What kind of bottom,volume and glass schedule are you running with that quad set up?
Hi stoneburner,
I relate. To create flex (in a surfboard) a load must be applied to it. In most cases we create flex from the rider inputs. Changes in direction create acceleration (sometimes referred to as “G-Forces”) in order to go in the new direction. Our bodies want to keep going the old direction, so we feel the force of change through our legs. The applied load is through our feet to the board (at 2 points.) Of course, these 2 point loads VARY fore/aft (longitudinally) and left/right (laterally.)
To promote flex in the board there are a ton of ways to do it. One of the less obvious but most common is to make a thinner board (thinking HP shortboards that Pros ride.) Board flex with respect to its’ thickness is a cubic factor (assuming Simple Beam Theory.) For example if you double the thickness of a board, it’s NOT twice as stiff, it’s actually 2-cubed, or EIGHT times stiffer. There are other things to consider like Slenderness Ratio and scaling factors, so as you go 1/4" thinner the board is even more flexible in the next 1/4" thinner, but in general you get the idea, “If you want it to bend, thin it out.”
To promote flex you can also use different materials, under this category I’ll also put “material placement.” I alluded to what I’ve been doing (using off-axis glassing) and locking up flex in other degrees of freedom, like torsion. You can also use lower modulus fabrics, like Innegra, or higher performance bi-directional fabrics, like Carbon Graphite depending upon the goal one is seeking. By the way Carbon is an Engineer’s favorite composite because it is bi-directional, its’ tensile strength is just about equal to its’ compressive strength (in a viable matrix,) UNLIKE fiberglass which has tensile strength close to Carbon, but almost no compressive strength. Kevlar is like this too, but has MUCH higher tensile strength than either Glass or Carbon. In general, you can stack fabric patches where you want stiffness, and minimal, off-axis fabric where you want more flex. Likewise you can use different foam (or other cores) to promote flex. I mentioned using iFoam has been very interesting. There are other foams which exhibit good elastic properties as well.
Here is a very interesting thing that happened a few years ago, I built a board with variable flex. I was doing a bit of SUP with a couple of guys when it was small. One of the guys was Jim Weir who owns a company called ULI boards (inflatable SUPs.) He calls me over to his little Jeep and as he’s inflating it and he says “Watch this” and he stands on it between two milk crates and the 14 ft air-filled race board is holding his weight. Got me thinking. Roll ahead a few months and I meet Rouven Brauer (Bufo) who owns HydroFlex. So we end up building the first SUP from iFoam with NO stringer (the shape was like a wet noodle on the shaping racks, ha) and a hard external (minimal 4s glass job. Long story short, Bufo’s boards gain strength by applying internal air pressure. He has a Schrader Valve (tire valve) potted into the board and a small bike pump is used to pressurize the board. His focus at the time was to prevent dents and buckles. What I was after was to make a “floppy” large board and find out the behavior as I added pressure to the board. (NOTE: EPS breathes air (and water,) and iFoam breathes air but NOT water (like Gortex) and PU sorta breathes air, and water, slowly.) I was very surprised to find how much influence internal pressure has on surfing characteristics (and for SUP, paddling characteristics too.) I found that no pressure SUCKED, the board plowed in all phases. On the other end of the scale, too much pressure SUCKED as well, the board would lock in a turn and I’d end up face down splatting in a bottom turn. But the best part was I found there was an ideal pressure for that one floppy board, it really became lively, and sprang out of turns. Higher pressure paddled better. (This is good to know for Racer boards.)
Finally, I came up with a stringer set up which mimiced the optimal flex of the inflatable board. Enter Robb Green (but that’s another story I’ll save,) and the boards work great without having to do the pressure-proof skin and valve stuff. I liken it to the Hotrodders who bag their cars, then leave it at one setting, eventually going over to coil springs and removing all the other supporting gear.
Hi Harry, A_Symms do not sell well… …yet. Although our shop got an order from a shop in S. Australia, we sent a batch of them to their shop in the Bells/Melbourne zone. That said, I’ve done quite a few custom asymmetrics mostly surfboards and some surfSUPs. Want to do a tow board or big wave gun, working on some personal boards for small waves here which are asymmetric. I figure it like this, a kid’s got 600 bucks to spend on a new board because his old one is thrashed, he goes into a surf shop, and what’s he gonna do? (Go with the big label, or hot/cool name at the time- the asymmetric looks almost Alien to the other boards in the racks, which makes it the orphan, and more of a target for dismissal, “What’s this?? Ha, not very even shape, ha haha!”)
“Inverted Vee” or “InVee” got your attention? “Brah you been riding them for years, that’s why” ha, you know how they work. Jeff is one of the most underated shapers, I swear. So many combos can be done with it. Pretty hard to handshape, well suited for CNC. I’m doing a set of small-wave boards for myself using it, so I’m in testing, or going into testing, ha. Oh the dk green gun you saw (above) with the orange fin boxes has inverted vee (with double invees in the tail,) but more on that later, waves will be big up there in a couple more days, board is 10’6" and testing will begin.
I’ve been liking the “lollipop” fins that Carl showed me, I know Burch was using them on a series of boards, you can search for video of the fins in action surfing G-land, it’s amazing footage if you know that wave. My one qualm with say, a lollipop keel fin, is that I want it to bend more one way than the other, (whoa, asymmetric bending pattern, but I’d have to embed spring steel into a hollow slot in the fin and wrap it in carbon- a bit of a propulsor fin I reckon…
@Icc
“a path out of the current design/build cul-de-sac is evident”
That is so eloquent, wow, props- and it implies so much… This reminds me of an Engineering Design Class I had decades ago, “Build a Better Bike Seat” in which participants teamed up and did just that, made what they thought was a better bike seat. Part of the course was “Industrial Espionage” which was actually quite relevant, since surfboards are VERY MUCH “Monkey See, Monkey Do” Anyways, just about EVERY “design team” came up with a pear-shaped seat (yawn…) Actually one guy named Tom, worked alone on his seat, it had a double snout with a slit down the middle, ended up selling it to an exercise bike company and made a bunch of money.
So, yes, a “Paradigm Shift” is in order, but no, it won’t happen in small increments. George Greenough said it best, “Nothing ventured, nothing gained…” How much gain do we want?
Don’t mean to bust your chops, but because you’re an Engineer I have to say something about nomenclature. (I realize you’re area is Hydrauics/Fluids/Civil so maybe you can school me on this. “Cavitation” is boiling and subsequent collapse of a fluid. Best example I was taught was the Pressure Cooker scenario. Two ways to boil water: 1. Heat it, 2. Lower the Pressure (or both.) The lesson I saw was from Bell Helicopters, with the viscous coupling from the fast spinning turbine engine (30,000+rpm) and the slow spinning Rotor. This assembly sits inside a chamber full of fluid/oil. Inside the chamber, the power driveshaft terminated in a flat circular plate, spinning real fast. An identical flat circular plate was connected to the Rotor and the plates faced one-another. As the plates were brought closer together, LOW PRESSURE developed between the two, and the fast plate influenced to slow plate to speed up. As the plates ALMOST touch, the pressure (or suction to make the rotor spin) is incredibly LOW. So low that in the Worst Case Scenario, the fluid would flash to vapor, and for a moment a gas bubble would form, and just as suddenly the bubble would collapse. During this collapse, the bubble can do SEVERE DAMAGE EVEN TO HIGH STRENGTH ALLOYS. This effect is called “Cavitation.” Entire viscous couplings made of high-strength alloys have grenaded from those little bubbles. I know cavitation occurs in dam spillways but that’s more your area…
^^^Half poking at you Greg, but the wording bothers me a bit is all, LOL. I think the term “Separation” is what we are talking about (true surfboard fins produce LOW pressure but nowhere near the magnitude of a viscous coupling,) in which flow becomes so low on one side of the fin, that the laminar flow actually “detaches” from the fin and turbulent, not lift-producing flow, results. Once this smooth flowing water gets ripped away from the fin, it is very hard to re-attach, unless some sort of “influencer” is used.
To address the question, separation leads to TURBULENCE, and it is this turbulence which produces DRAG.
So, yes, there is an inherent problem with the Standard Thruster Fin Configuration. DRAG. I spent quite a bit of time studying naval architecture for bow design on a series of SUP Race Boards I did. It was interesting to find that Hawaiian Canoes (4 man,) would experience substantial drag when they went over shallow waters, like the brakes were applied! Turns out the bow generates a shock wave, kind of a cone shape, or HALF cone, which bounces off the bottom and hits the hull amidships, turbulent water touching the hull is the result, and the canoe slows down.
Likewise, looking at a thruster fin set up, each fin produces a shock wave(s) *multiple shockwaves, in a low speed, mid speed, and high speed range, like octaves in music. Turned out the two front fins created shock waves which angled back to a convergence point… …at the MIDDLE FIN. I validated this the hard way with the early Asymmetrics, which didn’t feel much better than a thruster, yet we knew they should work better. By offsetting the middle fin, the convergence point was missed by the middle fin more of the time, and it didn’t get caught up in the draggy turbulence. One caveat, this only occurs at certain speeds, so the standard thruster is a bit of a tease, “Works really well… …most of the time.”
One time you wouldn’t think about this drag scenario- Paddling. I do not have hard data but seat of the pants says the offset center fin A_Symm thruster paddles quite a bit faster than a standard thruster. Note: Single fins, twins and other variants paddle faster than standard 3 fins but only in certain speed ranges or configs.
On one of the Peru/Chicama trips my friend Mark took a fish I made him (and Steve Pendarvis put a soft deck into.) That fish was a quad. I had the fins spaced further apart than mine, I believe it was 11-1/2" x 1-1/2 + 4, 5" x 1-1/2 + 3. There is a fast section at Chicama they call “El Hombre” it’s right about at the 1 mile mark into the wave. Most regular boards don’t make that section until the waves are huge. Mark made that section with that board regularly. He said the board felt like it was on rails and he could drive really well for more speed. Perhaps it was in part the fin placement? Or the flex of the board? When I moved my quad rears around what I mostly noticed was 1. the “sequential” release of the shore-side fins in bottom turns. 2. the increase in yaw when the fins were “bunched” together front and rear. Mark’s style was very drawn out, he was “speed surfing” so maybe by giving up some of that “windshield wipery” feel of the board, you can get more down-the-line drive, thus speed. When my board had more yaw, I had to put more effort tensing my legs to draw out turns. I only made “El Hombre” a few times (I usually collapsed before that section, ha) but not on any one fin config.
Which quad? The gun (shown above) is heavily glassed, double 6 both sides with laps, then glassed again single 4 both sides, no laps. I’ve described the fins set up and bottom contour some where up there.
The other quad was the one I took (and left,) in Peru. I described the final fin set up above also, the bottom contour was flat up in the first 10-12 inches then single con increasing to about 3/16" a few inches ahead of the front fins, then quickly dissipating to flat at the rear edge of the rear quad fins, a slight vee (or what appears to be vee,) after that off the tail. WITHIN this single concave are some double concaves starting just behind the front foot and maxing out mid-fin at the front fins, then quickly “flaring” out into broad doubles (the end result being what “looks like” vee off the tail, but it’s actually the center portion of broad double concaves.) Glassing was standard 4 bottom and double 4 deck, sanded finish. Volume was right around 30.5L
Hope this helps, and I got the right board.
Best regards,
George
One time you wouldn’t think about this drag scenario- Paddling. I do not have hard data but seat of the pants says the offset center fin A_Symm thruster paddles quite a bit faster than a standard thruster. Note: Single fins, twins and other variants paddle faster than standard 3 fins but only in certain speed ranges or configs.
i validate George’s theory through personal experience, offsetting the center fin improves paddling I’d say around 50%. But you can really feel the difference.
George be interested in what you think aboout ehat Ryan’s doing with those crazy shapes. They look thin and flexing(carbon rails?) but super fast. Kind of reminds me of a merger of what Jim Richardson has going with his Surflight strategy and mixing it with what Jeff Alexander does. Takes me back to Morey’s essay in the 70’s of the benefit of soft boards that didn’t fight against the water as it flowed through it making it faster and more manuverable. Kind of like how your fin set up which was genius. Something only an engineer would see i,e, the effect of the bow wave to the following plan shapes it encounters at convergence. I guess like in some of the new ship/sub designs you want the convergence and turbulence to happen well behind the vessel to not only improve its hydrodynamics but all present a false signature for tracking by folks who are looking for it. Turbulence creates the sonar/radar signature afrom the heat/sound generated for tracking and destroying.
Funny how Jeff, Jim and you don’t really get the creds you guys deserve. But that part of being an innovator versus a marketeer I guess
Aloha - Bernie
“Likewise, looking at a thruster fin set up, each fin produces a shock wave(s) *multiple shockwaves, in a low speed, mid speed, and high speed range, like octaves in music. Turned out the two front fins created shock waves which angled back to a convergence point… …at the MIDDLE FIN. I validated this the hard way with the early Asymmetrics, which didn’t feel much better than a thruster, yet we knew they should work better. By offsetting the middle fin, the convergence point was missed by the middle fin more of the time, and it didn’t get caught up in the draggy turbulence”
Absolutely nailing down why quads are inherently faster then tri’s.
Ryan Burch at G-Land: https://www.youtube.com/watch?v=SJpEHK6VjcA#t=52
Agreed. But where does the shock wave propagate from? Tips? Base? Variable? I’ve only seen pics if them in plan view. And then, only with flow running parallel to the stringer.
George, can you talk about this and how going rail to rail frees two of the three fins at a time in sequence.
watch Ryan’s board in detail, just the board and tune out all the rest…
too me it’s vibrating a heck allot in clear flat water unlike what you would see in a heavier board or some built with a more standard design…
I can only guess that thy are thinner in relation to their length, and at speed they skip over the water instead of plowing through it like you would normally see with your standard gouging style of surfing. There’s got to be some form of flex and bottom action going there especially since the boards seem long and thin in comparison to what the other pros are riding. Plus when you look at his snapped board it looks really thin and flimsy. I’m guessing he’s pushing boundries but I’d like to hear George’s take on it all.
Also looks like completely the opposite direction of what Curren and Tomo were/are doing with their ultra short fishes and MPH’s but with the same indo results.
for awhile now I have been in the camp that the ultimate board would be one only as big as your stance so you don’t have to move your feet, kind of like snowboarding or towing in.So that your surfing becomes something more of reaction to what’s happening around you at each moment versus planning moves and body positions ahead of time. Something GT and us Griffin afficiando’s term as mind surfing your board, you think it, and it happens, no effort it just happens. Those experiences are a rare find but I see it in Ryans indo footage.
And yes quads are fast but Ryan’s riding thruster setups in his assymetricals and not quads with “llollipop fins?”
Hello All.
Good to back.
I timed this well. Sways is looking healthy.
Cheers to George.
Hi George, thanks for another blast of great detailed information. I think the machine haters will have to take a step back now. The intricacies of the “out there” boards you’re building require a higher level of accuracy. I’m going to keep my eye on your work and see how far you take things. Have you tried using an assymetrical setting for the fins on a symmetrical shape? I bet that would change things up quite a bit.
Sharkcounty that is what I was getting at with George. Anxious to hear what he says.
We could do the experiment ourselves.
I could just take Bernie’s Assym and take the measurements. I wonder how much difference using the fin placement from a 6-8 on a 6-0 or 6-2 makes. Then again, I could probably just move the rear to the side a bit and then slide the fronts up and down a bit in the proboxes to offset them. Heck I could take the double fin layout from Thrailkill and add probox sidebites. That would allow me to move the center to one side or the other and the sides up and down a bit. I guess it’s time to cut some foam, or add some boxes.
George in your fin setup numbers, is the + number for tow, inches from the stringer at the nose?
First, it’s so awesome to read your responses, George. Thanks so much for doing this. You are definitely someone who is a teacher, generous with your knowledge, and confident enough to share your wisdom/experience. I appreciate it.
Why use a middle fin in your asymms? Why not lose the dragging anchor all together?
Totally agree, this has been a great read, so much food for thought.
When you template , size and place these 3 fins at their optimum they assist the board in everything including planing with no feeling of drag, just pure Where Do You Want To Go Energy .
This is not possible with off the shelf fins and few have worked with custom made fins to seek this like some did in the very early 70’s with single fins and boxes for placement changes .
Its a lost art :-(
Yeah George thanks I copy on the double inside single radial concave for shorter quads, but how soft/subtle are the invees on that gun, I could barley make out any crisp shadow lines across the bottom. And whats the concept and how does it play off of adjacent rail foil?
…Also earlier you spoke of board asymmetry and rider toe/heel bio-mechanics, are there any rider bio-metrics, aside from obvious rider wt./ board volume that you incorporate in custom design.
I’ve worked with and spokento a lot of guys in the industry, but you really distill and deliver potency.
Hi Bernie! I think the 40+ boards Ryan did were a snapshot in time. He had a budget and was consigned to build anything he could think of, then test the boards in surf venues throughout the world. “Snapshot” meaning, he built those boards for himself in the space of ONE month, by himself. That is one way to hammer out designs. I had a design course long ago and I recall the professor saying, “Fill the room full of typewriters and put monkeys at each one, eventually one will type out some Shakespeare…” (I am NOT saying in any way that Ryan is a simeon, focus on the approach.) If I presented a blank check to you, saying “Come up with boards of your own design” it would be a reflection of what you were into at that moment in your journey. If I presented the same offer 3 years prior (or ahead,) we know you would have different boards laid out, thus the “Snapshot.” BTW, that is one HECK of a surfboard building feat- staying creative, building in unconventional ways, hats off to him!
Regarding what I think about what Ryan is doing, you are seeing a lot of background pulled from a lot of different places, with a VERY short development phase. I think it would have been really cool if he had a shaping/building area right at the venue (G-land, Chile, wherever…) and build 4 boards. Then use them. Then build 4 more (unfettered with outside concerns, like people/money/time/etc.) and so on until at the end of 5 or 6 “cycles” the designs become mutate closer to perfection. Even BETTER would be to share the info, rather than keep us guessing (NOT just dimensions, not enough, sorry,) and STILL EVEN BETTER YET share the experience of many Surfer/Shaper/Builders in a collective forum… …oh wait, that’s Swaylock’s, or potentially anyways… …as you’ve said, there are those who do not seek credit, so logically there are others who do. Stan Pleskunas and George Greenough said it best when I asked them if I could build a “Half Pipe” Sailboard like they were ripping on one afternoon in the mid-1980’s, “Sure!” he quipped, “That’s what it’s for” said Stanley. That stuck with me for decades now. They didn’t give a shit, they were onto the next thing already…
@Icc
“Absolutely nailing down why quads are inherently faster then tri’s.” You know what? my guess is the quad rear fins are in the shadows of the front fins, racers call it “drafting” but I cannot say for sure, there is only theory no direct supporting data. I did one time address the “shadow” thing when I was working on the Titan IVB Project where the nose cone created a shock wave (called “the Bell”) inside of which the entire 200 ft long vehicle “rode” inside. With the Quad set-up, there is a good chance this shadowing is happening (at times,) and the benefit is less drag. I should say that the effort to create the initial shockwave at the front fins increases a bit but not as much as the fins individually. *“Shock Wave” is a pretty harsh term but is accurate, there’s NO sonic boom here, basically the water is being struck, and like ripples in a pond (shockwaves,) those ripples travel/propagate out from the source, and into other objects (fins.)
Thanks for posting that video! VERY revealing, note how much accelerating he’s getting, clearly an octave (or two) faster than conventional boards.
“There’s got to be some form of flex and bottom action going there especially since the boards seem long and thin in comparison to what the other pros are riding. Plus when you look at his snapped board it looks really thin and flimsy. I’m guessing he’s pushing boundries but I’d like to hear George’s take on it all.”
I said before, “EVERYTHING’S a spring” even the water. The board is for sure bending and more importantly, rebounding in near perfect sync in most of those edited shots (they are NOT going to show you a “low lights reel” of all the shitty boards that didn’t work, which is actually a shame, “Dead Ends are learning” one of Larry Gephardt’s sayings.) Ryan’s boards are light, they are chattering on the surface. Not sure that they are undulating too much, maybe they are (check out Dragon Boat racing in Thailand on YouTube some time, watch the Bow Man, ha ha.) I haven’t met much success with perimeter stiffening, like parabolic stringers, or carbon rails. The boards, especially those without center stringers exhibit “frame roll” which is the twisting of the rigid rails inward when the feet press down hard on them. That’s a good example of Lateral Bending, visualize the board as an aerobic trampoline, the frame being the rigid rails of the board. If you have a concave bottom contour under your front foot, and you spike a turn real hard, the board bends slightly rail-to-rail, turning that concave into a flat area or even belly, which can either be bad or good. For me it was never too good. I think I see some frame roll a couple times in that video. Water is also acting like a spring, MOVING water is “harder” and rebounds quicker. Almost like there’s a “ball of water” under Ryan and he springboards off of it. Further the fins act like “fences” and contain some of the spill to keep that ball of water momentarily under him a little longer to exploit. Again, just some thoughts, not sure if they make any sense… …flexy fins would aid or hinder in this effort. Also, the length of the fin base can be relevant. Ryan is using a type of lollipop fin on most of his boards. Some are like standard thruster fins but with a large tip. Greenough did a lot of work with those.
Hi Yorky! Good timing! Nice to have a positive environment to come back to. That’s the way I remember how Swaylock’s was like, there’s plenty of other forums where those types can hide behind their keyboard and try to compensate for their own shortcomings. They can have it! ha!
Hate a machine? interesting. Door planers are machines. I’d shape a board using a seashell if that’s all I had. Anyways, a good reason to use a maching is repeatability. Using CNC has allowed me to change ONE little thing in a shape, like “50 thousandths more tuck behind the wide point” with everything else equal to the previous shape. Literally isolating shaping elements. Plus the programs are getting better. Overall, it has changed how we’ve learned how boards work. In the last 8-9 years, I’ve found out what little increments of change can do to how a board feels. BUT the software allows us to create “fresh slate” designs as well, as mutations are the big jumps, the big gains, in board design. I should mention that I’ve “hand shaped” well over 6,000 surfboards (using an electric planer) and I don’t miss the sweat labor, yet still there is an appeal to hand shaping (with an electric planer,) and I still will do a shape now and then. If I had 50 iFoam SUPS to shape in a rush, I’d think otherwise, but I don’t do large numbers of anything, not even with the machine. We own our machine free and clear.
Changing the fins on a symmetric shape makes a HUGE difference. If you haven’t tried it, I strongly suggest you do. Where to start? Hmmm, depends upon how/where/what you surf. No be-all answer there. More vertical fins are more pivoty, and fins with rake provide more spring, so match that to how you want to surf going from Heel-side to Toe-side. (I’m talking TURNS, and NOT just “going left” or “only rights,” though that works too.) Again, “Nothing ventured, nothing gained…”
Yes, the “+” in my fin nomenclature refers to the “Toe” (reflected as distance out from the nose, so +2 is a long straigh stick, starting at the fin dot for the rear edge of the fin and pointing forward out toward the nose, but NOT right to the tip, but 2" away from the tip.) So, 11-1/4 x 1-1/8 + 3, is 11.25" up from the tail block, 1.125" IN from the rail, pointed 3" off the nose, this positions the REAR of ANY fin, I call it the Fin Dot.
Thanks, glad you appreciate it, at the least it’s entertaining, but there might be a spark in that ^^^ 4,000 word pontification which may inspire someone, someday to build a bitchin’ board! Thanks for chiming in!
“Why use a middle fin in your asymms?” Funny, I’ve been into my twin keeled fish lately, I think I’ve come across an ideal rocker or something, it seems that it can do no wrong. That said, the original push was that the most “vert” set up has been thruster, meaning vertical surfing vs horizontal, off-the-lips, up the face, combos like that. Quads and twins can be made to do the same, but the three fin goes right into the moves. (long explanation as to why, counter-intuitive, as it involves an actual “stalling” of the fins/board, or at least a slide of the rear end. Picture an old “Hook and Ladder” firetruck with the steering up front AND in the back (the Tiller.) That “rear steer” sets up a better trajectory to hit the lip vertically. The original push we wanted to make was to pursue vert surfing. NOT all the designs we’ve done are exclusive to this.
Hi Greg! Not sure which 3 fins, do you mean the 3 rear fins I’ve seen in your set-ups? Every bit of feedback I’ve heard of that set up has been positive, obviously you’ve tapped into something that works, and is VERY DIALED IN! Bigger guys really like the hold, you’ve distributed the fins to share that load, versus pegging it all onto one fin. Very smart because no particular fin will come close to its’ stall limit and produce drag. I need to think more about that as I don’t know much about it. Larry Gephardt tells me how he will “hand plane” his fish and put it up on rail. The fin actually promotes lift, and supports the board whilst on edge. Do you foil your own fins? I ask because at that level, the fins have to be perfect. Up close, Geppy’s personal fins are works of art.
Right on! Good food! Stay tuned!
Best regards,
George
Sorry I wrote so much I didn’t see the question in time. The InVee is distinct and strong. It runs under a quarter inch deep at max for the doubles, the single up front is around 1/8+
By the way, I’m stoked as I got the message today the board was shake down tested in smaller (15ft Ocean Beach, SF) today. They were impressed by how well it rolled over on rail (what the guys look for) because heavy boards like that usually are resistant to going into a turn. It’s working, so Mav’s tomorrow, hoping for more positive feedback.
Best regards,
George
Here’s a ghetto screen shot of the contours and another shot of the rail slice of InVee:
George,
Precision is the beauty of CNC. For example, the same rail profile shape can be accurately reproduced and/or proportionally re-sized repeatedly. As you say, this allows one to credibly vary one aspect of a design at a time.
Rail profile shape seems to be relegated to some mystical realm.
Regarding rails, do you use science/math/engineering to design your (specific) rail profile shapes? If so, which principles?
Could you discuss and elaborate about the performance effects of various rail profile shapes?
Good stuff in this thread, some nice pearls. Thanks for your consideration**…**
I was speaking of Thrusters , the same can be achieved with 4 fins , my 5 fin , twin fins ,and my tri fin and all came from finding this during single fins .
It has been neccessary to make and foil my own fins to create this effect , hopefully I will be able have them made some day .
Only problem is I have too many sizes to cover the range of boards I make ;-(
I will make you a set to try if you like in any of these types , could be fun ! :-)
Greg
George,
Thank you for sharing so much. I’m editing and re-phrasing my question.
I’d like to know where you stand on stringerless construction. Have you explored it very much? Do you see any potential advantages it could have over conventional (stringered) construction? Would you have any particular suggestions for someone building a stringerless shortboard? Let’s say, for the sake of a generic baseline example, a standard 6’0" x 2.25" thick shortboard.
What does it take to make such a shape structurally viable or comparable in feel to a stringered board of the same shape?
Thank you again for all that you have already shared.
Kind regards,
Andrew
Hello George,
I was reading through your posts and the the discussion on fins and thought it would be too out-there to ask about your ideas on fnless boards, then saw your response to riding a Mentawi wave and that you’ve ridden mats. I ride paipo boards/bellyboards - both finless and finned but am wanting to get another finless board. I have three ideas - a 1" thick or so version of an alaia (for speed with control coming from the rails) with a virtually flat bottom, a board with a single deep concave or thirdly a board which utilises bottom ridges and contours. What direction would you go? The other consideration is that I love the capacity to really duckdive/glide underwater that a Paipo Nui/alaia/Galera NoFin offers so don’t want something that has too much volume. My experience is that finless boards handle steep/hollow conditions well but can have problems in fuller sections/around whitewater.
Thanks for for your time.
Bob