Loran termination

[captndale]

I just got this from the Local Notices to Mariners:

SPECIAL NOTICE

SUBJ: TERMINATION OF ALL U.S. LORAN-C SIGNALS
1. IAW THE 2010 DHS APPROPRIATIONS ACT, THE U.S. COAST GUARD WILL TERMINATE THE TRANSMISSION OF ALL U.S. LORAN-C SIGNALS EFFECTIVE 2000Z 08 FEB 2010. AT THAT TIME, THE U.S. LORAN-C SIGNAL WILL BE UNUSABLE AND PERMANENTLY DISCONTINUED. THIS TERMINATION DOES NOT AFFECT U.S. PARTICIPATION IN THE RUSSIAN-AMERICAN OR CANADIAN LORAN-C CHAINS. U.S. PARTICIPATION IN THESE CHAINS WILL CONTINUE TEMPORARILY IN ACCORDANCE WITH INTERNATIONAL AGREEMENTS.

This was a completely unexpected surprise to me. I thought that the current plan was to maintain LORAN for the forseable future. I have always kept an old LORAN unit on my boat as a back-up to the GPS.

 

[SkipperJohn]

I heard this the other day...
I have so many numbers in my old LORAN I never transferred to my GPS. It was a long time coming. The first shutdown was supposed to be back in 1999 if I recall.
I recall the nightmare of waiting for the LORAN to catch-up and how difficult sand time consuming it made anchoring over a small wreck. But my RayNav 570 treated me well for many many years!

 

[Tortuga James]

I had a guy give me 20 pages of Loran C numbers from a couple of old school grouper/snapper commercial fishermen. My Furuno GPS has a conversion utility, but the margin of error is too big to be of any use trying to find tight spots. I was considering trying to pick up a Loran unit but I guess that is out now.

 

[SkipperJohn]

There's a conversion program you can get from NOAA. You run it on your PC. but I'm guessing it wont have the precision needed.

 

[Wookie]

I am sad. I kept my old Furuno and a couple of hang books from some shrimpers for hangs all over the west coast of Florida. Problem with conversions is that you have to know what offsets were entered in the original loran. I have found a few hangs usually within a half-mile of the loran numbers, but if anyone has a better system for converting besides the NOAA site, I'd love to hear it.

 

[Tortuga James]

if anyone has a better system for converting besides the NOAA site, I'd love to hear it.

I used that too. It didn't help. I spent a whole day working those numbers I converted and didn't find anything I would drop a paying customer on.

 

[boydski]

I used that too. It didn't help. I spent a whole day working those numbers I converted and didn't find anything I would drop a paying customer on.

I've found the conversion error when converting from Loran to GPS to be very consistent and predictable. While researching and locating wrecks for my book, a lot of the information that I was given was in the form of Loran numbers.

When converted to GPS, like James, the wrecks were no where to be found. However, after searching in the area for a couple of them, I noticed the offset and direction was nearly identical every time we'd find the wreck. I then started applying this offset to converted coordinates and we'd usually locate the wreck within 50' or so of the offset position.

You might try this in your area and be able to come up with a consistent offset that will put you close enough to find it with a fish finder.

 

[Tortuga James]

That is helpful info. Now I just have to reference a given loran number against a known gps location, and figure the offset. Since all my numbers are within 40 miles of each other, the offset should be consistent. I think I will do it on several locations to verify the consistency.

Thanks Scott

 

[oldsalt]

Instead of converting, has anyone tried changing the datum in the GPS when using LORAN coordinates? It worked when we were doing some sonar searches off Oahu a few years ago.

 

[SkipperJohn]

as I understand it, that's just a conversion done internally in the unit. I have had some friends who have had some poor success trying to find small pieces using that method.