On Aug 14, 5:25 pm, Evan Gatehouse
wrote:
....
I think (from memory) the IMO rules require you to see only 2 boat
lengths from the BOW. So visibility can be impaired say anywhere
within 1800' of the bow...
....

I haven't read the IMO treaties and case law but the way it was taught
to me was that a lookout had to be as far forward and low as
practicable (preferably but not necessarily off the bridge). Five, as
written, clearly doesn't allow 1800' blind spots, but maybe the courts
do. However, I don't mean to quibble. You are absolutely right to
assume that you are invisible to all targets that pose a risk of
collision unless you have had positive communication with them and
come to a passing agreement.

-- Tom.