Dingproof surfboard for the DIY guy - Best bet?

General Discussion
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Is nylon (cordura) better than other synthetic fibers like dyneema, spectra, dynel, xynole, innegra S, kevlar, twaron, etc.? If it is, why isn’t it readily available from stores that sell composite materials? Nylon has been around for a long, long time.

Any suggestions for layup? My idea is to vacuum bag on either a thin layer of glass or surfacing veil on the foam core and let that cure to give the foam a hard shell which can handle higher pressure when vacuum bagging on the rest of the fibers and prevent the core from soaking up excess resin from the laminate. Then either some sort of bulker or a heavyweight non-crimp(knit) bi- or triaxial fabric, then some sort of impact resisting synthetic cloth and thin layer of glass on top for something to sand into. Maybe a patch of some carbon/kevlar grid under the feet for reinforcement against pressure dings. HD foam insert for leashplug and fins of course.

On the other hand I can’t help but think that some reinforcement under your feet and on the rails would go a long way in preventing dings.

Another option I’m considering is a sandwich board without wood but with tech fibers. I’m repairing a sandwhich board with carbon and kevlar right now. The guy who owns it have just taped over a bunch of dings, mainly after running over the board with his car, and kept surfing it. Although it has a number of cracks, they only go into the sandwich material so it doesn’t soak any water and i still lightweight after many years of abuse. This guy usually kill a regular board in a year or two. It a nightmare to fix though as you sand so easilly through the thin glass on top and into the kevlar.

This looks kind of interesting for shock absobing http://www.auxetic.com/science.htm

22

surflight

jim richardson and mike croteau

http://www.surflight.com/Surflight/Technology.html

Factory Tour Video

http://youtu.be/cRdSmhwc4_s

 

Tom Morey Super Skunk Swizzle

http://www.youtube.com/watch?v=D3NJdJPf-Pw

 

Allan Gibbons - Nextboard

http://youtu.be/jFTDn41OREc

I built this board, and couple of variations, in the summer of '06 (this is the only one left). I then filed for, and was granted, a “provisional” patent, meaning that there was some protection, for 1 year, and I could legally use "Patent Pending"For something in a field as small as surfboards, the process was pretty straightforward (I recommend anyone who’s interested to spend some time on the USPTO site. It’s fascinating), and it probably would not have been that difficult to get a patent. However, I felt the design and process needed a few more iterations before it even got to that point, and that takes $$$.If I kept versions of every project that I’ve worked on, I’d be buried! So I’d rather move stuff along and make room for the next thing. - Allan Gibbons

 

23

Is it better? Maybe.  Is it different? Yes.

Many of the fibers you mentioned aren’t available woven into cloth.  Some break down is sunlight, some don’t bond with epoxy, but are encapsulated by it.  Why isn’t it available in composite stores?  No demand probably,  It doesn’t work at all in a regular production setting.  It is so tightly woven that you must use a wet out table/ vacuum bag.

As for you build ideas, yes.  That is how I do all my builds now.  Vacuum on a layer of Cerex N-Fusion.  Let it cure.  Vacuum on a layer of Cordura, and let it cure.  Then depending on what I’m after in terms of flex, adding layers of warp cloth, twaron fibers or whatever.  On my stringerless builds. I vacuum on a corecell deck, and use carbon rails.  SIngle layer of cordura on the deck over that.  Carbon rails.

 

Lemat, you are an engineer!  You should know better than to make statements like that.  Strength has many measurements.  Fiberglass is glass, and glass is brittle.  On straight impact tests, cordura laminates are far more resistant to puncture than fiberglass.

McDing, let it go.  I’m making boards with it.  I’ve posted them.  At Plasket Creek campout, I’ve shown them to everybody.  I’ve let other Swaylockers ride them.  It works.  If you haven’t done it, you don’t know.  Let the argument go.  Thanks.

24

No, I could find sources for fabric in all the above mentioned fibers. Some are very expensive though.

lemat, I don’t worry too much about flex. My boards are usually quite thick anyway. Looking for strength (ding resistance) with reasonable easy build (vacuum bagging) and reasonable cost(less then a store bought board) . 

25

Haavard, I made a board for a guy who’s very hard on boards… used 6 oz S glass lammed with epoxy over a poly blank.  He’s Very Happy with it.  No reason you couldn’t vac bag if you wanted to… “strength (ding resistance) with reasonable easy build (vacuum bagging) and reasonable cost(less then a store bought board)”

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I saw a lightweight innegra/fiberglass blend that could possibly work out in an fg stack.

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Yes, Everything is available at a price.  Cordura is the same cost as fiberglass, and is available for the cost of a phone call and shipping.  I get mine delivered to my door in about a week.  And that is small quantities.    I usually order 10 yards of 60" wide, so I slit it and get 20 yards of 30"  You can order as little as a few yards at a time.

The only draw back it a wet out table, and vacuum bag.

As for impact, I did drop tests with a weighted steel rod.  Fiberglass punctured as low as a few feet, while cordura was up to 8 feet.  They make bullet proof vests and parachutes with it.  You aren’t going to see that with fiberglass or innegra.

28

nylon 6-6 : young modulus <5GPa, Tensil elastic strengh modulus :1000MPa, elongation to break 20%

E-glass : young modulus 73GPa, Tensil elastic stengh modulus : 3400MPa, elongation to break 4%

Remenber that for a well design composit, matrix must have an higher elongation to break and a lower young modulus (stiffness) to take advantage of performance of reinforcement fiber.

That’s way Nylon fiber is industrialy only use in elastic composits (with elastomere matrix). Current epoxy resin have elongation to break around 5% and 4GPa young modulus. Nylon fiber with those kind of epoxy have more or less same mechanical properties than a film of resin alone of same thickness. I confirmed it with laboratory test tool. An other big problem with those fibers is resin adhesion without specific sizing.

29

elongation to break 20% for Nylon 6,6 elongation to break 4% for e-cloth.

Lemat, I respect your knowledge as an engineer, but that last statement is just silly!  Epoxy alone is a strong as epoxy saturated nylon 6,6?

Get out of the classroom and into the laboratory.  Mix some epoxy, and paint it on some foam.  Then take some epoxy and laminate some cordura to some foam.  Equal mils thickness.  Do a simple impact test.  Drop a weight onto both samples. Tell me which one fails first.  I have done the test. 

Again, parachutes are made from it.  Try that with just a film of epoxy?

And lastly, Epoxy has excellent adhesion to untreaded Cordura fabric.

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No argument from me. You’re the guy that gets all worked up when you talk your shit and the world doesn’t pay attention to your brilliance.

31

:bawling:

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back to haavard’s original question… dingproof is a unicorn. Anything can get dings given the right circumstances. Overall durability is really what you are after. Heel dents aren’t even really bad, as long as they don’t compromise the structure. They are a sign the build isn’t overdone.

Having owned and ridden a lot of “techie” boards from some of the earliest Coils to bamboo and now cork-skinned stringerless EPS, here are my 2-cents:

DIY simplicity - 2# stringerless EPS, vacuum bag 4/4/4 deck and 4/4 bottom (s-glass). Rides great, insanely light, super easy build, minimum of materials.

More Techy - 1.5# EPS, vacuum bag 4/4 bottom, carbon rails, cork deck with 2oz. under, 4 oz. over

You could get all elaborate with technical layups, but honestly s-glass is good stuff and if vacuum bagged on will give you an insanely light and strong laminate. Most of the tech materials I’m seeing used are unnecessary and the same can be accomplished with a well thought out glass schedule using s-glass and creative overlapping of layers.

I’ve never had a problem with any of my stringerless EPS boards. I don’t feel like chasing tech down a rabbit hole for perceived improvements for problems that don’t exist. Start simple and see what problems arise. Then solve those problems. Don’t pre-optimize to solve non-existant problems.

33

When Benjamin Thompson give is test results on sways, i think that low strength polymer fiber (nylon, pet) was a solution. My empirical hammer test was good, I made test boards and final results were not so superior.

So I apply mechanics theory to understand, here a simplified approach:  

According to Hook law, a material with young modulus of rigidity (E MPA) stretch ( elongation A %) while he take load (constraint C MPa) C=EA. At limit Cmax=EAmax. Amax is limit of elastic elongation, when you go over material no return to initial shape when load stop, so Cmax is elastic tensil strengh.

Fiber is anisotropic :  high stiffness and  high strengh in only one direction (tensil in fiber direction). That’s way if you stretch fiber it resist but it don’t keep is shape for all other load direction. Matrix (resin) is quasi isotropic, more or less same strengh and stiffness in all direction.

In a fiber/matrix composit you connected materials according to their volume fraction (Fv %) (how much of each material there is in final composit).

Ccomp=EcompAcomp=EmatrixAmatrixFvmatrix+EfiberAfiberFvfiber

Because they are connected both elongate same way : Acomp=Afiber=Amatrix=A. If you take a 50% fiber and 50% matrix composit,

Ccomp=EcompA=(Ematrix+Efiber)A

Ccompmax=(Ematrix+Efiber)Amax. Ecomp= Ematrix+Efiber; Amax= the lower of Afibermax or A matrixmax

The stiffer material (greatest E modulus) take most of the load until it reaches the maximum elongation of the less elastic material (lower A).

On a well design stiff composit made of  fiber reinforce/matrix, Efiber>>>Ematrix and Afiber<<Amatrix. Current stiff material (high E) have low elongation (small A) Fiber resist to tensil load while matrix transmits forces and keep shape until max fiber elongation.

Enylon=Eepoxy, Anylonmax>>Aepoxymax. So Ccompmax=EepoxyAepoxymax. A composit of nylon and surfboard epoxy resin have more or less characteristics of epoxy.

I was a bit disappointed!

For months i made software simulation and accurate lab test, tensil, 4 points flexural, izod. I see that low strength polymer fiber+surfboard epoxy have more or less same characteristics than epoxy !

I read again Benjamin posts and simply with some words he say it, skinz (nylon veil)+epoxy is like a coat of epoxy of same thickness. FUCK I don’t see it first time !(cry)

In fact all this study make me understand a lot on surfboard structure that help me to improve my build. (happy)

So i am a lab rat that make engineering studdy and lab test for industry and to teach studdents. But in other hand i made about 100 boards those last 18 years, with al kind of tech and exotic material mix. Some travel all over the world and was used by comp surfer.

Sorry for the frenglish, it’s tricky to explain mechanics in a foreign language.

34

I like the KISS idea. I’m even considering using a PU core with somthing like 4oz s or h-glass/4oz innegra(or other synthetic fiber)/4oz-s glass and vacuum bagging it to keep the weight down a little. Could make for a durable board at approx. the same weight as a regular 4+4oz PU (maybe slightly heavier) . Then again I have alot of stuff laying around that I want to test. Maybe it’s time to make some test panels.

35

So what you are saying is that any fiber with lower modulus of elacticity and longer elongation to break than the epoxy only works as a bulker, the only possible advantage being a possible weight (and cost) saving over a thick layer of epoxy (if the fiber is lighter than epoxy)? However, once the epoxy crack in a ding, won’t the fibers start taking additional load and possibly prevent the ding from getting larger?

 

 

36

Exactly. But as epoxy is mostly a “fragile” materiel that give shape, once crack appear there is a lost of rigidity and integrity even if a ductil material (polymer fiber) reduce crack propagation.
To be a really effective structural bulker those fiber must be use with elastomer resin. Result can be amazing. I studdy and build parts for competion car that can take hard lmpact. Try to adapt this to surfboards for a while with interesting results but not still find the optimal way…

37

haaaa’’ wots that mean?

 

cheers huie

38

yes the new tri axles are very good i have been using them on the bottom of the raw  **cork decks i like it **

 

 

cheers huie

 

39

Haarvard,

I came across exactly the same principle only a few days ago - match the elasticity of the reinforcement with the resin. Maybe it was on the Colan or Hexcel website, I don’t recall. Or maybe a composite boatbuilding site.

Also, optimal resin loading in other industries is 40 to 60% by weight of cloth. No one in surfing is doing that (except maybe the spun tech guys Mike Daniels?) so we always overload our cloth and introduce brittleness (you could argue, however, that a good proportion of the overload is absorbed by the core, so the cloth resin loading approaches optimal when a good laminator is at work)

My solution to your problem is to either use a Marko blank or similar that doesn’t suck water, or use PU with epoxy. Of course if you can’t access blanks in your neck of the woods, then you’re stuck with EPS and you’re left debating protecting the core with non absorbing foams or simply using a bulletproof skin. I think it’s all a zero sum game. Expensive core / light skin; more expensive combination core / even lighter skin; cheap core / expensive skin.

40

havard it must be 4 yrs since we had the wood discussion on compsand ?

 

 and here i am   4 yrs latter saying when and thats the biggie’‘’ you get it right? the other fabrics applied to surfboards do not come close

for performance and longevity

 

 cheers huie