I’m shaping my second board, aiming for something similar to Ryan Lovelace’s Pedestrian model, and I’m seeking advice on twin fin placement.
I’ve already roughed it out, got the deck/rails/and bottom squared and sanded to 220 and the nose and and tail rocker put in.
Now the fun / scary part starts
I need to add my fin placement, figure out my taurus channel and then shape the rails.
I’m unsure as to if I should shape my rails or do the channel first, because the channel exits out of the rail at around 3.5 / 4 inches.
Board Specs:
Dimensions: ~6’0" x 19 7/8" x 2.5" (currently 2.75", will reduce via a 1/4" deep Taurus channel)
Volume Goal: ~30-32 liters
Nose Rocker: 4.5" (I left myself 1/s an inch of foam here to the 2ft mark)
Tail Rocker: 2 1/4" (I left myself 1/8 an inch of foam here to the 2ft mark)
Tail*: 6" wide at the end, 15" at 1 foot from the tail
Rails: Considering either 60/40 or 70/30, leaning toward narrow, pulled rails - this board is replacing a 6’1 x 19.75 x 2.38 thruster I had but recently snapped (twice).
Construction: EPS stringerless blank, 3" wide 6.5 oz carbon tape inset deck stringer(maybe on the bottom too, but it seems like it would be hard to glass), 4 ounce carbon/fiberglass rail wraps, glassed with the top/bottom being 4 ounce linen wrapped in 6 ounce s glass.
Bottom Contours:
Single concave Taurus channel exiting near fins (around 3.5-4" from the tail) starting 8 to 10 inches in
Slight vee near the end of nose (going into the chest area) rocker and last 4 inches of tail (inspired by my
About Me & Surf Conditions:
36 yrs, 6’3", 180 lbs, fit
Surfing mostly La Bocana (beach like reef break, powerful) and Sunzal (point break, slow, long walls) in El Tunco, El Salvador
Conditions: Typically 2.5ft to 4ft+ waves at 16 seconds period - I want this board to work in head high to 2x overhead - when it hits 6ft+ the 7’2 paddy comes out.
My Initial Fin Placement Thoughts - after reading the twin fin placement posts:
Distance from Tail: 6" (rear base)
Rear of fin box: 1 1/4"
Toe-in: 1/8"
Cant Angle: 4°
What I’m Seeking Advice On:
Fin placement recommendations (distance from tail, toe-in, cant angles)
The goal is to prioritize speed and hold without being excessively “tracky” and still carve up into the pocket of a bottom turn.
Which order of operations, i.e., rails vs concave, should I do first?
Finally a good explanation on how to measure and draw out rail bands (yes I’ve looked at the greenlight stuff and everything I found on youtube, but I still don’t understand the relationship between rail bands and amount of pull/ tuck. I’m looking for something that doesn’t include some pro shaper eyeballing and shaping perfect rails bands with his planer first try.
Any insights or specific measurements based on your experience would be greatly appreciated!
Yeah my first board i did one rail with surf form the got " inspired" to better to learn my planer and did the second band with the wen (unmodified planer) i like both of the rails the only problem is they are different. The surform is rounder the planer one more pulled down and performancey. I know theres a relationship to railbands and rail shape i just havent found it explained in a way i grok yet.
I’m definetly not in a position to teach somebody rail bands, but may I ask where you struggling?
To prep the eps blank I found the “Bruce Jones in the shaping bay” video very helpful.
To get the measurements for your railbands you will have to draw a number of crossections of your existing shaped- to- thickness blank on a piece of paper and take your measurements from there with a set square .
That’s it basically .
I think the common practice is to do bottom rails first , then top , bottom contours last- at least that is what make sense to me. Don’t cut away any references that help you stay on track (apex , stringer marks etc)
I went back and rewatched this. At minute 24:30 he starts measuring the rail bands, and he goes, “and I know thats where they go because I’ve done this a thousand times.”
I know , I was referring to the part where he positions the bars perpendicular to the stringer to check if the bottom plane isn’t twisted.
Sorry for the confusion:)
One of the best “cheats” for shaping rails is to copy the rail on a board you like. Im not sure if you have one around with the type of rail you plan to put on the board, but it if you take a piece of metal/plastic and bend it to form to the rail you can use that to shape your board with. When I do this, I’ll then trace the piece on paper and measure straight lines that I then use to shape the rails. I usually do it this way: bottom of rail to top diagonal line where the top curve meets, then some mid point (depending on top of rail, this varies) to further inside the board to give shape to rail on the deck (now you have 2 “cuts”- one less angled on the top and a steeper on the bottom), then meet the sharp angle on the sides of the rail and make it flush (top rail is 90% done), then tuck the bottom of the rail. Again, this is a super generalized version since the rail will be fluid depending on the positioning of the board, but I hope this thought process helps you. When I shape rails and take of materials, I try to follow the line as close as possible on both sides and make a sharp edge that way it sort of acts like a guide line for my next measurements to shape the rails. I find this helps them be more symmetrical but also time efficient. Lastly, listen to your hands!
Also, your measurements for the fins seem good, will be a drivey and fun board. Volume estimate sounds right, too.
I described a method in another thread in which you can turn the bottom rail using a sanding block and sandpaper. But if you take a cut or two with your planer on the bottom of each rail you will have the start of a basic 60/40. Forty being the bottom. Clean it up and blend with a firmly padded sanding block and some 60 or 80#. Terry Senate once told me that the best tool for blending a rail was his hand. He would use a piece of “taped edge” Dragon Skin or 60# in his hand and form his hand in the shape of the rail he wanted. Then he would finish it off with Screen. It my opinion no matter the method, it is best to have the blank on edge in the shaping rack.
Thanks man, i came to that conclusion yesterday after being somewhat “stuck” the last few days and went and bought some graph paper with the intention of doing exactly what you said. I have a recently deceased 2.38 thick thruster i love the rail of. I feel like if take measurements off that at the middle, 1 ft from the nose and one foot from the tail the rest should mostly figure itself out.
Also thanks for the feedback on the fin position this was the push i needed to get back in there and fuck some shit up.
It was alot of material to pull away to get a tucked 2.38 rail out of what was a 2.5inch square rail block.
I drew in rail apex is at .75 inches from the bottom, .5 and 1 inch lines the i worked the middle 4 feet with the planer focusing on the middle three, one i got two those the lines i mentioned i went full hand samd, surform, screen with 80 grit, 120 grit 220 grit.
The big thing i focused on this time was keeping track of doing the same thing to both sides. If i did three passes on one side, i did three on the other before moving on.
Took me at least 8 hours yesterday but im really happy with how it came out. Its a flat deck with a significant chine but i like it, i domed the chine in on the tail so it wouldnt feel weird underfoot
For the fins, i marked em out at 6 inchest from the tail but at that distance the tail is like 12 inches wide, my foot is 11 inches .
So i drew in new lines at 7 inches where the deck is like 12.5 inches wide.
Is moving the fins forward that much gunna make a crazy difference? They are 1 1/4 inches off the rail and 1/4 inch toe. I had no idea how far back twin fins sat in a board relative to thrustes and quads . Its no wonder all my five fins feel skatey as fuck
The width of the tail where your foot will be doesn’t matter a whole lot unless your preference is that. Technically speaking, a board set like that will be a good in between of drive and maneuverability, but then again recreational surfers often don’t have robotic foot placement anyway. As always, there’s give and take with surfboards. 6 inches from the back is typically what you see on shorter, wider, retro boards. For instance, I am making a twin (6’4” x 20x 2.5ish) and I am setting them (probably) 9 inches from the tail (a swallowtail, with 3 inches cut off) so it will have the extra maneuverability but not lose the drive and speed (it will also have channels, but thats a whole other thing).
So long story short, no, I don’t think moving it is a big deal. But yes, it will affect the board. If you want more speed and drawn out turns, having it where you’re at with your foot in front should be just fine. Moving it an inch forward or so may not change it a whole lot, but the further you set it forward the more slippery they feel.
Man, I really appreciate you taking the time to write all of this. The board has shaped up nicely so far—your first message pushed me to dive back into it. This board is going to have a channel as well; I’m doing my best to mimic Ryan Lovelace’s. Link here:
Next step is drawing out the torus channel/vee, then shaping it.
Regarding the fins moving forward—I was under the impression that ideal foot placement on a twin was over the fins or at the back edge of them. I hate when my feet bog because I’ve stepped too far back, and that was the thought process there.
Yeah that’s true. Measurement from tail is just the general rule of thumb since there’s a certain common distance where people usually place you back foot. Given your situation, moving it makes sense. But even though your foot placement might be above the fins, it will be a bit looser than if it was set back where you originally had it. I still think it’ll be minimal. It looks like the board you’re mimicking sets their fins more than 6 inches anyway, as “performance” twins tend to do. 7-8 inches would be a good to target id say
Setting your boxes like 8 1/4 - 8 1/2 is pretty safe too. Especially if you plan to use a hybrid fin with a slightly wider base. Then if you want it to feel more loose you can throw in something more upright with less base. If it’s to loose go with something closer to a keel. Puting boxes to far back just leaves you less options. You’ll have plenty of drive and still sensitive with a hybrid fin (5 1/2” base) at 8 1/4 . 1 3/8- 1 1/2 off the rail. 6.5 -7 Cant. 3/16 toe
IMO the Pedestrian Ship channel is not really a Torus channel (below).
The Pedestrian Ship channel is more of a Venturi channel (but only loosely).
Torus
