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Author Topic:   Lowrance HDS: TRAILS
jimh posted 06-19-2012 08:04 AM ET (US)   Profile for jimh   Send Email to jimh  
The Navico operating system (NOS) in the Lowrance HDS series of chart plotter and sonar devices provides for recording boat movement in a file called a TRAIL. The track or trail of the boat movement can be a useful feature to have, and the NOS provides for management of multiple TRAIL files.

In my boating I typically start a new TRAIL file at the beginning of each cruise. At the end of the cruise I stop the recording. The TRAIL file is stored on the HDS device's internal memory, but it can be copied to a removable memory card. Using this method I offload the TRAIL file to my laptop, where I archive them.

The TRAIL recording is controlled in the TRAILS tab of the WAYPOINTS, ROUTES, and TRAILS page. This page is accessed from the UTILITIES position of the page carousal. See

The TRAILS tab is shown in

The TRAILS tab allows you to set the name of the trail, toggle its recording on and off, and select the option to display the trail or trackline on the chart plotter screen.

Two other parameters of the NOS also affect TRAILS and are important to set: the LOGGING TYPE and the global parameter for TRAIL display.

The LOGGING TYPE will set the criterion for adding a point to the track line. The LOGGING TYPE is set in a separate screen and in a separate section of the operating system. See

for details on the LOGGING TYPE parameter and its options.

While the TRAILS tab permits selection of trails to be displayed, there is also a global variable for display of trails which must be set to ON for any trail to be displayed. The global variable for trails is in the SETTING MENU on the CHART submenu. See

for details on the global variable setting. If this global variable is set to off, no trails will be displayed on the chart. With the global variable set to on, the trails that will be shown can be selected in the TRAILS tab.

jimh posted 06-20-2012 07:26 AM ET (US)     Profile for jimh  Send Email to jimh     
In the NOS on the Lowrance HDS, the function to export the trails is found on the FILES option of the UTILITIES section. See

The export function is a bit clumsy to work with. When exporting data, the export function always exports all the waypoints, routes, and trails in the HDS devices memory. The export creates an archive file with all three types of data in the same file. The marriage of all three types of data into a single file can make management of the various different file types a bit awkward.

My solution to the problem of the all-in-one export is to use the GPX file format. I export the waypoints, routes, and trails into a GPX file. Once in the GPX format, it is not difficult to manually edit the file with a good text editor to remove the data that you don't want to archive.

For example, following my recent week-long cruise I had a trail file with about 5,000 track points. I used the export function to save this data onto a memory card, but along with it came all my waypoints and routes. I moved the GPX file to my laptop computer, and using a good text editor that understands XML formatting (in my case BBEDIT), I opened the GPX file. I then manually edited out all the waypoint and route data, and saved the remaining GPX file with a new name, reflecting the new content, that is, just the trail of our recent cruise. I now have an archive of just the trail of that cruise, without also including all the waypoints and routes.

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