Originally posted by knighttemplar1960:

The fair winds section of your sail is 75%. That means the wind is only against you 25% of the time. When its against you, you use a technique called tacking. Sail as close to the wind as you can get for a nice leg and then turn 90 degrees and catch the wind on the other side. You zig zag back and forth. Even when you calculate sides and the hypotenuse its always faster than paddling in the longboat, faster than paddling at wind speed greater than 1 in the raft, and faster than paddling in the karve at wind speed 3 or greater.

There is an algorithm in the human mind called "confirmation bias." Once we form a guess about what is going on in a situation we tend to notice the data that confirms our guess and fail to notice data that is contrary to our guess.

Our mental biases are shaped by the need to make good guesses and to be quick about it. If, in a short space of time, you notice several things that support some guess, there is a pretty good chance it is correct.

Wind direction while sailing is a problem that gives us time apply a more accurate kind of reasoning, for which, see above.