shen is meandering more than a bit, but if you read and reread and read again
to see what he is saying you will find he is troubled to agreed with me, but he
finds he has to.

shen, every last country signatory to the radio treaty of 1920 (1919?)
required
their radio stations to broadcast their call sign, frequency and city every
ten
minutes they were on the air. This was done specifically as an aid to
navigation for ships at sea and aircraft in the air.

recreational boats often did not have any such equipment until into the
1970's,
1980's and in some cases 1990's. Lots of recreational vessels were lost due
to
hitting rocks in reduced visability conditions until lorans and later gps's
became common. Stories of vessels lost such were common in the boating
magazines until the late 1980's.

All well and good. However there were many areas of the world, where the
coverage for RDF was poor and not all charts carried the exact locations of
all
transmitters.
To all this, add the corrections needed for using stations, inland, with
great
distance, and, the skill of the operator and proper alignment of equipment
and
you'd find any number of limitations associated with it's use.
I.e., it wasn't a cure-all, just another aid that had to be used with
caution.
By the 70's, a high percentage of recreational boaters in the US were
beginning
to use Loran, as it didn't generally require the skill that RDF did.

Shen