Simple Simon wrote:

At any rate, the worst case scenario of pea soup thick fog
is but one case of restricted visibility and the majority of
the other cases definitely allow in-sight situations in or
near an area of restricted visibility. In sight situations
are ruled by the in sight rules which specify give-way and
stand-on status for vessels in sight of one another.

Jeff, Otnmbrd, Shen44 and Rick have up till now maintained
there is NEVER a stand-on vessel in or near an area of
restricted visibility while I have maintained there IS a stand-on
and give-way vessel in or near an area of restricted visibility.

I'm right and they're wrong - that's the bottom line.

Correct, if you replace IS with CAN BE. The in sight rules don't
just suddenly become invalid just because visibility becomes
restricted. The definitions are clear: "in sight" and "restricted
visibility" are not 100% mutually exclusive. That's why the "in
sight" rules apply not when visibility is not restricted, but
when one vessel can be observed visually from the other.

I maintain that my sailboat even in a thick fog is going at
a safe speed by virtue of the fact that the hull speed is less
than seven knots max.

That's crap. There is no way you can seriously claim that
7 knots is a safe speed in thick fog. You should surrender your
master's licence immediately and take up golf.

Many fogs have little or no wind so
I may well be going even slower. Even if the winds are brisk
in a fog and I'm going hull speed I'm still going at a safe speed.

Wrong.

In effect, I'm standing on and I'm doing it completely legally.

Even wronger. In thick fog you would not be under in-sight rules
and so could not possibly be legally standing-on.

If I hear the fog signal of a motor vessel I know right away
if and when we come in sight of each other I am the stand-on
vessel and the motor vessel is the give way vessel.

Nice try, and I admit there is some logic in this approach, but
it is nevertheless a flagrant violation of 19b, 19c, and 19e,
the point being that sound signals do not allow either you or
the motor boat to determine what your likely relative positions
are going to be once your range closes sufficiently for you
to be able to see each other. The whole point of 19 is that
it recognises that there might not be enough time for whichever
vessel would become the give-way vessel, once the in-sight rules
kick in, to take effective action to avoid collision.