Scenario: Returning to Home

If you can do autonomous waypoint navigation, you can do return-to-home by entering the starting location as the destination waypoint.

What this requires in addition to the DVL: This requires the ROV software to be able to accept one of the DVL position output messages, such as $GPRMC, and then self-pilot toward a desired coordinate.

For this usage you do not need to initialize the starting position to a known point unless you want to. If the entire journey is using the startup (0,0) position, the ROV should be able to navigate back using the startup coordinate system.