Designed for Rowing, and can be used in other scenarios. The idea is to drop a marker at your 'starting point'. The app will mark that spot, and start tracking the straight line distance from that spot to your location (in yards or meters), don't worry about drifting off of line and then back to line. Drop another marker at the appropriate distance. With two markers - the app can now draw a line from the starting point, through the second marker, and into the distance. This distance can be configured on the settings page. Now the app will track the distance from the previous marker, again, in a straight line. As you go 'over' the extended line, the app will flash the screen and/or give you an audio alarm (configurable on the settings screen). Once you drop another marker, you will see your 'line' - the total distance traveled (since you started the app), the total line length from starting point to the last marker, as well as your 'direction of travel' (or bearing).