# Rail function

We have all heard of the various names and shapes of rails. However, I have not seen a good explaination of how a rail works. I have heard of a hard tucked under edge holding water beneath the board and then releasing, creating an increase in glide(perhaps translated to speed). How does a tucked under edge and the fulcrum of a rail really work? Some long boards have an egg shaped rail around the entire board, that seems like it would make an unstable wobbly board. Any one out there who really has a handle on this. Can’t be a mistery.

We have all heard of the various names and shapes of rails. However, I > have not seen a good explaination of how a rail works. I have heard of a > hard tucked under edge holding water beneath the board and then releasing, > creating an increase in glide(perhaps translated to speed). How does a > tucked under edge and the fulcrum of a rail really work? Some long boards > have an egg shaped rail around the entire board, that seems like it would > make an unstable wobbly board.>>> Any one out there who really has a handle on this. Can’t be a mistery. I hope somebody with more experience follows my post, because experience is the only teacher here. Here’s my understanding. And it wouldn’t surprise me to be shown wrong. Flat glide: The wider the flat on a board’s water entry, the more stable it will be in a flat glide. Rail tucks make boards wobble in a flat glide. Turning glide: You lean onto a tucked rail, and it provides a flat surface to glide on. You can turn back into a slow lip. You lean onto a low hard rail and it digs in. Bail. Trim: Rail tucks curve a little more than the wave face. Water flowing under the curved rail adds stability and pastes higher on a wall, but slows the board down. On a trim, hard low rails resist flow from under the board, across the rail. To maintain forward motion, the surfer must trim away from the wave slightly. Trickier than a tucked rail, but this trim speeds the boards forward motion. In white water: When a surfer stupidly gets low and slow on a fast moving pit white water will merely wash over a low hard rail. You stop and bail. White water will lift a tucked rail and throw the board beachward. You regain speed and try to catch the pit. The practical difference is between a low speedy rail, and a high forgiving rail. Most boards compromise somewhere between the two. I like a mid-board rail line that’s .8" to .85" above the bottom. I like my tuck to reach no more than 1.2" under. My favorite lower rail is a quarter .8" tube, no tuck. But I like chasing fast tubes. For mushy breaks, a little more tuck is appropriate. For tucked tail rails… To me, we passed them up a while back. We return to them for nostalgia. Im sure lots will disagree.

We have all heard of the various names and shapes of rails. However, I > have not seen a good explaination of how a rail works. I have heard of a > hard tucked under edge holding water beneath the board and then releasing, > creating an increase in glide(perhaps translated to speed). How does a > tucked under edge and the fulcrum of a rail really work? Some long boards > have an egg shaped rail around the entire board, that seems like it would > make an unstable wobbly board.>>> Any one out there who really has a handle on this. Can’t be a mistery. Here is an excerpt from Snakes’ online book. I have also attached the URL for you to check out. You have to go to the URL to view the different rail designs - I couldn’t paste the pics. It seems to be a good resource that answered many of my rail questions – the rest have been answered by Jim the Genius, Herb, Noodle and the rest of the ‘Swaylock Crew’. Magoo The Complete Surfing Guide for Coaches - Bruce “Snake” Gabrielson Rail Design Before attempting to shape the rails, the shaper must have a good very idea of the final rail design wanted. Ideas vary on which rail shape is the best for different kinds of surf. Every few years another shaper comes along with a “new” design he thinks is best for the area where he surfs most of the time. These “new” designs are really old designs that have been around off and on for years, but may be used with the fashion of the day. This section is intended to be generic, and not favor one particular design over another. Generally, sharper and lower rail line designs are used for large or steep and hollow conditions. In these waves, the rail is needed to bite more into the wave so the board can remain stable at faster speeds. Sharper rails are also needed if sweeping turns are planned that use more rail than fin. “Brewer” rails were designed so a surfer could experience the freedom of softer rail design while still maintaining a low rail stability. These rails are used in conjunction with Brewer fins for maximizing control on larger waves. Years back, Greek Surfboards promoted a knife edge for maneuverability using a low rail design. Their boards provided maximum rail control while compensating by adding rocker and bottom design for lift and overall maneuverability. Where small thinner beach break and reef break waves are prevalent, softer “egg” like rails are common. This design is useful in breaks like the South Bay area of Los Angeles and the majority of breaks along the East and Gulf coast. A soft rail allows the surfer to completely exploit his fin’s turning radius. Since torque is equal to force times distance, non-biting rails allow turning from near the tail to be fast and effortless in smaller surf. Tricks and many higher scoring contest maneuvers are also easier to perform with soft rails. The chief problem with soft rails in faster waves is speed. Since more actual rail contact is made with the wave face on large or quick breaking waves, soft rails will create more friction and thus more drag. More knife like edges with turned down rails work in small fast waves, but can catch on larger non-steep waves and create problems. Shown in Figure 5.7 is a general summary of various rail designs. Each rail type is discussed below in terms of where it is most effectively used. This is a typical overall estimate and not to be construed as accurate for every wave type when other factors of the overall board design are taken into consideration. The reader is also cautioned that the board’s bottom and rail design must go hand-in-hand for the rail to be effective. I Best in big or heavy waves and also in fast point breaks. II Best in slower beach break and reef break waves. III Best in small beach break or shore break waves. IV Best in fast or steep beach break or reef break. Most effective in smaller waves but sometimes found on big wave boards. http://http://molasar.blackmagic.com/ses/book/ch5.html

The practical difference is between a low speedy rail, and a high > forgiving rail. Most boards compromise somewhere between the two. I like a > mid-board rail line that’s .8" to .85" above the bottom. I like > my tuck to reach no more than 1.2" under.>>> My favorite lower rail is a quarter .8" tube, no tuck. But I like > chasing fast tubes. For mushy breaks, a little more tuck is appropriate. The above dimensions are my shaped foam dimensions. The actual glassed rail heights are .9" and .95"