"For example" wrote in message
.. .

The 80' ketch I sail on has these lights on its main mast,
they are on a pair of struts that extend maybe 1 foot forward of the mast
which must give them coverage little better than the steaming light (the
'all round reds' for NUC are on the same struts).

You can see a picture which just about shows them if you go to
http://www.oytnw.org.uk and follow the link 'The Boat'.

Steve