Thanks BillAnother great post…
But you’re leaving us dangling…
do you go for a stiff sandwich core since your mentioning Dcell or with something soft?
Well initially I was just referring to single skined boards. So let stay there for a moment. Since the stresses on the skin/shell has to be shared by the backing material right under it, we need a backing material that can handle it.
As I mentioned you can have a crispy backing or a tenacious but flexy (rubbery) backing.
In the crispy zone, lets consider a foam. Then the ideal backing would be a harder foam more like Divinycell. The fiberglass skin glued with resin to the Divinycel would help hold this “semi sandwich” skin, in column better. If it hyperloaded on a particular spot it would resist the fiberglass from folding in because the crispy foam just wouldn’t dent in easily. And it would also not tear away easily allowing the fiberglass buckle up and slip out of column.
To be fair here this is the idea behind the density gradiant in a Clark Foam blank. Light, weaker, more expanded foam in the center of the blank. With it getting progressively more dense and strong near the blanks surface. From a simplicity standpoint, this is the ideal core and skin. And in the “old days” where the demands on the whole structure weren’t as geat, this proved to be a very good solution. as long as the blanks kept pace with the thickness of boards so that the shaper wasn’t shaping away all the crispier foam at the surface just to get the board thin enough.
Assuming we want blanks to be easy to shape, we may have hit the limits of this solution. Clark can make the blanks more crispy, but they won’t shape as fast or as clean. But a crispier surface that gently blends into a softer core would make a much stronger board using a single skin solution. This is why I have never really been a big fan of the ultralight blanks. I have always felt that a better board is made with a firmer foam and lighter skin. Especially back when boards were thicker as this allowed more flex options. As boards got thinner and surfers younger and smaller, there was a great need for thinner blanks. Not just for easier shaping but to retain the quality of the single skin construction. Eventually these boards became (arguably) too flexy. Or at least lacking in a prompt and snappy return to normal state. Hence the visible surge in alternative construction materials, schedules and techniques. Many of which required long set up times and materials not compatible with Polyester Resin.
And is that why Bert has found balsa to be the best compromise as a sandwich core versus something like corecell, dcell, honeycomb aluminum, carbon, bamboo, cedar, or guava?
I don’t know Bert and am not really familiar with his specific construction methods. But Balsa seems like a reasonable choice to use in a sandwich skin. It is light, has a certain resiliant give to it (rubbery) and though not crispy it is firm enough to resist crushing in, even in fairly thin sandwiches. I think it is a great compromise material. Kind of like a softer Divinycell with a slight rubbery and tough character. Polyethylene or Polyproplene are other rubbery foams, but still too soft on the crushability index. Add some Strofoam to it (Arcel) and you have something also very interesting. Balsa though, has a certain unidirectional grain and therefore strength characteristic that can’t be duplicated by omnidirectional foams.
On the other hand Jim Richardson at Surflight is wrapping his “tuned” blue foam XPS lever springs with milky white “polyproplene packing foam” with high spring memory before covering them with a skin of urethane in a completely different approach to building a sandwich board. Hard on the inside and soft on the outside.
This is a great concept, but very, very hard to get working. Having a tuned skeleton core that could blend the qualities of this internal spring out through the whole board would be great. But it is very hard to control all areas of the board that experience torsion, twist, rebound, memory etc. The area of the skeleton core can be easily controlled but the farther you get from it the more unusual issues pop up. So unless you create a controlable skeleton that encompases the whole board it may not be the answer. To make the spring core spread through the whole board may create weight problems.
That is why I tend to favor a skeleton under the skin that can be placed were needed to augment the shortcomings of the skin in certain areas but not become a whole sandwich shell or singular core spring.
So does the skin need to be indestructable to compensate for core failure or not?
Yes if you rely on the skin or shell to carry the loads. On the other hand if you create a skeleton that carries the loads and distributes the stresses out more evenly (or specifically if you desire) then you can have a board that won’t buckle unless the designed limits of the support skeleton are exceeded. Additionally, the skeleton can be designed to snap back agressively with good rebound and memory. And that flex can be specifically located. On the other hand the skeleton won’t do anything to help with foot dents etc. Broken boards indicate another problem. Energy from the wave or breaking force is being wasted because it is hyperloading and compiling at a single point. This is also happening when the surfer is riding the board, he just doesn’t notice it. But energy is being wasted because the flex is not being controlled especially if the loading by the surfer is getting near the limits of the shell. A skeleton can absorb and transfer these loads/energy and distribute them to other areas or give them back rather then wasting them in hyperloading.
And is this why Pope, Aviso, Halun, and Hydroepic are pursuing a different build solution than Surftech, Boardworks, XTR, and Pointblanks. I noticed that Greg has aligned himself with Halun, Wayne Rich with Pope, Jeff Johnson, Matt Bilos, and Jim Richardson are looking at Aviso and who knows what syndicate Bert’s aligned himself up with… EVryone else is just pushing their plugs…
It’s all about the skin and tissue then and not the blood…
Depending on how you set up the goals and what you think will be a really cool solution, you wind up with a bunch of different products.
Here is the big problem. If you focus on impact strength, as in less or no dings. You wind up with a really hard shell to resist impacts. When you make the outer perimeter of the shell strong enough to resist dings, it can also make a very stiff structure. Kind of like an egg. Hard shell, soft core, very little lengthwise flexibility. That is an exaggerated example, I admit, I just want the point to be clear.
So how do we get a hard shell that doesn’t ding, but produces a controlled flex with good memory and rebound. This isn’t impossible and Bert may be right on track as may be others. But the next problem is how do we produce this in a manner that will make it profitable to do so and not just a personal technical wonder but also an economic wonder that is accessible to millions of customers. Tech is good, but if the tree falls in the woods and no one knows it…so what. What good was it.
A lot of the contemporary solutions just came by luck as boards got thinner. This allowed harder shelled boards to exist without them feeling too rigid and dead. That is why Surftech became popular in longer boards where beam theory allows them to have better flex characteristics in spite of their hard shells. It is also why various sandwich skins are now working better on shorter boards, as they are thinner these days and generally thinner than longboards (tankers).
I guess I’m surprised as big and as important as the sways community is we don’t have at least a couple PHD CHEMICAL engineers who work for DOW, or NASA guys, or other rocket scientists who actually make their living doing this stuff under the microscope of getting it right so you don’t kill off a bunch of folks versus a random grouping of tradefolks and suppliers arguing about highly technical information. There’s folks out their that do this stuff for a living, that get paid big bucks to make all the appropriate decisions regarding this stuff nationally and globally so why aren’t they here speaking up to set us it all straight…
Oh shoots I forgot again…
this is just a forum on surfer dudes talking about their surfboards…
Gotta quit snorting the acetone…
Don’t be so hard on outsiders, they have no obligation to us or surfing. Surfers need to recognize that, “the enemy is us”! Look how long it took machines to shape foam. Even though the rest of the worlds industries were shaping all types of metals for years with automated machines.
We couldn’t even figure out how to standardize the measuring of boards let alone design a machine or software to shape them. Sailboards at one time, had long flat tail sections in their rockers. And shapers of the day were putting a straight edge on it and then measuring the nose rocker. How inconsistent would that be?
A World Champion that was one of my team riders, got some boards from another shaper. The team rider asked me about why I measured rocker using the center of the board as the referrence point. I asked him why he was asking. He said the “other” shaper measured the nose and tail rockers by measuring the distance from the floor to the tips of the boards!?! How inconsistent would that be?
And you wonder why professional industries aren’t flocking in to help us out? They think surfers are a bunch of idiots…and for the most part I can’t blame them. And I mean no offense…I am a surfer too.
Long before shaping machines were created, I was visited by Discovery Magazine in the early days of their Discovery TV channel. They wanted to see how I made these “amazing” boards for Hawaii’s amazing waves. They came with the full production suite. Cameras, directors, sound guys, Actors… in this case Peter Graves. They were very keen to check out the science of surfboard making. Boy were they surprised! They just couldn’t believe that it was all a hand made, personally intuitive process. It blew their whole Scientific approach and expectation right out the window. They couldn’t find a story in it. Then they had a brilliant moment and asked if I “Tank Tested” my boards. I said of course I do. They were so excited!! They said, Lets go see the facility. I said ok, and promptly drove them down to the beach!
mean while down by the beach Tom Nollar shows up in a tizzie with a blank I sold him years ago questing a board like the one Velzy glued up in 59 with a scarf on the nose and another o the bottom ,
“it had so much rocker velzy was shaking his head,you are really making us work!” or some such,…
so out comes the yellow 9’2 velzy hand shape and the nose is too wide ,says he in that remnicient of Ben Gunn tone treading the line between here and not here we of the beach find comfortable and amusing
“the nose has to be more like this phil edwards here”
so out comes several templates on this finely cured 10’3’’ phil edwards thickie…
one two three rejected until yes that’s damn close…
the velzy is put on the ground and tom steps fore and aft with measured step and
" YEP FOUR STEPS TO THE NOSE THAT’S PERFECT"
the blank is trimmed to length to take the clamps to
take the half template
spread the tail wide to affect the “PIG” outline and ‘hips’
we’re off like the fifth at Tanforan
well it got dark as I was turning the rails
aaaaaa…shaping in the dark are ya?
ha ha thats a first
[its not but I dont say it aloud]
the next day tom shows with a fin freshly ripped from a hobie
mahogany and balsa and maybe brazillian cherry it is
takes some time to resist that option but I finally prevail
and set to work evolving a “rising sun” of balsa and redwood with zap a gap glue and hand pressure…praise zap cause I’m glueing and shaping wedges
at the same time
no table saw mind ya
and am shaping within an hour or so
the blank for the fin is so thick the job is stalled while we calm henry’s concern about the thought that we could make two out of one if we had a saw…
in the end I needed all the thickness to get it true
by dark 230 I have the fin as roughed as the board was,
I finished it off ,the board,nicely in the daylight and enscribed it VELZY LIVES…
the fin I woke and finished shaping before drinking water.
setting back water a full two and a half hours…
so tom didnt show today I finished Jimmy’s board and another 9’spec board and they wait attention in the darkened workshop
…ambrose…
whats this have to do with resin?
nothing.
just an episodic relief from tech measurabillia
inspired by the test tank comment…
That is why I tend to favor a skeleton under the skin that can be placed were needed to augment the shortcomings of the skin in certain areas but not become a whole sandwich shell or singular core spring.
interesting post…good to know there are more scientific minds out there…
you had me going and then you made the above statement…much of the mindset out there is of homogeneous structures when in fact, as Greg once eluded to, one could attack the problem via engineered componentry…there’s been much discussion here regarding hard decks and rails, and soft bottoms and cores…bert once mentioned that he uses 4 different epoxy formulations in just one of his boards…anywhere from hard to flexible to achieve the desired results…
meanwhile, my focus recently has been on the dreaded length/thickness ratio of the composite structure…its the low hanging fruit of the tree…
The epoxy boards Rich built were urethane foam and came out lighter than his polyester glass jobs. This is because epoxy is lighter (by 20%) in glassing at the same schedule. This is the main reason for the denting. Weight is the constant. You can’t compare by glass schedule, you have to compare by board weight. Weight is the measurement that matters.
to Greg.
The above statement raises a few red flags when i try to interpet your meaning.
Are you saying epoxy/glass laminate on urethane core will dent sooner than polyester/glass on urethane core when using same laminate thickness/cloth and identical cores?
Can you elaborate a little? It seems reasonable that thicker laminates would be needed to compensate for weaker cores.
But requiring thicker epoxy laminates for identical cores…?
-bill
i’m glad this thread is still alive, there’s alot to this stuff.
Mahalo Bill
nothing like knowledge and experience…
When you say:
Having a tuned skeleton core that could blend the qualities of this internal spring out through the whole board would be great. But it is very hard to control all areas of the board that experience torsion, twist, rebound, memory etc. The area of the skeleton core can be easily controlled but the farther you get from it the more unusual issues pop up. So unless you create a controlable skeleton that encompases the whole board it may not be the answer. To make the spring core spread through the whole board may create weight problems.
That is why I tend to favor a skeleton under the skin that can be placed were needed to augment the shortcomings of the skin in certain areas but not become a whole sandwich shell or singular core spring.
AND
On the other hand if you create a skeleton that carries the loads and distributes the stresses out more evenly (or specifically if you desire) then you can have a board that won’t buckle unless the designed limits of the support skeleton are exceeded. Additionally, the skeleton can be designed to snap back agressively with good rebound and memory. And that flex can be specifically located. On the other hand the skeleton won’t do anything to help with foot dents etc. Broken boards indicate another problem. Energy from the wave or breaking force is being wasted because it is hyperloading and compiling at a single point. This is also happening when the surfer is riding the board, he just doesn’t notice it. But energy is being wasted because the flex is not being controlled especially if the loading by the surfer is getting near the limits of the shell. A skeleton can absorb and transfer these loads/energy and distribute them to other areas or give them back rather then wasting them in hyperloading.
Are you talking about an exo-skelton in the sandwich like this stuff…
Flexible cell Nomex Honeycomb,
Nomex® Honeycomb or equivalent Aramid Honeycomb is a lightweight, high strength,nonmetallic honeycomb manufactured from aramid fiber paper. After the honeycomb is formed, it is coated with a heat resistant phenolic resin to increase its strength. The core material exhibits high strength to weight ratio, low density, good thermal insulation and is very bondable. The honeycomb has a service temperature from -450F to 3500F. Aramid fiber honeycomb is used as the core material in composite panels. These panels “sandwich” honeycomb between two “skins” which can be metal, carbon fiber, fiberglass, or any other thin yet strong material. Once these skins have been bonded to either side of the honeycomb, the resulting composite structure has extremely high strength-to-weight and rigidity-to-weight ratios. Aramid honeycomb is becoming increasingly used in highperformance non-aerospace components due to its high mechanical properties, low density and good long-term stability
Or an internal skeleton like this stuff:
AeroFlex™ Internal Frame System
AeroFlex™ provides absolute control over surfboard flex. The elimination of torsional flex enables our boards to keep a solid edge through powerful turns. Critical maneuvers become even more extreme as AeroFlex™ unloads energy from the rider’s input. It’s an ultra-light solution to creating flex patterns that help you surf better!
AeroFlex™ technology enables the rocker (a critical element of performance) to interact with the wave face. Generating more rocker exactly when it is needed dramatically improves performance in critical maneuvers
I love this sound bite too…
And you wonder why professional industries aren’t flocking in to help us out? They think surfers are a bunch of idiots…and for the most part I can’t blame them. And I mean no offense…I am a surfer too.
Sometimes we forget this…
I’m not Bill… He sure brings a lot to the table with his recent answers though!
The skeleton concept as pictured in the AeroFlex images would seem to hold much promise. Plus, it’s perfectly suited to any backyard/garage techies with access to a router. With a few swipes of a router and some carbon tow strands epoxied in, you could easily create a skeleton of your own under whatever skin you choose to apply.
Carbon tow has been used for years by the RC airplane modelers to stiffen their wings.
http://www.rcgroups.com/forums/showthread.php?t=49183
Check the channels viewed in the cross section…
Interesting concept…
I was thinking more of along the lines of what a luthier would do to strengthen and “tune” the top and back of a guitar or violin.
Be interesting yo look at the patterns used there for the ribbing and how they shave down certain areas to “tune” the flex characteristics or the top ot bottom shell to produce the desired sound…
Also what kind of wood strips do they use?
Maple?
Birch?
Maybe even bamboo strips to maintain the spring…
Found my answer…
Sitka Spruce…
the different scalloped bracing patterns on the inside of a guitar are amazing
Carbon rods would work fin too.
Great story Ambrose! There is science in there somewhere, as we all know, but it is typically masked by all the personal artist drama that goes into each board. That drama is so far from the regular world’s test tank mentality that outsiders rarely even know it exists, let alone see the odd esoteric value in it, that makes getting a new board such a special experience to surfers.
As much as l love tech, new things and advancement of the craft, the scariest thing on the horizon is the loss of perception, on the part of consumers, that getting a surfboard should be a very special and personal experience. All the way from getting ideas from magazines, trying friends boards, dreaming, wishing, talking about it with friends, designing, sketching, dreaming more, begging, saving up for, choosing a builder, ordering, telling your friends it is coming, dreaming together, looking toward the day, waiting, suffering the delays, etc…till finally that custom made foil is in hand where you can fondle its exquisite form in all its glory while waiting for its first taste of saltwater!
Molded boards, Costco, Sam’s Club, and Ghost shaped forgeries won’t ever have that pixi dust appeal and magic that getting a new surfboard should have, to keep the allure of surfing alive and well.
Windsurfing tracked a very similar course and it firstly devastanted the custom board market and shortly after ruined windsurfing totally, because that special appeal that custom built hardware brings to a sport or activity is simply…magic and very powerful mojo. It can’t be replaced with generic mass production even with great marketing hype.
Some activities are so unique that they draw great energy and validation from the simple artform and craft, surrounding the creation of the equipment used to actually do the activity. So much so that, for example, the very life blood and heart of the surfing is deeply entwined into the allusive aura of the custom made surfboard.
Maybe we can survive the loss of this but I am not so sure. Motorcycles are more popular because they can be customized and personalized. Mountain Biking was huge in the '90s when zillions of small maufacturers were creating all kinds of cool aftermarket parts in wild colors, to customize bikes. But as quick as those items became stock additions on the next years generic production bikes they lost their pizazz. Before long Shimano, crushed many of these small creative manufacturers and as they died off so did the facination and popularity of the activity itself.
Mahalo Billnothing like knowledge and experience…
When you say:
Quote:Having a tuned skeleton core that could blend the qualities of this internal spring out through the whole board would be great. But it is very hard to control all areas of the board that experience torsion, twist, rebound, memory etc. The area of the skeleton core can be easily controlled but the farther you get from it the more unusual issues pop up. So unless you create a controlable skeleton that encompases the whole board it may not be the answer. To make the spring core spread through the whole board may create weight problems.
That is why I tend to favor a skeleton under the skin that can be placed were needed to augment the shortcomings of the skin in certain areas but not become a whole sandwich shell or singular core spring.
AND
On the other hand if you create a skeleton that carries the loads and distributes the stresses out more evenly (or specifically if you desire) then you can have a board that won’t buckle unless the designed limits of the support skeleton are exceeded. Additionally, the skeleton can be designed to snap back agressively with good rebound and memory. And that flex can be specifically located. On the other hand the skeleton won’t do anything to help with foot dents etc. Broken boards indicate another problem. Energy from the wave or breaking force is being wasted because it is hyperloading and compiling at a single point. This is also happening when the surfer is riding the board, he just doesn’t notice it. But energy is being wasted because the flex is not being controlled especially if the loading by the surfer is getting near the limits of the shell. A skeleton can absorb and transfer these loads/energy and distribute them to other areas or give them back rather then wasting them in hyperloading.
Are you talking about an exo-skelton in the sandwich like this stuff…
Aloha Oneula
That is one solution. But I wasn’t talking about a sandwich skin and a skeleton. Though I am not against it. I was using a more simple view using single skin technology. Mainly to sort out the issues in a very familiar and simple construction.
Lets get something straight first. In these discussions I am not really promoting a particular method of construction, nor am I saying one is better than another. So don’t misunderstand my rambling thoughts as we wander through this subject. I am not selling or promoting any particular construction make up, materials or techniques. Just sort of thinking out loud really, to get a handle on the forces and ways to control them.
My mention of a skeleton can be viewed in its most abbreviated form. Take a standard PuPe board. Basic shape for a short board or fun board. Use the smallest stringer possible. Material doesn’t really matter. Use Superblue Clark foam. Glass 4 oz bottom double 4 oz top. Before glassing, cut a triangular groove next to the stringer on bottom from nose to tail. Same on deck but taper it out it out 3"-4" from tip of nose and tail. Make it almost 3/16" wide at the deck and about that much deep. Prepare 3-5 strands of fiberglass roving to wet out.
Wet out the roving and then twist it a bit and drop it into the groove and cut the ends. Fold the glass over it and lam the bottom. Do the same for the deck. Finish board as usual.
The board now has a strength spar on each side that matches the deck and bottom curves. And is attached to the stringer creating a partial “I” beam. The Spars under load are kept seperated by the stringer, the core foam and the fact that they are attached to the deck skin.
So now you have these fiberglass rods (spars) on each side of the board. Imagine the spars, stringer and immediate foam around them to be like an archery bow if held up vertically. Don’t underestimate the power of this. It is very simple and has profound effects.
This is the base of the skeleton. And its tapered shape due to the foiled thickness of the board from nose to tail naturally regulates flex. I am not praising this or saying it is the end all or even trying to get anyone to make one this way. Just that it works and is what it is.
Just get the picture of this primitive skeleton and the effect it has on dispersing the boards stresses throughout each spars length. And removing the stress and load from the 4oz skin. It can’t be hyperloaded at any point. Using these I have had boards buckle regularly in 3-5 places rather than ever break or buckle at a single point. It is like taking a fishing rod and trying to break it by holding it at the ends. The stress won’t focus or hyperload at any point and the rod will simply bend in a circle. It does the same thing in the board. It also reduces the skins shearing effect on the foam it is attached to.
It is important to discuss here, Compression and Tension. As has been stated many times, under load surfboards generally go under compression on the deck and Tension on the bottom. Therefore, it is easier to control flex from the deck because Compression is easier to control then Tension is. If one was going to argue, and win, they would have to say that Carbon on the deck and Kevlar on the bottom would be logical choices. In spite of the opposite, that a famous Hawaiian shaper once said in the surf magazines. But a certain amount of allowance in the amount of Tension is good. That is why K Cloth didn’t work well in Hawaii. The flat weave (no twist in the strands) didn’t allow the glass to have any spring to it. It made very light laminations due to laying very flat and thin, but it didn’t have a flex factor that matched that of common surfboard resin. Or the environment of Hawaiian surf.
In case it hasn’t been mentioned before, traditionally, surfboard resins and fabrics have been designed with similar abilities to elongate and compress. Otherswise the resin will shear away from the strands of fabric.
Material choices aside, there are many other factors like twist (spring) in the fabrics, flexability of the resins, and the core’s characteristics, that can greatly complicate analysis of the whole package. So I am simplifying a huge concept down to a single spar on a single skin board.
When surfing a board goes through all sorts of contortions. I am not convinced that making a board overall stiffer as some suggest is a good solution. Varying amounts of flexibility can be a good thing as long as the return is predictable and the limits of the flex can be kept within functional parameters. I have done consulting for two World Champions in Unlimited Offshore Powerboat Racing. We had many discussions concerning how rigid a hull should be. Often times a flexible Zodiac can move through the water with remarkable speed and comfort and this didn’t go unnoticed by these guys. Keeping a boat together at 100+mph in rough water isn’t only about making it stronger. It is also about making it compliant.
When Bobby Owens was my team rider, he used to “stress crack” his boards diagonally, from just turning! Would they have surfed better if they didn’t twist so much?? Hard to say. Harder still to test.
Flexible cell Nomex Honeycomb,
Nomex® Honeycomb or equivalent Aramid Honeycomb is a lightweight, high strength,nonmetallic honeycomb manufactured from aramid fiber paper. After the honeycomb is formed, it is coated with a heat resistant phenolic resin to increase its strength. The core material exhibits high strength to weight ratio, low density, good thermal insulation and is very bondable. The honeycomb has a service temperature from -450F to 3500F. Aramid fiber honeycomb is used as the core material in composite panels. These panels “sandwich” honeycomb between two “skins” which can be metal, carbon fiber, fiberglass, or any other thin yet strong material. Once these skins have been bonded to either side of the honeycomb, the resulting composite structure has extremely high strength-to-weight and rigidity-to-weight ratios. Aramid honeycomb is becoming increasingly used in highperformance non-aerospace components due to its high mechanical properties, low density and good long-term stability
I have used Nomex a lot. All the way back to 1970. As a sandwich it has uses but I am still just talking about single skins and skeletons, so we can better analyze flex and controling it.
Or an internal skeleton like this stuff:
AeroFlex™ Internal Frame System
AeroFlex™ provides absolute control over surfboard flex. The elimination of torsional flex enables our boards to keep a solid edge through powerful turns. Critical maneuvers become even more extreme as AeroFlex™ unloads energy from the rider’s input. It’s an ultra-light solution to creating flex patterns that help you surf better!
AeroFlex™ technology enables the rocker (a critical element of performance) to interact with the wave face. Generating more rocker exactly when it is needed dramatically improves performance in critical maneuvers
These guys sound knowledgeable. Torsional flex is a good thing to a point. It allows the rocker and vee to be altered to suit the riders needs at anytime. A rigid board doesn’t allow for this kind of adjustment. Though the merits of this can be argued to death. How much is enough, too much. Design distortion, energy loss, fitting the board into places it wouldn’t go if rigid etc, etc.
Try to imagine a skeleton that you could then lay a soft skin over (not really possible) but so you can imagine what kind of skeleton would allow the skin and rider to be supported. Then try to add back the least amount of core material and skin to make the skin able to hold the rider and water pressures.
Sandwich boards resolve many issues and are a simple fix and maybe the best fix for them. They reduce foot dents, reduce breaking, can be lighter, and lend themselves to molding.
But they create a very generic flex characteristic. Sort of like shaping rails with sandpaper arched over them rather than using shaping screen. The screen will track various contours. But the sandpaper will always bend on the same arch and you can easily see it in shapers boards who use arched sandpaper to turn rails. Their rails will always look the same.
In the same way a consistent sandwiched shell over the whole board will produce a very predictable stiffness that will require a lot of alterations to make it “feel like a surfboard ought to”. Quotes are to indicate the riskiness of the statement. Who knows how they should ultimately feel. But feel they must, to make customers happy and creating a familiar path from the old to the new may be wise.
The problem this brings up is the labor expense and the research needed to get the right flex in the right places. Current industry standards of production shops are just not ready for this. Regarless of how much better it may be.
I love this sound bite too…
Quote:And you wonder why professional industries aren’t flocking in to help us out? They think surfers are a bunch of idiots…and for the most part I can’t blame them. And I mean no offense…I am a surfer too.
Sometimes we forget this…
This is because epoxy is lighter (by 20%) in glassing at the same schedule.
Aloha Greg
Interesting stuff!
Why is it 20% lighter?
deck countour has got to play a major role in buckling as well...convex is stiff then suddenly gives on extreme loads..corrugated might win that test
Aloha meecrafty
Considering all basic and common boards, I don’t think there is much effect on the buckling of boards from the deck shape. The arch is concave and extremely forgiving. The convex shape rail to rail has limited effect compared to the lengthwise concave sweep of the deck. And since all boards have pretty much a similar rail to rail shape it can be factored out. By the time the stress is enough to flatten the convex deck the deck skin is already having sever problems.
Corrugating the skin will obviously stiffen it a lot. But it only does so with the downside of a very progressive rush toward failure at some point. Stiffer is not really the goal. Taking the load off the skin and its backing is.
bert once said it takes him anywhere from 9 to 14 hours to make a sunova…
WOW! 14 hours, I am not surprised. Just cruisin PuPe boards take about 5 hours including shape.
Bill,Your perception of compressive strength and it’s importance is right on (so nice to hear someone who makes surfboards nail that one).
Thanks Greg
Believe it or not…I actually knows some stuff HA!
Strength to weight is so important and also so misunderstood. One of the great reasons for making boards lighter is that you can now put some weight back, but put it were it will do the most good with the least harm. Lightness for the sake of lightness has its limits.
Slim,The added layers I’m talking about in weight [1.25lbs.] are successive layers. The first layer weighs more because you have to wet the foam and create a foundation for that first layer. This foundation layer on an EPS blank weighs about 3/4 of a lb. more than the successive layers on a 9’er.
May I ask another follow up question? That would be 2lbs. for the first “foundation” layers and 1.25 lbs. for each additional layer of 6oz. glass on a 9’0", right? When you say a layer of epoxy is 20% lighter than a poly layer, which layer of epoxy do you mean? (i.e. is a layer of 6oz. with poly resin for a 9’0" 2 lbs epoxy times 125% = 2.5lbs poly or 1.25 lbs epoxy times 125% = 1.56 lbs poly?)
(then i guess there is the hotcoat and usually a gloss coat to factor in too on most longboards).
thanks!
Kia Ora bb
i use about 350 grams of epoxy to lam side with 2 oz +4oz (there is still some excess)
just a guess to why it is lighter
it wets out well
would the specific gravity have something do with it (Just a guess)
longer working time (allows time to carefully remove excess resin)
would really like to know the reasons it is lighter ???
greg ?anyone???
cheers paul
Kia Ora bbi use about 350 grams of epoxy to lam side with 2 oz +4oz (there is still some excess)
just a guess to why it is lighter
Aloha Paul
I am looking forward to Gregs explanation about his 20% lighter comment.
it wets out well
Good guess, but so does polyester
would the specific gravity have something do with it (Just a guess)
Sounds logical. I haven’t weighed a “Cured” volume ounce of Poly or Epoxy in a while. Poly has more VOCs so you gotta weigh the cured resins to compare actual weights of a finished product.
longer working time (allows time to carefully remove excess resin)
A good laminator can stretch a very tight and dry polyester lam and have it kick off before the cloth will pull back and begin to suck air into it or allow the resin to begin draining out under the glass or into the foam. Both problems of which you need to leave excess resin in the lam to solve unless one is skillful enough to prevent it with a good speedy technique and rapid gel times.
So while slow gel times may be of advantage to some less experienced it wouldn’t be needed among skilled craftsmen. Epoxy has a pretty slow gel time so stretching the cloth out tight and dry and having the epoxy go off soon enough could be a problem requiring extra resin to solve. Sealing the blank helps prevent this but requires another step and resin that could add to weight if it wasn’t applied correctly. Not to mention the time it takes for the extra steps.
Additionally, with UV cure Polyesters, you can have all the time needed to pull a very tight and dry lamination and then just pop it under UV and gel it on the spot.
would really like to know the reasons it is lighter ???
Me too!
greg ?anyone???
cheers paul
Quote:This is because epoxy is lighter (by 20%) in glassing at the same schedule.
Aloha Greg
Interesting stuff!
Why is it 20% lighter?
Here is some outakes from Gregs posts that I dug up that touch on this:
Epoxy is stronger so the board comes out stronger with better resin.
Since epoxy is stronger it takes less resin in the laminate to do the same job as polyester. And epoxy has a slightly lighter specific weight. This makes a lighter board even with the same blank used for the poly. In fact with epoxy on Clark foam you can use a green blank and it will come out the same weight as the same glassed poly lamination using a blue. And MUCH stronger.
You can laminate ANY foam with epoxy. Not just urethane. This gives you the option of making your own blanks.
Our new epoxy system is faster than MEK initiated poly so production times are quicker.
Cosmetically epoxy is clearer making a whiter board. Yellowing is also slower than with poly.
Epoxy can be cleaned up with soap (GoJO type) and water. There is no need for clean up solvents.
Epoxy has very little vapor (odor) so work can be done almost anywhere. No masks are necessary with just moderate ventilation.
You use approximately 1/3 the amount of epoxy resin to build a board as you would polyester.
These last three, immediately above, give you an indication of the reasons epoxies are better for the environment and for labor.
Epoxy gives the laminator more work time and there is no real “gel” time to catch you. The resin just gradually thickens as it begins to harden. This allows a higher quality laminate.
All the newer fabrics (Kevlar, carbon, s glass, etc.) were designed for use with epoxy. Not surprisingly, they all perform best in an epoxy matrix.
The real secret to epoxy is the resin to fiber ratio. The weight savings can translate into the ability to use more cloth, or a heavier (stronger) blank. A 4 oz epoxy laminate is only marginally stronger than a 4 oz. poly. But the 4 oz poly is as heavy as a 6 oz epoxy. Strength to weight ratio. Now what John said about s cloth was exactly right. Now if you add s cloth into that heavier cloth, epoxy lamination, now were talking about some real advantage! And one other thing I mentioned above, with epoxy you use 1/3rd the amount of resin as with poly. So the cost isn’t what you think. It’s only marginally more to use epoxy. I have a customer in New Jersey, Fly. He claims that a 15 gal. set of epoxy goes as far as a drum of poly. They cost the same and he gets the advantages I posted above.
Howzit J.Troy?!? Been having some problems with RR on Clark blanks, so far, mostly with superlites. I am more inclined to believe that more glass is necessary to make a p.u. board hold up. The 20% seems about right, when using regular 4oz warp E, the things will dent way more than regular p.e. The worst problem I’ve seen yet is that the foam seems to shrink inside the lamination, making that wierd “cottage cheese” effect that I’ve mentioned in another post. I tend to agree with Jim Genius about the foam destructing inside the blank. I also am inclined to agree with him that epoxy over p.u. is no stronger, or better, than p.e. Although more plys would solve some strength problems, I believe that the main danger is that foam shrinkage inside. I have been developing my theory on that, and so far, I feel that because the epoxy makes a more impenetrable seal on the p.u. foam, that the pressure inside the blank ( temp. induced) cannot equalize itself into the glass fibers and back again, unlike the weaker bond of p.e. on p.u. that would allow a subtle ‘breathing’ effect. It’s another story with stryrofoam, where the bead nature of the material would allow the internal pressure to regulate itself inside the blank. That is, unless you have a vent, as recommended, for the lighter weight foams. I’m getting ready to do a couple more p.u.'s for my team guy, this time, I’m going to double-up the bottoms, but I’m still sketching on the whole process, due to that ‘wierdness’. Since I saw that effect, I’ve discontinued promoting, and personally glassing, RR on p.u., until I can figure it out. I have started my styro projects though, and RR is definitely the top stuff for sure! I am behind the epoxy system all the way, I really like the way the whole system works, but the p.u. problem is unacceptable. Also, I work with ‘Topper’ Driggs, and he (we) are the RR distributors for Kaua`i. With 92 gallons of RR on the way over, you can see my concern. Aloha…RH
The more I read posts the more I feel I must have gotten real lucky when making my first board. I used a Walker Foam Blank, standard density, sealed with Home depot lightweight spackle, glassed with Resin Research Epoxy and s-glass. I used tints and everything came out perfect. No fisheyes, no blush, no nothing. I used the board 5 times now and have not a trace of a pressure ding on the deck. Normally, my bony knees just thrash the decks of my boards. Did I have beginner’s luck or what?
Howzit J.Troy?!? Been having some problems with RR on Clark blanks, so far, mostly with superlites. I am more inclined to believe that more glass is necessary to make a p.u. board hold up. The 20% seems about right, when using regular 4oz warp E, the things will dent way more than regular p.e. The worst problem I’ve seen yet is that the foam seems to shrink inside the lamination, making that wierd “cottage cheese” effect that I’ve mentioned in another post. I tend to agree with Jim Genius about the foam destructing inside the blank. I also am inclined to agree with him that epoxy over p.u. is no stronger, or better, than p.e. Although more plys would solve some strength problems, I believe that the main danger is that foam shrinkage inside. I have been developing my theory on that, and so far, I feel that because the epoxy makes a more impenetrable seal on the p.u. foam, that the pressure inside the blank ( temp. induced) cannot equalize itself into the glass fibers and back again, unlike the weaker bond of p.e. on p.u. that would allow a subtle ‘breathing’ effect. It’s another story with stryrofoam, where the bead nature of the material would allow the internal pressure to regulate itself inside the blank. That is, unless you have a vent, as recommended, for the lighter weight foams. I’m getting ready to do a couple more p.u.'s for my team guy, this time, I’m going to double-up the bottoms, but I’m still sketching on the whole process, due to that ‘wierdness’. Since I saw that effect, I’ve discontinued promoting, and personally glassing, RR on p.u., until I can figure it out. I have started my styro projects though, and RR is definitely the top stuff for sure! I am behind the epoxy system all the way, I really like the way the whole system works, but the p.u. problem is unacceptable. Also, I work with ‘Topper’ Driggs, and he (we) are the RR distributors for Kaua`i. With 92 gallons of RR on the way over, you can see my concern. Aloha…RH
Aloha Rickholt! Great to hear from RR guys in Kauai.
I have never heard or seen that problem w/Clark and RR epoxy. How long does it take for the cottage cheese effect to appear? Was it a consistant problem with all the Clark blanks you glassed? Ive used superlight, ultralight and superblue and ive never had a problem. I usually glass superlight 6/4 deck and single 4 bottom…Too bad Gregs in Australia right now so well have to wait for him to get back to hear his opinion on the cottege cheese effect.
Agree with your take on polyester on PU.
Im going to try the 1.2lb EPS blanks from Jim Richardson at Surflight and have it run through Eric Arakawas DSD. Greg recommended triple 6 deck and double 6 bottom so ill see how that goes.
After using RR resin for the first time and then going back to glassing with poly the differece was huge. I dont really ever mess with poly anymore unless im doing a ding repair for a friend.
Is there alot of interest in epoxy on the garden isle?