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I think that a navigator may indeed choose to use your method as
described.

That does not mean that the RFIX is dead or should in all cases be
abandoned.

It seems to me that the quality of, and the navigators' confidence in
the orginal EP is the question.

EPs have explicit assumptions built into them. The value in the RFIX
(in my opinion) lies in its utility in questioning the assumptions,
and giving the navigator a means and technique to revisit them. This
technique has enhanced practical utility in being widely used and
understood, so it is easy to have others review the work and assist in
the exercise.

In the example you give here a navigator may choose the EP2, the RFIX,
or some other point as the actual best estimate of position when
exercising judgment on the preceding navigation and LOPs. If there is
a reasonable level of confidence in the LOP2, that point would be
somewhere on LOP2. If there is a high level of confidence in the
estimate of Track Made Good, your outcome EP2 may indeed be the
selected 'position'.

When navigating solely by means of RFIXes over an extended period,
most navigators would question the outcome should their RFIXes and EPs
continue to diverge at an increasing rate over an extending period of
time. Imagine your drawn example repeating over a series of LOPs with
increasing divergence in each successive EP3, EP4, EP5, EPn . . . --
What would you suggested course of action be then?

Should my navigation reveal a plot such as you have drawn, I would be
very very very interested in a re-examination of the vector components
of the original EP and the track made good estimate, seeking a very
good explanation (or at the least rationalization) of the widely
divergent RFIX and EP2 positions. The RFIX would be one set of data
used in such an examination. It may assist in revealing a systemic
error in one of the inputs of the Track Made Good (compass error, mis-
estimation of set and drift, mis-estimation of vessel speed, etc.). I
would not blindly follow the RFIX or EP, but rather seek to reconcile
and explain their divergence before selecting any position as my EP.

The FIX, EP, DR, and RFIX all have a place in the navigators'
conceptual toolbox, and can all serve to assist in determining the
safe passage of your vessel. A navigator should not be a slave to any
one of them as all are fraught with peril should they be used in
isolation from the others.

The RFIX, a hybrid of a FIX and a DR, is useful, but one should not be
a slave to it. Your EPRF, a hybrid of a FIX and an EP is indeed useful
as well but would serve a navigator poorly if relied on without access
to other traditional methods.

Rob

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