SHAPER's HOT SEAT: George Gall

So this thread is about Q&A, right?  

I know GG has done a lot of R&D in various forms of technical construction techniques, so I guess my first question it this:

"If cost / time / effort were not a consideration, what form of construction and glassing layup would you favor for a personal board, and why?"

George,

Could you tell us what you think about flex in surfboards.  How does it affect performance?  How  would full length-board flex (lateral) affect performance? How would performance be affected with tail flex only? Lateral vs. torsional tail flex, or both?  How would you incorporate flex into a build?

You made this comment about flex awhile back.  Could you elaborate/explain in a little more detail?

PlusOneShaper wrote:

...HINT:  it's not the downstroke but the return stroke that matters.

Best regards,

George

I recognize these these are broad and sweeping questions.

Thanks for your consideration.

_____

I'd like to know what is happening with the assym boards george was working on a few years ago. If I were buy a new board, I think I'd look at one of those between 5'8" and 6'4".

we are assuming george still posts here ...

I'm glad he is on facebook , as his boards and work shine THERE

@GregTate-

My last surf session was on a 5'8"x20-3/8"x2-7/16" twin keeled fish.  Been messing with them lately.

@gdaddy-

Just the brief version:  already doing boards with off-axis lay-ups and super flexy foam with awesome results in performance shortboards.  All hand built.  Ok, that's already been done, and I've taken it to more versions and have not plateaued yet (the limiting factor is time.)

IF I could dream, I would explore two strands of surfboard research and bring them together.  First would be more detailed FEA using programs similar to what the America's Cup designers have been using.  I would push the Finite Element Analysis further, not just modelling the structure/mass of the board but ALSO the wave.  Unlike flat water's "bobbing water" and wind gusts sailing vessels deal with, waves are VERY challenging to model on the computer.  This is because the face of the wave is curved, dynamic AND accelerating.  As a visual tool look at some ping pong balls floating in a perfect grid on the water, 1 foot apart.  As the wave approaches, peaks up and crests, the spacing of the ping pong balls accelerate away from one-another. This has not been explicitly tapped into by current board designs, at least not intentionally.  A board could be "adjusted" for a particular "angle" or attitude for optimal function at that moment...

The second thing would be to incorporate SMA's into an ultra-lightweight aerostructure.  Shape Memory Alloys could be somehow embedded into a good baseline board shape.  The board would probably be hollow, even valved, and the SMA's would be controlled by a miniaturized on-board programmable processor.  By varying voltage through the wireframe of the board, the shape and flex of the board could be changed.  The wireframe would dual purpose as tensile members and shape changing.  A basic example would be SMA bands embedded laterally, likely in pairs, so bottom contour could go from convex belly to concave(s) in milliseconds.  Also imagine a board "puffed up" for easier paddle then shrunk down for tight surfing once you're going...

What I just said ^^^ would be in the millions of $$$, but you said no limit...   (I can provide some basic layups for the more realistic answer I gave, ha)

@Barry

Hi!  Been wanting to meet with you just to talk shop, time is my problem, I really dig your hands-on real deal approach, bravo!  "What makes a surfboard go?"  OH MAN... (smart aleck response: Waves, Gravity, Muscle.) LOL    Actually, the typical board is static, it needs those external elements to go.  To make a board go WELL, now that's a life-long journey, even with the collective brain trust here on Swaylock's.  For some, it doesn't matter, "I just wanna get a couple waves before sunset..."  vs where things might matter a little more, "What if we changed the foam and glassed a load strip in it?"  Other than that, I too am shaking my head...   ...let me just summarize with "Anything in the board's character to work with waves, gravity and muscle in a way in which the rider likes."

@stoneburner

Great question.  I think a LOT about Flex in Surfboards...  ...I've had arguments with reputable shapers, saying "boards don't flex" but my training tells me otherwise, in fact EVERYTHING is a spring, even a rock, even water, especially MOVING water (or You, moving across water (a relative intertial frame shift for discussion's sake.))  First, and I don't mean to be a smart ass, but nomenclature is Longitudinal for lengthwise flex, also called Straight Bending.  Bending from rail-to-rail is Lateral, or I've heard some call it "curling" on surfboards is less understood (until the introduction of "parabolic," or "perimetric" stringers.)  The twist, as mentioned is Torsion.  All 3 bending modes are important, and I have tested and validated what I thought was desireable (THANK GOD FOR 1" WIDE CARBON GRAPHITE TAPE.)  I've placed tape in various directions on boards, to completely/partially lock out discrete bending modes.  eg. glass on 1" carbon tape at 45 deg X's on a board to lock out Torsion.  (90 for Lateral, etc.)  This is where I got in a LOT of HOT water with some kneeboard builders, firmly convinced the twist is what made their boards go, but in general I've found Torsion to be the enemy.  Surfboards (thin ones especially,) will bog down with they twist too much.  Surfboards are glass in such a way to leave them wide open for too much torsion, the cloth comes off the rolls at 0/90 since the beginning.  The 0 deg, or "warp direction" is good for Longitudinal control (of bending.)  (90 or "fill direction" is good for Lateral control.)  Most boards do not have cloth at 45 degrees, thus are wide open to twist and non-immediate rebound.  You will benefit with "off axis" glassing, that's been done for decades, I've met success with it, but be careful, if you do -20 deg with one pull, it is suggested to do a compliment of some sort (I don't mean, "hey bro, good job,") to counter the single offset behavior.  That said, I've done a lot of building on Asymmetrics with asymetric layups to promote certain behaviors and to block out others.

I've kind of hinted at the downstroke/return stroke thing.  Basically, you can break down the action of a board flexing into two operations.  First, your body English is transferred into the board (board bends.)  Then you unweight, and the board comes back to original shape, OS.  The first transfer has a surfer in control, loading up a turn, then kind of "leaping" off the board.  At this point the surfer is VULNERABLE, being unweighted, and REALLY depending upon the board to come along with them to the next position/mode of the ride.  If the spot you are leaping toward MATCHES what the board does- stoked! But if the board leaps not enough or too soon, then you'll find the mismatch to throw the timing off the remainder of a ride.  (Believe me, we've seen this here, a couple of the board builders in our area are really into flex and you can spot a killer set-up versus a not-so-killer-set-up!)  Thus, the rebound energy, how it returns to OS, is VERY important.

@sharkcountry

Hi Harry!  Did you see the black a_symm last time you were here?  That was my personal board, it gets borrowed SO much that I haven't ridden it in over a year even though I nudge and ask about how my board is doing.  I've been getting the shapes a little less asymmetric looking and focusing on asymmetric rocker and asymmetric glassing (see above.)  Also been wanting to mix the foam up like I talked about, haven't had the time, but I'd like to do a mix of EPS (rigid,) PU (semi) and PPE (bendy) in various parts of the board to enhance behavior (both in surfing and paddling.)  Still messing with fins, but I think I somehow nailed the fin position out the starting gate as I've come full circle on it...

Good stuff, keep it coming!

Best regards,

George

.... great to see you here , [by]  George !

  your wisdom and experience has been missed !

  cheers

  ben

@fins

Hiya Chip!  Hope you're good mate.  Hoping for a more conducive environment to share ideas, there's plenty of other forums for the other stuff.

Really liking your dedication to fins, seeing a lot of success with the "lollipop" style designs per Greenough/Ekstrom/Burch et al.

@GregTate

Most of the classic fish were flat or belly-to-flat.  Soon after they were single con throughout but spun out at speed.  Vee throughout the board is loose but robs all kinds of speed (with rare exceptions.)  Then there's the latest that Frye and Gephardt have been doing which is like a belly with a double concave inside of it.  Right now I am doing something along the lines of what Jeff Alexander has been doing for decades and it works well.  He does a rotating/spiral INVERTED vee.  Spiral can be seen as changing depth with repsect to width of the section in question.  As one progresses down the board the Invee will get deeper (or shallower,) then flares off the tail behind the keels.  Main noticible effect is the board gets a lot looser whilst still going super fast.  So, logic says since it's so loose now, why not drop the rocker a bit more?  Which in turn makes the board go faster.  Right now the boards are an octave if not two, faster pretty much to the board that the keels need rethinking.

Once that is done I should have a good package going...   ...oh, and then there's the flex...  ...and weight distribution
 

Best,

George

Hi George..Great to see you sharing your knowledge here.

I know I've bothered you with PM's in the past in regards to asymmetric outlines and fin set ups (thanks again  for being generous with your time and answers then), and am interested that you mention you are moving toward less asymmetric "looking" boards (I assume you mean asymmetric outline and fin set ups by this) and towards asymmetric rocker (I assume this affects lateral bottom contours as well). Given that I've never felt completely comfortable with "conventional asymmetrical thought" due to the inherent associated foot positioning issues, forehand versus backhand, with the different rail lines and fin set ups, etc, the asymmetric rocker path appeals to me greatly.

So after that long winded pretext my question is this:

Given your experience with asymmetric design and the feedback you've received over the years, which performance characteristics in your asymmetrical boards have been your objective? In other words, which traits of a normal symmetrical board on its forehand and backhand have you been working to eliminate or enhance?

Many thanks.

Rohan

Hey George -

Great to see you here.  Dale Solomonson always has great things to say about you.  He was on about some of that "filler" cloth, I think it was nylon, a while back, he said you were having some success.  I never did get around to trying it.  What I did pick up as a wise, simple, thing to do: I started doing a 45/45 orientation deck patch.  Given my already heavy glass schedule, I can't claim to have seen big changes, but it sure didn't hurt anything.  Thanks for the reports back in the day.

My question is: What do you think about quads, and if you are doing them, what are your thoughts about rear fin position, i.e., "McKee" esq. v. edge and closer to the front fins, ala Robin Mair?

Thanks for taking the time to share George -

George;  I like to combine a down rail flowing bottom contour (the break line from soft to hard is what I find chalenging for customs) with a spiral vee on a fish with a more speeddialer fin set-up on anything under 6' for riders 180 lbs or less, but thats just me....

Anyway, here's my question!  What's your favorite right hand break (on the planet that you have surfed) and what would you shape for that break for a 60 + year old George who is still in good (and repaired) shape?

@RDM-

Hi Rohan!  Ha, NEVER a bother Rohan, yes I recall those exchanges, I hope it got things going the right direction (re. fins, ha)

Very good question "...which traits of a normal symmetrical board on its forehand and backhand have you been working to eliminate or enhance?"

I want to address the surfer, before the board.  "Biomechanics" of the rider.  I designed suspension systems in 3 rockets (up to 40 ton payloads going 6,000 mph through the jet stream (150 mph side wind,)) and our main "skill" that we learned was to visualize the "load path."  Looking at a surfer, WAIT! Better yet give this a try: standing on a floor with feet in surf stance, lift your heels off the floor a little bit- now hop.  Note the muscles you used, visualize the joints moving and how much they moved, "What stays tense?"  NOW, standing, same stance, raise your toes off the floor, the weight on your heels- and hop.  Totally different feel isn't it?  

Dang it, if we surfed parallel like a skier then we could really exploit a symmetric surfboard, but we put one foot ahead of the other and created a SURF STANCE.  It is the mechanics of the rider in a stance which may dictate the need for asymmetry in various aspects of the board.  To anwer the question in part, I'm trying to enhance the use of the board for both heel side and toe side turns.  (Toe Side Turn would be front side bottom turn, hopping with heels off the floor.  Heel Side the opposite.)  Herein lies the rub, as humans, we adapt, we get accustomed to, and we tend to exploit, what we have.  With a symmetric board we have adapted our two stances to one board, nothing wrong with it, just know that you adjust to make it happen.  For example, when riding a shortboard, andyou are driving down the line frontside and want to go into a cutback, you will take a half step back onto the tail and set the heel side rail.  This shift costs speed, you're "checking" yourself (bringing up your chest, or your forward bearing weight, or drive, to make the shift in order to ride the other rail into a turn.)  Just yesterday I had a 40-something y.o. surfer, very good, who thought he had plateaued in his surfing, comment how the A_Symm board constantly maintained speed, and held speed through manuevers like figure-8 cutbacks and backside off-the-lips, he laughed at the board the day before, dismissed it.

A board can be built to exploit these two stances- enter Asymmetry.  Aussies, Carl Ekstrom and several others understood the need to accommodate the fact that we have a stance decades ago, like a half-century ago.  First, asymmetry was expressed in the obvious aspect: the Outline.  Delving further and further into it, the realization came that other aspects like bottom contour, rail(s,) rocker, and fins must also be addressed.  Right now I am into making the outline a little more subtle rather than trying to make a visual statement.  I would say rocker is more important but must be adjusted in conjuction with other aspects, as mentioned.  Also, I see bottom contours being varied from one side against the other, in fact the supposed "centerline" of the contours gets shifted as well.

Overall, I think it takes quite a bit of understanding of how a board works, and each of the constituent parts, can add or subtract to an end-use behavior.  That said, if you have a favorite board that backsides really well, and a frontside board that does the compliment, then "weld" the two together, (the challenge then being which side is "how far forward" relative to the other side, to eliminate checking and stance shifts.)

@TaylorO-

Dale!  Tell him I love the 'Nuematic he custom-built for me 10-15 years ago, it's saved my sanity on many occaision!

Yes, biasing cloth is a great trick, amazing what some salient placement of common materials will do.  That filler cloth (also called a "bulk modifier") was nylon-based at first. A company called Innegrity came up with the biaxial version so you could use it in conjunction with performance fabrics, instead of 30 layers of expensive pure carbon graphite on a project for example. Typically, the "in-between" layers on multi-layer jobs do not get put to work like the inner/outer layers.  Enter "foam sandwich" construction- then I took it a step further and used thick weave burlap (with a very fluffy microsphere matrix,) as the in-between layer.  This might be what Dale is referring to, I later called it "Liquid Foam Sandwiching," because it was pretty easy to go around 3-dimensional curves, unlike veneers and foam sheeting.

Quads-  Built a LOT of them.  Story time.  My business partner and I were approached by a Peruvian pro-surfer/shop owner who wanted some of our boards.  Well, not boards, SHAPES.  He wanted to SHIP shaped blanks to Peru then get them glassed there for a fraction of the cost.  They were our normal thruster performance shortboards. We built crates around 40+ shapes and this pro guy's Dad's shipping company got them to Peru UNSCATHED. Two months later I go to Peru, took what I thought was a good quad, 5'10" x 19-3/4" x 2-3/8" Round Tail, fins were: front 11 x 1-1/4 + 3  rear 5-1/2 x 1-1/4 + 1 (my nomenclature is "from tail x from rail + pointed off nose.")  Chicama can get PERFECT, it's not a death wave but VERY machine-like when it's good.  I was lucky and got it for two weeks, and the guys I was with had the place to change our my Future boxes, literally machining right on top of the old ones, allowing for changes in position.  I focused on the quad rear boxes.  I found that during long bottom turns, the shore-side fins would both pop out at the same time.  For what I was doing, those drawn bottom turns, it meant I was checking myself (my chest would come up, disturbing the forward drive I had.)  At times it felt like the fins were letting go too harshly, like an almost spin out.  So I moved the rear quads inboard and found that about 2" in from the rail (for THAT particular round tail) allowed the fins to release SEQUENTIALLY, and I could bear down all the way through the turn with a nice transition.  I also felt the board needed a little more yaw resistance so I shifted the quad rears AFT more, too much, then came back a bit.  

The ideal position on that board was 11 x 1-1/4 + 3, 5-1/4 x 2 + 2.  If I had a "formula" it would be to "take the front fin position, 11 in this case, divide by 2, then subtract another 1/4"."  The distance in from the rail have been roughly like the thruster up front then double it and take away 1/2 to 3/4"  As for pointing at the nose, I mimic the thruster in the front for common quads, and do a little less for the quad rears.

Here's a dedicated quad I did recently for a board you'll be seeing at large Maverick's and Peahi:

17 x 1-1/8 + 3, 8-1/4 x 1-7/8 + 2 (see bottom of post)

@surfteach-

Hi Brian! 

How you been?!  I think we should have qualified that question a little bit, because on that wave, I did absolutely nothing, just sat there.  A right hander called Rifles in the Mentawai chain.  A special day, about 8 ft faces, and it was fuckin' perfect, all day long. Then all the guys went in, the wave came right to me, looked like I would never make it but was committed. Dropped in, set trim and it was like being behind a sheet glass water fall for the entire ride.  I was on a 6'3" x 18-7/8" x 2-3/8" round tail thruster.  MAN that one particular wave was perfect, "I was intoxicated with the exuberance of my own velocity." I think if I could build a decent one, I'd try a FINLESS, minimal board, maybe a modernized alaia, out of carbon or a metallic?  about 16" wide, very sinky, so I felt more "involved" with the wave, rather than 'a jockey on a big horse'- "Me and the board, as one..." ha, I'd want the board to drop away into the wave and with my sage experience, land in perfect stance.  But really, it seems that's where we are headed, to the aesthetic of the entire ride, rather than the flash glamour of another backflip gymnast platform move.  (I've pulled a few air reverses/allie oops in my day (banging my cane on the porch,) so I can talk those moves down a bit...ha)  BUT you said 60+,  maybe instead, have a protective suit, like a motorcross/Imperial Storm Trooper type deal with O2 supply, ha, and just body surf the perfect tube.  Maybe shape the body plates out of foam so the suit would plane, thinking Squirrel Suits/Wing Suits but for surfing...

Thanks guys.

Best regards,

George

Thanks for all the good information.

How are the assyms selling? Are they popular, still kinda one offs? I don't see them on your website, so I'd guess they are mostly customs. I think the assym is much overlooked but will prove to be the right path to follow. The idea of having a looser shorter side and a stiffer side makes a lot of sense.

This comment you have...

"Right now I am doing something along the lines of what Jeff Alexander has been doing for decades and it works well.  He does a rotating/spiral INVERTED vee.  Spiral can be seen as changing depth with repsect to width of the section in question.  As one progresses down the board the Invee will get deeper (or shallower,) then flares off the tail behind the keels.  Main noticible effect is the board gets a lot looser whilst still going super fast.  So, logic says since it's so loose now, why not drop the rocker a bit more?  Which in turn makes the board go faster.  Right now the boards are an octave if not two, faster pretty much to the board that the keels need rethinking."

That got my attention. Looking forward to seeing where you take this.

Also, there's been a lot of talk about fins lately. Do you have favorites that you use with your boards?

Thanks, and I hope to see you in the future, and maybe get myself the latest version of your assym.

We've been building the same boards for decades, with a tweak here, a tweak there,

the result a current design paradigm so nailed down pro boards are essentailly mirror reflections with differentiating stickers,

After rereading George's highly succinct and wholly logical design treaties several times,

a path out of the current design/build cul-de-sac is evident.

Awesome stuff, George,looking forward to your thoughts on fin design.

Dang George...  My mind is still expanding like the universe...  

I'll pass on your love to Dale the next time I see him.  It was the Innegra that he talked about.  I love the idea of burlap and microspheres... A man after my own heart.

I eased off on my more extreem asym to mostly fin placement.  I love everything you said about asyms...  So true.

That gun looks great. 

As you moved your rear fins back and in, did you find you may have lost some top end speed?

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.

@sharkcountry

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?

@GregTate

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.

@TaylorO

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.

@peterg1

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

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.

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.

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.

@oneula

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.

@oneula

"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.

@yorky

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!

@sharkcountry

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.

@ghostshaper-

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.

@greggriffin-

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.

@pinnypinny-

Right on!  Good food!  Stay tuned!

Best regards,

George

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...

_____

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

Not only is George a mad surfboard scientist, he is a great surfer. About 25 years ago he busted an air over me on a twin fin, on a shalow reef!

First Mahalo nui for doing this.

As you are no doubt aware the “step ups” surfers are riding today are way shorter than this oldphart can fathom. Recently thought I would build one.

Made several mistakes. Bear with me here, just an out of touch old grey beard.

Ordered a US blanks 7-0 A w/ +½” tail rocker.

Laid out a nice 6-8,  my son comes by and it’s “oh Popz”

Came out 6-2 but I lost some nose rocker.

Board is a winner, my concern is mostly nose rocker, I am thinking of jumping down to the 6-5 A which has a stock nose rocker @ 5 1/16” Ya know I'll lose a little so I'm plotting but what is the norm?

Question is, on a 6-2 “step up”  what kind of nose rocker (and tail if you will) are the pro’s ( and or better riders) using?

Any advice will be greatly appreciated.

Aloha

@greggriffin-

That is very impressive Greg, I love the attention to detail.  It's probably one of the many reasons why people love your boards so much.  Is there a particular foil you are trying to create?  And, is the foil the same at the root of the fin as it is going out to the tip?  (Surfboards being not self-powered, are VERY sensitive to the littlest detail and I find anomalies in the fins are usually much more profound than anomalies in the shape, both being important to get that last 5% or so...)  I'd love to see a set of those fins, better yet I'd love to try a set!! ha. Thanks Greg!

@stoneburner-

Man recently I replaced/upgraded my Vee-wheels in the gantry of our shaping machine, and I got to say I cannot believe how perfect the rails have gotten.  The hard part about CNC is to make what you see on your Design Monitor to be exactly what the machine cuts.  Our accuracy is better than 30-thousands of an inch across 11 feet.  I was cutting some boards for Carl Ekstrom and just as we finished cutting one of his boards he pulls out this Contour Gauge of the rail.  As the cutter is spooling down, he puts his gauge up against the cut shape, and he says, "Yup," turns to me and starts laughing, "How 'bout that.." he said.  (He also put his Gauges (Rail Profiles) up against the computer screen to check and it was spot on.   It's been almost 10 years and none of this was easy, it took and is still taking a lot of effort to get those great cuts.  Once dialed-in though, it can cut all day, every day, EXACTLY as instructed.

"do you use science/math/engineering to design your (specific) rail profile shapes?"  I really just learned what "felt" "right" while surfing.  Rails definitely affect the "feel" of a board, The ways in which the rails work and along different parts of a board AND in different wave positions, make the rail the least understood.  It has been best to follow what others who have met success have done and try it, that way you would meet with some degree of success.  So rather than use analytical tools (with the exception of FEA, which would be GREAT for super complex stuff like this,) I try to take the other approach- "field testing."  In engineering, testing costs in a LOT of ways, money, time, support, meetings, etc. But NOT with surfboards.  Look at it this way, if Boeing designed the 747, no theoretical testing or component testing, just put it together and hired some "test pilots" from the local prison, it would take quite a few "cycles" before they got one off the ground.  In contrast, a surfboard is simple, easy to build, fun to test. Surfboards are "quick to prototype" and that's why I say go out there and try stuff.  To contradict what I said about paradigm in design, the rail is so complex that it is beneficial to do "empirical testing."  One of the best people on the planet at this is Tom Morey, who understands how rails work to the highest degree. Other shapers/designers who can make a rail work are Dick Brewer and Mike Diffenderfer.  Many others as well, but that should supply someone with enough info to start some good test boards.  Brewer says to make the critical part of the rail to look like a "ping pong ball" and Diff said, like a "ball bearing."  So for the classic rail as we know it, that is a good guide.  Morey's stuff is along another branch, he can make a rail hold, just look at guys stand up surfing Pipe on Body Boards without flippers. Speaking of hold, Skip Frye and Greg Liddle come to mind for that kind of rail.  And the down rail, which Hynson got inspiration for from T-Boy, who studied under Quigg.  Don't forget MacTavish, (I can see this list is going to get big, I'll stop.)

As you divert from the classic ping pong ball, you either pinch it, or fatten it.  Pinching it tends to make the rail penetrate the water, but also can provide hold along the sharpened radius.  Fattening, or leaving a "vertical side wall" to the rail will allow the board to travel through rough spots like whitewater.

Unfortunately, there is NO RIGHT ANSWER to the best rail, so all rails in some way are valid.  I use many different rails.  This is a weak answer, but is what comes to mind as the guiding force behind how I would find a killer rail for a series of boards as they develop.

@newschoolblue-

Hi Andrew, I am all for stringerless or composite stringers!  But I must qualify that statement, "I like stringerless boards with alternative glass jobs."  I am willing to give up one thing to gain another, because I think the gain is large and worthwhile.  Stringers are the centerline.  Gordon Clark put a lot of effort into finding the right combinations of wood(s) and foam to produce a quality product at the time, many others contributed to this effort.  The concept of a stringer should not be completely dismissed.  If you are building a board from that era, or building a board of conventional materials, the stringer is actually a very refined thing.

That said, although I use boards with stirngers all the time, I know the stringer does very little to prevent twist in a board, and does quite a bit to decrease straight bending. This is almost the opposite of what we should have in a high performance (or future performance) surfboard.   We want a lesser amount of twist and we want more straight bending.  And we want the straight bending to be very responsive (with good timing to rider inputs.)  I suppose we could build a "torque box" inside the board, but what a waste when the board itself is a torque box.  Plus being of monocoque construction, (exoskeleton,) a stringerless surfboard is freed up to allow more articulation, THEN we pare down the degrees of freedom by choosing various skins (I tend to like fabrics,) and orient them in potentially ideal directions.  In addition to this, we can use various foam cores (or NO core,) in different parts of a board.  We can have the same foam thoughout, with different shear/elastic properties.  Eventually someone is going to figure out which parts of a board needs to be springy and which part needs to be stiff.  (AND I MEAN FOR REAL, NOT FROM A MARKETING POV.)  So far no one has figured it out, the surfing will not appear as it does now.  I am surprised more builders are not hauling ass on this, it's not like we are all building Mars rockets, you can build the "golden bb" in just a few days and change humanity (er, "surfing humanity"...)       Pressure.  Most builders are under pressure so they cannot pursue this quest, either time, money, production obligations, market confidence, coolness, or style act as preventative forces.   It's wide open, and I think stringerless, flexy base materials are the start, then add the physical constraints and enhancements.

@bgreen-

Hi Bob, I think all 3 directions with the finless sound good.  Like I mentioned, I've seen guys at Pipe stand up surf a finless bodyboard (without flippers on,) totally locked in and going about as fast as any surf vehicle I've seen.  How?  I thought for a long time "Oh he's dragging a foot, or his butt" or something but it would slow the board down, so I don't know how or why yet.

So there's the hope.  Most bodyboards are flat or subtlely concaved, others might have channels but I've seen the simple ones produce.

There is one guy in my area I've worked with on finless boards and we got it to work well.  He can do a bottom turn standing tall (NOT in a squat) and the acceleration is amazing.  That said, the absolute traction/hold is not adequate enough to be compared to a finned surfboard.  There was a time when I thought fins did almost no "foil lifting," that their main real function was to act like a weather vane, keeping the board pointing the right way...  ...so the rail could do its' thing and produce decent hold and forward drive. 

Thus, one thing needs to be tested: a finless board that has some sort of "dragger" on it, probably on the aft corners.  Not sure what, but the goal should be "not a fin" just based upon principle.  That dragger would allow the rail to be applied to the rail face- (for a "grippy" rail look at Skip Frye's boards, I've ridden them without fins and they totally hold in light trim, until the back corner pops out.)  The shape of the rail probably should hold-in best around the back foot area, less so up front.

"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?"

I'd keep it simple Bob, and build a series of boards starting with the flat one first.  I would work very hard on the rail shape, especially at the "business end" of the board (tail, below waterline,) and make it hold in.  Probably study good bodyboards.  Look at Morey's latest finless boards.  I would keep the board fairly narrow.  The radius of curvature of that part of the rail will be crucial and speed-dependent, so I would watch what speeds the board holds in the best (eg. a finless that holds well in the low-speed dynamic will probably not hold well in the high speed regime.)  I would build my rails out of material that I could shape post-glass.  I've done that, packed a fish rail with microspheres, surfed it, then shaped it down, surfed it, went into the beach, got my sanding block out of my backpack and whittled- learned a LOT, in fact, more than I could have imagined, I didn't know the shape and volume of a rail would matter so much, I thought most of it stayed dry, ha.  Plumber's putty works well for this also. That's my advice.

@obproud-

I hope I didn't do that air-over-human maliciously, I was kind of a dick back then.  Way too aggro in the water. The only thing that bums me out about the old days was being a localizer dick.  After traveling and being at the other end of it, I got my mind right and enjoy doing airs over people a lot more now...     ...That said, it was a LOT less crowded where we live back then, ha.  Seriously though, I'd like to know more about that, I only did that maybe a few times, it was probably on a fish or quad fish.  Too funny you'd remember that.  Was the board black or blackish-blue?

@Icc-

3D Printing.  In one of the first posts I mentioned SMA's, my thought was to do the material network using multi-material 3D printers (they said unlimited budget..) and build a board from the inside, out.  But Shape Memory Alloys have not been put through a printer yet, and a lot of R&D must be put into how to induce pre-stress into the printed material even though it would be printed "unstressed".  My guess is to induce an electric current though the SMA as it is printed and hardens, then pull the voltage.  The printer will allow us to built board without wastage.  The board would probably not get any glass, maybe microwave it to get a slick skin on it?  ha.   Not sure what the power consumption would be for SMA's in a "Shape Shifting Surfboard" but either a battery or maybe the metallic network itself could also purpose as a battery/capacitor?

Anyways, backing off the super metal alloy trip.  Foams of various physical behaviors will be shot through printers very soon, trust me I know, I cannot disclose.  Stitching a board together from the inside, out, will allow for total control of all aspects.  It is NOT too far fetched.  We will not be the target market, we will get the trickle-down from aerospace.  We will get the subsequent breakthroughs from a someone working in a garage.

@mattwho-

"Came out 6-2 but I lost some nose rocker.

Board is a winner, my concern is mostly nose rocker, I am thinking of jumping down to the 6-5 A which has a stock nose rocker @ 5 1/16” Ya know I'll lose a little so I'm plotting but what is the norm?"

Hmmm, a little confused, if the board is a "winner" then the nose rocker is perfect.  Don't "fix"it.  Do you think maybe the board might be working so well to earn Winner status because of the lost nose rocker?  That was the main reason I squared the nose off certain types of boards, (and dropped the nose rocker,) it REALLY made a difference!

I need more information on this.  Get a straight edge (I bought an 8 foot one) and lay it along the board, bottom, up, to get a rocker measurement.  A common way to find rocker is to lay the straight edge along the bottom, touching the board at the center, 37" from each end in your case.  I "hold" the straight edge with tent clamps, teeter tottering on the EXACT center contact tangent point.  Get me the rocker numbers at the nose and tail and 1 foot in from each end, and maybe I can tell you that there's something wrong, but it's a winner now(?)

BTW, NEVER trust the rockers to be repeatable every time you shape.  I shaped by hand for 30 years and chased the lotus, then for the last nearly 10 years I've used the CNC machine.  The machine showed how much blanks VARY- I built rocker templates of my "magic" boards: build a rocker template!  better yet, build a rocker gauge so you can adjust it.  Next time you shape, do the same number of passes with your planer then finish up by using the rocker template to get you close to that same Winner Board.

Best regards,

George

Hello George,

 Is the Morey board you were thinking of,  "the one" - http://catchsurf.com/the-one-surfboard.html  Looks like there is a step in the bottom or some sort of break in the rail line.

Regarding your idea of a "dragger" - could this board be akin to what you were thinking:http://chris-garrett.myshopify.com/pages/finless-friction-free-surfboard 

Is it possible to say more about your style of finless board? If not, that is ok. Thanks again. 

Bob

how does the inverted v differ in performance from a standard rounded concave? similar dynamics with less drag?

have you tried varial foam for stringerless boards?

interesting theories on the bending direction that is best. i have found that getting 'straight' bending instead of 'torsional' bending can be amazing in critical sections on high performance waves with power but not so good for waves were you have to generate your own speed. i have come to really love the consistent performance of a very thin center stringer in an eps core across most small-medium sized wave conditions.

@mattwho-

Okay I got you now,

"Don’t have board here data from build sheet is as close as I can do for now.

4 5/16 @nose 1 ¾ @12” ½ @ 24” 1/32 @36”

2” @ tail  1 7/16 @ 12”  15/16” @ 24” 1/[email protected] 36”"

I heard Rusty say that 1/4" of tail rocker can do the job of 2" of nose rocker.  I visualize the board doing a bit of a "wheelie" when rocking back onto the tail, and MORE tail rocker will do that for you.  That said, I think your back half numbers look fine.  You can do with a little more nose rocker, but also lengthen the board slightly.  Are you using U.S. Blanks exclusively?  Try their 65R, it will have the right rocker for the board and allow for good thickness throughout.  Let us know if you do this and meet some success with it, because your effort may help someone else on here some day!

@bgreen-

Yes, that's Morey's creation!  I think you can smoothly transition the two types of rails, I've actually been involved with a couple variants of this.  I really think it will be a viable board in the near future, right now I think the finless is wrongly influenced by wider designs like Bauguess' Mini Simmons boards, probably better to go narrow and pretty parallel like the ancient alaia design.  This will increase the amount of pressure on the critical contours and produce more lateral resistance which would allow the rail to do its' thing.

Here is the "dragger" concept I meant (the link provided did not work, so I could not see what it was.(see at bottom of thread, forgive my ghetto sketch)  The one caveat I would have is the dragger I show could be very dangerous.  It needs to be "flexible" but not so flexy that it would "flutter" at speed.  This would be too much drag.  You want it to be a gentle flexing but yielding enough to get some lateral drag, but going forward the board would be slippery still.  In turns, I'd want the draggers to bend a lot, like the tail fin of a Thresher shark, it would hold in well but the "spring back" of the dragger would not be too forceful, that would be bad.

Notice the arrow I drew in the Rear View/Cross Section, I am pointing to the spot where you need to pay attention to the radius of the rail transition.  I'd keep sanding this until it held in the speed range I was interested in, then keep sanding until it got worse (bracketing) so I know where I was in the design.

"Somebody want to make this?"  or anyone already have?  Dare to fail!

[edit] Bob, I forgot!  here is a little video of a series of finless and semi-finless boards we did a couple years ago.  Notice he can do a bottom turn standing up straight, not in a crouch over the center of the board.  Note also the bursts of speed with the finless, one trip up to Malibu, he was able to surf all the way through to the inside on a day no one else came close to doing, I credit the lower friction of the finless board in part at least!  *Semi-finless means the bottom was not totally flat, but had runners or bumps of foam to do the work similar to to Tom Morey's rail but under the board a bit.  I ended up calling these lumps "lifting bodies" since they are not fins, but protruding rounded/lump ridge-like channels.  

https://www.youtube.com/watch?v=97wslAzfGLM

Best regards,

George

Hello George,

The dragger reminds me of the tail of Gus Acosta's WaveArrow. I also recently saw a board Doug Haut from Santa Cruz shaped himself. This board has a tail which is a dragger -swallow combination.

Thanks again.

Bob