Checking out the breaking wavesMost will know that wave height is a function of wind speed, duration and the distance of open water the wind blows over, i.e. fetch. Recently I've researched this a bit and was surprised by some of what I read.
For example, a fetch of 10 nautical miles with wind blowing for 2 - 3 hours at 10, 15, 20 and 25 knots will develop waves of 0.3, 0.5, 0.8 and 1.1 metres respectively.
There is a maximum height waves will develop at a given fetch and wind speed no matter how long the wind blows and this is referred to as a fully developed sea. Waves will only increase from that height if the wind speed increases.
Its interesting also to note the effect of fetch on wave height. If the fetch is increased from 10 to 20 nautical miles and the wind blows for 4 - 5 hours at 25 knots the maximum wave height produced is 1.4 metres. That's a slight increase of .3 of a metre for a doubling of fetch.
Waves are complex and affected by other factors such as water depth and shoreline topography. Its worth the time to read up on something that has such an effect on our kayaking.
Nice picture :) I remember it well! I would like to go back and do it again but I could do without repeating the experience of having one of those waves crash on me :)
ReplyDeleteSounds like a plan Clyde. A bit closer to home that also has similar conditions is Motion between Torbay and Middle Cove. Maybe we could check that out some time.
ReplyDeleteTony :-)
The three articles in Ebb & Flow on waves are a good introduction to the topic. Back issues of Ebb & Flow are available on line on the KNL website in pdf format. The articles on waves appeared in: Fall 2006 Vol 6(2); Winter 2007 Vol 7(1); and Spring 2007 Vol 7(2).
ReplyDeleteMalcolm