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Old 02-24-2010, 04:31 AM   #1
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This news article from the BBC claims satnav systems to be at risk from jammers. Click the link and read the article. It is a scary scenario, not just for cruisers but for people all over the globe and even many miles from the sea.

Aye // Stephen
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Old 02-24-2010, 05:01 AM   #2
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And with no more Loran.... what will the fishermen be doing?

With screwy GPS signals...what will the average cruiser who doesn't really navigate anymore be doing?

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Old 02-24-2010, 05:06 AM   #3
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And with no more Loran.... what will the fishermen be doing?

As they always do; managing under difficulties

With screwy GPS signals...what will the average cruiser who doesn't really navigate anymore be doing?

As they always do; shouting for help from the Coast Guard
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Old 02-24-2010, 04:17 PM   #4
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"Some at the conference argued that with the growing maritime use of sat-nav, crews were less able to revert to classic methods of map-reading and "dead reckoning"."

Here is the problem!!!

Back to the roots and let us be in doubt about our true position... a very good reason not to forget about the old navigation techniques: Maybe dead reckoning on a paper chart and checking these with the actual gps data and not just looking on the screen once in a wile. *Doing more eye balling and taking bearings to double check the actual position and many more things come to my mind!*

Uwe

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Old 02-24-2010, 04:45 PM   #5
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"Some at the conference argued that with the growing maritime use of sat-nav, crews were less able to revert to classic methods of map-reading and "dead reckoning"."

Here is the problem!!!

Back to the roots and let us be in doubt about our true position... a very good reason not to forget about the old navigation techniques: Maybe dead reckoning on a paper chart and checking these with the actual gps data and not just looking on the screen once in a wile. *Doing more eye balling and taking bearings to double check the actual position and many more things come to my mind!*

Uwe

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Hubby and I have serious GPS "trust issues" which stem from his military background. We both assume it could be wrong and prefer to verify with bearings.

We seldom actually use the GPS we have. We've got three onboard, none of them stand-alone GPS of the type that most cruisers have aboard. They are all built into electronics which were purchased for other reasons--one is part of the Airmar weather station, one is a little mouse gps that goes with the computer and the last is built into a little Nokia N810. I must admit, the little mouse one does a nifty job with out computer based chart plotter and the Nokia has a nice little program Maemo Mapper that allows us to keep NOAA charts on it and to plot our course which we then can email to friends or evaluate our progress/drift/leeway/etc with.

However, we don't really use the GPS we have for our actual navigation. Our last boat had an old GPS that just showed you the lat and long--no plotting. We'd turn it on to check Lat/Long and mark it on the charts while doing our DR. That is pretty much the extent of our use of GPS even now with the ones we have. When we're coastal and can see landmarks, we simply prefer to use the binoculars w/compass and take bearings.

To each his own, I suppose. I'm just happy that we started sailing pre-GPS and became very familiar with "normal" navigation techniques so that GPS can just be a little "bonus" for us

Fair winds,
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Old 02-24-2010, 06:37 PM   #6
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I am in absolute agreement with both Uwe and Red here.

Back to basics, as Uwe says. Without the basics you have little chance of knowing if the GPS is giving reliable information or not.

Plotting the information from the GPS, as Red mentions, is a good method of checking this with your DR or EP. There is nothing the matter with getting a couple of bearings either or, if away from land, even brushing the cobwebs off the old sextant. Just do not rely on the GPS for the time of observation.

What it all boils down to is that we have an excellent system of navigation which, unfortunately, permits those with little or almost no knowledge to venture far from land. If all this technology goes south, who will still manage to navigate? Well, to answer my own question, those who can plot DR positions, those who can work out tidal triangles, those who can use a sextant.

With many a lighthouse being extinguished and with the demise of DECCA and other radio aids to navigation, if GPS is compromised many a navigator (sic) will be in a precarious situation. One may imagine that, as an old navigating officer, I am gloating at this situation. How wrong you would then be. This situation scares me. Anyone tampering with the GPS is on a par with the wreckers of old who extinguished or showed false lights in an effort to get vessels to run aground where after they would be plundered and their crews, possibly, murdered. We may condemn piracy but this is not an iota better. This is not just some computer freak having fun and taxing his or her brain against the system. This is not a third world pirate robbing a vessel to survive. This is first world terrorism without a cause, done for fun and is no less than attempted murder. The sooner authorities get to grips with this the better.

Aye // Stephen
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Old 02-25-2010, 01:07 AM   #7
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Its not just the jammers that you have to worry about. Many of the US satellites are now on their last system redundancy. Meaning any further failures will result in the satellite going off line. This will result in many areas having NO GPS coverage until either the Russian or European satellites come online. Both these systems are still awhile away so it could mean that for many transport industries its back to basics.

As many older, and newer for that matter, GPS systems do not show how accurate they are many sailors that rely on them exclusively will not like the result.
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Old 02-25-2010, 02:50 AM   #8
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We carry one of these!

And our sextant, nothing like getting stars morning and evening, just to watch for the green flash, and be sure we still remenber how to do it!

Really inexpensive insurance. As H.W. Tilman wrote'Nothing is worse than running ashore, unless one is not sure which continent one is aground on'

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This news article from the BBC claims satnav systems to be at risk from jammers. Click the link and read the article. It is a scary scenario, not just for cruisers but for people all over the globe and even many miles from the sea.

Aye // Stephen
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Old 02-25-2010, 04:36 PM   #9
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We carry one of these!

And our sextant, nothing like getting stars morning and evening, just to watch for the green flash, and be sure we still remenber how to do it!...
And that is a lot of fun!

Sailing off shore or crossing the ocean, shooting the sun (or stars) and using the HO 249 tables and ending up with a position that is not too far away from your gps-postion. *I know this is very basic, but just imagine how proud you can be if both postions just differ less than 10 nautical miles . *But, as we live in modern times we also use a progammable scientific calculator *and there are programs designed for PSc that do the claculation. Just following the program and therefor very foolproof and no one can hack my calculator. And isn't it still a wonderful feeling to hold a sextant in your hand and use it?

Uwe

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Old 02-26-2010, 05:08 AM   #10
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Quote:
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And that is a lot of fun!

Sailing off shore or crossing the ocean, shooting the sun (or stars) and using the HO 249 tables and .......................Just following the program and therefor very foolproof and no one can hack my calculator. And isn't it still a wonderful feeling to hold a sextant in your hand and use i
Agreed Uwe, but for maximum enjoyment / satisfaction forget HO 249 and the calculator. The Marque-St. Hillaire method or Long-by-Chron (my preference) together with logarithims, haversines and cosines from Norries tables will give hours of pleasure.

Concerning the black art of astro-nav, I am a bit of a purist but I think it's fun. When the GPS goes south, it might save you from a day sitting on a sandbank or worse.

One question arrising from this sat-nav failure issue is, how do we obtain accurate time if the GPS fails? When I take my sextant out these days, I use the GPS for the time. In the past, the world was covered by radio stations broadcasting continuous time signals for navigators. Now they are few and far between. Conventional radio is going over to digital broadcasting which, for accurate time signals, is unsuitable due to transmission delays. Certainly, chronometers can be rated against the time signals from the BBC World Service but, coming only once an hour, they are not continuous and certain areas are not very well covered by transmissions.

Without accurate time, when taking sights other than at meridian passage, we will have to revert to lunar distances, which has its limitations.

Anyone interested in trying astro-nav but daunted by the maths or the use of tables can do the calculations on a laptop. There are some good Excel spread-sheets available (here) to help you with this; not quite free but very reasonable at only 10 bucks.

Aye // Stephen
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Old 02-26-2010, 02:40 PM   #11
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Thank you for this valuable hint, Stephen! Might try it this summer (hopefully Göteborg via North Sea).

Concerning the exact time: As the broadcasting stations quit their SW and LW services and move into the internet there are still the time signal radio stations providing the radio clocks with exact time signal and changing our alarm clocks automatically from winter time to summer time (ever watched an analog *radio clock changing its time on a sunday morning in march at 3am?) *

Besides that we carry three rather cheep quartz wrist watches on board that show the time digitally (two in spare). For one of them we keep a "correction table" (as done with the mechanical chronometers back then). We set it at the beginning of the season and if it looses/wins time corresponding to BBC, we write it down. With taking the sight, we write down the time displayed by the watch, add/subtract the correction and end up with the *pretty exact time. The errors produced like this are neglectable, concidering the errors that evolve working with the sextant when the seas are not flat. *

Back to the GPS: As we too started off shore sailing before GPS, we know and still use the old navigation techniques. And if the true positions derived are somehow the same the GPS shows, everything is fine. In the beginning of GPS we did not even have exact positions, the dada we got were only second best, the data for theUS-military use were the exact ones.

*It was in the beginning of the 90ies, we were on Grenada /Prickly Bay when we heard a story that right here a yacht tried an "instrumental aided landfall"... and hit the rocks. *Since many years even we civilian users get exact positions and got used to rely on them and this kind of instrumatal aided (blind) sailing became standard and avoining the *(known) rocks became easy. (Chart tables on sea going yachts shrunk to the size to place a note book on or disappered completely and it would not surprise me that there are now more electronic charts sold than paper charts).* Even professional users adopted to the alway exact GPS-data as already mentioned. Like the big car ferries between Helsinki and Stockholm! Did I remember right that the landbased correction of the GPS-data have been turned off (DGPS)? *I don't want to imagine these big ferries speeding through the archipelago with jammed GPS-signals! Do they have a back up system besides GPS?

One aspect has not yet been mentioned: the MOB- and distress beacons that send out GPS derived positions. So, as we believe that we have the best and most sophisticated rescue equipment on our yacht ... in the case of need it could be that the SAR-activities will take place behind the horizon... * .*

Uwe

SY Aquaria
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Old 02-26-2010, 02:46 PM   #12
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sorry, I goofed on the link.

here's a nother try:*List of Time Signal Radio Stations

Uwe

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Old 02-26-2010, 07:04 PM   #13
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The people that concern me most aren't those who happily cross oceans with GPS and no back either in the locker or in their head but the people who cannot find there way around in pilotage waters ( close inshore ) without a plotter. Zero spatial awareness... the ones who would gaily sail into a rockwall in broad daylight if the plotter said they were on a safe track.....

And it isn't just small boat sailors either.... I know ( or at least knew... he is off my invite list these days ) master who did serious ( ie about $20M) damage to his ship in broad daylight about 5 years ago due to having no understanding of 'overscale' issues or the quality of the survey upon which the electronic chart was based.... as one investigator said... ' you would have thought that being between Rocky Cape and Stony Point would have given him a bit of a hint...'
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Old 02-27-2010, 06:08 AM   #14
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Ah, yes Frank, there are always the guys in all walks of life who are so certain of themselves as to be dangerous. When I was a cadet and attending nautical college my navigation teacher always a claimed, "the navigator who is absolutely certain of his position is a danger to himself, his ship, its crew and others".

This was true. By virtue of the fact that navigation and cartography were one not precise sciences, good navigators always were cautious navigators. Then along came GPS and, in the eyes of many, changed that. We went directly to a state where everyone knew exactly where they were and, generally speaking, they were right. But, they were wrong in abandoning the precautionary approach. This applies just as well to authorities as to individuals. Lighthouse authorities have withdrawn many a buoy and light on the grounds that they are no longer needed when we now universally use GPS. Radio aids to navigation have been withdrawn and entire radio navigation systems abandoned. In my opinion, this is a case of having all eggs in one basket - I just hope that we don't end up with a huge omelette.

Thanks for the useful list of radio signals Uwe. I am surprised that there are so many. However, regarding radio controlled clocks, also known as atomic clocks, these are great but hardly a useful tool for the ocean navigator as, I believe, they are linked to one specific source of time. A clock linked to WWV (Collins) will not update itself in Europe where the signals from WWV cannot be received nor will it search for and link to, say, GBZ (Authorn) or DCF77 (Mainflingen).

I am a great believer in using new technology but if it is to be used at sea then it has to be fail proof or provided with a back-up system.

Aye // Stephen
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