Rails
Thrusters…
How are thinner or thicker rails going to effect a boards performance if any.
Rocker…
on semi-guns or step up boards does the rocker change much compared to a standard Nose Rocker hovering around 5-6" and tail rocker hovering around 2-3".
Thicker, in general = a little harder to get on edge, but more hold/suck-into the face, little harder to “release.” Thinner, kind of the opposite. Gotta remember, this is so general - 'cuz, where, mid/tail/nose/ etc.
Rocker… I’d go with yeah.
Taylor nailed it larry…just out of curiosity I recently made made myself a board with super thin release rails - very knify…surfed it tonight…it feels very sensitive and fast…although I didn’t get too many rides to fully evaluate the thing…I’ll do some more research soon i promise…
Made an 8’ a little while ago now and put the razor rails on it. Goes really fast for it’s size, although that could be partly due to it’ thickness (2"). Seems to really like to be pumped on a long, fast wave.
Thickness of rails should be relative to speed. Rails have to be sunk into the wave’s face to slow the board down on one side or the other, thus making you turn.
If you go very fast and your rails are (too) thick, you won’t be able to sink them, so no more control.
If you go very slowly and your rails are (too) thin, you will sink them so deep that they will catch and you won’t recover.
As a rule of thumb: small, slow waves = thick, boxy rails. Big, fast waves: thin, pinched rails.
cool,
I appreciate it.
I’m looking at shaping myself a semi-gun w/ a round pin. I’ve only made thrusters in the past and want to collaberate ideas/theories together before I start working.
I’m 6’ 3" 230lbs. The board I’m planning on doing will be 6’10 x 20" x 2 7/8"
My typical shortboards run 6’ 6" x 20 3/4" x 2 3/4" w/ rocker set @ 5 1/2 N & 2 1/4" tail w/ the peak 10" behind center.
I’m figuring the altering of the rocker will play a roll in speed.
I’m planning on dropping the tail rocker down a little and thinning out the tail a bit as well for more bite in larger steeper surf. Good idea or bad?
If you’re looking for larger, steeper surf, thinning out the tail is a good idea but dropping the tail rocker down is not: less rocker in the tail means more speed (less drag) but less control. In bigger surf, the speed is already “built in”, you don’t need to create more. What you need is to be able to control that speed. Thinning the rails and tail will help penetrate the wave’s face at high speed, lots of curve in the rocker is another control feature. Of course, not too much either, or paddling in will become an issue. There’s a fine line to be found here: try and try again since what works with you doesn’t necessarily work as good with others. But start with those basic rules. (I learnt that from an article by Mike DIFFENDERFER and Tony CHANNIN in a 1969 SURFER MAG. issue, and it has never proven to be wrong ever since… so I stick with it.)
I agree that thinner rails, thinner tail, and more tail rocker give you more control on boards for bigger waves. I like a little “kick” in the last few inches of nose, but about the same general rocker as you have planned.
I also think thinner and softer rails and a thinner tail make for better hold on steep faces, because the water wraps around the rail and “sucks” it into the wave face. Bigger rails are for smaller boards and smaller, mushier waves, where you want to stay on top of the water at lower speeds, even on turns.
Nobody addressed the width issue.
For bigger surf, most guys go narrower, so thicker rails work just fine, with the narrower board! You make thin rails with a narrower board, you won’t catch any waves!
You KNOW you go faster on bigger waves, so do you want narrower to control the turning, or do you want thinner rails?
For sure, narrower and thin rails DON’T work.
For sure, wider and thick rails don’t work either!
You’re right if your talking BIG WAVE boards… for me, around here, a big wave board is for overhead + surf, since it only gets to double overhead a couple times a year, if we’re lucky. So there’s really no need for that true “gun,” with the narrow, gun planshape and thicker rails. I just shaped a 7’2" for a guy for our big days, and used a regular shortboard rail profile. The length will get him into waves just fine.
But for a true gun, I agree you need to go narrow and full railed.
Not sure…
My small wave boards were usually just under 6’ single fins, around 20" wide.
My best all around Oahu and OceanBeachSF boards were 7’3" x 18.5" x 2.75" flat decked rounded pins. Had a whole slew of them.
Now, after turning 57, I’d just go an inch and a half wider.
If you’re looking for larger, steeper surf, thinning out the tail is a good idea but dropping the tail rocker down is not:
If you narrow the tail, then the tail rocker can be flatter while gaining precise control and more speed as well. Also, if you narrow the tail, then you don’t need to thin the board out through the tail as much either. Like This: Regarding tail thickness, it’s like LeeDD said, a narrower board can have thicker rails. . . … . . .this applies not only to the maximum width of the board but also to the tail width, . . . . .a narrow tail is so easy to roll onto the rail that a thicker tail can be used. 
Hey Lee…
Interesting, your thoughts about rail volume and wave catching…
Do you feel that thicker rails inherently help with wave catching or is it the general thickness of the board that you’re referring to here?.. (I notice that you mention your board was flat decked…how about a domed deck?)
Interested in your reply…
This board is a rounded pin, but about 20" wide. That’s why you can’t call it a gun. It’s for overhead surf for a 40-year-old guy that rides only a fish and occasionally a longboard. A 12 inch nose and about a 15 inch tail, 2 5/8 thick, single to double concave. Moderate rocker, moderate domed deck, relatively thin in the tail and rails for a 7’2". Wide point 3 inches back.
Designed for ease of catching waves, and more of a roller coaster, climb and drop styled surfer.
Make sense?
Personally, I think volume is the main thing, but if your rails are thin, then you need super crowned deck to achieve volume, then you need super arched feet to tip the board when you turn.
Personally, I walk around on flat ground, not telephone poles, so I like flat decks and thicker rails.
To allow for that shape to work in juicier waves, I need narrow.
Of course, I adjust board width depending on speed of the waves.