NavList:

Bob Goethe, you wrote:
"At need, naval ships typically, I believe, jam GPS in a 50 mile radius around them.  Depending on how they are distributed, a dozen ships could render GPS unusable across 6,000 square miles of ocean.  Evidently, this is pretty much an annual exercise for NATO.  I imagine these sorts of things pop up in the Pacific as part of the ANZUS alliance exercises."

Let's see, we've got an "I believe" and a "depending... could" and an "evidently" and an "I imagine". Call me skeptical! Do you have a reference for an entire sea being rendered GPS-dark by a NATO exercise? For all of the past twenty years since GPS became fully operational, traditional navigators have been trying to invent disaster scenarios in which, at long last, the skills of the celestial navigator will be not merely useful, but praised and valued. Celestial navigation rides to the rescue! And those scenarios exist in fantasies in large numbers. But how do they compare with the real world?

Frank Reed