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Map the bottom of a lake with GPSMAP 50s

ddabcd277 47 Points
edited April 2014 in GPS Recommendations

Is it possible а bottom of a lake to be mapped with lets say GPSMAP 50s? The idea is to be made a 3D model of the bottom.


  • sussamb 827 Points
    No ... GPS don't work underwater.
  • Boyd 1992 Points
    What is a GPSMap 50s? I believe the "s" designation means it's a Sounder - like the 520s for example....
    the sounder version, GPSMAP 520s, comes with a powerful dual frequency transducer that clearly paints depth contours, fish targets and structure whether you’re fishing in freshwater or off the coast. The 520 and 520s also are CANet® compatible, so you can share sounder data with another chartplotter on your boat.
    I don't know if there's a way to save the sonar data, but if you can then you might be able to do what you want. In fact, I read an article about making your own marine maps in the last 6 months SOMEWHERE, but I can't find it now. Seems to me they were using Lowrance or some other brand and not Garmin though.
  • ddabcd277 47 Points
    I am sorry echoMap50s not GPSMAP (sleepy):

    Well, in general it doesn't matter GPSMAP or echoMap.

    The idea is to be made a 3D model of the botom of a lake from the data of a sonar and the GPS. Not a marine map with those buyos, water ways etc. I also don't know what these devices save as a data. Or if they are proper for such a task.

    Most probably they save the depth in the left track. So maybe if there are many points with depth a 3D model can be generated for example. If the whole lake is crossed. I don't know. Thought someone might know or have did a similar task.

    I also read that Lowrance made free their software for making marine maps. But as I wrote the task is not making a marine map.

    Thanks Boyd.
  • Boyd 1992 Points
    edited April 2014
    Actually the article I read was about making your own map of the bottom of a lake using sonar data. Wish I could find it now, sorry.
  • Boyd 1992 Points
    edited April 2014
    Found it! Rich Owings from e-mailed me this after reading a thread I started about Lowrance maps at gpsfiledepot. :)

    Sounds like a lot of work!

    In order to get the most accurate data, Lowrance recommends using a grid pattern when recording sonar logs in order to cover multiple points of reference. Around the areas of my lake that I knew had breaks, humps, ledges or any other irregular bottom contour, I made multiple passes since I knew those areas were more likely to hold bass at different times of the year.
  • privet01 227 Points
    With the typical gps accuracy of 3 to 11 meters, I wouldn't claim them to be the definitive map of the area. But certainly they are better than none at all. Just keep that in mind if you decide to boat at high speed near any shallow area, trusting only the map you made.
  • ddabcd277 47 Points
    Thank you Boyd. Useful article.

    I will also write to Garmin UK to see what they will reply.

  • ddabcd277 47 Points
    Unfortunatelly, Garmin tech support weren't very helful. They couldn't reply can the Garmin sonar logs be uploaded into a third party software and a dem model be createn from them. Seems this is only possible with Lowrance.

    Regarding the GPS accuracy this is not a problem as an RTK GPS can be used instead of the consumer GPS.
  • gatorguy 326 Points
    Dr. Depth's software was one of the least expensive (all are kinda expensive) solutions for creating fairly accurate contour maps from your sounder data. It was pretty popular, reportedly easy to use, and well-known to guides and captains too leading Johnson Outboard to swoop in and buy them last year. Rather than continuing to offer the software it looks as tho they've decided to make it a Humminbird-only service much like the Lowrance premium pay Insight Genesis custom maps.

    With the very good Dr. Depth now unavailable I haven't seen anyone gushing over the other options on marine forums. One that does get mentioned tho is 3DField, a windows program that does appear to be compatible with Garmin software.

    I've no idea how easy it is to use. I had planned to use Dr. Depth myself, and I already have a Lowrance Gen-2Touch Chartplotter/Fishfinder. Using Insight Genesis isn't cheap, but nothing about marine is.
  • ddabcd277 47 Points
    Thanks gatorguy! It is kind of a solution.

    Just one question still bothers me. Which transducer will be more appropriate then for such a task - a garmin downvu, chirp or the traditional garmin txdr will be enough? DownVu transducers, like the lowrance structure scan, are making a 3D image of the surface. Should be more appropriate then? On the other hand chirp txdrs are making better target separation but are much more expensive.

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