Using GOOGLE EARTH for Boat Navigation
[This article is an updated edition of a previous article that appeared in the old forum at
http://continuouswave.com/ubb/Forum6/HTML/003601.html
and portions of that article are included here.]
The amazing application GOOGLE EARTH provides a method for creating geo-position data. GOOGLE EARTH calls their stored locations "places." GOOGLE EARTH places can be organized into folders. The individual places or a folder of places can be exported to a file from GOOGLE EARTH. GOOGLE EARTH only exports in their own file formats, either .KML or .KMZ. Note that .KMZ is just a compressed version of .KML. There is not a particular advantage to using .KMZ that I can see if the data set is small.
Geo-position or "place" data in .KML can be translated to other formats by many convertors. An on-line convertor at
http://kml2gpx.com/
offers to perform conversion to .GPX format from .KML at no cost. You can download and save the converted data from the on-line convertor. The simplest way to do this is to right-click on the hyperlink "Download your new file [here]," and choose the option to download and save the file. (This may vary somewhat with your particular browser.)
The downloaded file may have a filename in the form fileName.gpx.xml. You can rename the file to just .gpx.
The data from GOGGLE EARTH is now in .GPX format. You can import this data into many chart plotters using their native import function, as most modern chart plotter devices understand .GPX, a sort of lingua franca of position data.
The .GPX files generated by the on-line service KML2GPX.COM have been tried with a couple of chart plotters and found to work. The chart plotters tested so far are:
--PolarView NS from Polar Navy;
--HDS-8 from Lowrance.
Although there are other methods of converting .kml file data to .gpx file data, they involved obtaining an application for your specific computer operating system, learning to run the application, and perhaps having to purchase the application. Since the kml2gpx website works for any computer platform, is fast, and is free, I cannot see any particular reason to not use it. I therefore do not attempt to collect, describe, and evaluate other applications for various operating system environments, with one exception. I will comment about one particularly useful, low-cost, and multi-platform application, GPSBabel.
The wonderful application GPSBabel provides another method for translation of "places" from GOOGLE EARTH contained in a .KML file to a .GPX file. In GPSBabel set the input file type to be "Google Earth (Keyhole) Markup Language," and set the output file type to be GPX XML.
This method was also tested and found to generate .GPX files. The GPX file worked fine with PolarView NS. The file did not work with the Lowrance HDS-8. The HDS-8 import failed with the error message:
"Import failed--File version 1.0 not supported."
A resolution was found for the problem of the import failure for .GPX files generated by GPS Babel to Lowrance HDS-8. The remedy was described in detail in another article. See
Exchanging Navigation Data Among Different Chart Plotters
http://continuouswave.com/ubb/Forum6/HTML/002884.html
for a detailed narrative of the process necessary to overcome this error in the HDS operating system. The article also offers some general advice about using GPSBabel.
It has been seen that some chart plotters are not particularly robust at parsing .GPX files, so it could occur that a perfectly good .GPX file may not be able to be imported to some devices. If this occurs, GPSBabel could be used to translate the .kml data directly to a proprietary file format that is native to your chart plotter.
Just to be clear, the application GOOGLE EARTH has a built in function for importing geo-position data in .GPX format into GOOGLE EARTH. No extra work necessary. It is in the export of data from GOOGLE EARTH to a format like .GPX that a little helper is needed.
Within the GOOGLE EARTH application, organization of geo-position data is possible in many ways. For example, a group of waypoints can be collected in a folder. The folder can be saved and the information exported. The range of options for manipulating geo-position data in GOGGLE EARTH is just about limitless, and it will be impossible for me to describe everything that could be done, due to both the limits of the scope of this article and the limits of my own knowledge. Many tutorials exist to explain of the features of GOOGLE EARTH and how to use them, and I recommend taking advantages of those resources to enhance your own understanding of the application and its features. I can get GOOGLE EARTH to do a few things I want it to do, but I don't feel particularly expert at using it and won't try to teach others; far better resources exist for that.
In contrast to GOOGLE EARTH, most recreational grade marine chart plotters offer very limited organization and manipulation of geo-position data. An example is found in the Lowrance HDS first generation chart plotters. A geo-position data export function exists but is limited to exporting all data at once into one giant file. In Lowrance jargon, waypoints, routes, and trails are geo-position data that are available for export, but there is no means to select a subset of the available data. All data gets exported. The chart plotter does offer some manipulation of data on its display, permitting individual waypoints to be turned on or off, historical tracks of boat position (trails) to be turned on and off, and routes to be shown or not. The individual waypoints can be edited--individually. This can be a tedious task on an older chart plotter like the first generation HDS because there is no keyboard for input of data; all data input must be accomplished by driving the cursor around a keyboard replica and selecting individual letters and numbers with the cursor--an extremely inefficient method of data entry.
Using GOOGLE EARTH for Boat Navigation
Re: Using GOOGLE EARTH for Boat Navigation
Jim--this is a very interesting and useful article.
Most of the areas where we boat are uncharted. Although the shallowest of them have fairly clear water and the shallowest water is easily detected by eye because of its green color, the lack of charted depths requires us to proceed more slowly than desired.
The Google Earth application with its aerial views shows well defined shallow water. It would be easy to define safe routes through the waters using Google. The only problem is putting the routes on our plotter. We use a Navionics+ map chip in our Raymarine Dragonfly 4 Pro MFD. The Navionics web site allows us to upload or download "user data" from and to our map chip.
I need to spend some time studying the Google application to see if I can create routes on our Navionics + chip data.
If interested, you can view a good example of one of our favorite small cruising areas in Google Earth. Our place is at Compass Point on Little Lagoon and we enjoy cruising there. If you use the Google Earth search function search for "Little Lagoon, Gulf Shores, AL 36542".
Most of the areas where we boat are uncharted. Although the shallowest of them have fairly clear water and the shallowest water is easily detected by eye because of its green color, the lack of charted depths requires us to proceed more slowly than desired.
The Google Earth application with its aerial views shows well defined shallow water. It would be easy to define safe routes through the waters using Google. The only problem is putting the routes on our plotter. We use a Navionics+ map chip in our Raymarine Dragonfly 4 Pro MFD. The Navionics web site allows us to upload or download "user data" from and to our map chip.
I need to spend some time studying the Google application to see if I can create routes on our Navionics + chip data.
If interested, you can view a good example of one of our favorite small cruising areas in Google Earth. Our place is at Compass Point on Little Lagoon and we enjoy cruising there. If you use the Google Earth search function search for "Little Lagoon, Gulf Shores, AL 36542".
Butch