After reading the threads on longboards and hard rails below, I was a little surprised at some of the comments by very knowledgeable people. Either all my understanding and experience of how rails work is completely backassward or we are misusing terms to the point they say the opposite of what they should. The following rant is based on years of riding experience, a little shaping experience and the Rocket Science and Balance articles in Resources. I maintain that hard edges slip and soft edges hold. Hard edges release (they shed water quickly and efficiently). Soft edges hold or grab water, bending it. Hard edges do not “take energy” from a wave, soft ones do. Try this experiment: Turn on the tap and put the convex side of a spoon up against the flow of water…the water will “grab” the spoon and pull in in the direction of the convex. Put a spatula in the same stream of water and it will be repelled (almost as efficiently as puting the concave portion of the spoon in the stream). Now imagine those shapes of edges on a rail. Which one holds (is literally sucked into the wave face) and which one planes on top of the water surface (almost repelling water). Hard edges on the tail allow water to escape from the bottom quickly but mostly the are counteracting the downward pull of the fin(s) (Loehr’s Balance Article). If you put soft rails on the tail, both the fin and the rail are pulling the board’s tail downward (excellent nose rider but no speed down the line). Hard edges will hold the tail up keeping things relatively neutral (you can really feel it when you just catch the wave and start to drop). The Hawaiians used round soft tails on finless boards using the downward pull to keep the olos on track. I will admit that under some circumstances a THIN hard edge will hold a sticky track (paipos and skim boards) but they will lose the “grip” unexpectedly due to slight changes in the angle of attack. My thought is that the thin edge is changing from a “planing surface” (Rocket Science) to a penetrating surface (fin). As soon as you add bulk to the edge the grip/tracking will disappear. Hard edges work great with boards that are surfed from the fins since the rails are not needed to get the board to do what you want it to do. You want a hard edged rail to release, not stick when you are making rapid direction changes. Soft curves are great for single fins that use the rail like hulls and fish. Best of all; attributes of each can be blended on a given board so that they enhance the other design elements. Mix poorly and the board is a dog. The edges can be blended on the same rail too; look at a tucked edge, chines or Greenough Edge bottoms. Bottom rail line: Soft = hold, Hard = release.
i like your post. one thing i’ve noticed on longboards (specifically “performance” longboards) is that you can put a super hard edge in the tail and increase the tail rocker which gives you a very versatile board. the added tail rocker decreases your turning radius, and also allows water to better follow the curve while nose riding increasing stability on the nose. not the best ever noserider but a good turning noserider nonetheless. just my nickel’s worth…
Bravo!! Well put, Lee!
I totally agree with Lee V. The two boards that I am riding the most at the moment are 50/50 railers.Modern old longdoards glassed heavy with vinylester resin.You can actually feel the board being pulled into the wave.When surfing backhand in small surf the 9’6" will noseride almost parallel to the wave.There is a good example of how the water is sucked around a soft railer in the latest issue of Australian Longboarding.The picture is of the late Bobby Brown (page 53) taken in the 60’s.You can see the water being sucked over the deck of his board.In contrast there is a photo Beau Young (page 59) on a similar sized wave and the water is being squeezed of the bottom of the board.
I’m glad that my post has spured some thought and discussion, I love when all this wealth of knowledge starts really flowing. So if I understand correctly, the hardedge rails are essentally decreasing the surface on the water (rail edge) allowing the fins to really drive the board and turn easier, essentially almost a “looser” board. However, because the water is flowing so freely it’s also going to cary speed much better then the 50/50 or 60/40 rails most of us use. Right? Harder edges are most definitely going to be needed for faster, hawaii, mexico, etc. type of waves. The rounded rails however, really grab the water, the curve of the rails seems to almost perform a ‘suction’ of water that wraps, covers, and thus stablizes the board for greater hold in the line and increased stability while walking and nose riding. However, it’s also this suction of water that really limits the overall speed of the board. These are more for that costa rica cruiser or fun point break type of ride?
My 2 cents… Isn’t it also true that a hard rail would tend to ‘chatter’ more in a choppy situation than a soft rail? This would seem to be the hard edge catching on the chop. I agree with the release of a hard rail and the stickyness of a soft rail in general (for examp: push a soft rail, and a hard rail, through the same flat water and the hard releases while the soft sticks), but, so it makes more sence to me, I also need to try to take into account the dynamics of the wave and the surfer on the rail. Water is coming up the face and flowing over the rail at an angle. The surface of the board that contacts the rising water in the face is where the most telling pressure is applied. This, combined with the way the water releases over the rail, gives the board it’s feel. Traditional 50/50 rails are not catchy rails, they mush into, through, and around all the different warbles and bumps in the wave face. The feeling when riding a 50/50 railed board is very neutral. not catchy. I think of it as ‘watery’ since the water is really wrapping around the rails and you surf ‘through’ the water more than over it with this kind of rail/board. Hard rails do supply release, but also a postive edge that can be used to hold a more exact line than can be held with a 50/50 rail. The feeling of a hard railed board is not neutral at all but more precise. It needs to be driven because that hard angle does ‘catch’ the moving water, as well as release the water as the board moves through it. So I think nailing it down to certain terminology can be difficult. Slip and hold is one way of describing the difference, but to say a hard railed board will slip out easily and that a soft railed board will stick well just sounds wrong (to me) also. As a mental test I did this, but I haven’t the opportunity to try it for real… we need Karl Locherfeld (I think that’s his name…!) We generally don’t ride with our boards flat on the water’s surface so…Think of the wave pools that have the stationary wave with the water flowing up and over the hump at speed. Hold a 90 degree angle in that flow of water and if you dig the edge in, it holds and a great deal of pressure is created. Lay it flat and the water shoots off the angle easily. Hold a rounded rail in that same flow and dig it in - less hold and pressure, the rounded form allows less catch, and lets the edge slide down the incline. lay it flat and the water tension will drag at it more than the 90 because of the water ‘sticking’ to the curve. Is the positive pressure of a sharp railed board ‘slip’, or a more positive feeling and predictable hold (& faster release) of the water? Does the softer edged board give the feeling of ‘holding’, or a netural feeling of the water tension and round rails buffering the movement of the water? I’m not trying to disagree, just to get my own understanding of the process. Thanks, Eric J
…nothing wrong with disagreeing Eric, this discussion board would be boring if we all agreed. Your post kinda summed up my feelings on this, so I wonder, you a shortboarder too? …this post seems to apply more to the longboards (but granted, that’s coming from a shortboarder). I notice the opposite where I surf, Newport. We have tiny little steep waves, that break quickly. Without a hard edge you can’t grab a high enough line to allow you to generate speed on these little 2-3 footers (measured cali style) - because being a ‘pumping monkey’ is the only way to grab the energy. Longboarders are rarely out at Newport on small days, and those that are can’t keep up. Conversely, I put soft rails almost all the way back on the Mini Gunn I just built. It has the same thin rails and crowned deck I put on all my shorties, yet it feels like the most stable board I’ve made. I really havn’t had it out in ‘big’ surf yet, but for what I have seen, it seems the faster I go, the more stable it was… I can only attribute that to all the water that wraps around on the deck. The board just doesn’t work in our normal small surf…
Observe water rapidly flowing across (parallel to the surface) the width of a board which has a fairly flat bottom, a clean, tucked edge or hard downrail. As the water contacts the sharp edge, itll simply shear/jump off, bypassing the contour of the rail that wraps back up toward the deck... the more velocity the water has, the more it wants to release from the rails edge. But if you try the same thing with a board having a rounder bottom and softly rounded rails (thin or full), the water will adhere, i.e. follow the surface and wrap around the outer edge toward the deck… in this case, the faster the water flows, the stronger the attraction of water to board. A very thin edge (like an 1/8" laminated fiberglass rail on a finless paipo) will completely shear/release the water flow, but can be made to provide a great deal of bite/hold if the angle of rail penetration (relative to the curve/surface of the water) is increased, as during a hard, carving turn. In contrast, the 5 3/4" thick, round soft rail of an inflatable surf mat can both provide both clean release and a high degree of hold, yet with minimal surface penetration, because it conforms itself to variable internal pressures as well as exterior forces from the wave face and rider. In cross-section while surfing, a mats rail contour can be full thickness in front at the entry point, yet tapered down to 1/2" thin (and cleanly releasing) flexible edge in the back. In general, boards (especially for standing) which are designed to quickly plane and release the water flow are dependant on the riders ability to maneuver/position them, as well as fin(s) to provide lateral stability and direction, especially when operating at lower angles of rail penetration. Sharp, hard rails offer precise (often unforgiving) handling, and are very reactive (not always in a good way) to twisted, choppy waves. But displacement hulls rely on a balance of bottom, rails and fin(s). They often run through bumpy water well, and are more fluid, less apt to bounce around. Well designed hulls require very little rider athleticism to achieve speed and handling, almost surfing themselves. The thickness of a rail, its buoyancy distribution, contour, angle and depth of penetration, skill and weight of rider, a flexible shape or not, the wave and its surface condition, fin(s) or lack of... all have a significant influence on turning and how well a design moves across a wave. To complicate this subject further, its also possible to combine the elements of a flat (or concave) bottom and sharp release edges, with the roll and control of thin, softly rounded rails… just ask Lee V. about his edge board!
Rook, Well… I learned on shortboards, got old, surfed less, started to ride longboards for a while, and am currently getting back on shorter boards… not that that really clarifies things. Truth is I started writing just to disagree, but the more I wrote, the more I was thinking that the statement’s Lee made were true - but - (I Think) from a specific point of view. What a rail does to the boards ‘ride’ when we push on it (a pumping monkey is a good example) is way different than what it does when IT is gliding over & through the water. Having the hard edge to work off of gives certain properties to a board, just as the soft edge. Some of the ‘What the rail does’ discussion needs to be from the rail-in-the-water perspective, and some from the surfer-on-the-rail perspective - I think that may give more of the whole picture. But it bugs me that we will never nail-down all the variables, since they are not consistently quantifiable. Board sizes, fin configurations, bottom contours, foil, outline, flex, weight, materials, wave conditions, swell type, maybe temperature… all come into play. It’s a package. Those with a lot of experinece in the water, and in the shaping bay, can look at a board and pretty much know if it will work well or not. The general experience of trial and error is worth more than anything, and that is why I try to read every post by the more experienced folks here. I surf on LI/NY. Lots of mush and sand-bottomed rollers, & sometimes speedy insides, where I usually go. Current favorite board is a 6’6" twin with low rocker, low but soft rails, and heavy glass. It goes in just about anything around here. When it’s real small I like a modern 9’6" longboard with harder rails in the tail (I’m too old to be the pumping monkey!). I hope others chime in on the rail disccussion too. To me it’s hard to get a clear picture of what’s most important to understand here - like I said, too many variables. Best, Eric J
Interestingly, when surfing across a wave, the same hard, sharp release rail contour on a flat-bottomed board will have a tendancy to catch on bumps/chop moving up (shoreward side) the waves face, if the angle of the board relative to the water is lowered... this also has a direct influence on ones riding style, i.e. handling being limited to the rear/tail of the board. In contrast, a displacement hull with softly rounded rails will be more forgiving, much less apt to catch a rail on the outside, with control and drive usually being generated from the center/forward section of the board.
First off, I am a short boarder. Second, I don’t think we disagree, we are talking about two different aspects of what rails do. Since my initial discussion wasn’t prefaced with a whole bunch of caveats and conditions, it wasn’t very precise. So, here goes. I was talking about the way a rail works on a trim, using a clean, steep, mid-sized wave face. The “catchiness” of the outside rail wasn’t part of my thinking (although rail shape and “sharpness” definately affects that aspect). Nor was I talking about the ease of breaking a line in a turn. When you guys say that the hard rail holds a high line, I will guess that you are riding thrusters and that the forward rail (what there is of it in the water) has a tucked edge. The fins are what hold the high line, with the round portion of the forward rail holding a bit. If you put the same edge as your last 4" of tail, along the entire length of your board you would see what I was getting at. You would have to constantly adjust the boards attitude to keep the track because the sharp edge would constantly be slipping. I completely agree with the “feel” afforded by different degrees of sharpness. That crisp feel in a turn is a result of release along a sharp edge, be it a tucked one or as radical as the Greenough edge, as the water breaks from the flat to curve. There is a very definitive feed-back to the rider. On my edge it feels like a little burst of acceleration. With a tuck it more of a slicing feeling (to me). With a round edge like a hull or mat, the turn feel smooth as there is no sharp transition between the planing surface and the rail. The cool thing about knowing the hydrodynamics is being able to apply them to a design so you get the exact response you want. None of these shapes is necessarily better or worse than an other. But if you slap a knife edge, down rail along the entire length of the board and expect it to hold a nice, even high line trim on a steep clean wave…you are going to be very disappointed. I agree with the idea of using a sharp edge on smaller waves too. They are too slopey and slow to get an advantage out of a round rail “holding” a trim. Efficient planing is the call and the sharper the edge and flatter the bottom, the better. With chop a sharp edge begins to act like a sideways fin (think Fat Penguin) as it plows into a chop. Suddenly the rail grabs and tracks in the chop then releases as it exits. The old grab and go, leaving you walking off the nose or railing out the back. Cool discussion…Only at Swaylock’s!!!
LeeV wrote “When you guys say that the hard rail holds a high line, I will guess that you are riding thrusters and that the forward rail (what there is of it in the water) has a tucked edge. The fins are what hold the high line, with the round portion of the forward rail holding a bit. If you put the same edge as your last 4” of tail, along the entire length of your board you would see what I was getting at. You would have to constantly adjust the boards attitude to keep the track because the sharp edge would constantly be slipping." ------------------------------------------------------------------------- I have found the opposite to be true…weird?? A recent observation on one of my boards was that the sander left a hard edge that ran from the tail past center on my 6’4" but i decided to give it a go. The board was okay on the open face but in the barrel it felt “sticky” and and it was difficult to make fine adjustments in the barrel since it wanted to follow the same line or “catch” sometimes. Took the board home and went at it with some 220grit and those problems dissapeared.
A few things First of all, the spoon analogy is flawed. It is flawed because the water on a surfboard doesn’t release into air. Instead it rises to the surface level. If you could observe this, you’d see that the water flow behind a “hard” rail is quite turbulent, and this creates a lot of drag (or grab), on the rail. Water doesn’t release on a hard rail, in reality. It still tries to conform, but laminar flow is much more disrupted on hard rail than on a soft rail. So, the more hard the rail is, the more drag you get. A very common board today has down rails near the tail, creating drag at the rear, and rounded rails further up. I think it is pretty easy to see how this helps you turn if you apply a little mechanics to a surfboard in action and consider where the drag is relative to the center of mass. Some tail drag is pretty necessary for surfboard control. One last thing. A surfboard, once standing, is not a displacement hull - it is a planing hull. There is a world of difference. http://www.blakestah.com/surf/
When the surf gets bigger around here (Central Coast,NSW Aust)5’plus I ride my short board , a 8’ thruster with super hard rails that are hard about 2’ infront of the fins.The waves are steep and hollow and you need to be making your first turn as you are getting to your feet,particularly when surfing the points.You need the drive and aceleration that a hard edge gives.I do get bucked off on ocassions, possibly due to the edge running so far foward, but this is a small price to pay for the speed that can be generated by rail to rail transitions with out having to pump the board.There is no way I would try and ride my soft railers in this type of surf. I have tried and it hurts.
From what basis do your ideas arise? I`ve never heard such peculiar opinions.
Fellow Surfers, Rail configuration has everything to do with performance. This has been obvious since the days of wooden planks and skagless surfboards. Round surfaces sit down in the water. Flat surfaces sit on top of it. Round rolls - sharp cuts. If you want to go fast the less wetted surface you have the faster you go. If you want control however what ever part of what you have in the water has to have some form that has a functional reason for being there. Rails on surfboards are in a constant state of evolution simply because everyone has their preferences about how they want their surfcraft to perform. The extremes in rail design are probably best exemplified by comparing a 60’s Velzy 10’0" pig hull with and modern towin board. Both boards are quite heavy and the tow board has a great size to weight ration than the old school longboard. The bottom configuration and rail configurations of the two boards is opposite. Both boards will handle rough water beautifully but for different reasons. The old school board is deep in the water and thus unaffected by rough conditions and the rounded nature of it foil makes it a very calm affair in turbulence. The tri fin tow board sits up on top of the water and is always on a rail edge (Rail change being and instantanious maneuver) planning across a steep wall or down a steep face on edge. The bottom has so much concave that the board is like a hydrofoil sitting way up on top of the water when at speed. The rails are relatively much sharper and cut through the chop much like the two hulls on a boston whaler and the pair of them creat stability when the board is on the falts. The sharp end cuts into the wave face on steep walls allowing for rapid adjustments in trim and are quite responsive. A single fin tow board is another animal. Has anyone seen one up close? Entry, Bottom, and rail configurations on this type of board is a combination of soft to hard much the way the cross section of a fin is made. Rail configuration is one of the principle elements of surfboard function. Performance is a combined function that proceeds from release to drag to release. How much and where is what counts. Rails that change in configuration perform these functions. Ones that remain the same from nose to tail are either very calm or very touchy. Some boards swoop and glide, some slash and drive and some are submarines and there’s everything between a bird and snail out there. Look at an albacore sometime and you’ll see and marvelous combination of foiled form and everything from round to sharp each in its proper place. The rails on the best single fin board I have go from sharp to round to sharp. There are nonillion variations on the theme and I’ve only seen a few. A real answer would be difficult to formalize because of that subtle difference between cutting and holding or hard and soft, which in the end is really what to difference is. An good combination of the two is where performance comes from. Some of it comes from applied observation and good sense and some of it is just a happy accident. I’ve had the good fortune to experience both. No Worries, Rich
I have felt the same thing but the hard edge rail was very thin or angular (like the down-railers in the mid seventies) so the edge was penetrating the surface…The “stickiness” is a good explanation of the feel…Was your edge tucked or actually at the apex of the rail?
You are taking advantage of good release to gain speed and to counteract the fins being pulled into the face. The pulled-in outline of a semi-gun is also helping hold you in and on line.
Ok…take your spoon and spatula to a swimming pool and try it…youll feel the same thing and the analogy will be easier for you to understand. As for hard edges causing drag…anything moving on or through water will create “drag”. Sharp edges create less than curved edges. You theory, if I understand it, should have airplanes falling from the sky. Drag in the tail of a surfboard IS a good thing, like you say. But its from the fins more than the rails and tailblock. Yes, I agree a displacement hull is different than a planing hull.
The drag depends on the angle of incidence. I think you may be misunderestimating the angle of attack and its influence on the tail angle in the water. Take a hard down rail near the tail, and move it along nearly parallel to the water, and I agree, release will occur. Now, take the same rail, and push it in 20 degrees and pull it through the water. See what happens. Now, move it to 90 degrees. I think everyone can agree the soft rail has MUCH less drag when oriented at 90 degrees to the water. Anytime the rail is down enough to cause a cavitation behind the rail you will experience increases in drag. The drag is exactly the reason the rail doesn’t slip as easily when crossed on a steep wave face. Airplanes flying is about maintaining attached flow, and deflecting that flow by angle of attack, with the flow deflection also creating a reactive force (an opposing vector in direction and magnitude) creating lift at the wing. It has nearly nothing to do with how a planing hull works. These are not hydrofoils, they work differently. As for where I got my ideas, I usually find them in boxes of Cracker Jacks along with my diplomas and dotcom stock. http://www.blakestah.com/surf/