“I get asked all the time about where to go and how to get there,” said Weatherstein, a marine master technician at All Star Marine in Essex, Md. “I tell them to follow such-and-such a creek and they say, woah, we’re new to boating. We don’t know where that creek is. How cool is it for them to punch it into an app and it takes them there?” Think of it as having a first mate in your pocket.