Are the days of satellite GPS navigation numbered??

[p435]

When I read the title of this thread "Are the days of satellite GPS navigation numbered??" I was wondering. Continuing reading I understood it is about sextants and do they disappear.

Here I how I look at it.

When I get question about my sextant on board, I reply with the following question: "When you need to travel from Berlin to Paris, do you use a high speed train or plane or 6-horse-coach?

For me a sextant and the mathematics behind it is simply sexy. However, I regard a sextant as the equivalent to a 6-horse-coach.

Why?

An experienced user of a sextant might be able to determine his position in a circle of 5 NM in the best case.

Each of the the 3 mobile phones and the 2 tablet PCs I have on board determine my position in with in about 15 m and better.

A simple calcuation: 5 NM / 15 m = 600. Thus, all my mobile devices are 600 time more precise than a very experienced sextant user. I have for an emergency case paper charts on board.

Who still wants to travel the romantic way with a 6-horse-coach will and can enjoy this way of travel.

The end of GPS - replacement by a quatumn based system - will come one day. However, I bet it will not be in the next 10 years. Everything connected to quantum physics is not for the next years. More for the future. I heard the first time about quantumn computers more than 40 years ago. They are not yet around the corner replacing land based high speed computer systems. Thus, a quatumn navigation system is for me as sexy as a sextant but it will be the future. One day.

[merrydolphin]

No. It will always be a back up. Particularly for military. The Naval Academy started to phase it out but brought it back as a requirement.

I used, and as an Astronomy/Planetarium educator, taught Celestian Nav.
It was all we had for years, no choice. That said I was first in line to buy a GPS when they came out in the 80’s. Just a little box about the size of a large book. All it did was give you 3 sets of numbers. Lat, Lon, and time to next fix in hours and min. As all the sats were not up yet. But it was MAGIC. And only $2600 on 1990 economy, $6300 today. It was an ouch but happily paid it! Magic indeed.

As a current US Sailing instructor we still require full Celestial nav for offshore students. Full 3 line fix. I do not agree with this. I think a basic “life boat celestial nav” knowledge should be sufficient for this non professional course of study. Basic noon hang for sun and lat by Polaris etc. an emergency plastic sextant. Etc. Heck, Webb Chiles crossed the Pacific Ocean just memorizing the DEC of key stars and using a PLUMB BOB for zineth, and nothing else. Nothing. Got him his lat quick and simple.

[coopec43]

I thought I had read it somewhere. (But this is a requirement of the Indian Merchant Shipping)

Every ship, shall carry a sextant and a chronometer.

Merchant Shipping (Safety of Navigation) Rules, 1997

[GordMay]

➥ https://www.dgshipping.gov.in/Conten...ationRules1997

“The Art of Navigation” ~ by Matthew Bonvento October 19, 2017
➥ https://www.marinelink.com/news/navi...-art-the430490

“... STCW Table II/1 specifies that a Navigation officer is to be able to determine their position and compass errors by use of celestial navigation ...
... SOLAS, Chapter V, Regulation 19 no longer requires the carriage of a sextant and a chronometer. These do however, fall in to the alternative means of navigation that every vessel is supposed to carry.
In recent history that alternative meant Radio Direction Finders or LORAN.
However with the discontinuation of LORAN in the U.S., and only a smattering of LORAN in Europe, the only truly alternative means of navigation are celestial and piloting, neither of which is dependent upon the GPS.
Independence from the little magic box accomplishes two things: first, you have a secondary means of knowing your location should that box fail; second, officers are using their hard-learned skills and keeping sharp as navigators ...”

“SOLAS V carriage requirements” ~ The Master Mariner

“... The requirements for shipborne navigational equipment are contained in SOLAS V/19.

In summary, these are:

All vessels are required to carry the following:

adjusted magnetic compass, pelorus ring, and means of correcting the heading
nautical charts and publications sufficient for the intended voyage
ECDIS with suitable backup arrangements
GNSS receiver
means of communication to the emergency steering position
sound reception devices for totally enclosed bridge wings ...
... more

[Icarus]

I do use a sextant at times in conjunction with a Tamaya 2000 nav calculator and of course navigation charts..
Best fail-safe backup.
Besides, it keeps me grounded to navigation and a participant rather than an onlooker where I am.

[oceanshoretiga]

I have a binnacle compass that works fine - on a steel boat. But, the last time I tried I couldn't find anybody to swing and adjust it. So, I compare it to the GPS/chart plotter compass regularly. I also have a phone and iPad on board for GPS and compass.

[Andrew Lippman]

Using a photograph of the night sky to determine position: What a nice idea! Quite naturally, I asked ChatGPT and it confirmed the plan. You still need to know the time accurately. Here is a clip from the response:

Accuracy:
General Accuracy: With high-quality equipment and ideal conditions, you can achieve positioning accuracy within a few hundred meters.
Amateur Equipment: Using a standard DSLR camera and common astrometry tools, accuracy might range from a few kilometers to tens of kilometers.
Professional Equipment: Using advanced telescopes and precise timing equipment, such as those used in professional astronomy, accuracy can improve to tens of meters or better.

[Andrew Lippman]

At night you can find your lat/long by sighting on Polaris (latitude) and another star and the precise time (longitude.). Of course this is northern hemisphere only. A sextant is all you need.

If you want to do this with a photograph, then you need to derive the equivalent angles from the image. My guess is that this would be less accurate then just using the sextant.

[Statistical]

Originally Posted by Andrew Lippman

At night you can find your lat/long by sighting on Polaris (latitude) and another star and the precise time (longitude.). Of course this is northern hemisphere only. A sextant is all you need.

If you want to do this with a photograph, then you need to derive the equivalent angles from the image. My guess is that this would be less accurate then just using the sextant.

The advantages would be it could be automated and continuously running as well as not requiring increasingly perishable skills. Given how amazingly well GPS works 99.99% of the time not sure there is a market for such a device but it is a cool idea.

[CaptTom]

Don't forget that cell phones have inclinometers in them. And compasses. Look at the apps which show the night sky in real time. I can imagine an app which uses some input from the sensors, and tells the user to line up on something specific in the sky. Maybe using the camera input, either to direct the user or directly analyze the star pattern.

But, yeah, that's more of a fun project than anything which will be of any interest to the masses.

[Jef & Marin, Netherlands]

Originally Posted by coopec43

Good thinking. Thanks!

As far as a binnacle compass is concerned I haven't got one as yet (I have been buying an EPIRB, VHF Radio, Flares etc)

The compass I have been looking at is a Plastimo Olympic 135 which at $531 is a lot of money. Are they really necessary these days or can I get by with something less expensive?

https://www.bluebottlemarine.com/pro...8&gad_source=1

Coopec43, 161 UK pounds at Cactusnav UK
https://www.cactusnav.com/plastimo-o...d-p-16548.html

[Johan Leopard51]

you would have to be many many many nautical mile and entirely unaware of where you were before GPS went AWOL to be in real trouble.

ok: you could find yourself in a vast shallows area but then you stick to visual as no GPS plus map on earth ever invented knows your position relative to that big rock that juts out because they are not charted on any map anywhere at within 2m scale on not GPS accuracy.

[coopec43]

Originally Posted by Jef & Marin, Netherlands

Coopec43, 161 UK pounds at Cactusnav UK
https://www.cactusnav.com/plastimo-o...d-p-16548.html

I'd say there has been a mistake there. Have a look at this photo of a Plastimo Offshore 105 (The photos look identical)

https://www.theboatwarehouse.com.au/...h-mount-black/

[oceanshoretiga]

Sextants can also use twilight first navigation stars. When I crewed on a yacht from Hawaii to Samoa, pre-GPS, one of our favourite times were at twilight when all crew were in the cockpit spotting stars for the skipper to 'shoot' with a sextant. After 16 days, the first island (Kiribati) 'came up' right on time and where predicted. A very skilled skipper.

[coopec43]

Originally Posted by oceanshoretiga

Sextants can also use twilight first navigation stars. When I crewed on a yacht from Hawaii to Samoa, pre-GPS, one of our favourite times were at twilight when all crew were in the cockpit spotting stars for the skipper to 'shoot' with a sextant. After 16 days, the first island (Kiribati) 'came up' right on time and where predicted. A very skilled skipper.

Kiribati!

I landed in Kiribati on the way to Nauru for an 18 month Cost Management assignment.