Where the thickest part of the rail foil is shaped helps determine the fulcrum on which the board pivots when on rail. It can also help determine the overall turning radius... thickest part forward = more rail in the water/longer turning radius. Thickest part aft = less rail in the water/shorter turning radius.
On most of my really long longboards I shape the thickest part slightly aft of center to reduce the amount of rail in the water.
A sure fire volume measurement can be accomplished in a rectangular water tank. Measure water level, sink board and measure the rise of the water. Multiply water rise by length X width of tank to determine the exact volume of the board.
Rail volume? Most boards have a dome deck to a greater or lesser degree that would have to be taken in to account. The problem with trying to determine rail volume is determining exactly where the deck and bottom end and the rails begin... I.E. 2" in from the edge? 4" in from the edge?
Moving rail volume works a treat. I'm of the opinion that wide point, rocker low point and rail foiling should be manipulated to tune boards. I personally like my wide-point and rocker low point at centre and rail foil forward. This gives me gun style paddle in and drive, but short board arcs.
But I'm not about to sink my EPS rails in the water to get the water displacement.
I will tell you that the weight of the core on a 7'x23.5"x2 1/4"(different board to the pic) is 1lb 6 oz and the rails are each 1.7 oz. The core is around 1.5lb/ft3 (can't remember exact foam used). You can get approximate volume from this.
That was exactly my question. You can either consider the rail volume to extend to the limits of your rail replicating tool or use an arbitrary distance from the apex or a not so arbitrary way of determining this limit... I would even guess that the distance from the apex could change along the board, being much shorter towards the front and back ends of a board (like the line created by a continuous tucked under edge). That would mean a rail could be defined as the first x percents of the width at any given point as a reference. Or the rail could be defined as the part of the board that is outside the flat or almost flat panel made by the bottom of the board, but that distance looks short to me to define rail volume, as a lot more goes into the water when engaging the rails.
Among good surfers I find that we rarely talk about the actual shape of the rail, all our time is invested in getting the volume correct. I will be the first to acknowledge that rail shape is an important aesthetic feature in an attractively built board, but its worth in the area of function, though respectable, is often over-emphasized.
hmm, on second reading, I cannot agree with this statement. Bottom edge, length of edge, bottom corners, sharp or dull, and bottom radii are VASTLY important. Equal to if not more important than volume.
I've completely altered the ride characteristics of my boards changing the bottom edge geometry alone, no volume change. And I have both thin railed and full railed similar class boards that I like.
To each his own I guess.
Havaard, I don't think there is any "standard", but I use one inch from rail apex as the volume of a rail. If you can include that in your software that would be very good.
Crafty-You are not disagreeing with me as I did not write the quote. Reread the original post. It is a quote from an article written by Bill Barnfield for Surfing Magazine in the '80's. I will say that the article is exactly what I hoped it would be ---thought provoking. Having said that; it occurs to me that many of those who have posted comments have completly missed the point of the article.
Crafty-You are not disagreeing with me as I did not write the quote. Reread the original post. It is a quote from an article written by Bill Barnfield for Surfing Magazine in the '80's. I will say that the article is exactly what I hoped it would be ---thought provoking. Having said that; it occurs to me that many of those who have posted comments have completly missed the point of the article.
Among good surfers I find that we rarely talk about the actual shape of the rail, all our time is invested in getting the volume correct. I will be the first to acknowledge that rail shape is an important aesthetic feature in an attractively built board, but its worth in the area of function, though respectable, is often over-emphasized.
crafty wrote:
hmm, on second reading, I cannot agree with this statement. Bottom edge, length of edge, bottom corners, sharp or dull, and bottom radii are VASTLY important. Equal to if not more important than volume.
I've completely altered the ride characteristics of my boards changing the bottom edge geometry alone, no volume change. And I have both thin railed and full railed similar class boards that I like. To each his own I guess.
Aloha Crafty.
This comment of mine has to be take with the mindset of 25+ years ago. At that time (and still some do) people would ask for a "(insert famous shaper name here) Rail" or "(famous shaper name here) fin". Usually this would be based on the "SHAPE" of the rail with little regard to volume of that shape and how that volume was way more important to the board "fitting" the rider then the shape was.
For sure the shape is necessary and important but only for those who are requesting the shape because they know it is suitable for them and their waves. Not because it "looks" like a certain shape someone has told them is the correct shape.
I was referring to my world class team riders and emphasizing that we focused more on getting the volume of foam in the rail as being the first consideration in a board "well fitted" for the rider, rather then the latest "cool rail shape". Once the proper volume was established for the rider, equal concern and detail was applied to the rails shape, to make sure the board best fit the wave conditions.
My primary purpose, in most of those articles for Surfing Magazine, was to rattle everyone's entrenched thinking and to get them freshly thinking about things that they may never have considered much before. Most surfers and shapers are primarily driven by what they SEE and what they HEAR. Very few can get beyond the drama of those powerful influences, to begin noticing, let alone understanding the subtleties and less visible features that really make the bulk of the differences in how boards work. Guys will agonize over the tail shape, because they can easily see it, but will know nothing about the rocker amounts or proportions of that curve and how much more it will hugely effect the boards function compared to the tail shape.
Volume is another one of those, nearly invisible things, that powerfully effect a boards ride..... yet people will strain over the look of the rail and totally miss the importance of volume because they cannot see it easily. Of course 25-30 years ago common rail volumes were vastly different then today and those thicker boards offered a much wider diversity of possible rail volumes. When you have more volume then you really need, the shape is being smothered by the excess volume and won't matter much till you correct the volume issues. Since today's board's volumes have matured toward the minimalist end of the spectrum such that excess volume is no longer a problem, I probably wouldn't write that article in quite the same way today...... as I wouldn't be trying to shake people loose from the entrenched bulky standard of 25+ years ago.
Hope that helps clarify my comments. As I agree with you Crafty that details in Rail shape, especially things like edges can hugely effect a board's ride. But if the rail has way too much volume, you may never get past that to feel the details of the rails shape. I should also note that the same applies to rails that don't have enough volume, but that is another whole discussion!
Of course 25-30 years ago common rail volumes were vastly different then today and those thicker boards offered a much wider diversity of possible rail volumes. When you have more volume then you really need, the shape is being smothered by the excess volume and won't matter much till you correct the volume issues. Since today's board's volumes have matured toward the minimalist end of the spectrum such that excess volume is no longer a problem, I probably wouldn't write that article in quite the same way today...... as I wouldn't be trying to shake people loose from the entrenched bulky standard of 25+ years ago.
Very good point.
I'm curious tho about North Shore boards. Are they not generally round/soft railed, even today? Here on the EC, you see more variety in rail shape. Just curious.
No doubt, volume is critical. But I think the issue here is the word "volume" because its not easy to measure it. IMO, "thickness" is a better term, and much easier to measure and apply during the designing and shaping process. Even if you told me "your rail there is 0.15 ft3, it would be meaningless because there is no practical way to use that information. But I can measure thickness pretty easily, as the contour guage shows. Im not suggesting that your article is offering rail volume measurement as a way to design properly, just making a general observation and comment about the topic on this thread.
For me - very important topic - I'd have to say this is the area that is my greatest challenge now. Rail volume and how thick it should be in the middle compared to say 18" from tail and nose. Different depending on wave size, power etc. Rail templates are priceless for learning - the learning never stops!
Wow. talk about parallax, i have been working on rail volume calculations over the last couple days without seeing this thread! i believe i have the simple formula to calculating it. i need a couple more days to test it, as to the question of where the rail starts and ends is relative to board width in the centre. ie a 18" wide shortboard rail will be approx 1" in and a 23" longboard would be around 2" in on a old school 50/50 rail....
Red_Boards post makes a lot of sense.
Where the thickest part of the rail foil is shaped helps determine the fulcrum on which the board pivots when on rail. It can also help determine the overall turning radius... thickest part forward = more rail in the water/longer turning radius. Thickest part aft = less rail in the water/shorter turning radius.
On most of my really long longboards I shape the thickest part slightly aft of center to reduce the amount of rail in the water.
A sure fire volume measurement can be accomplished in a rectangular water tank. Measure water level, sink board and measure the rise of the water. Multiply water rise by length X width of tank to determine the exact volume of the board.
Rail volume? Most boards have a dome deck to a greater or lesser degree that would have to be taken in to account. The problem with trying to determine rail volume is determining exactly where the deck and bottom end and the rails begin... I.E. 2" in from the edge? 4" in from the edge?
contour guage.jpg
JohnMellor,
Moving rail volume works a treat. I'm of the opinion that wide point, rocker low point and rail foiling should be manipulated to tune boards. I personally like my wide-point and rocker low point at centre and rail foil forward. This gives me gun style paddle in and drive, but short board arcs.
Haarvard,
You're a credit to the community.
Here's one way of checking rail volume.
[IMG]http://i119.photobucket.com/albums/o155/rted99/PIC_0013.jpg[/IMG]
But I'm not about to sink my EPS rails in the water to get the water displacement.
I will tell you that the weight of the core on a 7'x23.5"x2 1/4"(different board to the pic) is 1lb 6 oz and the rails are each 1.7 oz. The core is around 1.5lb/ft3 (can't remember exact foam used). You can get approximate volume from this.
That was exactly my question. You can either consider the rail volume to extend to the limits of your rail replicating tool or use an arbitrary distance from the apex or a not so arbitrary way of determining this limit... I would even guess that the distance from the apex could change along the board, being much shorter towards the front and back ends of a board (like the line created by a continuous tucked under edge). That would mean a rail could be defined as the first x percents of the width at any given point as a reference. Or the rail could be defined as the part of the board that is outside the flat or almost flat panel made by the bottom of the board, but that distance looks short to me to define rail volume, as a lot more goes into the water when engaging the rails.
hmm, on second reading, I cannot agree with this statement. Bottom edge, length of edge, bottom corners, sharp or dull, and bottom radii are VASTLY important. Equal to if not more important than volume.
I've completely altered the ride characteristics of my boards changing the bottom edge geometry alone, no volume change. And I have both thin railed and full railed similar class boards that I like.
To each his own I guess.
Havaard, I don't think there is any "standard", but I use one inch from rail apex as the volume of a rail. If you can include that in your software that would be very good.
Crafty-You are not disagreeing with me as I did not write the quote. Reread the original post. It is a quote from an article written by Bill Barnfield for Surfing Magazine in the '80's. I will say that the article is exactly what I hoped it would be ---thought provoking. Having said that; it occurs to me that many of those who have posted comments have completly missed the point of the article.
Crafty-You are not disagreeing with me as I did not write the quote. Reread the original post. It is a quote from an article written by Bill Barnfield for Surfing Magazine in the '80's. I will say that the article is exactly what I hoped it would be ---thought provoking. Having said that; it occurs to me that many of those who have posted comments have completly missed the point of the article.
Aloha Crafty.
This comment of mine has to be take with the mindset of 25+ years ago. At that time (and still some do) people would ask for a "(insert famous shaper name here) Rail" or "(famous shaper name here) fin". Usually this would be based on the "SHAPE" of the rail with little regard to volume of that shape and how that volume was way more important to the board "fitting" the rider then the shape was.
For sure the shape is necessary and important but only for those who are requesting the shape because they know it is suitable for them and their waves. Not because it "looks" like a certain shape someone has told them is the correct shape.
I was referring to my world class team riders and emphasizing that we focused more on getting the volume of foam in the rail as being the first consideration in a board "well fitted" for the rider, rather then the latest "cool rail shape". Once the proper volume was established for the rider, equal concern and detail was applied to the rails shape, to make sure the board best fit the wave conditions.
My primary purpose, in most of those articles for Surfing Magazine, was to rattle everyone's entrenched thinking and to get them freshly thinking about things that they may never have considered much before. Most surfers and shapers are primarily driven by what they SEE and what they HEAR. Very few can get beyond the drama of those powerful influences, to begin noticing, let alone understanding the subtleties and less visible features that really make the bulk of the differences in how boards work. Guys will agonize over the tail shape, because they can easily see it, but will know nothing about the rocker amounts or proportions of that curve and how much more it will hugely effect the boards function compared to the tail shape.
Volume is another one of those, nearly invisible things, that powerfully effect a boards ride..... yet people will strain over the look of the rail and totally miss the importance of volume because they cannot see it easily. Of course 25-30 years ago common rail volumes were vastly different then today and those thicker boards offered a much wider diversity of possible rail volumes. When you have more volume then you really need, the shape is being smothered by the excess volume and won't matter much till you correct the volume issues. Since today's board's volumes have matured toward the minimalist end of the spectrum such that excess volume is no longer a problem, I probably wouldn't write that article in quite the same way today...... as I wouldn't be trying to shake people loose from the entrenched bulky standard of 25+ years ago.
Hope that helps clarify my comments. As I agree with you Crafty that details in Rail shape, especially things like edges can hugely effect a board's ride. But if the rail has way too much volume, you may never get past that to feel the details of the rails shape. I should also note that the same applies to rails that don't have enough volume, but that is another whole discussion!
Very good point.
I'm curious tho about North Shore boards. Are they not generally round/soft railed, even today? Here on the EC, you see more variety in rail shape. Just curious.
No doubt, volume is critical. But I think the issue here is the word "volume" because its not easy to measure it. IMO, "thickness" is a better term, and much easier to measure and apply during the designing and shaping process. Even if you told me "your rail there is 0.15 ft3, it would be meaningless because there is no practical way to use that information. But I can measure thickness pretty easily, as the contour guage shows. Im not suggesting that your article is offering rail volume measurement as a way to design properly, just making a general observation and comment about the topic on this thread.
For me - very important topic - I'd have to say this is the area that is my greatest challenge now. Rail volume and how thick it should be in the middle compared to say 18" from tail and nose. Different depending on wave size, power etc. Rail templates are priceless for learning - the learning never stops!
Wow. talk about parallax, i have been working on rail volume calculations over the last couple days without seeing this thread! i believe i have the simple formula to calculating it. i need a couple more days to test it, as to the question of where the rail starts and ends is relative to board width in the centre. ie a 18" wide shortboard rail will be approx 1" in and a 23" longboard would be around 2" in on a old school 50/50 rail....
Pages