Thorny subject: Sextant and GPS era

[Flagman101]

Hello, last week-end I got unwillingly into a thorny discussion with an other boater about Sextant and GPS.

So anyways this post is not to argue the necessity or not of knowing how to use a Sextant.

What I'm looking for is actual accounts of sailors, getting lost or in trouble because they're GPSs broke down and did not know how to navigate without a sextant.
Actual bleue water sailors.
I have never heard a single story about that.

[danielamartindm]

Originally Posted by Flagman101

Hello, last week-end I got unwillingly into a thorny discussion with an other boater about Sextant and GPS.

So anyways this post is not to argue the necessity or not of knowing how to use a Sextant.

What I'm looking for is actual accounts of sailors, getting lost or in trouble because they're GPSs broke down and did not know how to navigate without a sextant.
Actual bleue water sailors.
I have never heard a single story about that.

Nor I; but that might just mean that if vessels have been cut off electronically from the GPS system, the skippers knew how to use their charts, dead reckoning, and a compass to reach safe harbor- as they SHOULD know how. How few real world situations would threaten disaster if GPS satellite positioning were lost? Perhaps a few, but not many IMHO.

[Flagman101]

Of course I'm not suggesting that one sails off with NO navigational knowledge. On the list of top 3 essential trainings, coastal navigation is there. Know how to use charts a plot your course and route.
Thats for your input.

[james247]

Originally Posted by Flagman101

Hello, last week-end I got unwillingly into a thorny discussion with an other boater about Sextant and GPS.



So anyways this post is not to argue the necessity or not of knowing how to use a Sextant.



What I'm looking for is actual accounts of sailors, getting lost or in trouble because they're GPSs broke down and did not know how to navigate without a sextant.

Actual bleue water sailors.

I have never heard a single story about that.

I can use both. gps has never let me down. On a small boat say under 80ft the use of a sextant is never perfect the Cox hat puts you in about 500m of accuracy. Not an issue deep at sea shouldn't be an issue as you approach land albeit more cautiously than you might with the accuracy of gps.
I carry a laptop with gps, a gps of a screen linked to other dedicated equipment like the vhf radio, a hand held for emergencies and part of a grab bag and a sextant with all the tables required and a calculator which requires just the sextant reading and the heavenly body your looking at. A sextant used horizontally is a great tool to work out location based on know land based points and vertically for distant off based on know height locations lighthouse mountains etc.
Guys it's a package. A compass is useful.

[John_Trusty]

No experience losing GPS etc., but perhaps an elementary comment for those not familiar with celestial navigation who may read this thread. Celestial is not like GPS navigation as it is not self-contained. You don't pick-up a sextant and do some arcane magic to tell your position. In basic terms, you need to know how to take a precise angular measurement of a specific body, where that body is above the earth at that time, and how to find your distance from that earthly position. Getting that angular measurement is only one-fifth of the problem.

[double u]

"... charts, dead reckoning, and a compass..."
I wonder where that would land one after 1/2 Atlantic-crossing...

[Flagman101]

Originally Posted by double u

"... charts, dead reckoning, and a compass..."
I wonder where that would land one after 1/2 Atlantic-crossing...

Irrelevant. If your are navigating with GPS you will get to safe harbour. Also if your using sextant.
One could probably make landfall using only compass, charts and dead reckoning but how close to target?? No idea.
Ever ear a story where someone lost GPS system and ended up lost?
That is my question.

[Pete7]

Originally Posted by double u

"... charts, dead reckoning, and a compass..."
I wonder where that would land one after 1/2 Atlantic-crossing...

Wasn't there a Japanese bloke who sailed around the world with nothing in a small boat, just pointed in a direction and went for it.

I have been looking at plastic sextants of late, but they seem to command serious money on e bay. I sold one previously making a small profit. It will now cost me twice that to buy another :-(

[Flagman101]

Originally Posted by Pete7

Wasn't there a Japanese bloke who sailed around the world with nothing in a small boat, just pointed in a direction and went for it.

I have been looking at plastic sextants of late, but they seem to command serious money on e bay. I sold one previously making a small profit. It will now cost me twice that to buy another :-(

Ancient Polynesians are said to have mastered sailing by the stars. They ended up sailing a good part of the pacific. No GPS no Sextant no compass. Just follow a star.

[Dockhead]

Originally Posted by double u

"... charts, dead reckoning, and a compass..."
I wonder where that would land one after 1/2 Atlantic-crossing...

It doesn't matter.

We need precise position data for PILOTAGE, not so much for navigation.

I would not freak out in the middle of the Atlantic if I lost all position data.

I would just do dead reckoning, keep a good hourly log of speed and course, and you'll at least hit the right piece of land. When you get in sight of land, then you just do normal non-electronic pilotage. You can get a very precise position in pilotage waters with a normal three point fix.

It wouldn't really be a big deal.

Losing GPS would be way down on the list of dangerous gear failures. I'd much rather lose GPS than the autopilot, for example. I might even prefer losing the GPS, to losing my microwave


And BTW I DO have a sextant on board. But it's for sale. Now that GLONASS is fully operational, and with every phone and tablet on board receiving GLONASS plus GPS, losing satellite position data is almost inconceivable.

[Dockhead]

Originally Posted by Flagman101

Irrelevant. If your are navigating with GPS you will get to safe harbour. Also if your using sextant.
One could probably make landfall using only compass, charts and dead reckoning but how close to target?? No idea.
Ever ear a story where someone lost GPS system and ended up lost?
That is my question.

How accurate DR is depends on a lot of things, including skill of the navigator, but I suppose most people could hit +/- 50 miles at worst starting out in the middle of the Atlantic.

But once you are in sight of land, then you just use normal pilotage techniques to get to where you want to go. Even if you lack a chart (!), you can just sail up or down the coast until you find a harbor, then follow the buoys.

Compass, chart, speed log, and hand bearing compass will do you just fine.

[Flagman101]

Originally Posted by Dockhead

It doesn't matter.

We need precise position data for PILOTAGE, not so much for navigation.

I would not freak out in the middle of the Atlantic if I lost all position data.

I would just do dead reckoning, keep a good hourly log of speed and course, and you'll at least hit the right piece of land. When you get in sight of land, then you just do normal non-electronic pilotage. You can get a very precise position in pilotage waters with a normal three point fix.

It wouldn't really be a big deal.

Losing GPS would be way down on the list of dangerous gear failures. I'd much rather lose GPS than the autopilot, for example. I might even prefer losing the GPS, to losing my microwave


And BTW I DO have a sextant on board. But it's for sale. Now that GLONASS is fully operational, and with every phone and tablet on board receiving GLONASS plus GPS, losing satellite position data is almost inconceivable.

One could argue that the error possibility of using a sextant is much much higher then the possibility of completely loosing GPS navigation

[Hobie_ind]

Originally Posted by Flagman101

Ancient Polynesians are said to have mastered sailing by the stars. They ended up sailing a good part of the pacific. No GPS no Sextant no compass. Just follow a star.

I've read a few books on Polynesian navigation and it is impressive in it's complexity. Much more complex than 'just follow a star'. Years of training including memorizing many stars for different destinations and times, coupled with weather, wave behaviour & interactions, clouds and bird activity.

My takeaway and experience with a sextant is that using a sextant is FAR easier and quicker to master.

If anyone is interested, one of the books was 'The Last Navigator' by Steve Thomas (ex-host of This Old House). Not a bad read. https://www.amazon.ca/Last-Navigator.../dp/1439233497

[Dockhead]

Originally Posted by Flagman101

One could argue that the error possibility of using a sextant is much much higher then the possibility of completely loosing GPS navigation

Indeed.

As someone above wrote, celestial nav requires a lot of other input than just a reading from a sextant, and requires skill.

I would gladly use sextant and sight tables if I had it with me, in the middle of the ocean with no GPS, but I don't think it's essential at all.

And celestial nav is of no real use in pilotage waters, because it is too slow.

As you yourself mentioned, coastal skills -- pilotage -- are key. And you actually need these whether or not you have a working GPS. Pilotage is something of an art; DR on the contrary is not rocket science.

[Flagman101]

Originally Posted by Hobie_ind

I've read a few books on Polynesian navigation and it is impressive in it's complexity. Much more complex than 'just follow a star'. Years of training including memorizing many stars for different destinations and times, coupled with weather, wave behaviour & interactions, clouds and bird activity.

My takeaway and experience with a sextant is that using a sextant is FAR easier and quicker to master.

If anyone is interested, one of the books was 'The Last Navigator' by Steve Thomas (ex-host of This Old House). Not a bad read. https://www.amazon.ca/Last-Navigator.../dp/1439233497

Of course. Just did not feel like writing a book about how here on the forum.