Submitted by Nick Bone on Mon, 04/30/2018 - 07:20
Surf in em nearly everyday and understand how and they work but what i dont understand is how they can or what causes them too swing.
On the Morn Peninsula, rips are more or less essential for a waves too work. And so when your out there having a good time, the rip can either just stop or even swing off it ruining the wave. The sand will still be there, but the wave will turn into mush. The banks fown the Portsea end arent your typical left bank - channel - right bank where the rip can swing between the two. The water usually has one exit and thats were my curiosity kicks in.
The only thing i can think of is a weird angled set doing something?
Not quite sure what you're talking about - is this about how a rip can alternate its angle/trajectory? Or how it starts and stops?
We get the same here on the Island with our beachies.
Rips can change strength and direction within minutes, generally a bank works best when rip is pulling straight out or into the waves, but if pulling away even if the waves look good, its generally very hard to position yourself deep enough and even when you are on the waves you can feel the water pulling away making hard to surf and feeling fat, even when from the beach the shape appears good.
IMHO the changes in rip direction and strength can just happen when you get changes in tide/water depth causing water to move in different ways, iMHO it's often not just the bank and channel where you are surfing that decides direction and strength, but also the banks either side, even aspects like if banks up or down the beach stop breaking or if there size increase with tide etc
Sometimes you even get banks that's rip direction will swing back and forth in different directions and strength, depending on where sets have hit.
Also remember sand is constantly moving even if you don't see it, building and getting pulled away.
This is outside my area of expertise, but one of the causes for short term changes in rip characteristics is surf beat, which is essentially a very long period wave (more like a surge) associated with the arrival of a set of regular breaking (wind) waves.
Without realising it, many surfers would probably have a feel for how surf beat works - you know when to jump (or not) off a point depending on how the sets are breaking, because you know that the right timing will flush you out into the lineup, and the wrong timing will throw you back on the rocks.
With regards to rips, I would presume that small differences in nearshore bathymetry (across banks and gutters), in association with irregular wave breaking patterns and surf beat setup (and other factors such as the tidal phase), means that rips can change direction and strength at any time, depending on certain influences at that point in time.
If you were to superimpose an excess of water from from a different angle (for example, from the other side of the channel because a set has broken there not at your bank) across an otherwise steady rip, it's easy to envisage a change in the volume of water being funnelled back out to sea. How this change materialises (increase in speed, angle, or even the rip moving perpendicular along the bank) depends on a large number of factors specific to your own circumstances.
We also have to remember that as surfers, we're essentially only measuring it via one outcome. And that is: whether it degrades or enhances the surf quality. We're not interested in the volume of water, or sand transport, or its association with the consistency of the sets.
My bad. Pretty much both. Whats in my head never comes out good in text let alone speech
Same with here ID. If the rip isnt running through the wave i.e /// direction through a right and \\\ for a left. Even when the rip is straight can cause issues.
I think youve hit the nail on the head though Ben, whereas there isnt just one simple answer, rather just the surf itselfs, there is alot of factors come into play.
Cheers for the feedback!