Thorny subject: Sextant and GPS era

[Pelagic]

Originally Posted by captmikem

It appears many people believe one can just unbox a sextant and get a position.

That is possible for a noon site, which will only give you latitude, not a position.

Dutton says one needs at least 1000 sights before one can count on accuracy.

I have taken thousands of sights, literally. I was second officer on a RO/RO and probably took 100 a day. (I always take 3 sights of a body and average the time and sight to reduce errors). I haven't taken a sight in over two years, and if I needed to, would be rusty and it would take time to work one out, and double check for errors. which would not give me a position, but an LOP. Now if I were doing a round of stars, I could shoot them all in about 10 minutes or so, (If I happened to have 249 "Selected Stars) aboard, but it would probably take me a good while to work them out. I can not imagine someone who has not been proficient with a sextant getting anywhere near their position with a sextant. It is just not a skill one learns in an hour, or two hours.

If you happened to have say.. Mary Blewitt's or another book aboard as a refresher, along with the tables, an almanac, and accurate time. and you knew and had practiced the basics of taking and working out a sight, then you could (on a sunny day) theoretically fix your position probably within a day or maybe a 12 hours if you were lucky.

Folks nowadays do not know how lucky they are to have an accurate fix whenever they demand it. Having a sextant aboard is of little use unless one has the skills, knowledge and associated texts, along with accurate time, to use it.

M

Well said!
....it is both a mental and physical skill requiring continual practice to become proficient. Something akin to juggling, the more you do, the easier it is to adjust to a rolling deck.

I navigated between Vancouver and all thru the Caroline Islands in 1980 on a small adventure cruise ship, using primarily the sextant and DR.

I recognize that it is a skill, where i am no longer proficient, but still knowledgeable enough to keep out of trouble based on whatever observations nature gives me.

Who knows when a malvolent hacker or AI may test us in the future, with no GPS!

So any budding deep sea sailor should know how to fine tune his DR into an EP and if approaching a charted danger, take an assumed position and prove it!

Coasting, I'm happy to ask a fisherman.

[double u]

"... to track him and drop waypoints along his track..."
u are one smart (& not to forget cool) customer, krautophone DH!!!
I'll remember that!

[double u]

to add to my post (118):
I see no RATIONAL reason to carry a sextant, NA & tables (I never took horizontal angles & only one elevation angle, & this only "to have done it", in 100.000 plus nm, my sextant was much too precious to me for risking it for such mundane tasks), none, but plenty of emotional reasons for an ocean crosser to carry one, plenty.

[Pete7]

Originally Posted by Dockhead

The Russians are pretty good with IT security, maybe better than we are.

Rumour on the streets is they have gone back to using manual typewriters for classified information. Tricky to hack into a manual typewriter from another country.

Pete

[PapaLulu]

Concur with Hobie regards Polynesian navigation. Their ancient technology has reemerged in a very robust way, thanks to Nainoa Thompson and others who have sailed the Polynesian sailing canoe, H'okulea. The book Hawaiki Rising- Nainoa Thompson and the Hawaiian Renaissance is a fascinating read and answers your question. They have GPS as a backup but have now circumnavigated without using a sextant. Seems like several techniques are applicable to bluewater sailing when relying on dead reckoning.

[double u]

each key will be making a slightly different sound & they should be identifieable by their frequency if language is known (of course this would require eavesdropping...)

[double u]

Originally Posted by PapaLulu

Concur with Hobie regards Polynesian navigation. Their ancient technology has reemerged in a very robust way, thanks to Nainoa Thompson and others who have sailed the Polynesian sailing canoe, H'okulea. The book Hawaiki Rising- Nainoa Thompson and the Hawaiian Renaissance is a fascinating read and answers your question. They have GPS as a backup but have now circumnavigated without using a sextant. Seems like several techniques are applicable to bluewater sailing when relying on dead reckoning.

they didn't use charts???

[Lake-Effect]

Knowing a sextant, for most recreational sailors, is probably as useful as knowing all the fruity, arcane nautical terms, or more than 10 types of knots: you will probably never need to use that knowledge... but the fact that you were interested enough to master it suggests you probably understand most of the more useful navigational stuff too.

Learning the sextant also forces you to better understand the planet and its motion in the universe, and gives you more appreciation for what others accomplished before there was GPS.

I don't ever expect to need to use it, but I am slowly learning with a plastic sextant. Inexpensive fun.

[ZULU40]

Originally Posted by double u

they didn't use charts???

no but they did have a sextant, of a sort

[boatman61]

Theres always this to get by with come the doomsday scenario that seems to obsess so many..

https://youtu.be/hOLjEj8OxJM

[jtsailjt]

Originally Posted by double u

"... to track him and drop waypoints along his track..."
u are one smart (& not to forget cool) customer, krautophone DH!!!
I'll remember that!

DH may well be very smart but this anecdote of his about entering an unknown harbor on a dark night by following an AIS track with not even a chart of the harbor, with shoals all around is about the furthest thing from proof of his "smartness." We've all done really stupid things and got away with it but there are impressionable, inexperienced people reading this site and I'd hate for one of them to think this was anything close to a smart solution to arriving at a strange harbor after dark without charts. As I'm sure even DH would agree, the smart thing would have been to either sail on, heave to outside the harbor, or anchor somewhere nearby until visibility improved at dawn. "Get there-itis" is something that I've also been afflicted with in the past and was lucky to survive and have learned that it MUST be resisted by anyone who wants to have a long sailing (or flying) career.

[boatman61]

Kinda like the deep draft boat looking to anchor in the Solent on an ebb tide in the lee of the Isle of Wight..
Head over to those 30-35 ftrs.. likely they are local boats so we should be fine..
2hrs later they discover they are bilge keelers.. and their boats got an increasing list..

[estarzinger]

Originally Posted by Flagman101

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.

Well, we in fact ran across such a case - a couple hundred miles north of Bermuda. We had both been thru a storm, he had salt water throughout his nav station which killed his gps; the storm had confused his DR, and he did not know which way was bermuda. He followed us in.

This was years back, when main gps were pretty expensive. It is an unlikely scenario today with gps chips in pretty much every hand held battery device made.

More recently though, we ran through some serious lightening activity, which killed a number of our comms and gps antenna. I presume thru emp. But at that point we had so many gps on board a couple devices still worked. I did pull out the sextant and take sights for a couple days just to be sure they were not corrupted.

[Dockhead]

Originally Posted by jtsailjt

DH may well be very smart but this anecdote of his about entering an unknown harbor on a dark night by following an AIS track with not even a chart of the harbor, with shoals all around is about the furthest thing from proof of his "smartness." We've all done really stupid things and got away with it but there are impressionable, inexperienced people reading this site and I'd hate for one of them to think this was anything close to a smart solution to arriving at a strange harbor after dark without charts. As I'm sure even DH would agree, the smart thing would have been to either sail on, heave to outside the harbor, or anchor somewhere nearby until visibility improved at dawn. "Get there-itis" is something that I've also been afflicted with in the past and was lucky to survive and have learned that it MUST be resisted by anyone who wants to have a long sailing (or flying) career.

I'm afraid I must agree.

It was a basically stupid thing to do, and I don't recommend it to others.

We were dog tired fighting a freak East wind and that clouded my judgement. We should have sailed on, or diverted on an easier point of sail to Poland or somewhere.

Thanks to Double U for the compliment, though.

[Drew13440]

How ironic to see this thread. It may not count to the OP, but I was lost yesterday in a major, sprawling American city unable to get a GPS signal. Almost missed an airplane home because of it. The device worked fine, FWIW, after landing 1,000 miles away.


There is of course no physical danger involved in interviewing multiple gas station attendants for directions, but as others have pointed out here, going to sea without DR and piloting skills is unwise. It is poor seamanship, IMO.