Waves Waving at you

Waves

Most boaters do not think much about waves till they encounter a big one. Most boats can handle waves quite well. The energy of a wave increases as the height of the wave increases and the depth of the water also plays a factor on the energy a wave has.

It is logical that a big wave has more energy in it than a small wave has. I was quite surprised to learn that the energy of a wave increases by a factor of 4 as the wave height doubles. This means a 8 foot wave is four times as strong or powerful as a 4 foot wave. 

I sail a small 18 foot day sailor on the Caloosahatchee River. Most of the time it is pleasant to sail on the river. The river is a dredged river and boats can cut across Florida from Ft Meyers to West Palm Beach and not have to go around the tip of Florida. The River often gets large boats crossing the state.

I was sailing one afternoon when a 50 or 60 foot motor launch came full speed down the river. The boat had a wave wake that was about four and a half feet high. When I saw him coming and saw he was not slowing down or going to give me any right of way, I headed for the bank. The free-board on my boat is 22" and when the first wave hit, about the top third of the wave came over the side before the boat floated up on it. When the second wave caught the boat, the boat rode the top of the wave and I was surfboarded right up on the bank of the river. The big boat never slowed.

I will say it was sorta fun, but I was majorly upset. The big wave and the way the riverbed became more shallow as it went to the bank let the wave pick me up and beach me. The wave energy was impressive.

Out on open water there are what are called rogue waves or freak waves. Rogue waves are simply unusually large waves appearing in a set of smaller waves. These rogue wave will have a height of at least twice the size of surrounding waves and often come from a direction different from the prevailing waves. They are unpredictable.

Rogue or freak waves have been reported in the Pacific that have been over 50 ft in height. My 4 1/2 foot wave in my boat with 22" sides was more than enough to give me a good respect for waves and the wave energy they can deliver. I do not want to see a rogue wave, because I know it would freak me out. 8-)

NOAA NWS JetStream – Online School for Weather: Wind, Swell and Rouge Waves