Andren Software makes a program called LoranGPS:
"The LoranGPS program is a tool for fishermen and divers to
manage collections of Loran or GPS readings and print an
organized book of listings and maps. It is fun to use and
will make your readings work better for you."
"The LoranGPS program is for Windows 95/98/NT/ME/00/XP and
includes a conversion calibration capability that makes
the conversion of loran to GPS the most accurate available.
This version includes track plotting capabilities that will
work with almost any GPS. E-mail us for information on how
to obtain a demo program."
Even if the function of organizing listings and maps is not
a requirement for your purposes, it also has the ability to:
"Convert from Loran to Lat/Lon (GPS) and visa versa.
Calibrate the conversions with local knowledge."
"Enter up to 32,000 readings per file using GPS and/or Loran."
"GPS Lat/Lon readings are accepted and displayed in
multiple formats such as: degrees, degrees/minutes,
"Along with each reading you can include a Rating, Description,
Color, Symbol, Date Code, and Comments."
From another page:
"The LoranGPS program automatically converts Loran to Lat/Lon
or Lat/Lon to Loran and saves both in the readings file. If
you enter both Loran and GPS for a given spot, the reading
is considered a calibration reading and no conversions are
performed on it. The conversion equations the program uses
were developed by the Navy years ago and are quite complex,
but they are the most accurate available."
The program sells for $85, and is compatible with all
versions of Windows:
POSAID2 is another program which is free, and works in DOS,
and is available from the US Coast Guard site:
"POSAID2 is a DOS program for converting Loran-C Time
Difference measurements to Latitude and Longitude."
It is accompanied by this disclaimer:
"All users of this software program are hereby put on
notice that use of this program to produce certain
desired results is entirely at the risk of the user.
The Government makes no representations regarding the
reliability or accurateness of the program and
specifically warns all users that the program is not
intended as a real-time navigational program."
More on the page:
Doc Dan's Fishing and Hunting Information Software
is another option:
"A PC program using tide, sun, and moon data to predict
the best times to go fishing or hunting. Includes
LORAN <-> GPS conversions."
"What do you need to use it? Just a computer that?s IBM
PC compatible and that runs any of the Microsoft Windows
programs. The cost of this program is $24.95 plus tax
for new subscribers"
My money would be on the first program, but I thought
you'd like some options.
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A user's guide on this topic is on skermit-ga's site, here:
Additional information may be found from an exploration of
the links resulting from the Google searches outlined below.
Searches done, via Google:
"loran to GPS"