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Go Back   SailNet Community > Skills and Seamanship > Seamanship & Navigation
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Seamanship & Navigation Forum devoted to seamanship and navigation topics, including paper and electronic charting tools.


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  #11  
Old 02-11-2010
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Could be from well-honed terrestrial navigation skills?

Quote:
Originally Posted by AdamLein View Post
By the by, how do you know how accurate you are?
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  #12  
Old 02-11-2010
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Quote:
Originally Posted by AdamLein View Post
If anything, the solar flare problem is more an argument in favor of ensuring mariners are adequately trained in coastal piloting, not CN. According to the article, GPS is used by ships entering harbors, in which an error of tens of meters can mean the difference between safe passage and grounding, and also in which CN is never used.
Solar flare will NOT cause "tens of meters error". The article states 10 meters of uncertainty. Far less than the amount of uncertainty that "ships entering harbors" bore successfully before.

"Before it was turned off on May 1, 2000, typical Selective Availability errors were about 50 m (164 ft) horizontally and about 100 m (328 ft) vertically." Even with flaring, GPS will be no worse, and in fact considerably better than its pre May 2000 civil capability.

Last edited by wwilson; 02-11-2010 at 06:22 PM.
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Old 02-11-2010
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Quote:
Originally Posted by AdamLein View Post
By the by, how do you know how accurate you are?
I know because I was tested by my peers; I test myself near off shore ship channel buoys;
and the verticies of my triangular fix are that tight.

Last edited by Flybyknight; 02-11-2010 at 06:32 PM. Reason: sp.
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  #14  
Old 02-12-2010
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Well Loran C has been turned off by the order of Obama. RDF stations in USA have been turned off. So that leaves GPS, Coast Piloting and Celestial Navigation... So break out the Astrolabs, Back staffs and Octants...
Hmmmm wonder when those last three have been used??
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Old 02-12-2010
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I thought you would know, since you are rumored to have all three... and were one of the last to use them.
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Well Loran C has been turned off by the order of Obama. RDF stations in USA have been turned off. So that leaves GPS, Coast Piloting and Celestial Navigation... So break out the Astrolabs, Back staffs and Octants...
Hmmmm wonder when those last three have been used??
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  #16  
Old 02-13-2010
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Wow . . .

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Originally Posted by Boasun View Post
Well Loran C has been turned off by the order of Obama.
Wow, I haven't been lurking around here in a while, so I don't know how far your tongue is pressed into your cheek, but do you really think that Obama had any hand in shutting down the Loran system?!?! The Coast Guard has been planning this for a long time.
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Old 02-13-2010
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Wow, I haven't been lurking around here in a while, so I don't know how far your tongue is pressed into your cheek, but do you really think that Obama had any hand in shutting down the Loran system?!?! The Coast Guard has been planning this for a long time.
Indeed... so why didn't it happen until this administration?
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  #18  
Old 02-14-2010
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The USCG was upgrading Loran C to eLoran when it got shut down.
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  #19  
Old 02-14-2010
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Mea Culpa, sorta

Quote:
Originally Posted by Boasun View Post
The USCG was upgrading Loran C to eLoran when it got shut down.
OK, I just started lurking around sailnet again and I got myself in trouble already. Poking around and talking with Dad, retired CG Aux Officer, I find that the Coasties had been defending Loran. The trouble begins in the 1970's when the rest of the military dropped Loran.

Interesting tidbits from the Commandants Corner: "One Sixth of the Loran stations, TODAY, are running on vacuum tube technology!!"

"Since the early 1970s OMB and the Office of Telecommunications Policy in the Executive Office of the President had recognized that the combined cost of overlapping navigational systems was simply too high."

USCG: Commandant's Corner - Journal


Further, the Coast Guard Commandant formally stated in Nov '09 that Loran was no longer needed for Maritime Navigation in view of other technologies.

LORAN-C General Information - USCG Navigation Center

So, the Loran system has been in decline, from a public policy standpoint, for 30 or 40 years. The Coasties, until last year, defended Loran with regard to their particular constituencies. That, however, doesn't make it good policy or a wise investment in general. The system is 52 years old!

So, Obama was brave enough to kill it. Good Riddance. You can probably buy a handheld GPS for the cost of a half dozen vacuum tubes. Neither system is perfectly reliable in any broad sense, neither is CN. Prudent seamanship would include more than one option for navigation info. We just happen to have lost one expensive option.
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Old 02-17-2010
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IMHO CN and GPS should only be used for voyaging and bringing you up to the coast. Once there, to me GPS is never more than a check against MarkI Eyeball navigation more commonly known as pilotage.

If CN and GPS are used in this way, a 1 mile variance is actually more than good. Sure a GPS is good when visabilty is poor but it should never be depended on in proximities closer than 1 mile. Many charts are not that accurate.
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