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ARE ALL LORAN C MACHINES CREATED EQUAL..??

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ARE ALL LORAN C MACHINES CREATED EQUAL..??

Old 04-22-2007, 09:52 PM
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Default ARE ALL LORAN C MACHINES CREATED EQUAL..??

Looking to perhaps get a different used Loran-C machine to use in fishing some numbers I just got. Are all Loran -C machines equally accurate or are some substantially more dead-nuts-on than others..??

Is there a big variability in accuracy between brands is what I am basically asking and if so which brands are the better ones..??
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Old 04-22-2007, 11:46 PM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

.. or are some substantially more dead-nuts-on than others..??

There's nothing about LORAN that's "dead-nuts-on". Most any of 'em will get you close, but you'll likely still have to do an area search to locate the exact bottom structure. I'm sure someone will chime in that their unit was dead-nuts-on, but then again, there's always someone that will lie about anything.
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Old 04-23-2007, 11:43 AM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

Dude, it's 2007
Have you heard of GPS?
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Old 04-23-2007, 09:54 PM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

aj bruno - 4/23/2007 10:43 AM

Dude, it's 2007
Have you heard of GPS?

to use in fishing some numbers I just got.


You will not find the Loran number spot using a GPS. Oh you will get somewhat close. Maybe 1/4mile. That's a LOT of fuel burning and looking.

Here on the Gulf Coast Sitex was what was mostly used. I did have a XJ-1. Kind of sorry I sold it now.
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Old 04-23-2007, 10:00 PM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

I used to have a Micrologic that would bring you back to the same spot with incredible accuracy. Sold it with a previous boat a few years ago.
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Old 04-24-2007, 08:39 PM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

I've got a Furuno LC-90 on my boat, purchased a another used one last year because some wreck numbers I have are still in TD's and you need them if someone can't hook you up with the GPS numbers. New Furuno LC-90's are still over 1K in price and as far as I know they are the only one still manufacturing them.
I had the micrologic also, great unit! I had a extra one someone gave me and I passed it on to buddy.
Is it worth a couple hundred bucks to find a some numbers out of a old salty's book? F_ck Yeh!
Once you've got it down in your GPS you are sitting tight.
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Old 04-24-2007, 08:44 PM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

Cant you enter the loran numbers in your gps and have it convert to lat/lon. This may not be possible but I tried
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Old 04-24-2007, 09:46 PM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

Old timer did in fact give me some TD waypoints that he will never get around to fishing. Received a Northstar 800 from a different guy who sold his boat. When I went to use it, the coupler went bad. Just bit the bullet and ordered an O.E.M. coupler.

Several charter capts. said to try and stick w/ the same brand machine that the TD's were made with to get the most accurate results. Conversion with a GPS unit is said to be 'off' a bit and some of these spots I've been told are small. So loran for conversion purposes is a must I think.

May look for a Si-tex as a back up as well. Thanks for your replies.
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Old 04-25-2007, 11:24 AM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

Loran does have a high degree of accurate repeatability when returning to saved points, higher accuracy than GPS for many reasons. (I'll catch it for that one, for sure)

Unfortunately, that highly accurate repeatablility to saved poiints is only within the same LORAN reciever that originally stored the point. Manually addiing points into a different LORAN reciever will get you the area of the 'point', but the accuracy will be no greater than GPS can provide. You might get a slightly higher degree of accuracy if the point is manually added to a LORAN unit of the SAME manufacturer of the LORAN unit that originally located the 'point', but not necessarily.

As an aside, for those that will argue the accuracy of GPS over LORAN;

Both systems do exactly what they were designed to do. GPS was designed to accurately navigate ICBM's to a target on the 'otherside' of the world. - For a Nuke, accuracy within a couple of hundred feet was more than adequate. System accuracy far exceeded expectations and provided accuracy within a few meters, hence, as an ancillary benefit, was useful for maritime and aviation navigation.

LORAN, on the other hand, was designed as a navigational system for ships and planes. It's purpose was get the 'pilot' within VISUAL range of the desired destination.

The reason LORAN has higher repeatability for any given point is because the transmitters are stationary and any signal interference (i.e. - topography) is constant (excluding weather, sun spots, electrical storms, etc. - which effect GPS as well) between the transmitter and receiver at any given point.

GPS satelites, using 3 or more calculations, move about 3 dimensionally, one day the GPS unit uses satelites A, B, and C to display a Lat/Long and next day it uses C, D, and E. The difference between distances may not be a great deal, but the 'triangulation' could (and usually is) several meters off. Wiith a plus or minus of 3 or 4 meters you could be as much as 75-80 feet from the originally stored 'point', not much for navigational purposes, but more than enough to miss returning to a 30' "honey hole". Since most small boats and private aircraft still depend on LORAN for primary navigation, it is unlikely LORAN will be retired anytime soon.
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Old 04-26-2007, 07:13 PM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

njmello - 4/26/2007 3:24 AM

Loran does have a high degree of accurate repeatability when returning to saved points, higher accuracy than GPS for many reasons. (I'll catch it for that one, for sure)

.................

As an aside, for those that will argue the accuracy of GPS over LORAN;

Both systems do exactly what they were designed to do. GPS was designed to accurately navigate ICBM's to a target on the 'otherside' of the world. - For a Nuke, accuracy within a couple of hundred feet was more than adequate. System accuracy far exceeded expectations and provided accuracy within a few meters, hence, as an ancillary benefit, was useful for maritime and aviation navigation.

LORAN, on the other hand, was designed as a navigational system for ships and planes. It's purpose was get the 'pilot' within VISUAL range of the desired destination.

The reason LORAN has higher repeatability for any given point is because the transmitters are stationary and any signal interference (i.e. - topography) is constant (excluding weather, sun spots, electrical storms, etc. - which effect GPS as well) between the transmitter and receiver at any given point.

GPS satelites, using 3 or more calculations, move about 3 dimensionally, one day the GPS unit uses satelites A, B, and C to display a Lat/Long and next day it uses C, D, and E. The difference between distances may not be a great deal, but the 'triangulation' could (and usually is) several meters off. Wiith a plus or minus of 3 or 4 meters you could be as much as 75-80 feet from the originally stored 'point', not much for navigational purposes, but more than enough to miss returning to a 30' "honey hole". Since most small boats and private aircraft still depend on LORAN for primary navigation, it is unlikely LORAN will be retired anytime soon.
Wow just where do some of these myths come from absolutely amazing
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Old 04-26-2007, 09:35 PM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

Kerry - 4/26/2007 7:13 PM

njmello - 4/26/2007 3:24 AM

Loran does have a high degree of accurate repeatability when returning to saved points, higher accuracy than GPS for many reasons. (I'll catch it for that one, for sure)

.................

As an aside, for those that will argue the accuracy of GPS over LORAN;

Both systems do exactly what they were designed to do. GPS was designed to accurately navigate ICBM's to a target on the 'otherside' of the world. - For a Nuke, accuracy within a couple of hundred feet was more than adequate. System accuracy far exceeded expectations and provided accuracy within a few meters, hence, as an ancillary benefit, was useful for maritime and aviation navigation.

LORAN, on the other hand, was designed as a navigational system for ships and planes. It's purpose was get the 'pilot' within VISUAL range of the desired destination.

The reason LORAN has higher repeatability for any given point is because the transmitters are stationary and any signal interference (i.e. - topography) is constant (excluding weather, sun spots, electrical storms, etc. - which effect GPS as well) between the transmitter and receiver at any given point.

GPS satelites, using 3 or more calculations, move about 3 dimensionally, one day the GPS unit uses satelites A, B, and C to display a Lat/Long and next day it uses C, D, and E. The difference between distances may not be a great deal, but the 'triangulation' could (and usually is) several meters off. Wiith a plus or minus of 3 or 4 meters you could be as much as 75-80 feet from the originally stored 'point', not much for navigational purposes, but more than enough to miss returning to a 30' "honey hole". Since most small boats and private aircraft still depend on LORAN for primary navigation, it is unlikely LORAN will be retired anytime soon.
Wow just where do some of these myths come from absolutely amazing
I was wondering the same thing myself. I have been in aviation for over thirty five years now (where did the time go?) and this is the first I have ever heard about LORAN being an aviation based system. Yes, it was used in some aircraft for a brief period of time but it was never an aerospace related navigation system.
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Old 04-26-2007, 10:28 PM
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Default RE: ARE ALL LORAN C MACHINES CREATED EQUAL..??

FWIW, Loran was used for many years for both marine and air navigation, until GPS came along. That's not something I read - I used it in both boats and airplanes.

Loran is not as accurate as GPS since GPS dropped SA. Loran accuracy varies alot from area to area depending on the station locations and distances, but generally it will give you 50 foot to 200 foot accuracy. A GPS will usually give you 30 foot accuracy or better on the water.

But converting LORAN numbers to GOOD GPS coords takes some patience and some work. Most GPS units will convert the numbers, but don't correct for terrain and atmospheric errors in LORAN. That means the converted GPS coords may be off by as much as a mile. But the error is consistent within an area within a radius of several miles. So if you can get both LORAN numbers and good GPS coords for an object in the same area, you can compare the GPS coords to the converted LORAN numbers and compute a correction for both Lat and Lon values. Using these corrections will put you within the original accuracy of the LORAN numbers, i.e., 50 feet to 200 feet.

I have done this, in different areas, and it works.
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Old 04-27-2007, 11:46 PM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

Various LORAN units accuracy or lack thereof was/is not very discernibly different between mfgr's units. A better question is user-friendliness. One of the very best in that regard was Furuno's LC-90 Mk II ( not the plain LC 90). Contrary to Sublimes's note above however, Furuno stopped making LORANS a year or more ago. I believe Sitex is the only mfgr presently selling units that receive/display actual LORAN( newer tech, more accurate eLORAN really) info , not phantom-conversion type, and those units can also process GPS/WAAS info simultaneously if equipped with both their eLORAN & GPS receiver antennas. Not too long ago, another poster here noted that one LORAN mfgr in the past even incorporated a trackplotter into their product. Can't recall which though.
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Old 04-28-2007, 11:13 PM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

Been fishing with lorans for 20 years. i do Lot of wreck fishing. I have always found t my machines to be very accurate. i have used raytheon, Apelco,Sitex and Micrologic. I have always found my snags and I don't lie.
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Old 04-29-2007, 08:33 AM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

The Apelco (made by Raytheon) 6500 LORAN has a trackplotter (in answer to a previous question on this thread). I have one, and it works pretty well.
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Old 04-29-2007, 09:09 AM
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I have an Apelco LORAN C on my boat as well as a Northstar GPS. I use them both. I have a lot of LORAN numbers from my commercial fishing days and have yet to hit them all to convert them over to GPS. In addition, it is nice to have a back-up for those times when the government decides to enact regional GPS outages.
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Old 04-30-2007, 09:25 AM
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Default Re: ARE ALL LORAN C MACHINES CREATED EQUAL..??

I have used LORAN in both boats and planesl. I have not flown for many years and not since LORAN was changed to the C system, which is more accurate than the original system.

I use both GPS and LORAN on my boat, independently powered (a penchant for redundancy left over from my flying days). The LORAN reports Lat/Lon in UTM co-ordinates - my GPS is set to report in the same format. Both units have 'steering screens, will store way points and save tracks as well. With both on at the same time the difference is usually less than 1/10 of a degree ( about 30 seconds in Lat/Lon). Using the '20 second rule' (a difference of 1/100 th of a foot error per 100' traveled in a given direction) that amounts to about 6' error per mile. Since you cannot actually hold a course within 30 seconds, the true course will 'sway' a minute or two to either side of the 'rumb line', thus cancelling a portion of the error.

If you Google "UTM Coordinate System" you will find many helpful sites that explain it better than I can. There are also charts and formulas for converting UTM to Lat/Lon and vice versa.

I am a land surveyor by trade and measuring distances accurately is a necessity. Minimizing accumulated error can only be accomplished with an understanding of what produces the error. GPS land surveying techniques, combined with local CORS (Continuously Operating Reference Stations) and a lot of math with provide accuracy to with 1/10 of a foot (approx. 1 1/4 inch) over many miles. CORS are not available to LORAN units and range is limited.

Just for fun, using previously stored points, I have 'steered' by compass with both 'steering screens' on and found that, by compass alone, I can end up as much as 5-6 degrees off course due to error introduced by wind, current, tide and magnetic deviation. 'Steering' by GPS in Lat/Lon mode up to 20-25 miles the error is negligable but by 40 miles the the difference between GPS and LORAN becomes noticeable. The 'spot' can usually be found somewhere between the GPS reported position and the LORAN reported position when BOTH are reporting in UTM mode.

Most of us are fair weather fishermen/sailors relying on 'piloting' per recognized landmarks. At night, in fog, adverse weather, or out of sight of land, I would never rely on just ONE navigational aid. I learned to navigate before LORAN and still carry an independantly powered RDF (same as used on ships and aircraft 40 years ago) on board as a back up. Modern electronic aids has made navigation very easy for everyone - but knowing the limits is more important than knowing how how to use them.

Just my $0.02.
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Old 04-30-2007, 10:58 AM
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Kerry - I am a land surveyor and I use GPS equipment, combined with CORS, for land measurement regularly. The total system provides 3D accuracy within 1" over many miles. I think this exposure provides me a cleaar understanding of the GPS system. It is true that GPS accuracy is higher now, than in the past, since purposely injected error no longer occurs and with the addition of the Russian satellites to the system, the newer GPS units have more data to work with at any given time.

Every navigational system has unintended error injected from uncontrolable external sources, atmospheric and electronic interference to name but two. GPS units do all of the 'math' calculations 'on board' based on timed signals from satellites within range, to provide a Lat/Lon display on screen, generally accurate to within a few meters. The math calculations are basic trignometry and use 'triangulation' to arrive at a mathematical solution, ergo, a point on the surface of the earth. These 'calculations' are conducted within nano-seconds (depending on the speed of the processer in the unit). External error is injected from the following sources; you (the object) is moving, the earth is turning (moving), the satelites drift 3 dimensionally (moving), time sequences between satellites vary slightly and atmospheric conditions.

The GPS units do not have the 'onboard' capability to monitor, store or calculate the drift or variances in time between satellites used for the calculations as there is no need for that kind of accuracy for navigational purposes. The variances (except atmospheric conditions) are monitored and stored in land based receivers and the corrections are calculated and satellite information is updated regularly. The updates are called 'epochs' and the corrections are calculated from CORS stations around the world, current satellite positions, and the amount of monitored variance in time and distance.

'Leap seconds' are added to accommodate time & distance (up, down, right, left) variances in order to keep the system's accuracy within parameters (+ or - 20 meters). Without applying 'epoch' corrections to the GPS unit that is doing the calculations, error is introduced by 'rounding' the 'onboard' calculations each time a calculation is done (usually several per minute).

Without 'epoch' correction, and using an entirely different set of satellites at a later date the 'error' can be as much as several hundred feet from the original 'spot', thus diminishing 'repeatability' from day to day over a period of time.

Land surveying's extremely high degree of accuracy (and repeatability) comes from the fact CORS stations (like LORAN trnsmitters) do not MOVE. The error introduced by topography between the transmitter and any given spot is consitant, reducing error, thereby increasing accuracy/repeatability.

Google 'LORAN Repeatability' for a full explaination of the reasons LORAN has higher repeatabilty.
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Old 05-01-2007, 06:58 AM
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...I have used LORAN in both boats and planesl. I have not flown for many years and not since LORAN was changed to the C system, which is more accurate than the original system.
So you have not flown since 1957? 50 years ago!

....I am a land surveyor by trade and measuring distances accurately is a necessity. Minimizing accumulated error can only be accomplished with an understanding of what produces the error. GPS land surveying techniques, combined with local CORS (Continuously Operating Reference Stations) and a lot of math with provide accuracy to with 1/10 of a foot (approx. 1 1/4 inch) over many miles. CORS are not available to LORAN units and range is limited.
Quite dumbfounded what CORS have to do with recreational GPS as used by most fisherman and quite frankly they have absolutely nothing to do with GPS SPS accuracy and really why CORS has even been mentioned is irrelevant to the type of GPS accuracy people are using here. Let’s not confuse the issues with mention of CORS, totally irrelevant!

....Kerry - I am a land surveyor and I use GPS equipment, combined with CORS, for land measurement regularly. The total system provides 3D accuracy within 1" over many miles....
Again CORS has absolutely nothing to do with recreational GPS accuracy and if 1" is supposed to sound good then I don't think 30 odd metres (100 feet) with today’s constellation is very good at all, it is generally much better than that.


....I think this exposure provides me a cleaar understanding of the GPS system. It is true that GPS accuracy is higher now, than in the past, since purposely injected error no longer occurs and with the addition of the Russian satellites to the system, the newer GPS units have more data to work with at any given time...
There are no recreational GPS receivers that support Glonass, so talk of Russian satellites is irrelevant in the context here. In any case there simply are not enough Glonass satellites at the moment to make much of a difference even if there were recreational receivers capable of including them.

....to provide a Lat/Lon display on screen, generally accurate to within a few meters....
GPS is not accurate to a "few metres" this is simply myth and misinformation! GPS accuracy is less then 13 metres @ 95% and in worse case scenario is less than 36 metres, 95% of the time. This is the accuracy a SPS user should be working to, this "few metres" stuff is rubbish. And don't forget there is the other unknown 5%!

....use 'triangulation' to arrive at a mathematical solution....
GPS position determination does not use "triangulation"

....in land based receivers and the corrections are calculated and satellite information is updated regularly. The updates are called 'epochs' and the corrections are calculated from CORS stations around the world, current satellite positions, and the amount of monitored variance in time and distance....
Would appear there's a bit of confusion between epochs and ephemeris? And again CORS hace absolutely nothing o do with the discussion here. Precise ephemeris is based on the main monitor stations but doesn't have a lot to do with many of the CORS. In any event precise ephemeris isn't available until at least 14 days after the event and again totally irrelevant to the discussion here.

....'Leap seconds' are added to accommodate time & distance (up, down, right, left) variances in order to keep the system's accuracy within parameters (+ or - 20 meters)....
Leap seconds has absolutely nothing to do with the systems accuracy what so ever. The leap seconds transmitted as part of the nav message is simply to keep displayed local time in conjunction with the user time zone/offset correct. GPS time (as such) has not been changed since Jan 5/6 1980 when GPS time equaled UTC time. GPS time has not changed since Jan 5/6 where as due to the earth slowing down since that time there is a requirement for leap seconds to correct GPS time to current UTC time. GPS accuracy is not based on "time" but "timing", don't confuse the two!

Now as for Loran! Loran's absolute accuracy ranged from 0.1 to 0.25 nautical miles and back in the days when Loran was at its peak that was good but hey that was some 40-50 years ago and times have changed. Repeatable accuracy was very variable and generally less than 100 feet (more at times) but today this type of repeatable accuracy is considered quite poor compared to GPS.


Regards, Kerry.
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Old 05-01-2007, 08:09 PM
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....Without 'epoch' correction, and using an entirely different set of satellites at a later date the 'error' can be as much as several hundred feet from the original 'spot', thus diminishing 'repeatability' from day to day over a period of time.
Oh missed this one Certainly some myths getting about!
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