1. Get a chart and plot your TD's on it. Then simply re-plot them as LAT/LON
2. Software is available that allows you to enter TDs or LAT/LON and does the conversion for you.
3. Some GPS units have "phantom LORAN" function; That is, they have software built-in that allows you to enter coordinates in either format and then display them in either format.
No matter which route you choose, its prudent to re-save your waypoints as "present positions" as you cruise to them. The conversions all induce a degree of error.
Loran will go offline completly in Feb 2011. So any software that you are thinking of buying may not work after Feb2011.I just removed all my Loran stuff from my boat no need for it anymore. Some station have already stop transmitting