well, jeffies, *if* you can see Lighthouse White Diamond and you can see
Daymarker Eel and you can measure the angle between relative to your boat THEN
you know where you are IF you have a chart that accurately portrays where both
are.

jeffies, that be different from wondering around in the fog looking for rocks
to hit.

jeffies, DR is just guessing, and the degree of uncertainty can not be
determined. That is physically impossible.

And why is this "qualitatively different" from any other method of
navigation?


remember, jeffies, when you claimed to have a degree in physics from some
junior college? Well, if you had that associates degree in physics you
might
have heard of the PhD thesis written a hundred some years ago by a young
man
by
the Al Einstein.

Please, can you explain how "On a new determination of molecular dimensions"
relates to this problem? You don't even know what Bert's thesis actually
was!




One
could also say that the compass represents another reference

no, one can not. one can ONLY state which direction magnetic North is
and
which direction relative to that the boat is pointed, but *no* deduction
can
be
made as to which direction actually is actually going. none.

I never claimed you had absolute certainty with infinite precision about
the
direction of travel. You're the one claiming that's the only definition
of
DR.
In fact, formally speaking, the DR plot by itself makes no such
presumption;
it
only describes the position based on the ship's heading and speed through
the
water. If you had any understanding of DR you would know this. Once
again,
you
just prove you don't know what DR is.





but that would be
too complex for jaxie.

wasn't too complex for Einstein when he wrote his PhD thesis on the
subject.
you can read that thesis, if you want, by looking up The Special Theory
of
Relativity.

Einstein's PhD thesis was not special relativity, it was "A New
Determination
of
Molecular Dimensions." And Special Relativity did not focus on the
relative
motion issues that are significant for ship's navigation. That was fully
addressed by Galileo in his "Theory or Relativity" 300 years earlier.
Einstein
only mentioned it by way of recapitulating traditional physics before
showing
how Special Relativity is different. It looks like this is yet another
topic
where you can show your ignorance.