Took the boat out to the lake for its first open water autonomous test. It worked well. The turning rate happened to be perfect for the (nearly) slowest speed it can go. It navigated three GPS points, one lap across the cove and back.
The existing lid to the boat doesn’t fit with an Arduino Uno plus servo shield sitting on top so I ran it without a lid. After the first a lap I brought it in to inspect it and noticed that the electronics had a light sprinkle of water from the prop splashing. Enough to cause me to end further planned tests for fear I might short a sensor or something. No video unfortunately.
Battery test indicates it used about 12% of the 2200 mAh. Distance measured using Google Maps is approximately 600 feet.
So, a wild ballpark estimate of total possible distance with this battery would be 5000 feet, nearly 1 mile.
I’ll make a cover out of foam board today and try a longer distance test tomorrow.