the reason we se different thing is due to pre concieved ideas/myths based on carpark discussion with the surfing hierarchy. everyone says hard edges is release.so that is what is naturally attributed
however with visual observation, you can see that the outline radius of the tail pulls away from water contact. you cant actuallly see the hard edges.
if the rail had a chine or hard bottom edge all the way up the rail would it still be wrapping over the rail like that?
I SAY YES IT WOULD
Hey guys, not sure I belong on this discussion but I’ve dragged a million different objects through the boat wake off the swim step while traveling to fishing grounds and this looks exactly like when you skim an oar paddle and if you were to push down on the paddle and then unweight it… not pushing into the face too hard, but not letting it skim either… just sorta burying the rail… looks exactly the same. try it behind a displacement hull at about 6-7 knots… if the paddle is a beefy one thats thick and heavy the water does the same thing over the inside rail… it sorta rolls up and theres air on that inside edge… but its real eazy to bury them into the face. thin paddle made for skiff just realease… no matter how hard you shove them in you can’t get them to suck into the wave… the only thing you get is a really big rooster tail… just keeps bouncy back to want to skim.
Ryan in the first pic has just started to shift his weight from the back of hte board towards the front. he’s not in trim… this is important… notice angle of spray off the rails… nearly sideways and not angling backwards… water doesn’t shoot off like this if you are going fast in trim…
notice how there’s a depression behind the board… his tail isn’t really in the water right now… nose is really high up… I bet if there was a further back shot there’d be a rooster tail right here.
Next shot he’s moving forward, leveling the board for trim… nothing has changed drastically… I like the shot of the inside rail more better… thats exactly what an oar in a boat wave looks like… cool!
oh hey you can watch vids of people boat surfing on youtube… anyone know how to screen grab?
guess just wanted to interject that he’s moving the board not in trim so keep this in mind while analyzing water is doing. I think the forward placement of a single fin also make the backwash alot cleaner.
sorry for hte ramble. LOL
Snapz Pro (not sure if they make a Windows version…
IMHO, the water is nearly sideways because of the shape of the hull. It is convex, so it doesn’t turn the flow of the water as far aft as a flat or concave bottom would.
But you are correct that the speed of the surfer, and the angle of the board relative to the flow, has an effect on this spray also.
Right on Greg Tate! “So much to learn”. That’s what drives us isn’t it? Otherwise it would become rote and boring. More photos would prove this out.
(I think)
Silly, you know more about design than I probably. Doesn’t the issue of turbulence have a factor in the way the water would wrap or not?
This is what it’s about fellas, exchange of thought…the more the merrier.
I think a series of about 10 images starting much earlier would give us all a better idea of what is going on. I could see right away that his weight is totally off the back foot in the second shot.
The way the wave curls up on the toe side rail is interesting.
A couple of thoughts… I always thought that hulls don’t have hard edges except in the tail. They have a rolled bottom going into a pinched rail but no hard edge like a tucked under rail. Am I correct?
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is there an easy way to explain what is going on ?
i see spray off one edge and i dont know how to even explain the inside edge.
looks cool , you dont see this angle to often.
nice board ryan !
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I see a board moving thru the water, just like pushing a hand thru sand.
At the front the water it hits sheers off as spray to the outside because theres no wall and on the inside it swells up against the wall, just like sand.
You can see by the blue lines how much volume its displacing.
Theres no magic water wrapping on the rail.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/me2tms1.jpg[/IMG]
The way that board is surfing seems really bizzare for some reason. Almost like the wave is wrapping under the bottom of the board.
yes we do see different things! I agree the board is not on the wall, but I can see the angle of the ripples and the shore indicates that the photo is rotated anticlockwise. This means the rider is leaning to the right. This means that he is counteracting **centrifugal force. **So I see a mixture of wrap and displacement on the starboard rail.
[img_assist|nid=1050627|title=bottom turn in the flat creates high pressure area from centrifugal force|desc=|link=none|align=left|width=640|height=480]
Here’s yet another terminology issue… “hard” rails and “hard” edges. Because there’s no standard set of terms for a lot of things in the surfboard/surfing world, there’s a lot of confusion. I’ve learned that there are hard rails and soft rails, and hard edges and soft edges, and the two are independent of each other. You can have a hard rail without an edge, and visa versa.
The term “hard rail” means a rail with a small radius… like a pinched rail or a hard down rail, which may or may not have an edge. It’s the radius that the term “hard” refers to. So in my vernacular, hulls have hard edges in that they have very pinched or even knifey rails - the term “hard” referring to the “hard,” tight turn the radius makes. Hard rails like these do much the same thing as edges… they release water… keep it from wrapping around the rail. A hull rail is a low volume rail, so pinching it is a good call for getting release rather than a fuller rail with more volume and an edge.
The term “hard edge” refers to a distinct corner with no radius… an angle, not a turn, in the rail shape. A hard edge is what you find in the tail of most modern boards. A “soft edge” would be like the tucked edge under a modern rail somewhere between the middle and the back third of a typical shortboard.
It all goes back to separating rail volume from rail shape… a distinction that is often overlooked, IMO.
On the toe side, the rail is displacing water… pushing it downward, but also outward, into the base of the wave. The little curl of turbulence that’s formed along that rail that starts around the front foot and gets bigger as it moves toward the tail is, I think, a combination of turbulence from cavitation, but even moreso, from the little “waterfall” of water coming down from above the board to take the place of the displaced water.
http://www.youtube.com/watch?v=MLpS9K24pgQ&feature=related
stop at any point where the surfa is doing a slight bottom turn looks exact same as pic above… only difference is hull has no rail fins so spray coming off is much cleaner.
I don’t know if I’m right when I said that, but I imagine thats whats happening. I think a board carving an arc has a certain amount of sideslip due to centrifugal force. I also think that a board carving mid wave has a certain amount of sideslip due to water moving up the face and rider weight pressing downwards. So I imagine as well as forcing water from high to low pressure there is also an effect a bit like dragging a squeegee into a pool of resin - the slip will cause some to go from one side to the other - but maybe the fluid that goes from the hull towards the wall doesn’t wrap but stays under the surface ie it releases even off a rounded tuck.
However all pro standard HPSBs follow a similar design nowadays - they have down rails with a rounded tuck up front - they have boxy rails with hard edges in the tail - a common explanation for this is given as wrap Vs release. In support of the wrap theory two of my early boards featured chunky rails up front that were boxy - not much tuck on the underneath, instead a sort of rounded corner. The deck was flat and where it met the rail sort of boxy - but not as hard a corner as the underneath. Despite being thick rails the boards were unstable and were prone to accidentally sinking rails. That was the assessment of a friend who rode one of them too. So my theory is that the corners were interrupting wrap and it is wrap not just rail thickness that makes them resist accidentally sinking.
Thanks for that. I think that distinction- between hard rails and hard edges- should be part of common parlance. Example- I have a board with full, round rails but a distinct hard edge the whole length of the board. It works great, plenty of volume for paddling but the rails do not feel sticky at all.
It looks like the water goes like this................
CASE SOLVED! thanks Resinhead.
Oh My God!!!
Now He’s got super technology on his side… Aaaaaaaaaaa!!!
At first I thought that was a video of me, from the future, dancing…
AHAHAHAHAHAHAHA!!! epic 
what i also found cool was the water/spray’s change and kindof wobble in the second photo from the moment that i transferred my weight forward (notice the second pic my back foot is lifted slightly)…cool couple of pics, i may upload the video for fun but you can’t see much more than there is in the pics!
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It looks like the water goes like this................
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So heres my 100%, iron -clad, irrefutable explanation as to why wrapping is a hoax, no more than cosmetic splash. It looks like the water goes like this.......BUT
Water stucks to a convex, like the ol' chestnut example of a spoon under a running tap.
And to wrap any amount of water , even a fraction of whats in the pics, and over the length of a rail and considering the speed of the water, requires a whole lot of suction.
Logically, if a teaspoon creates a fair bit of force, then a whole rail length pulling all that water constantly around the rail would produce a considerable amount of constant lateral force /suction. That bits obvious.
So looking at the photos, if you contribute even a few litres per second to wrapping along an entire rail, then wrapping does occur, there real amounts of water being pulled around the rail and its more than just cosmetic splash..
And so wrapping is real, its a real effect, real forces and makes a difference that should be considered.
Answer this......
Would fatter rails would give more or less suction than thin ?... .
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.
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.
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So which did you say ?.
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Does a McCoy at 3 1/8 thick Vs a chip with 1 in rails have more wrapping effect, or less ? Surely there would be a sizeable difference considering the difference in wetted surface, volume... water sticks to curves right ?
So then all thick boards would be slower than thin boards ? Because the suction created by wrapping would slow a thick board. Or all thin boards are slower ...?
But this isnt so, because wrapping makes NO difference beyond the visual.." It looks like the water goes like this...."
Theres no wrapping / suction effect.
Granted.....it looks like the water goes like this.....but it doesnt do anything.
,
,
.
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No forces, no volume beyond cosmetic splash, no effect.
Because if it existed it would make a big effect on performance in all areas.
“And so wrapping is real, its a real effect, real forces and makes a difference that should be considered.”
Or…
“Theres no wrapping / suction effect.
Granted…it looks like the water goes like this…but it doesnt do anything.
No forces, no volume beyond cosmetic splash, no effect.
Because if it existed it would make a big effect on performance in all areas.”
So, which is it???
(Edit - try as I did, I couldn’t get rid of the “italics” even though it doesn’t look that way when I’m writing…)
Not trying to be a dick, just curious what you think - I’m a full believer in high/low pressure, round/sharp edge differences. As has been pointed out - we are seeing different things… I’d suggest, in large part, because there different things going on. No one hydrodynamic feature is working alone.