surfed manly today and there were rips a plenty. Ive noticed that onshore days seem to create rippier conditions than offshore. is this co-incidence or can someone explain it scientifically?
we all know that channels between banks create rips, and the combination of swell and wind direction must impact rips (as well as the impact of large swells on sand movement). Can anyone specifically explain in detail how certain wind/swell combos create/affect rips ....or post up some links. cheers.
what causes rippy surf
Moderators: jimmy, collnarra, PeepeelaPew, Butts, beach_defender, Shari, Forum Moderators
-
el gringo rattis
- regular
- Posts: 314
- Joined: Mon Dec 12, 2005 1:19 pm
-
el gringo rattis
- regular
- Posts: 314
- Joined: Mon Dec 12, 2005 1:19 pm
Yes.Shaunm wrote:The moon?
A new moon or a full moon, means the tidal range between high tide and low tide is much greater. So generally when the tide starts to either drop or come in there is a lot of water movement occurring.
A new moon has the bigger impact as it's both the moon and the sun that are both pulling on the surface of the earth's seas.
So for instance when you go out 2 hours or so before low tide on a new moon it's quite likely to be quite rippy as a lot of water is moving out to sea. Generally the half hour or hour before and after a tide is the best time to surf as the tidal movement isn't so strong during this time.
I'm hungover so probably everything I wrote makes no sense?
el ringo - sure post up the link, i'll give the article a shot.
i actually find, say at bondi, onshore days have less close outs, the rips seem to create "banks" - at least there are some walls to ride (rare for bondi).
further to this, i wonder why offshore winds make the water surface silky smooth and onshore winds ruffle it up so much. i figure the air moving in opposition to the water movement must have something to do with, but why? im willing to implode my brain to understand these things
i actually find, say at bondi, onshore days have less close outs, the rips seem to create "banks" - at least there are some walls to ride (rare for bondi).
further to this, i wonder why offshore winds make the water surface silky smooth and onshore winds ruffle it up so much. i figure the air moving in opposition to the water movement must have something to do with, but why? im willing to implode my brain to understand these things
it does get ruffled mondo, out about a km or two a strong offshore starts turning the surface into chop going away from shore.mondo wrote:true guard, onshores push the wave down, make it crubmle.... but why is the water surface ruffled? why isn't it smooth like offshores? say, why don't we get "smooth onshore conditions"? - where the wave is shut down due to onshore wind, but is smooth like offshore winds.
Exactly as Marcus said. If you went out further to sea you would see the chop out there due to the offshore winds. It's because the waves we surf are relatively close to shore and the wind hasn't had much water to chop up over the small distance. If you paddle out to a reef which is pretty far offshore you will see the wind chopping up the water even when it's offshore, but this offshore wind straightens the bumps out of the swell and holds it back a bit from braking hence, not making it crumble over.
It's hard to explain but i'm sure you get the jist. If you've ever surfed in wind which is cross/offshore say 45 degrees to the direction your catching the wave, then if the wind is strong enough you, will notice the side chop in the wave, and this is not always the best, depending on what kind of wave your riding. Whenever there is wind there is chop being created, it's just over how far, the "fetch", the wind is blowing and how hard that determines how choppy the sea gets.
It's hard to explain but i'm sure you get the jist. If you've ever surfed in wind which is cross/offshore say 45 degrees to the direction your catching the wave, then if the wind is strong enough you, will notice the side chop in the wave, and this is not always the best, depending on what kind of wave your riding. Whenever there is wind there is chop being created, it's just over how far, the "fetch", the wind is blowing and how hard that determines how choppy the sea gets.
Guys, a bit of science here please. Nothing to do with the wind being offshore or onshore (except indirectly). Nothing to do with the moon (except for tidal rips like Box Head or Mundaka).
Rips occur when water is piled up into a concentrated area, generally by the action of waves, and then flows back into the area from whence it came, dissapating the potential energy that the wave action built up. In simple terms, broken waves push whitewater towards the beach. Said water builds up between the outside bank and the shore, and flows back outside, usually in the place of least resistance - the deeper channels.
Speed of rip depends on:
1. the amount of water being pushed out of place.
2. the capacity (width, depth) of the channel that the water flows out from
Long period swells, contrary to what some have stated, usually don't create much rippiness at all. Why? Because the frequency of sets in long period swell is much lower and there is plenty of time between sets for the water to flow back out. Short period swell, on the other hand, create great rippiness because the wave action is non stop. More waves per minute, less lulls, and that water keeps on piling up in the wrong place.
Sweeps work on the same principles, but here it's just that the wave action pushing water down the point sets up a current as water flows in from the top of the point to replace the water that's being pushed down the point by the waves.
OK?
Rips occur when water is piled up into a concentrated area, generally by the action of waves, and then flows back into the area from whence it came, dissapating the potential energy that the wave action built up. In simple terms, broken waves push whitewater towards the beach. Said water builds up between the outside bank and the shore, and flows back outside, usually in the place of least resistance - the deeper channels.
Speed of rip depends on:
1. the amount of water being pushed out of place.
2. the capacity (width, depth) of the channel that the water flows out from
Long period swells, contrary to what some have stated, usually don't create much rippiness at all. Why? Because the frequency of sets in long period swell is much lower and there is plenty of time between sets for the water to flow back out. Short period swell, on the other hand, create great rippiness because the wave action is non stop. More waves per minute, less lulls, and that water keeps on piling up in the wrong place.
Sweeps work on the same principles, but here it's just that the wave action pushing water down the point sets up a current as water flows in from the top of the point to replace the water that's being pushed down the point by the waves.
OK?
Check out this website:- http://www.scienceofthesurf.com/. The guy is called "Dr Rip" and has some useful info about the science behind RIPs. He is a professor at UNSW so he knows his stuff. I went to one held at Manly recently and it was really useful.
Also, If you can, get along to one of his free seminars held all over the place, its an hour or so well spent.
Also, If you can, get along to one of his free seminars held all over the place, its an hour or so well spent.
-
Nick Carroll
- Huey's Right Hand
- Posts: 26515
- Joined: Tue Apr 05, 2005 9:29 am
- Location: Newport Beach
Jesus christmas.
There's never one cause.
Many of Sydney's beaches are currently affected by rip/sandbar combos. This is because of the unusual (for summertime) bursts of swell energy which have been slamming us off and on since December 31.
Sydney's beaches are specially prone to formation of rip/sandbar combos following direct easterly swells, because the beaches are enclosed by headlands, forcing rips into play as a way for water to escape the inshore area.
Dec 31-Jan 4 pulled a lot of sand off many beaches and set it into offshore lines, with deep gutters between the bars and the beaches. Then the next solid episode, Jan 19-23, broke down those offshore sandbar lines and created holes, around which numerous rips were formed.
The rip/sandbar combos were magnified for much of last week by mega tide changes thanks to the full moon aligning with the Sun, to which we came closer on January 6 than at any other time of the year. (That's why you get hell tides around Christmas/New Year.)
Watch many of these rips settle a bit through this week as tides pull back down to less of a range. Then watch 'em get re-shaped with the next heavy burst of easterly groundswell during the week from Feb 4-8.
There's never one cause.
Many of Sydney's beaches are currently affected by rip/sandbar combos. This is because of the unusual (for summertime) bursts of swell energy which have been slamming us off and on since December 31.
Sydney's beaches are specially prone to formation of rip/sandbar combos following direct easterly swells, because the beaches are enclosed by headlands, forcing rips into play as a way for water to escape the inshore area.
Dec 31-Jan 4 pulled a lot of sand off many beaches and set it into offshore lines, with deep gutters between the bars and the beaches. Then the next solid episode, Jan 19-23, broke down those offshore sandbar lines and created holes, around which numerous rips were formed.
The rip/sandbar combos were magnified for much of last week by mega tide changes thanks to the full moon aligning with the Sun, to which we came closer on January 6 than at any other time of the year. (That's why you get hell tides around Christmas/New Year.)
Watch many of these rips settle a bit through this week as tides pull back down to less of a range. Then watch 'em get re-shaped with the next heavy burst of easterly groundswell during the week from Feb 4-8.
Who is online
Users browsing this forum: No registered users and 37 guests