NavList:

Howard G, thank you for your post about that book "Submerged" and other related navigation topics. Yes, I remember when you posted that in August. August is usually the quietest month for NavList traffic, but I was still a little surprised that earlier post did not get more attention. And sometimes, too, it's a simple as creating a post that is so comprehensive, it leaves nothing open! You may find that you get more reactions by asking/posing questions... Then other NavList readers have something to chew on, if you see what I mean. :)

The incident described in "Submerged" apparently occurred in 1987. The SINS system on that sub was apparently rather old at that point in time, but it was still one or two generations after the original Navaho-missile based inertial system that was modified for USS Nautilus, USS Skate (and maybe the other Skate class subs --those boats are often described as small Nautiluses, or production Nautilus boats, or, better yet, nuclear Tangs --and the Tang class subs were directly inspired by advanced German submarines).

Those early inertial systems certainly did not have the accuracy of the systems aboard the submarine in "Submerged". Even so, the navigators in 1987 were skeptical of their SINS. This gets me back to my original open question (I'll phrase it differently): How far was Nautilus from the pole (guesses welcome) at that moment when the sub's captain and navigator signed off on that little nav receipt that says latitude 90°00.0'? Five miles? Fifty miles?? More?! 

Frank Reed
Clockwork Mapping / ReedNavigation.com
Conanicut Island USA