Scenarios for losing GPS/GLONASS/Galileo constallations: are they plausible?

[anacapaisland42]

It's not only plausible it's inevitable....the only question is when!


and accuracy degrading happens now, we've had personal experience of this!



Bill

[Stu Jackson]

Maybe someone beat me to it, but...


What, you don't have paper charts?!?

[SV Bacchus]

Originally Posted by dannc

Add to the list the much more likely event of a lightning strike taking out the electronics.

Later,
Dan

Happened to us 6 months ago in the Bahamas, massive strike.

Originally Posted by 14murs14

And find me a lightening strike that will take out my 2 installed GPS receivers, the one in my In-Reach stored in a cabinet, the one in my tablet, the one in my wife's tablet, the one in my cell phone, the one in my wife's cellphone, the one in my laptop, and in my wife's laptop, and if they're aboard the one in my kid's tablet and phone? Seriously folks, if you've ever peed off the side of your boat you've put yourself in far graver danger from an actual risk based on actual deaths than you'll ever be in from relying on GPS.

We lost everything due to the strike EXCEPT what we put in a lovely Farady Cage known as the microwave! 2 phones, 2 laptops and a handheld VHF.

Originally Posted by Stu Jackson

What, you don't have paper charts?!?

We did and took our time coming back to the states for repairs. We made steady progress back to Florida but took a month and a half from George Town. No depth, no wind, a mag compass 90 degrees off and a skewed chart plotter (the only electronics that still lit up) that showed us sailing over islands when we were most certainly in the water.

We had paper and we sailed like good ole' Chris Columbus did so many years ago, except we only sailed in daylight - easy to do in the Bahamas.

A great experience in ridding ourselves of electronic dependency. The only big drawback was hand steering for 2 months but ultimately even that proved valuable to us. We made a much deeper connection with our boat.

So I say "If you lose GPS, keep on sailing!"

[Cpt Pat]

Again, if you want to engage in esoteric thought experiments there is a non-zero chance of the GPS constellation going out. It is a far smaller chance than literally every other thing that has killed the hundreds of people who have died on ships over the past decade. So if you're really concerned about safety, focus on those things, not the highly unlikely eventuality.

The FAA disagrees: concerns over loss of GPS are not implausible or alarmist. Which is why the FAA is leaving some of the ground-based navigation systems on line:

The Very High Frequency Omni-directional Range (VOR) Minimum Operational Network (MON) provides a conventional navigation backup service in the event of a loss of Global Positioning System (GPS) signal.

https://www.faa.gov/about/office_org...ograms/vormon/

None of that is of any use to mariners: the aviation navigation-aid stations can't be used at sea. My point is: at least some people appreciate the risk of having single-source navigation aids.

And, by the way, if GPS dies, so does AIS.

Those of us at sea in the Americas have no backup without reverting to 19th century navigation by sextant. We've got all our eggs in one basket. But pilots have a better lobby: AOPA. (https://www.aopa.org/news-and-media/...hutdown-update)

[Paul L]

Originally Posted by grantmc

USA invasion of Grenada was in 1983, since then USA has invaded:
Panama 1989
Iraq 1991
Haiti 1994
Afghanistan 2001
Back to Iraq 2003
Syria 2015

Yea, we are pretty prolific. I just used Greneda as an example because of the number of cruisers that are there.
Of course in that actual invasion cruising boats were just starting to use SatNav as GPS was not in place yet. With the early SatNav you'd be hard pressed to tell if it was jammed or just didnt find a satellite.

[Paul L]

Originally Posted by 14murs14

......

And to the other posters, no, DoD didn't turn of the then non-existent GPS constellation for Grenada and in fact the last time they fiddled with it during a war was during Desert Storm when they made it more accurate for everyone, not less. DoD isn't going to cause thousands to potentially die in aircraft crashes to prosecute a war, .....

I used Greneda as an example because the US did invade the tropical island and it has lots of cruisers there and around it. There was SatNav in use at the time.
During Desert Storm the GPS constellation was not complete and the military was short of military receivers, so they quickly changed purchasing rules and bought something like 8,000 commercial units working on the civilian GPS channels to fill the need for the troops in the field.

[zboss]

I’m pretty sure the radios that transmit ATON locations could be adapted to a makeshift GPS system.

[anacapaisland42]

Those of us at sea in the Americas have no backup without reverting to 19th century navigation by sextant. We've got all our eggs in one basket.




Don't discount the Sextant, the sun still is fairly reliable, those little scientific calculators sure make the calcs easy, today's watches are so accurate and paper charts haven't crashed or been hit by a virus yet.


Bill

[Stu Jackson]

Originally Posted by Cpt Pat

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Those of us at sea in the Americas have no backup without reverting to 19th century navigation by sextant. We've got all our eggs in one basket.>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Interestingly, almost all of the "Chart Kits" I've seen have these handy-dandy purple lines between major & minor points with distances and magnetic bearings. Heck, even if you don't know how to use a compass rose, the information is there.


I specifically mention the "Chart Kits" because you said "...at sea in the Americas..." and the kits have shown themselves to be the least expensive method of obtaining charts other than downloading from noaa for free. But few of us have large sized plotters and the chart booklets, which can be handy as 8-1/2 x 11 PDFs, are very ungainly to use. A friend, who sailed down from Vancouver to Mexico, printed scads of them out and put them into plastic sleeves. He gave up using them after the first week.


Of course, North America is not all of "the Americas" but probably contain most of the rec boats.


When I sailed up the coast from SF to BC in 2016, another friend loaned me her borrowed coastal scale charts for long range planning and hourly tracking, while I used Charlie's Charts book and our hh GPS for entering harbors and bars.

I believe hh GPSs are simply smaller chartpolotters, and most of us do agree (in writing! ) that even big screen chartplotters are not as much help as charts for long distance (more than two to four hours travel, ~20 nm) planning.

Your boat, your choice.

[Cpt Pat]

Originally Posted by zboss

I’m pretty sure the radios that transmit ATON locations could be adapted to a makeshift GPS system.

Nope. VHF range is limited to line-of-sight, you'd have to see at least three ATONs at all times to form a triangulation solution (which would almost never be possible unless we littered the seas with ATONs), and they'd have to put rubidium clocks in them. A GPS satellite is really in essence just a very accurate clock with a transmitter.

The best you could do with ATONs is transmit a non-directional beacon, and the vessel would have to use a radio direction finder (RDF). How many boats are still equipped with RDF receivers?

[Cpt Pat]

Originally Posted by Stu Jackson

Interestingly, almost all of the "Chart Kits" I've seen have these handy-dandy purple lines between major & minor points with distances and magnetic bearings. Heck, even if you don't know how to use a compass rose, the information is there.


I specifically mention the "Chart Kits" because you said "...at sea in the Americas..." and the kits have shown themselves to be the least expensive method of obtaining charts other than downloading from noaa for free. But few of us have large sized plotters and the chart booklets, which can be handy as 8-1/2 x 11 PDFs, are very ungainly to use. A friend, who sailed down from Vancouver to Mexico, printed scads of them out and put them into plastic sleeves. He gave up using them after the first week.


Of course, North America is not all of "the Americas" but probably contain most of the rec boats.


When I sailed up the coast from SF to BC in 2016, another friend loaned me her borrowed coastal scale charts for long range planning and hourly tracking, while I used Charlie's Charts book and our hh GPS for entering harbors and bars.

I believe hh GPSs are simply smaller chartpolotters, and most of us do agree (in writing! ) that even big screen chartplotters are not as much help as charts for long distance (more than two to four hours travel, ~20 nm) planning.

Your boat, your choice.

How close to shore and how good does visibility have to be to use that method? And technically, what you describe isn't "navigation," it's "pilotage."


Of course, a good mariner uses every navigation tool available, including his eyeballs and charts. They taught me the same rule as a aircraft pilot: "don't put all your trust in any one navigation system - a good pilot uses every available tool." But with offshore navigation (beyond sight of land) that's exactly what we are forced to do; without a sextant and other ancient knowledge of birds, sea state changes, etc. that has become esoteric knowledge. Yes, the Polynesian mariners did it, and I would love to have one of them come forward in time and teach me, but their methods are pretty much lost knowledge.


If GPS goes down, like the FAA has acknowledged it could; when offshore, we're simply SOL without a (currently nonexistent) backup.

[Moontide]

RaymondR has it right. I might add that can also do it without radar - just don't approach land at night. Kind of what I do for any new ports wven with GPS.

[Jim Cate]

Originally Posted by Moontide

RaymondR has it right. I might add that can also do it without radar - just don't approach land at night. Kind of what I do for any new ports wven with GPS.

If you don't know where you are, how do you know that you might be approaching land?

Even hove to, one does move some, especially in current streams.

It's good to know one's location! (even approximately, as per DR)

Jim

[StuM]

Originally Posted by 14murs14

Come to think of it, if you believe that the GPS constellation being taken out is a threat you wouldn't even walk around outside and would lock yourself in a concrete bunker resistant to an aircraft crash on any cloudy day, given that all those aircraft constantly flying over you are depending on GPS.

Only to tell them where they are in the sky. It's not GPS signals that keep them up there.

[hpeer]

14murs14 is making a great point that I think people are missing.

Let’s say you find $1,000 laying in an envelope on your nave table, the envelope says “Thanks, use this to stay alive.”

How would you use that money? What the best use for that money?

It most likely is not on a sextant, but more likely a better jack line system, feathers, mast steps, harness, new anti-skid, a rowabke dink, or a gazzilion other things.

Full disclosure:
AT1 Peer, USCG Elizabeth City 1973-1976

How about this: an automatic engine room fire protection system, new upgraddd fire extinguishers, new CO and fire detectors. And a fuse in your starter and alternator charge circuit.