Charts with TDs

[Scalloper 1]

Is there a place where I can purchase charts on LO showing TDs?

[guffins fisherman]

I have looked and looked.  If you can find an old fishing hot spots map, they had the TD's on them.  Funny thing is, a lot of fisherman don't even know what TD's are.  We use TD's extensively here in the eastern basin.  I know I may get hammered for this, but Bill Saiff III introduced me to the system and how it aligns perfectly with the structure of the eastern basin of Lake Ontario.  Furuno GP-39's will overlay TD's and give you your numbers too.

[Andre wallyandre]

Can I ask? What are TD's

[Iceman]

5 minutes ago, wallyandre said:

Can I ask? What are TD's

Me too, what are they?

 

thanks
 

John

[mr 580]

TD is Time Difference and goes back to the LORAN C system used prior to GPS.  LORAN was based on radio transmitters and was “turned off” quite a while ago.

[Andre wallyandre]

11 minutes ago, mr 580 said:

TD is Time Difference and goes back to the LORAN C system used prior to GPS.  LORAN was based on radio transmitters and was “turned off” quite a while ago.

Thank you

[mr 580]

When the military went to GPS then the LORAN network was not maintained and eventually was phased out.  One of the main radio towers was at Sampson.  GPS is faster and more accurate.  My guess is you would need to find old paper charts to get TD lines.  I had a LORAN unit and they would get you back - however GPS much more reliable.

[Scalloper 1]

3 hours ago, guffins fisherman said:

I have looked and looked.  If you can find an old fishing hot spots map, they had the TD's on them.  Funny thing is, a lot of fisherman don't even know what TD's are.  We use TD's extensively here in the eastern basin.  I know I may get hammered for this, but Bill Saiff III introduced me to the system and how it aligns perfectly with the structure of the eastern basin of Lake Ontario.  Furuno GP-39's will overlay TD's and give you your numbers too.

As a commercial fisherman for almost 40 years here in Maine. TDs are what we always have used for the same reason Bill S mentioned.

[Scalloper 1]

guffins,

Many of the plotters we use have the ability to overlay TDs on the charting screen. This is much more useful then lat long on many levels. I will dig a little deeper into my Garmin Ultra to see if that feature is offered.

[Sk8man]

One of the problems with the LORAN system was that if you were too close and in line with a tower the signal could be either lost or corrupted because it depended on triangulation among three towers for best accuracy. My old unit used to have the problem big time on Seneca near Sampson.

Edited August 4, 2020 by Sk8man

[guffins fisherman]

As far as I know, Lowrance will not do it. I cannot find it on my Garmin Echomap Plus. Maybe the higher end plotters will do it. It would be interesting to see a list of machines that will do it.

guffins,
Many of the plotters we use have the ability to overlay TDs on the charting screen. This is much more useful then lat long on many levels. I will dig a little deeper into my Garmin Ultra to see if that feature is offered.

Sent from my moto z3 using Lake Ontario United mobile app

[Scalloper 1]

I have the Nobel Tec Time Zero Explorer I use on commercial vessels for scallop fishing and the option to lay TDs over the charts are on that program. I have not checked on my Garmin yet

[Terp]

Something like this?

[scobar]

If you have no way to reference TD’s why would you want them?

I do have some logs from many moons ago I copied of my King LORAN, but I only used them for scuba diving points.


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[scobar]

Sent from my iPhone using Lake Ontario United mobile app

[scobar]

Sent from my iPhone using Lake Ontario United mobile app

[Scalloper 1]

21 hours ago, Terp said:

Something like this?

Yes just like that. I stopped by West Marine today in Watertown but the charts they had did not have TDs

[Scalloper 1]

17 hours ago, scobar said:

If you have no way to reference TD’s why would you want them?

I do have some logs from many moons ago I copied of my King LORAN, but I only used them for scuba diving points.


Sent from my iPhone using Lake Ontario United mobile app

I fished commercially for over 30 years using TDs because of reasons mentioned above the 12000 line on the 9960 chain follows the edge of the bottom almost perfectly, and many guys still reference areas to fish in TDs

Edited August 5, 2020 by Scalloper 1

[Terp]

Scalloper -  I have a book full of these charts for different sections of the lake. Let me get home and I'll message you the name of the book and publisher.

 

[Scalloper 1]

Cool thanks,

[Terp]

This isn't going to be of any help......... can't find this publication anywhere....

you might want to try online at Seabreeze nautical Books and Charts - Great Lakes maps