Hello Jeremy,
I was about to write exactly the same remarks as yours ...
Before GPS, some of (very
few of) us had access to Transit, which was accurate enough to grade sextant fixes accuracy, and apart from it - sometimes Loran C, or even Racal (in very limited areas) - there was no way to reliably and consistently assess accuracy of Celnav Fixes anywhere on Earth.
100 % agree with you on the importance of having a sharp and well defined horizon. I would just add : observe as close as possible from the surface - when and if achievable - at the lowest height from which the waves and swell are not visible/appreciable at horizon distance. And even though, do not hesitate to average observations : 5 is my magic number, because in 4 minutes or so, ANY height is absolutely linear with time to an accuracy of 0'035 ...
An excellent horizon, with an excellent sextant your cherish, maintain and trust ? Yes, you can get a Celnav Fix within 0.2 / 0.3 NM of GPS position. Be very careful with your time recordings then ! Just that simple ... with a bit
of luck though, but sometimes luck is to be deserved !
Some of our Readers will already have noticed that Sextants are (to be treated) like Ladies then ... :-)
Best Regards from
Kermit
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