Why don’t boards have rails similar to this? Wouldn’t it hold a line better, prevent sliding, and all that fun stuff? Or is this idea already around and I thought i was on to something?
-ian
The photo is obviously not proportioned, I was just trying to get the idea across in Illustrator.
c 1975 Jackson kneeboard, Australia. [attached]
LeeV, aren’t you doing something similar with your ‘edge’ boards, too , from memory ?
"chip"
i´ve seen such rails in a couple of surfboards in a surfshop near Mt. Manganui in New Zealand. They told me that the boards would kick ass, but i never tried one cheers clemens
Surfline surfboards in Ruakaka NZ is putting out some boards similar to that. A bit more like side channels though. Shaped by American ex-pat Brian Clarke. He rips them, but then he rips on most boards.
Check the resource archives, I’ve go two edge bottom boards. Remember that round holds and flat (or sharp) releases. With the board running flat, the edge releases and the board planes easier and faster. When you roll it up on the rail though, the bottom disengages and the round rail holds. Its an experiment on trying to get the best of both worlds. Jury is still out…Bob Duncan at Wilderness in Santa Barbara makes edge boards too.
Thanks all. LeeV, what if the depression were made top dead center of the rails, giving an almost double-rail design?
LeeV, what should I search for in the archives? I tried running a search on “two edge bottom” but came back with way too many hits. I’d like to check your designs. Do you have a direct link to the thread?
I think “Channel Rails” have been done…late 80’s. Not sure by whom. Also “Zepplin Rails” by Bob McTavish; in section, the round rail is made of a series of straight lines so the rail looks like the airships of WWI. All of these rails are looking for the hold of a round rail but the release of a hard rail…
The problem with these different shapes is the cost of manufacturing the board. They are time consuming to shape and even harder to glass and sand. They require a lot of finishing to get them right. That’s probably why they haven’t shown up on production models. That and the benefits may not out-weigh the hassle of making them. The tucked edge is the easiest to shape and glass and is the least quirkiest, so that’s what you see the most. A chine rail is also a version that gets used a lot (see Stewart Surboards).
Here a couple more.
Also check pg 13 of Surfer’s Journal vol 7 no 2. It shows a young Greenough and Cundith with an early kneeboard version.
If in Santa Barbara, check the maritime museum exhibit which displays some really interesting windsurf versions along with some surfing models.
Con Surfboards had kind of inverted version (the Shoe) with a step on top where the thick deck transitioned to thinner rails.
I haven’t seen a version with a step on both sides but don’t see why it wouldn’t work. How and why is subject to discussion but my take is the thinner rails allow for a more sensitive edge on a thick board, plus the channels direct water.
Lee, that board looks really fun! How does it ride? What conditions do you think it works best in, and what type of riding style compliments it best?
That Greenough board looks nuts! That’s a bit more than what I had in mind, and I can only imagine how much time went into that bad boy. I bet it goes in large surf.
The concept sounds and looks good, but application still is pure theory.
Seems the two edges also need more than normal rail pressure to hold, so dropping off the steep face is a real problem, and strong bottom turns sketchy at best.
You’d need to really THIN out the rails, to have two bottom edges.
Also seems some small percentage of extra drag in slower waves, not noticeable in faster waves.
Nothing wrong with rails already used, I’d try to improve my surfing instead. That’s me, of course. Design theory is always fun to try to apply!
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Lee, that board looks really fun! How does it ride? What conditions do you think it works best in, and what type of riding style compliments it best?
The roundtail is very touchy. If you stand in exactly the right spot, it is one of the most fun things I’ve ever ridden…It holds a high line and the bigger and steeper the wave the better. It makes turbo boost rail turns from the middle of the board. Unfortunately, if your feet are inches off the sweetspot it spins or bogs. Not sure why, probably the tail rocker or perhaps the way I transitioned the edge in the tail. I have dropped in on 8’ outside Newbreak (about as steep as a wave gets, yep even as steep as OB San Francisco) and she held in just fine. It works really well in small surf too.
The swallow tail is definately more user friendly. The sweetspot is larger and the spinning problem is gone (probably due to the swallow tail). It does not rail turn very well with the thruster set up, but does with a single fin (the board has Future outside fins with normal toe-in and cant, and a 8" Bahne center box for a thruster stabilizer or single fin) The thruster set-up flys if you really push the board from the tail. It does not flick well at all, you have to put it on a rail to disengage the bottom. It’s a great board for power surfing. It is pretty non-descript in waves under 4 feet.
Both boards were designed for glassy, slightly fat, reef breaks. I would lengthen and narrow them for OH+ inside out surf. Both boards don’t require any more pressure to bury the rail than a normal board, in fact probably less. You just need to lean them over to get the most out of them. They are both very fin sensative…so that is an endless process…The roundtail likes a Liddle flex fin whereas the swallow likes a Stage VI Greenough paddle fin. I’m still screwing around with the thruster set up. Rich Sanders is making me some carbon fiber puppies as the flexi ones I have suck.
Right now to me, the edge bottom lets you build a short board that paddles and planes like a much longer board yet turns like a board with very soft rails…Pretty much a personal preference kind of thing…I just like they way they feel in the water.
You might consider how thin your rails really are, and also factor in your weight!
Also, if the inside planing surface is 16" wide, then the outside template must be around 21, so it’s already a mini gunny board for someone your size.
NewB is easy on boards, from bunkers to twins to tris, it’s a relatively predictable wave going thru it’s motions over and over again.
Remember, I spent THREE semesters living a CalWestern University…no stranger to Newbs.
Take that board to Bird, or LJC, or Blacks, and all the characteristics I outlined will blossom!
Just adding my two cents (is that what you say?) to this post. A few years ago, I shaped something that looked like it. I hope you can see it attached. That thing had an “inner” planing hull (dead flat) and then channels under the rails. The idea was to reduce the wetted surface to a minimum when the board would start planning, thus allowing a wide board to handle speed better. Also the concaves were supposed to direct the flow through the tail and around the fin (single).
I was pretty sure that I was on to something great. Unfortunately, the glasser blew it… I can’t really blame him, he was a pretty good glasser (still is, by the way, although he doesn’t glass much anymore) having worked with Maurice COLE for a long time. I know for sure that I wouldn’t have attempted to glass it myself, most probably it could not be done… So I ended up with a new blank as a compensation and I shaped something else that COULD be glassed, and never knew if that one would have worked or not… What do you think?
My rails are quite thin but Duncan’s boards all have full rounded rails. I’ve never ridden one of his but he makes a million of 'em so they must work ok… Once you go up on a rail for a turn or steep drop, the bottom releases and the rail takes over, not both so they’ll hold as well as any other rail. When foiling the tail of an edge board, you do have to keep the extra 1/4 inch of “edge” in mind so you don’t end up with too much thickness at the tail.
John Mellor’s big Wilderness is a full on gun that he has ridden in some pretty big stuff, so the edge does not appear to adversely affect big drops or bottom turns. (Greenough’s edge bottom sailboards seem to hold a tack at speeds well in excess of anything you or I could achieve on a surfboard) I have ridden my boards in waves with 10’ faces and had no problems with turning or dropping (as long as I was in the right spot of the roundtail). That is probably the limit for those outlines and lengths though.
Maximum limit outside Newbreak on a low tide is every bit as steep/hollow/powerful as a 8’ face at Black’s, or Bird Rock…Remember, I’ve been surfing SD for 30 years…no stranger to any of the breaks you mentioned… 
I am definately not saying the edge bottom is the greatest thing since sliced bread or is the last word in rail design…They are an answer to a specific problem though. For me, in up to 10’ faces, soft or steep, fat or inside out, I have never experienced problems with holding or sliding on a bottom turn…
Lee,
Thanks this is fun stuff.
Based on you experiance with both boards and your comments about the spin and bogging with the round tail, would you recommend blending the edge with the rail (like on the swallow) as opposed to blending the edge with the bottom (like on the round tail)?
Thanks
i got a hold of a 6’4" that has a simmilar design. I assumed that it was for faster planing and a little more edge hold. the first “short board” that I could actualy surf well. its a “progressive surfboards” by dave johnson.
dims are 13.12" point nose x 20.75 mid x 15.5 fat pin tail and is about 3"thk.
the “channaling” starts about half way down from the nose at about 1"wide and gets progressively deeper twords the tail to about 0.5"deep. it was made in 1985. it planes early and is amazingley responsive.
got it for $100 used.
I would run the edge off the rail like my swallow or off the corner of a arctail like Greenough does. I would put a swallow in the tail so you reduce the planing efficiency to also reduce the spin cycle. I used a “staged” rocker that is most likely the culprit. Go flat to about 30 inches up from the tail and use a curvier rocker (1.5" to 1.75". Kick will reduce the spinning but also reduce the drive and rail turning ability so you’ll have to compromise). If you are planning to ride it consistantly in bigger, steeper waves, I would suggest narrowing the outline a bit also. Duncan keeps a steep (30-45 degree) angle between the bottom of the rail and the edge. Mine are steep in the nose to much flatter in the midsection. Greenough’s are like Duncan’s. I don’t think the rail shape (full or pinched) is causing the narrow sweetspot though.