...?I have an idea that a small box is commercially available with audio and visual light indication which can be placed on the coaming, and picks up a warning signal from aircraft in the vicinity...
...!Handy for the times when I am out of range of ATC, or reading the latest copy of "Bike" magazine instead of looking out of the window....
.... 
...!LOL...!
Cheers all...
...!Paul.
