A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2017 Jan 21, 20:20 -0800
Stan K, you asked:
"Which one of these, if any, corresponds to the point that Herbert Prinz discussed at a Mystic Seaport Navigation Weekend a bunch of years ago?"
Yes, that was the "symmedian point" which HP discussed in his presentation at the Navigation Weekend in 2008. We should have another one of those gatherings soon. Maybe in June? Or October? How about New Bedford for a change of scene? I know a great venue where I am confident we could meet.
Herbert Prinz in his presentation demonstrated the ruler and compass construction which Bill Lionheart described in his post. That's certainly interesting and neat to see once. But in practical navigation, it's probably over-kill. Personally, I think the most important aspect of this for a navigator is to know how to deal with a long, skinny triangle -- the fix goes near the short side. The rest of it is too narrowly focused on three sights. A navigator should see a good sampling of computer simulations of fixes and error ellipses derived from 3, 4, and 5 and more sights. With a little familiarity, enough patterns emerge so that the navigator can make a rational choice in a real world case. The lessons from that kind of "neural network" training should include realizing that the fix is near the short side (as I just mentioned) and also that the error ellipse is usually larger than the triangle (as Bill B mentioned) and that the error ellipse gets smaller while the "tangle" of plotted lines of position grows larger with a larger number of sights (more sights may look worse in the plot, but it's actually more accurate). We can and should train instinct on this sort of thing.
Conanicut Island, New England