No GPS? No problem.....

[S04]

Sextants are only as accurate as the time source and the skill of the operator, which needs a lot of practice. Most pleasure sailors would not have an accurate time if the gps was down. ................

I agree on the operator skill point but as for timing, a modern digital watch is sufficiently accurate for the timing of a celestial sight. Poor practice in using the instrument is likely to induce more error particualrly in a small craft. For all the sights I've taken and seen others take I have never seen anyone use a GPS derived time for the sight.

Another point is the accuracy of the sextant. When they were in frequent use they would be regularly checked for errors at different points on the arc and those errors used to correct the obs alt. I have a number of sextants and the three newest ones are all declared as "free from error for all practical purposes" but that was when they left the factory.

 

[newtothis]

Sextants are only as accurate as the time source and the skill of the operator, which needs a lot of practice. Most pleasure sailors would not have an accurate time if the gps was down. Sextants also only work when it is not cloudy. I once crossed from South Africa to South America on a Merchant Navy ship before GPS and we could not take a sight for the whole trip and had to use DR. All of the Navigation Officers were accurate on landfall within 30 miles. The highly experienced Captain was furthest away and a 16 year old first trip Cadet was closest which was the source of a lot of entertainment.

I would not feel the need for a sextant offshore today.

The average Casio wristwatch is more accurate than anything used in the pre-digital age.
As for cloud cover, if you have a vague notion of latitude, it's just a matter of turn left or right when you sight land.

 

[Mark-1]

As for cloud cover, if you have a vague notion of latitude, it's just a matter of turn left or right when you sight land.

And with zero knowledge of Astro Nav, no corrections and nothing beyond normal general knowledge you can get a reasonable latitude with a home made "angle measurer". I know because I tried it.

I was only four miles off but that's because my garden is close to a lat line and I was working to the nearest degree, if I'd read the next degree along I'd have been about 60 degrees off. Less accurate on a moving boat but the vikings managed with a bit of forked stick.

Having said that, I then learned how do Longitude properly and my first attempt with stars/planets(?) with the same "measurer" was 270 miles. I got better.

 

[zoidberg]

Quite, and for those who didn't know, it's where the angle of the lights are derived, 112.5 degrees being 10 compass points.

View attachment 208620

That's all very well - but what's your point?

 

[westernman]

That's all very well - but what's your point?

11.25 degrees.