In a recent Surfer mag, there was a picture from 1972 of a pro surfer sitting next to his fish surfboard with hard down rails from the tail to the nose and it got me to thinking that some of my favorite boards had down rails. In 1972 I also had a back yard made fish that was very light and had sharp down rails and in 1977 I had a bonzer that was very light with down rails. So I recently made a light 7' egg down railer with 1/4" deep and I haven't come to a conclusion as to whether I like it better than the conventional railed boards. It seems to be a little faster and the rails don't hang up as much as a softer rail. It seems that a c rail hugs the wave more and you have a little more control. I guess you can't have your cake and eat it too. I remember when surfing the bonzer that I could wait to the last second to stand up and make a bottom tun and then hit the lip, oh, what a feeling!
After listening to Maurice Cole’s interview, I checked out his boards at Sacred Craft. His tow boards, especially, have sharp rails nearly to the nose. I hear Griffin’s boards do, too, but I’ve never seen them. Maurice said that it’s a misconception that we need a soft rail in the first half of the board (it won’t catch), and a sharp rail is a lot faster.
So my most recent board has sharp down rails almost to the nose. I haven’t had the chance to ride it in decent waves, b/c I dinged it my 2nd session and haven’t fixed it, yet. My rails are really full, which I don’t particularly like. I was trying to keep the deck flat (compsand).
I’m dying to try an MC or Griffin, though.
Down rails do a couple of things. First, they lower the apex, creating a very asymetrical rail profile that shortens the tuck below the rail and elongates the curve on the deckside. This makes what I call the “effective bottom” of the board wider. So (and some people will debate this with me, I hope) you get a board that feels wider than it would otherwise.
The shortened tuck also creates more release than a more symetrical, rounded rail with a wider tuck, which makes it a bit faster, but also creates less “suction” as less water wraps around the rail. Combined with a flatter rocker, down-railed boards can generate tons of speed in minimal conditions. I still use them on fish… even my “modern fish” boards have slightly down rails.
I was thinking about this recently and to your point…I think that with the rail apex lower, you’re also planing higher in the water than a eggier 50/50 rail which may translate to less wetted area and less drag.
I have a Hynson BKQ2 that is fast as hell in even marginal conditions and a HARD downrailed longboard (I think it’s a no-label Wayne Rich) that positively SCREAMS down the line.
release
with flat bottoms the water exits the sharp transition on the opposite side quicker than rolling along the rail.
makes the bottom width narrower allowing for more floatation
need to be intune with rocker though
lopez says it was hynsons greatest contribution to surfing, the downrail effect.parish/lopez/barnfield pins with down rails and beak noses allowed the first mastering of pipe barrels. I think lopez called it surfing pipe on autopilot with those things. Before that it was only due to Butch’s insane bravery/experience
I’m confused by what you said about how down rails… “make the bottom narrower.”
When I use the term effective bottom, I’m talking about the planing area of the bottom. Lowering the apex and narrowing the tuck increases the bottom’s plaining area, making the planing surface wider. Raising the rail apex, and widening the tuck, removes planing area, so the board planes lower in the water… like what afoaf said.
you very rarely ride a board flat on its bottom unless you are on your belly proning to the beach in the whitewater.
most of the time you are on rail engaging the rail and fins at different vectors or AOA into the moving wave face.
the as you engage a rail water jets to the opposite side of the flat surface or bottom and edge of the outline.
the more defined the sharpness of the transition or “tuck” the quicker the release.
same for how the outline and the rocker comes into to play to give a point for the water to let go of the board versus holding on.
the faster you can get water to accelerate off your board theoretically the faster it should go. A completely hydrophobic surfboard surface that water doesn’t even touch should be the fastest as long as there no boundry layer issues. But control would be lost.
the smoother the transition at the “tuck” the more the water wants to cling to the surface at slower speeds.
the other problem is that sharp edges not aligned with the flow of the liquid will cause vortices and other disruptions like in river rapids which creates friction/grip which slows the water releasing from the surface.
that why all four components have to be designed to work togethor, bottom, rail, outline and rocker. And this also doesn’t discount the importance of the fins and their placement.
a sharp edge will have no effect if the rest of the four components are working against it. that’s why some folks experience the biting effect when sharp edges are just plopped onto a sharp without regard to the other design components.
that’s why tommy perterson’s “jet” bottom boards fascinate me. do they create a “foam head” boundry layer for you to ride on because they don’t make sense when you think about smoothing out water flow to accelerate it. I think control is the issue with them like the fireball fish. watch Curren as he gets sucked back into the foam ball of a 10’ monster in search2 and watch what he’s having to do weight wise… …
too sharp rails are a classic beginner shapers delimma. understanding how to properly turn a rail and set an appropriate tuck is one of shaping biggest lessons. the other is keeping control of all your curves…good shapers can do this with their eyes closed just using their hands.
but i’m just a rider not a surfboard designer
most of this is just intuition from riding and playing around a ton of different stuff since 1968
best way to learn is to ride everything in anything to see what does what when
I’m finding this interesting but need some numbers to understand how “down” the rails are.
I’m guessing that the mid section are around 5/8" undertuck from a rail apex at 1/2" up (on a 2 1/2" thick board)?
In these boards:
- is this sort of undertuck carried proportionally to the nose?
- or is there even less undertuck than this?
- and/or is the rail apex even lower?
After riding flat ply paipos and then getting on to a 60/40 railed bodyboard and then a surfboard, the difference between down rails and all others is clear to me.
Im using squared down rails on the prototypes of the Surf Foil product that Im about to put on the market.
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/pro313.jpg[/IMG]
[IMG]http://i153.photobucket.com/albums/s225/SURFFOILS/pro3017a.jpg[/IMG]
They surely feel to be faster, the response is instant and cleaner in release and I combine them with a flat hull at the back to keep the wetted surface and coanda/suction effect to a minimum.
Some people might not like a quick and responsive board tho ...
For a prone craft, squared and sharp bottom edges work better than any other Ive tried.
On a 2.5" thick board, I measure a tuck of less than 5/8"… more like a 1/2 or so… with the apex up about 1/2". But people measure tuck differently, so that may be the case here. I like to have the down part of the rail roll up to a 50/50 on boards that are foiled thin in the nose, but keep the down profile on boards that carry the thickness out to the ends of the board… like a retro fish or old school single fin. Angular down rails carried out to the tip of the nose come together to make a nice, natural beak, too. So you got that goin’ for ya.
can anyone post pictures of down rails profiles?Like those much talked Hynson down rails?
I wanna have some visuals if possible 
My stripped down round tail fish has down rails, though with a little ( and i mean little ) tuck. Keen to see how it goes. Though the rails go from up turned in the nose, then down in the middle, and still down in the tail, but with almost zero tuck.
Have anyone ever seen the McTAVISH "devil rails"?Aparently they lift up the rail when you hit the lip and avoid that the rail get stuck at lower speed.
I post a link so you can see what i'm talking about http://www.youtube.com/watch?v=Bd2AD5TL_hk
BEVEL… not devil! LOL
Yes… not the 2008 model, but one of the earlier ones. First took it out in small surf, and rode it like a mini mal… the 8 footer I’m talking about. I knew nothing about the board. Just rode it. I felt, during that session, that I’d like to try it out in some good surf. Months later, maybe even a year, I go down to the beach, and there’s a really good surfer just ripping the same board it head high, maybe a foot overhead. Just killing it. When he was done, I took it out. Really great board. Everything McTavish says about it is true. Funny… this is the first time I’ve seen that clip, or even heard anything about the board. Rails are heavily beveled, and they do let you go a bit more vert than your typical modern rail would allow on a board that size. And… the thing even noserides! No s#!t! It’s not a noserider, but you can step up and plant one right on the tip and hit holds!
…hello,
seems that you have a mistake with the name of the rails…
down rails is one thing, sharp, hard or tucked edge is other stuff
Well...I've made a little mistake but I'm not english as you see...:-P
so a down rail can “finish” hard, or with a tucked edge that’s it?
I have been looking for pics to clarify this for me… but with no sucess 
…look for semi guns of the 70s
also downrails come in hand with flat decks
what would you say from these which is a down rail?
