# HELP using a garmin GPS to run LORAN #s



## Fishermon (Oct 19, 2007)

I run into some Loran #s from an oldtimer. I need to know if I can use the Garmin GPS 540 to use these numbers. I was going through the settings and found 'Loran DT' with different GRI numbers? and some other data I don't understand. I sthat what i need to use to plug in the numbers? if so, my questions is, what's the chain number for this area (ex: I found one for the south east 7980..is that it?) and what about the secondary numbers. Also, will the garmin convert these numbers automatically into gps numbers? or while Im running in Loran mode, and find the spot, just hit the MOB and that should do it?...still trying to figure it out. ALso I heard that the Loran system was going to be shut down alltogether if so can I still use the garmin to convert such numbers?...thanks in advance.


----------



## lobsterman (Sep 30, 2007)

In Feb the Loran towers were shut down. I have not tried to use Loran numbers in my GPS since so I can not tell you if it will work. I do know that the software programs will get you close sometimes and you will have to do some searching most of the time. Some you will not find at all.


----------



## Fishermon (Oct 19, 2007)

what are the GRI and secondary numbers/ settings you use for this area...all I have to do is try guess. Thanks for the info.


----------



## sealark (Sep 27, 2007)

7980 was the chain and if it will convert the numbers they will be off buy as far as 1/2 mile or they can be closer. It will get you in the area. That is if it just converts the loran numbers like stated the system has been discontinued. I know my Northstar GPS converted the brass wreck from Loran and got me close to the GPS numbers I already had. I done that when the loran system was still operational


----------



## wirebiter (Jun 4, 2008)

Garmin is real easy to convert between. You can go into the setup and select LORAN C and all numbers in your memory will convert to LORAN. You can then input the LORAN numbers and go back to setup and select GPS. This will convert everything back to GPS including your new numbers. You might want to back up your current numbers since the conversion can be off a little and I am not sure they will reconvert to the same as before. Like Sealark said the area number for Pensacola is 7980, but you will also need to know they use W,Y coordinates for our area. If you can't tell I just did this recently. Hope it helps.


----------



## Fishermon (Oct 19, 2007)

W and Y..thats it...thanks...but %$^#* i already set the thing to LORAN meaning that all the numbers I had will be off when going back to GPS mode? don't get it. How do I back #s up?... using the SD card? So you're saying even if the LORAN towers are down I still can plug in Loran numbers on garmin LORAN Mode and then just reset to GPS mode? Thanks.


----------



## Sea-r-cy (Oct 3, 2007)

That is right. The garmin will be operating off the satellites instead of any land site. Depending where the loran numbers are will have quite a bit to do with the conversion accuracy. 

If you have a known spot, and have both good loran numbers and good gps numbers, see how close the conversion is in your Garmin. You may be able to adjust the known loran to unknown gps conversion of a new place and find it.

Even when loran was in use, there was a difference between locations shown on different brand machines.

I played with my loran years ago on our lake. Sometimes at the overflow tower I would get one number, the next time it might be a few mirco-seconds off. Loran was ok, but gps puts you on the same spot time after time. 
Good luck!:thumbsup:
Sea-r-cy


----------



## Stressless (Oct 2, 2007)

Fishermon said:


> W and Y..thats it...thanks...but %$^#* i already set the thing to LORAN meaning that all the numbers I had will be off when going back to GPS mode? don't get it. How do I back #s up?... using the SD card? So you're saying even if the LORAN towers are down I still can plug in Loran numbers on garmin LORAN Mode and then just reset to GPS mode? Thanks.


Technically yes... BUT.

The Garmin is doing a conversion of raw LORAN, even with offsets, that imposes errors as Sealark pointed out. Those errors go up arithmetically for each foot or meter you are away from the "cross point". the cross point is where the offsets in Loran = the exact GPS Lat Long. The only you know that is to enter a Loan # and GPS number of the same spot you KNOW is correct and fiddle with the offsets until it moves the Loran spot directly over the GPS location. 

Once you've "Zeroed" your cross point anything within a couple miles is goo to go for Loran.. the problem is byond that it's a hunt as you're never sure in which of the 360d the offset is from the actual GPS number. You're better off negating the Loran #'s and going strictly GPS. From someone that has spent hours on this problem on the equipment and on the boards researching. 

My $.02 only...

Stressless


----------



## Fishermon (Oct 19, 2007)

great info guys. appreciate the responses. I'll put some numbers there and will see what happens. Thanks a lot. :thumbsup:


----------

