Wednesday, December 7, 2011

About this blog

This blog publishs a tool to convert files from the Lowrance USR4 file format into the GPX file format. The tool is written in Python 3.2.

How it got started
I am a happy owner of the Lowrance HDS-7M Chartplotter. The device served us very well during a sailing trip through the Baltic Sea and the North Sea including the Channel. In total we spent 1500nm on the sea with the Lowrance as our plotter in the cockpit. The chartplotter was always logging all movements of the boat.

I all started when my Lowrance HDS-7M chartplotter had issues exporting Tracks, Waypoints and Routes into a GPX file, which I needed to further use it with google maps.
The export into USR4 file format worked perfect but when trying to generate a GPX file the device stopped after some time. Still not sure about the cause but it could be due to very large number of track points (>10'000) in some tracks.

Due to compatibility reasons with former formats the export into USR3 file format had been limited to 10'000 track points, so this was no solution either

GPSbabel (which is a great tool) currently cannot read USR4 file format so this did not help either.

The only solution I have seen, besides talking to the very helpful Lowrance support, was to write a converter myself which converts USR4 to GPX file formats. In addition I also wanted to play around with Python, so this was the chance to get it started.

I hope someone finds the tool useful.

Please help me improve it
Since I would like to improve the tool and also learn more on writing Python code, please feel free to send suggestions for enhancing the tool, files for testing and also hints on how to improve the code.

Kind regards


  1. Please explain how to use the Python program in the MacOS environment. I think your .EXE distribution is only for Windows--is that correct?

  2. Hi,
    I added now the MacOS executable file in the download section.
    Alternatively you could also use the sourcecode and call it as described.
    Please make sure that you have Python >2.7!

  3. Hello, whenever you need a reliable and free tool for converting kml files to gpx formats and vice versa for an easy way to visualize your tracks or routes. I recommend using this converter:

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  6. hi Stefan,
    This is really cool, I have been playing with the python code to see if I can pull out the depth data associated with tracks. Python is all new too me, and cracking binary is not something I have done before, but I'm pretty good in Matlab. Any chance of some pointers on pulling out depth data?

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