One simplified way of obtaining your position at sea requires only 3 things:
1. a sextant;
2. the Nautical Almanac; and
3. an accurate timepiece from which you can get GMT.
No sight reduction tables are required, and only very simple math.
I call it, "Latitude and Longitude by Meridian Transit".
Usually, this means the sun, but other celestial bodies could be used as well.
The method is very simple and it works quite well.
You obtain your latitude
by taking the traditional "noon sight", and apply the data from the Nautical Almanac for the sun's altitude.
You obtain your longitude
by taking sextant sights a few minutes before and after the regular noon sight, and recording the sextant readings and GMT times. No corrections are needed.
Before the regular noon sight
, you take a good sextant sight and record
the angle (Hs) and the GMT time.
You then go on to take the traditional noon sight for Latitude
when the sun reaches it's maximum altitude.
Afterwards, you reset your sextant to the same angle you measured before noon.
..with no corrections needed...and you follow the sun downwards until it just kisses the horizon, whence you record
that GMT time.
Add the before and after times together, and divide by 2. That gives you the actual GMT time of meridian passage
. Then, just enter the Nautical Almanac and look up the GHA of the sun for that exact time. The result is your longitude.
Now you've got both latitude and longitude.
The method is not as precise as taking multiple sights on multiple bodies and reducing them.
But, it does get you within a few miles and, for many purposes at sea, that's quite good enough.