Yeah. The chart method would be my last choice.

The good news is that I just found a great, free program that does exactly
what I want. It also converts lat/lon to TDs, and vice versa. It's at:

http://www.rdc.uscg.gov/Misc/POSAID2...5/Default.aspx

I've tried a few already, and it works fine. Yes, you have to crank each
event through manually and step through it, but it does the job. I may be
able to write a little program to automate the rote tasks involved.