Gary wrote in
news:aKiQf.130233$sa3.77836@pd7tw1no

When you take a bearing using RDF of a coast station that you want to
get to you don't steer the bearing on the RDF. That bearing is called
a
"curve of constant bearing" and is only part of the solution. The
curve of constant bearing can be either north or south of the actual
bearing to the station unless both the ship and the station are either
on the equator or on the same longitude. What you have to apply to
any other bearing to get the Rhumb line is half convergency. That
will give you the course to steer.

The same problem applies when using RDF bearings to plot a fix. Those
are not straight lines from the radio station but curves of constant
bearing and the resolution of the fix becomes a sperical trig problem
unless you use the half convergency tables to correct those bearings.
Of course the closer you are to the radio station the less the
correction.

GPS is better, way better.

Gaz

Jiminy Crickets!!
This has nothing to do with the post you were responding to.
Are you reading some book on RDF or something?
What you are talking about is long distance RDF, not the close inshore
stuff being discussed by others.

otn