Product Support

If you need support for a problem you are having with installation or program usage, you may contact us at (321) 725-4115 or via e-mail to: support@ You should also check out our FAQ section which answers some common questions.

Please try to resolve your problem by reading the full manual (not the short 15 page one) and our FAQ section first but if you can’t figure it out, call us.

If you are getting a message about WMM.DAT being out of date, see below.

Download the latest WMM.DAT file.

The WMM.DAT file is zipped and should be unzipped to the LoranGPS folder

Version Update

This section is only for the use of current owners of Andren SeaMarks/LoranGPS who paid for version 8.2 or later less than 2 years ago. This page also points to the list of maintenance updates in version 8.5 and the changes to V8.1 along with a download-able updater program. You can download the maintenance upgrade for free if and only if you purchased a 8.2 or newer version less than 2 years ago. Keep in mind this does mean that each time you update, you reset the clock.  It’s 2 years from the time you bought the program.  Our policy is to provide free updates for a period of 2 years after your purchase after which we charge a nominal fee.  Do not download this to upgrade an older version as it may crash for lack of some vital support files.  Also, this will only update an installed program.  It will not install or run by itself.

Update 8.2 or later Software to version 8.7

Download the latest update to the program (11.5 MB)  SeaMarks program must be closed to be updated.

Download the version 8.7 manual (7.2 MB)

Download the latest ASF tables 7/22/15 Note: If you have calibrated your tables and are satisfied with the results, do not use these.

If you bought a version before 8.2 more than 2 years ago, you need to purchase the upgrade and get the full installation package.

When you download this file (AndrenSetup8u.exe), place it in a convenient location like the desktop because you will need to run it. It is an unzipper that will place files into the LoranGPS folder. Make sure that it is pointed at the correct folder (it is programmed to C:\lorangps\). After installation, you can delete the installation program from the desktop.  If you have calibrated your Loran to GPS conversions, this update will not overwrite that calibration.  If you want to take advantage of our latest pre-calibrations, then download and install the ASF tables too.  That will overwrite any calibrations you made, so follow that by either re-running the Calibrate Conversions or just Recalculate LL.

Appeal for calibration data


In order to better serve the Loran/GPS community, I need more calibration points for various areas of the country. With this data, I can pre-calibrate more of the ASF tables to make it unnecessary for people in those areas to calibrate the program. My customers can’t use Loran now and thrash around with inadequate data such as read off maps. This makes for bad feelings about the program and many internet postings about how one cannot do a good conversion with a computer program. I will keep this calibration information confidential and only use it to improve the pre-calibrated ASF tables. Your waypoints will not be disclosed. If you want recognition for your efforts, I can post appropriate credits. Please send good calibration data taken with a real Loran and a GPS simultaneously. The more points, the better the calibration will be. For 9960 and 8790 data please indicate whether it was taken before 1/17/07 or after as the station timing changed on that date.

The current calibration data was donated by:

Beau Radford- TX, Bob Stapleton-Mexico Bch FL, Carl Andren-Sebastian & Canaveral FL, Dale Olds-Destin FL, Dave Timpy-Masonboro NC, Don Busby-St. Petersburg FL, Jeff Emery-Daytona FL, Floyd Carrington-LI, Frank Dorio-NJ, George Steller-LI, Jim Netherton-St. Augustine FL, John Lane-St. Augustine FL, Kirby Klys-Middle Grounds W-FL, Mike Mahaffey-Destin FL, Rick Barnhardt-Holden Bch NC, Ron Surrency-Jacksonville FL, Stephen Shaddock -Lake Charles LA, Tom Brodley-Carrabelle FL, Tom Downey-Jacksonville FL, Tom Littlepage-Mobile AL, Uwe Lovas-MD&NC, Val Thomas-St. Augustine FL

Click here to see the Modifications and Bugs found and fixed to date versus older versions going back to V7.0 (2008)