How did early US nuclear powered subs fix their position?

[Rip]

Originally Posted by timmyg00

Technically, a "fix" is position data received from an external source (Radio signals like GPS, visual references like the stars or land features/navaids, or radar fixes), so INS, SINS, or ESGN doesn't count as a "fix"; they are just very advanced dead-reckoning systems. Basically, you enter a position from a fix into one of these systems, and the system computes your expected position based on your course and speed. I think ESGN is still the standard for advanced DR systems today.

Older systems used for position fixes included LORAN and OMEGA (Radio Nav systems at LF and VLF) and NAVSAT (a precursor to GPS). GPS and visual (when properly performed and at slow speeds) fixes are the most accurate. Anything that takes into account at least 3 external references is considered a fix (3 radar positions of fixed objects counts as well).

TG

Very accurate. You must have been a forward ET or a Quartermaster

Also of note is that even without inertial navigation keeping track of a rouch ships position is not all that hard. The combination of the gyro compass and EM log for speed allows manual DR on the plot. You can even compute currents and adjust for that. The QMOW (quartermaster of the watch) is responsible for always maintaing a manual DR track for a sanity check and in case of dire emergency.

Also on the note of fixes we could add visual fix, radar fix, and the biggie Star Fix. One of my favorites. No better way to endear yourself with the Navigator than to be proficient with the sextant.

Just noticed you had listed visual, the navigation party favorite :rotfl: