Spearfishing Planet Store
Results 1 to 7 of 7

Thread: Loran Conversion 101 and Calibration/ASF offset exchange

  1. #1
    Join Date
    Jul 2007
    Location
    jax
    Posts
    443
    Than/ks (Given)
    0
    Than/ks (Received)
    4
    Likes (Given)
    3
    Likes (Received)
    14

    Default Loran Conversion 101 and Calibration/ASF offset exchange

    After all the work I see a few guys repeat at least once a year here and SB I figure a post with the ASF offsets you use locally and for what software would be helpful.Andren has a few on the website which are great service but we cover a huge territory and could help each other out.

    Or possibly a sticky with areas you have ASFs for and we could PM them if it would not be prudent or desirable to put them on the open net.

    Any thoughts?

  2. #2
    Join Date
    Jul 2007
    Location
    Offshore Sebastian Inlet
    Posts
    4,046
    Than/ks (Given)
    0
    Than/ks (Received)
    0
    Likes (Given)
    1
    Likes (Received)
    1

    Default

    With the permanent closure of Loran coming up in Jan 2010, this will be a good source for providing a tutorial on how to peform loran conversions, whether a single "offset" plugged into the GPS, or a more elaborate "calibration number".

    Now all of a sudden I suspect the "you cannot convert loran numbers" skeptics will now become hypocrites and start asking how we convert 5000 numbers accurately at one time.

    More to come.
    Last edited by inletsurf; 12-22-2009 at 09:56 AM.
    we are all wayfarers with a wish to stay alive
    for a cause for a dream
    theres much to move in a moving sea

  3. #3
    Join Date
    Jul 2007
    Location
    Offshore Sebastian Inlet
    Posts
    4,046
    Than/ks (Given)
    0
    Than/ks (Received)
    0
    Likes (Given)
    1
    Likes (Received)
    1

    Default

    FILE FOR VOLUSIA-BREVARD ONLY (CHAIN SOUTHEAST 7980 YANKEE ZULU Y-Z; 44XXX.X 61XXX.X) INTEND TO ADD FT PIERCE.

    For more info on chain selection visit: http://www.navcen.uscg.gov/Loran/LoranSelectChain.htm


    The attached file has calibration points in the Andren ("LoranGPS") .dbf format. The 4 "CALB" numbers for sebastian work incredibly well, and will put you within 30 feet for most 90' ledges out of sebastian. The volusia calibrations I'm not too familiar with. They are from www.volusiareefs.org, and although all are supposedly taken from simultaneous loran-GPS readings, the resolution of the Lat/Lon are 0.01 minutes, which can "build in" 80 feet of error just from the GPS reading. Combined with the loran signal error and measurement error, you can have another 60 feet added to the 80, giving you about 140 ft total error. Ideally you want DD MM.MMM resolution or DD MM SS.S resolution minimum, from a WAAS source.

    Andren's numbers for these spots are slightly different with seemingly higher resolution, they may be correct and more reliable. I've only used the volusia calibration one, and we found the reefs we were looking for. But the true test is finding a wreck or rockpile (bounded two-dimensionally). I would personally only use the "96" labelled ones in the "CHAIN" column, as the 9 indicates a highest weighting factor.

    Finally, if you do use andren, and you have your waypoint file already constructed in .dbf format, you can cut/paste the points into your file, BUT YOU MUST INSERT THE PROPER NUMBER OF ROWS SOMEWHERE IN THE FILE AND ADD THERE, AS OPPOSED TO JUST PASTING AT THE END OF THE FILE. I'm not a software expert and don't know why this happens but it took a lot of frustrating time to figure it out. Also, if you use Andren, MAKE SURE CHAIN 6 is set to SOUTHEAST YZ CHAIN.

    Further reference, these numbers come from www.andren.com and www.volusiareefs.org. Please visit these internet sites for further information on the calibrations and methodology.
    Attached Files Attached Files
    Last edited by inletsurf; 12-22-2009 at 09:57 AM.
    we are all wayfarers with a wish to stay alive
    for a cause for a dream
    theres much to move in a moving sea

  4. #4
    Join Date
    Aug 2007
    Posts
    56
    Than/ks (Given)
    0
    Than/ks (Received)
    0
    Likes (Given)
    0
    Likes (Received)
    0

    Default

    Well i'm glad someone started this thread, Now if someone could help me understand it, it would be great.

  5. #5
    Join Date
    Jul 2007
    Location
    Offshore Sebastian Inlet
    Posts
    4,046
    Than/ks (Given)
    0
    Than/ks (Received)
    0
    Likes (Given)
    1
    Likes (Received)
    1

    Default

    Anyone have some verified GPS numbers for these public wrecks published in the FWC artificial reef site for Monroe county, particularly wrecks/spots off the marquesas? I know they have GPS numbers associated with them on the FWC site but if they were loran obtained they are not accurate enough for a calibration number. It would help to have confirmed WAAS gps numbers for these public spots.
    Thanks
    we are all wayfarers with a wish to stay alive
    for a cause for a dream
    theres much to move in a moving sea

  6. #6
    Join Date
    Jul 2007
    Location
    jax
    Posts
    443
    Than/ks (Given)
    0
    Than/ks (Received)
    4
    Likes (Given)
    3
    Likes (Received)
    14

    Default

    -1.7 to -2.0 top line 444xx to 454xx
    -2.0 to -2.2 bottom line 590xx to 620xx
    Happy Birthday

  7. #7
    Join Date
    Jul 2007
    Location
    jax
    Posts
    443
    Than/ks (Given)
    0
    Than/ks (Received)
    4
    Likes (Given)
    3
    Likes (Received)
    14

    Default

    45012.5 61794.7 =3017.532 8049.281 Casablanca a 365' long wreck off Jax in 100'.

Similar Threads

  1. Yamaha fuel management calibration
    By lost spear in forum Boat Repair Questions
    Replies: 6
    Last Post: 01-26-2010, 04:40 PM
  2. Numbers/Coordinates/ASF offsets exchange
    By 100days-a-year in forum General Spearfishing Topics
    Replies: 3
    Last Post: 04-26-2009, 09:32 AM
  3. Has anyone done a LPG conversion
    By Greg in forum General Off Topic
    Replies: 2
    Last Post: 01-19-2009, 01:46 PM
  4. Free Loran Conversion Software
    By Surface Tension in forum General Spearfishing Topics
    Replies: 15
    Last Post: 05-02-2008, 11:18 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •