Chart a line that stays in the river. Record on the water with Tablet GPS — fixes snap to this chart so later plots can stack on the same water. The sim keeps traveling and loops the line. Ghost tracks on the map are every plot we have kept.
Chart
Start is the boat. Tap End on the water, then Plot.
Record
Not recording.
Simulate
No path yet. Plot, record, or open a saved route, then run it.