primary swell... secondary swell... please explain

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primary swell... secondary swell... please explain

Postby baggins » Mon Jun 18, 2012 3:11 pm

Ok so you may just want to throw a link at me to some site that explains this as its probably a real kooky thing to ask :mrgreen:

since MSW changed the look and layout of their forecasts I've noticed theres 2 swells that show - primary and secondary

whats that all about?

and how does that affect the 'Overview' part of the forecast?

cheers

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Re: primary swell... secondary swell... please explain

Postby Black » Mon Jun 18, 2012 10:11 pm

Waves are composed of one or more swells which may come from different directions, depending on how they interact they may increase or interfere with the waves produced at the sharp end so to speak. The best waves are probably made by a single (primary) swell with long period although a secondary small interference swell may not cause too much trouble. There's more explaining but thats my best explanation straight off. Primary is the main swell secondary is another swell which has influence.
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Re: primary swell... secondary swell... please explain

Postby baggins » Tue Jun 19, 2012 7:29 am

Thanks for that. Well explained makes sense.
I take it then that the result of primary swell combined with the secondary is what influences the overview prediction on MSW then?
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Re: primary swell... secondary swell... please explain

Postby Black » Tue Jun 19, 2012 9:32 am

Thats it as I understand it. :-)
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Re: primary swell... secondary swell... please explain

Postby PaulBareru » Mon Aug 12, 2013 11:09 am

The effect of a significant secondary swell can be huge - especially if the wave heights are similar but wave periods and directions are different.

If report says there is a nice 6ft swell coming into your spot with a beautiful 15s period, but then there's also a nasty 4ft secondary swell with a period of 8 secs - then what you'll see when you get to the beach is: a nasty 4ft swell with a period of 8 secs - with bomb sets coming through every now and then... probably not what you were hoping for then...
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