In a boat it’s easy to overestimate wave heights. This is because of a phenomenon discovered by William Froude in 1861. He found that, no matter how your boat is situated on a large swell, what you feel to be “straight down” is actually at right angles to the wave. So when you think you’re looking out on a level line to judge a wave, you are actually looking on an angle, distorting your judgment. The only time to make an accurate appraisal of the waves is when you are at the bottom of a trough, midway between two waves, and you are sitting relatively level. In a small boat your eye might be about four feet above the waterline. If you can sight along several wave tops in a row when in a trough, then the waves are about three feet high, which is what most of us judge to be “six-footers.” Sight along the gunwale, about two feet off the water, to judge smaller waves. Stand up to raise your eyes to six feet or more to judge larger waves.
Find more crafts online at boatingmag.com/boatcraft.
Want more cool things for kids to do? Check out McGraw-Hill’s The Anti-Pirate Potato Cannon and 101 Other Things for Young Mariners to Build, Try & Do on the Water, by David Seidman and Jeff Hemmel.