Jeff Morris wrote:

Neal's point has been (though he doesn't state it explicitly in this
thread) that a
sailboat is "standon" in the thickest fog and is not required to reduce
speed. He has claimed repeatedly that rule 19 does not apply to sailboats
because they are incapable of ever traveling at an unsafe speed.

One has to remember that what is paramount to him is not whether
rule 19 applies "to sailboats" but whether it applies *to him*.

Perhaps in the limited types of situation of which he has experience,
restricted visibility is associated with less wind which will mean
that his sailing vessel is likely already to be proceeding at a safe
speed, and may even already be at the minimum speed at which she can
be kept on her course.

That's not to say that rule 19 doesn't apply to him, merely that he
is already automatically complying with it because the conditions of
19b and 19e are already met.

So, in his own little universe, he's probably right.
For the rest of us, in the real world, the story is different.