NavList:

Sam, you're missing the forest for the trees. You can do it by crossing a pair of circles on a globe. On a flat map, it's not much different though you need to know a little about how circles look plotted on a given type of flat map. This gives you a very good estimated starting position. Then you work the problem as normal from that point where the circles cross. If you get intercepts that are still too long to plot, you re-scale your plotting sheet (for example, treat every mile as six miles). If necessary, the fix derived from that plot can then be used for one final run through the problem. You do NOT need any new equations. The equations that are being thrown at you are making you a less capable navigator, not more capable. 

Frank Reed
ReedNavigation.com
Conanicut Island USA