Hi Al , haven't got a clue what it is , there was I bobbing along and it just lay there looking like a giant divers helmet , no idea here though /forums/images/graemlins/grin.gif
Cor blimey , tis him what don't even sail anymore lol , what , no guesses Phil ? /forums/images/graemlins/shocked.gif /forums/images/graemlins/wink.gif
It's a port hand 'foul ground' marker. They'r often used to mark such things a sewage outfall pipes amongst other things.
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Spotted one like this in Scotland years ago which by compressed air rose to the surface and showed the whole fish cage. Quite spectacular to watch. But then again this might be some other special mark.
They can be used to mark pretty much anything that doesn't have its own specific type of marker.
Sometimes shape can be used to indicate port or starboard.
In the Solent they are sometimes used as race markers.
If lit (as this one is) it is a yellow flashing light.
I think nowadays (as opposed to a million years ago when I did me initial sea training) they are more accurately called 'special marks' /forums/images/graemlins/smile.gif
Well if it is a sewer outlet, its 15 miles offshore, which is a lot of pipe.
Mind you, the large red tower behind could serve as a giant fart pipe, so it may be true after all.