Anyone Still Use a Sextant?

[04 Marine]

I find two books to be really great. Please read great as easy to understand and use.

"One Day Celestial Navigation" Keeps it simple.

"The Complete On Board Celestial Navigator" Everything but the sextant. The current edition runs from 2007 to 2011. As I get back into using my sextant, I'm finding it a great guide to the subject.

[George Wade]

Originally Posted by nautical62

I purchased one of the plastic ones years ago and learned to do noon sights but took it no farther. I'm mostly a coastal/islands cruiser so it was mostly just as a curiosity. My experience was the same as Dave on MaxingOut said. I could consistently get my latitude within a mile or so, but longitude was a different story all together.

These plastic models can get you home because they are easy to wash and clean; easy to adjust if they at least have two mirror screws. Don't grip them too hard, they will bend; relax now you are sailing.

If you can get your latitude within a mile, you can get your longitude within 2~10 miles by practicing running fixes; and by taking many sights, quickly, that you average. Getting too fussy about getting it right often doesn't work out at all well.

Then find your destination by deliberately aiming to one side by a good amount: 10 ~ 20 miles. When you see the beach turn towards your destination until you get there. Of course you are going to have to adapt that hint to your destination.

[04 Marine]

It's been 30 years since I did any sailing. I had a plastic compass then and I have the same one now. Albeit, I just now getting back into sailing and using the sextant I find it rewarding at least then to locate yourself on the ocean using it.

As for the math, folks smarter than most of us have reduced that down to some pretty simple stuff. I would routinely take at least 3 sights and feel comfortable that I was inside of the results.

Although the math is a bit tricker, not much, you can use you sextant to determine how far you are from an object. Going off shore without one and some backup emergency navigation skills is asking for trouble.

[Talbot]

Originally Posted by 04 Marine

Although the math is a bit tricker, not much, you can use you sextant to determine how far you are from an object. Going off shore without one and some backup emergency navigation skills is asking for trouble.

Or you could use Norries Tables and just look up the answer!

[GordMay]

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Maritime and Coastguard Agency UK/EU ~ MCA Orals

Goto ➥ M.C.A. Oral Exam Information including a Massive Photo Gallery of Fishing and Merchant Navy Vessels

[Tramp]

The idea would be to preserve all practical methods, especially when they are fully independent. We once experienced full electrical power loss on a new boat (broken connector on alternator). The first line of defence was the handheld GPS, but we didn't have batteries for many uses (power-sucking little guy).
On the other hand, using tables in rough conditions may be a bit challenging (less than using the sextant, though), but is fully independent on electrical power.

So we keep the Sight Reduction Tables for Air Navigation aboard (just for cat. 1 regulations) and I try to practice sights (on my Freiberger, large) and then reduce them using the Nav4 Navigation Pac (additional module) by Thomas Metcalf on my slow but trusted HP-48G calculator (I added a body recognition program of my own devise) which runs on 4 easily duplicated AAA cells.
The whole kit (including note-taking bits) is protected by the sextant's (largish) box, see picture.

Precision is excellent (translate: at best 1/1000th that of a modern GPS, good enough at sea); be careful with the Moon, though (elevated horizon, by at least 5 minutes of arc, due to brightness of reflection). The most precise method (in my opinion) is crossed sights on 3 stars at dawn/dusk, because it doesn't depend on dead reckoning for translation of lines.

[barnakiel]

I use it. Ocean passages. I check it against GPS about 2 times a week just to make sure I can do it if my GPS(s) pack up.

b.

[Nauticatarcher]

If Captain Cook had had a GPS , which do you think he would have used?

[Cheechako]

at this point waste of time and money...

[George Wade]

Originally Posted by Nauticatarcher

If Captain Cook had had a GPS , which do you think he would have used?

Both. He was a surveyor and navigator.

[Curmudgeon]

It would be fun to learn celestial navigation and use a sextant. When I have the time, I just might. It's just geometry and a little trigonometry.

But for now, a backup handheld gps with plenty of spare lithium batteries in a waterproof case is my solution to losing electrical power in the boat. It's cheaper, too.

[Cheechako]

I found it more frustrating than fun! But interesting anyway.... Pretty hard to develop a good technique of accurately matching the horizon on a boat even in fairly flat water. I'm sure 100's of attempts would help! Then there is the part of trying to adjust sails and look up all the crap in the books, time adjustments etc. Only to find out you screwed up somewhere! Gotta have a super accurate clock also.... right now my computer reads 1 min different than my blackberry!

[Talbot]

Originally Posted by Curmudgeon

It's just geometry and a little trigonometry.

Not these days, using the air Nav tables and decent forms, it is just basic arithmetic. The only real skill is in the use of the sextant (and that is really experience more than anything else) and there is a little bit of skill in the plotting.

I have a set of forms which make this a relative doddle, and am happy to share whilst retaining the copyright. If you want them, send me a pm.

[Talbot]

Originally Posted by Cheechako

Gotta have a super accurate clock also.!

Slocum used an old tin clock which at one stage he boiled in water and then soaked in oil, so a pair of quartz watches should be sufficiently reliable to use as the chronometer. (keeping in a faraday cage of course!)

[barnakiel]

There seems to be a bit of 'urban legend' thing going on about the sextant, so:

- if Cook (but why just Cook?), if Cook (had) had GPS he would have used it, and probably he would have known (as he did) to use the sextant,

- using sextant / almanac IS easy - I can take the sight and calculate my LOP in about 10 minutes (a bit longer if no calculator available either), of course one has to spend some time&effort learning, but all sailing is learning no matter how much experience you already have, and yes - to me, it is fun,

- a single bad lightning bolt in your vicinity and you may end up with ZERO electronics, a single bad day for the US govt and they can switch off the GPS, - PLS read the most recent info on the state of GPS satellites and you will know why the 'new' Loran is being beefed up and introduced as backup,

I use the GPS a lot, and not just to get the fix. And I love and adore all the other things on board that blink and beep. But to me crossing an ocean without the sextant/almanac would be asking trouble. I understand that along the coast and for shorter passages sextant is not necessary (I never take mine out at such times anyway).

And finally, I hope I will make someone very angry when I state that I found most of those sailors who blah about the sextant being of no use next to ingnorant when it comes to proper use, terminology and limitations of the GPS too.

b.