On July 5, Andrew Sherman of Roanoke, Virginia, and his son Jack were fishing 40 miles off the North Carolina coast when a 23 Parker Pilothouse nearly ran them over. Suspicious because they didn’t spot someone at the helm, they chased it down and matched its 9-knot speed so Jack, a 21-year-old Naval Academy student, could jump aboard to stop the vessel.

What they discovered turned their frustration at nearly being run over into fear. The boat was unmanned. After alerting the Coast Guard, the two men used the ghost vessel’s multiple GPS units to retrace its path in the hope they might find the missing captain.

With Andrew operating the Parker and Jack at the wheel of their 21 Sea Hunt, they drove the two boats about a mile apart on parallel paths. When Jack discovered a pair of boating shoes in the water, he feared they’d arrived too late. But his father suspected the boat operator had kicked the shoes off to improve his chances of staying afloat.

In what should become a textbook example of maritime sleuthing, Andrew, 50, applied his lifetime of boating experience to find the missing fisherman. “I figured out which way the boat was drifting in the water and then I went back to the last place that boat had been on a straight line and when I got back to that straight line I more or less started doing these big (s patterns) back and forth,” Andrew told Roanoke’s 10News.

Within a few passes, they found the missing captain, Sascha Scheller. When Andrew pulled him out of the water, Scheller had been treading water for nearly three hours and had begun cramping up.

Scheller, an experienced boater and father of two, declined to be interviewed but went on social media so others might learn from the mistakes that nearly cost him his life:

Andrew Sherman said Scheller’s message is more important than the mistakes he made. “It’s not like we haven’t all made those bad decisions in our life. His big message to everyone, and I think it’s the best message, is, just be very cautious of letting your guard down,” he said.