Wave Mechanics

What you are looking at above is an APPROXIMATE ayout of wave mechanics at Aramoana/The Spit.

The swell moves in and the actual surfable wave, the mechanism that makes the waves form so well at Aramoana surf break is the wave crest snap that occurs as the swell moves over the Ebb Delta out from the harbour mouth.  This as the word describes ‘SNAPS’ the swell line into offset peaks which then barrel through what is called the ‘Swell Corridor’.   When the bathemetry of the sea floor comes to a certain height in relation to the wave size, the wave then begins to break.  What we have here at Aramoana is a dirty great dredged spoil disposal site right bang smack in the swell corridor of the incoming created surfing waves.  As the spoil mound grows it directly effects the incoming wave as it passes over it.  In bigger swells the waves begin to Shoal (rolling break) and then they reform and then break again, with diminished energy.  The mound also affects peel angle as the waves pass over the mound slows dow one side, and the wave breaks faster.  As the mounds’ sediment disperses it infills the inshore area, and the waves then do the ‘rolling forever’ thing where it gets more difficult to catch them and the dump very close to the shore.

“If the waves in a wave train have sufficient energy (normally a period equal to or greater than 15 seconds), they can continue with little loss of size or energy, for thousands of miles or until they reach land and break. That’s because at these periods (or wavelength) all the energy is traveling deep under the oceans surface, and there’s little that can stop it (except for shallow water). A wave with a 14 second period reaches down into the ocean about 516 feet. A 17 second period wave at 761 ft, 20 second at 1053 ft and 25 secs to a whopping 1646 ft! So you can see how little impact an opposing wind wave with a 7 sec period reaching down only 129 ft would have on one of these long period deep water swells.”

Original source

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