Wave group speed

1 year 7 months ago - 1 year 7 months ago #36875 by tve
Wave group speed was created by tve
In smallish ocean conditions I often find myself at the end of a run waiting for the next good waves to form. The other day I could repeatedly see a good wave form 3 waves ahead of me (too far and fast to paddle into), then 2 waves ahead, then one wave ahead, and finally my turn came and I could catch the next run.
Now I just found a great animation on wikipedia which shows the phenomenon quite clearly:

Imagine the red square, when it's on top of a wave, represents you surfing that wave. You go fast. At some point you close in on a green dot: the end of the wave group. The wave runs out. You loose speed. You look ahead and can see waves forming ahead of you but they're too far ahead. You now have to paddle hard to move faster than the green dot until you get to the region where the waves are getting taller again so you can hitch a ride like the red square...
Of course this animation is very one-dimensional and ignores the fact that often you can move sideways to get into taller waves where the wave group is out of phase with the one you're currently in...

NB: animation from Wikipedia   licensed under the  Creative Commons  Attribution-Share Alike  4.0 International 3.0 Unported 2.5 Generic 2.0 Generic  and  1.0 Generic  license.
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The following user(s) said Thank You: Henning DK

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1 year 7 months ago #36878 by tve
Replied by tve on topic Wave group speed
Thanks for digging my message out of the spam folder, Rob! I fixed-up the attachment, now it reads correctly...

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1 year 7 months ago #36881 by zachhandler
Replied by zachhandler on topic Wave group speed
The small waves are easy to catch and always get bigger. The big waves are hard to catch and always get smaller.

When I am  floundering in confused waves I sometimes chant this mantra: “small becomes big, big becomes small”. It seems to help me get my mojo back. 

Current Skis: Kai Wa’a Vega, Nelo 550L g2, Epic V12 g2, Carbonology Feather, Think Jet, Knysna Sonic X

Former Skis: Epic V12 g2, Epic V12 g1, Epic v10 double, Fenn Elite S, Custom Kayaks Synergy

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1 year 7 months ago #36882 by feeny
Replied by feeny on topic Wave group speed
Firstly, I can't take my eyes off that red dot!

The Mockes have, as one of their 5 rules of downwind, the mantra : "Little ones lead to big ones"

It's very very true. Even if the little wave doesn't get bigger, it is easier to catch and it increases boat speed, helping to catch the much-much bigger, faster moving ocean swell.

Though, that's probably different to the amplitude shifts in the diagram, as one is wind chop and the other is ground swell. 

But whatever, little ones definitely lead to big ones!

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