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***POSAID is not compatible with 64 bit computers***

The Coast Guard developed "Coast Guard POSAID2 ver 2.1a", a DOS-based program for converting LORAN-C time differences (TDs) to latitude and longitude. You may download the files here in zipped format. After you download the files, you must extract them using an "unzipping" application . There are many zipping / unzipping application available by searching the Internet. We do not endorse or recommend any available commericial products.

The conversion is based on the Sodano (1965) method taken from McCullough, J, et al, "LORAN-C Latitude-Longitude Conversion At Sea Programming Considerations". The original reference for the conversion is: Sodano, E.M., 1965, General non-iterative solution of the inverse and direct geodetic problems: Bulletin Geodesique, annee, Nouvelle Serie, no. 75.

The files contained in the zipped file are:

  • Chain Information
  • Frequently Asked Questions
  • Executable DOS File
  • Readme.TXT

Contact us if you have any questions regarding this tool.