Puzzle

To summarize the problem, a boat is proceeding upstream at 20 knots against a 10 knot current. A lady drops her hat and a minute later the boat starts a 180 deg. turn to retrieve it. It takes half a minute to make a 180 deg. turn. The question is how much of a delay does this cause in reaching their destination. People can make different assumptions to solve the problem and so differing assumptions could produce different and equally valid answers. We assume that without letting back on the throttle, the boat makes a starboard turn for the initial 180 and then proceeds downstream, makes another 180 and then proceeds back upstream. We assume that along the line, the hat is retrieved. For the sake of argument, assume at the point of the initial turn there is a piece of driftwood in the water and there is a big tree on shore. To get back to the point where the hat fell into the water is one minute plus the two 180 and then another minute upstream to get back to the piece of driftwood. So there is a total three minutes lost getting back to the piece of driftwood. The driftwood has gone downstream three times ten "knot-minutes" in the meantime. You can figure that exact distance if you want, but it is unimportant to the solution to the problem at hand. The point is that the boat makes as much headway relative to the shore as the stream makes downstream. So to get back to the big tree on shore is another three minutes. Total time lost is six minutes. If anyone feels this solution is incorrect or has a different solution based on different assumptions, please write me and I will include your comments in a future issue.