OK so who knows the treatment for dyneema to enable adhesion?

For some plastics I dealt with in the past it was very strong sulphuric acid and I think a potassium (?) chromate or dichromate or something. I gave up at that point. All obtainable but not easily doable.

Overner, thanks for the lead on Jeely. I will have a look. I won;t have the issues you are talking about as I'll only use it in a vac bagged structure between other materials

and carbon mixed with stronger and lower modulus fibers does work....

www.compositesworld.com/articles/dyneema-carbon-is-prepared-to-handle-all-impacts-

A reasonable analogue for carbon-kevlar or carbon-innegra

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Mark _australia said..

Overner, thanks for the lead on Jeely. I will have a look. I won;t have the issues you are talking about as I'll only use it in a vac bagged structure between other materials

I vac bag everything too. But, like aramids you need to bury UHMWPE under glass to prevent sand through. It is stiffer than glass and thicker for the same weight and doesn't wrap that well, so any mistakes are not easy to fix. It takes skill and patience to use well, I have built several sailboards with UHMWPE and my two pennies worth are that for a home builder I am not sure it is worth the effort.

Bouke needs to differentiate himself from the crowd and has built his reputation on tough constructions. But as a home builder, it doesn't save weight, it cost 5 - 10 times that of eglass and it is a pain to use with risks of delamination... not much going in it's favour!

Under the sandwich would be easier, but you could argue it is an expensive way to use a very high performance fabric and unless you know it has bonded well it may lead to delamination.

Regarding treatments, Bouke has already alluded to the commercially available versions - Corona and plasma treatment. Early experiments of mine included trying to make plasma in a microwave... f@@@ing dangerous... I also melted the UHMWPE in the process. I also tried sprayed bumper etch primers, which are an acid to prepare car bumpers for paint. Horrid stuff. Never again! As said there are techniques out there, but to be honest there are easier cheaper materials to work with, so unless you really have to, I wouldn't bother.
The other issue for you in Aus, is the temperature stability of UHMWPE. Over 100 degrees C it starts to change and roll into balls of PE. I imagine you guys could get surface temps of that sort on a hot summers day. And that might put a kybosh on using it.

Cheers :)

I'll stick with my current extremely durable stuff then.

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Mark _australia said..
and carbon mixed with stronger and lower modulus fibers does work....

www.compositesworld.com/articles/dyneema-carbon-is-prepared-to-handle-all-impacts-

A reasonable analogue for carbon-kevlar or carbon-innegra

Hmmmm, pure Dyneema is about 12 times as impact resistant compared to carbon. So an increase of 100% for a hybrid Dyneema carbon over pure carbon still leaves it is 6 times as impact resistant.........I mean that is not 30%, not 100% but 500%..... The other thing is that when it is woven into eachother, if the carbon breaks and the Dyneema keeps it together to prevent splintering, it still is pretty much impossible to repair. Not very good for the environment, nor your wallet. Those people from F1 also wanted to increase safety for the drivers against broken off sharp carbon parts flying around. They don?t care about repairability at all. For that you can use Dyneema/Carbon hybrid fabric. As Dyneema is already quite a bit stiffer than Kevlar and a lot more than Innegra, it also works better with carbon.
I also use carbon, mainly UD for the areas with higher compression loads. Like this, first of all it is stronger because UD is more efficient than woven carbon. Secondly, I put the carbon on top of the Dyneema. Dead easy to repair with full strength regain without any weight penalty. And off course the carbon is more impact resistant with the Dyneema underneath. Not did any laboratory tests but by experience it is 100% for sure.

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Overner said..

Bouke needs to differentiate himself from the crowd and has built his reputation on tough constructions. But as a home builder, it doesn't save weight, it cost 5 - 10 times that of eglass and it is a pain to use with risks of delamination... not much going in it's favour!

The other issue for you in Aus, is the temperature stability of UHMWPE. Over 100 degrees C it starts to change and roll into balls of PE. I imagine you guys could get surface temps of that sort on a hot summers day. And that might put a kybosh on using it.

Well the main reason I started experimenting with Dyneema was that in my first years on Fuerteventura, I was getting fed up with repairing my own board pretty much every evening after sailing. I was only doing board repairs in those days for customers, not making boards for others. We have a lot of rocks over here and while they are fairly easy avoidable, if you take risks, it is also very easy to end up on the rocks. In those days I made my own custom sails also with a strip of 8cm wide webbing over the mast sleeve as other wise it was shred to bits each time. Now my production sails have full Dyneema mast sleeves.

We are at a similar latitude as Australia over here and the heat has never been a problem for Dyneema. I heat out dents and use an infrared surface thermometer to heat it between 85 and 95?C but even accidentally going over 100?C has never caused a problem. I do not make black or dark boards, that is asking for trouble but that is not due to the Dyneema. Resin and PVC also go soft over 80?C. Which is why you can heat dents out.

Have any of you tried Diolen?Does anyone know the difference between it and Dyneema?

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We are at a similar latitude as Australia over here and the heat has never been a problem for Dyneema. I heat out dents and use an infrared surface thermometer to heat it between 85 and 95?C but even accidentally going over 100?C has never caused a problem. I do not make black or dark boards, that is asking for trouble but that is not due to the Dyneema. Resin and PVC also go soft over 80?C. Which is why you can heat dents out.

I stand corrected. Thank you.

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tarquin1 said..
Flax is huge here in France. I am pretty sure they are the largest grower of flax or lin as they call it in the world.
Yes i have read for and against it. I like it because it doesn't seem to crack like glass. It has much better impact qualities. It does use more epoxy though.
As you said from all the people I spoke to and research I did use local is much more important.
I thought Colan used Australian made glass. Are they buying the fibers overseas and weaving cloth with it.

I don't know any Australian made glass fiber.
Colans web site confirms glass fiber is imported from high quality manufacturers then woven in australia.

Paddle looks great.

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tarquin1 said..
Have any of you tried Diolen?Does anyone know the difference between it and Dyneema?

Diolen is like an elastic band, Innegra is a little better but still very stretchy when compared to other composite fibres. Both are really low modulus. Helps with toughness but is so much more stretchy than the resin and glass it is best as a bulker or pseudo sandwich. I heard a composite engineer once say the main benefit of diolen is it helps stop the resin running away...

Dyneema is comparable to eglass in terms of elongation on breaking (about 4%) and compression strength, so it compliments glass fibre in a composite rather than provides completely different characteristics, as you find with Diolen (200% elongation on breakage) and Innegra. But it has far more tensile strength and toughness than anything else. Which is why it is very attractive to use.

Bouke has managed to perfect using Dyneema fabric in boards, but there is a reason no one else is doing it very well!

I was in the shed this evening and have completely bodged the outline of my new freewave board! I hate polystyrene its rubbish!

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Mark _australia said..
Cheers :)

I'll stick with my current extremely durable stuff then.

Come on. Tell me your layup.....

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Overner said..

tarquin1 said..
Have any of you tried Diolen?Does anyone know the difference between it and Dyneema?

Diolen is like an elastic band, Innegra is a little better but still very stretchy when compared to other composite fibres. Both are really low modulus. Helps with toughness but is so much more stretchy than the resin and glass it is best as a bulker or pseudo sandwich. I heard a composite engineer once say the main benefit of diolen is it helps stop the resin running away...

Dyneema is comparable to eglass in terms of elongation on breaking (about 4%) and compression strength, so it compliments glass fibre in a composite rather than provides completely different characteristics, as you find with Diolen (200% elongation on breakage) and Innegra. But it has far more tensile strength and toughness than anything else. Which is why it is very attractive to use.

Bouke has managed to perfect using Dyneema fabric in boards, but there is a reason no one else is doing it very well!

I was in the shed this evening and have completely bodged the outline of my new freewave board! I hate polystyrene its rubbish!

i was wondering if your polystyrene comments are due to foam density. whilst i don't have the experience of most in this thread i have found i prefer shaping denser eps. the lighter stuff just sands away too fast. the denser stuff makes me feel like i'm crafting something. the process is slower so i can stand back look at shadows, take a bit more etc and not just sand a flat spot into the blank.

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Gestalt said..
we could all learn a lot from Sven Rasmussen when it comes to understanding the issues the windsurfing industry faces with contributing to climate change. We've all got to find our own line in the sand and i respect the idea that making boards last longer is part of the solution but when i really think hard about it, in reality, for me it isn't actually solving the problems long term it's merely just an easy first step. Companies should be looking long and hard at what starboard are doing. planting trees, cleaning up beaches, developing new materials, there are many ways to make boards with less impact than the sum of their parts.

It may be worth letting your mate know to have another look at materials. Resins are available with 77% bio content, EPS and PET is being recycled and even dyneema now comes in a bio based version which if you can believe the manufacturers has a 90% lower carbon footprint.

Ha, Svein Rasmussen...if there is anyone trying to use "BIO" as a marketing tool it is Starboard.
www.continentseven.com/times-of-headwind-coronavirus-starboard/ . There is a nice discussion below that.

As I?ve said before, so far it is all far inferior for mechanical properties. Recycled PET foam has far poorer properties than PVC, same for recycled EPS. Recycled EPS is excellent for insulation but not where the mechanical properties count as well. The stuff we?ve tried has waste in it so when you shape it there are harder and softer parts, pieces break out, etc. And "BIO" resin is actually worse for the environment. It is good companies are researching in this direction and some of this for some applications is usefiul but where higher properties are needed, simple laboratory strength tests is enough till they actually get close with the properties. No need to let end users test it and produce more waste rather than less.

As for planting trees, yes, nice but this still has to be paid and the costs will be added on to the product. Any end user could also decide to use the saved cash to invest in any environmetal project of their choice.

Someone mentioned real world use before, the people who "invented" stuff like carbon-aramid or carbon-innegra weren?t thinking about to make the best product. They were thinking about how can I sell something that sounds fancy and expensive so people are willing to pay more for it but is then actually no better than glass fibre and not repairable so people will need to buy a new board (or whatever) sooner. It is marketing BS. No one who is demanding on his own gear, has experience in repairing different boards and has good technical knowledge, would use it for his own boards.

Another example is masts, in the 80?s we were using 100% glass fibre masts. Then when carbon came up the engineers of No Limitz and Powerex said that carbon is on paper a better material but with very different properties which do not work really well together. So you either use a high % glass or carbon. And when using carbon, to get the same bend characteristics, you need to reduce the diameter and increase wall thickness. For a composite engineer quite easy to calculate. I had a chat with the people of No-Limitz on the BOOT D?sseldorf fair in Germany in ?89 where they explained this. So after moving to Fuerte in ?93 and breaking 8 to 12 masts of various different types and brands each year during the first years, I remembered this and I had a friend who went to the US and asked him to bring back some RDM Powerex masts as they weren?t available in Europe yet. Those first masts (still a 460 mast for a 5.3 in those days) lasted over 2 years. Never touched an SDM mast again. But since RDM masts became popular you see brands bringing out 60% Carbon masts to make them cheaper (and last less long?). That is putting the horse behind the wagon. Unless the same amount of carbon is actually still there and they just added extra glass which mainly just would add weight. But then you could ask why they can be cheaper.....So for the mere bending forces on masts, there is no point for glass if you use carbon. However glass does help for impact resistance which is usefull as carbon is brittle. So a 10-15% glass fibre content added on top of the carbon is useful. On F16 fighter planes made out of carbon, if an engineer drops his wrench on a wing, the wing is scrapped. This costs a million or more.

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Witchcraft said..

Gestalt said..
we could all learn a lot from Sven Rasmussen when it comes to understanding the issues the windsurfing industry faces with contributing to climate change. We've all got to find our own line in the sand and i respect the idea that making boards last longer is part of the solution but when i really think hard about it, in reality, for me it isn't actually solving the problems long term it's merely just an easy first step. Companies should be looking long and hard at what starboard are doing. planting trees, cleaning up beaches, developing new materials, there are many ways to make boards with less impact than the sum of their parts.

It may be worth letting your mate know to have another look at materials. Resins are available with 77% bio content, EPS and PET is being recycled and even dyneema now comes in a bio based version which if you can believe the manufacturers has a 90% lower carbon footprint.

Ha, Svein Rasmussen...if there is anyone trying to use "BIO" as a marketing tool it is Starboard.
www.continentseven.com/times-of-headwind-coronavirus-starboard/ . There is a nice discussion below that.

As I?ve said before, so far it is all far inferior for mechanical properties. Recycled PET foam has far poorer properties than PVC, same for recycled EPS. Recycled EPS is excellent for insulation but not where the mechanical properties count as well. The stuff we?ve tried has waste in it so when you shape it there are harder and softer parts, pieces break out, etc. And "BIO" resin is actually worse for the environment. It is good companies are researching in this direction and some of this for some applications is usefiul but where higher properties are needed, simple laboratory strength tests is enough till they actually get close with the properties. No need to let end users test it and produce more waste rather than less.

As for planting trees, yes, nice but this still has to be paid and the costs will be added on to the product. Any end user could also decide to use the saved cash to invest in any environmetal project of their choice.

Someone mentioned real world use before, the people who "invented" stuff like carbon-aramid or carbon-innegra weren?t thinking about to make the best product. They were thinking about how can I sell something that sounds fancy and expensive so people are willing to pay more for it but is then actually no better than glass fibre and not repairable so people will need to buy a new board (or whatever) sooner. It is marketing BS. No one who is demanding on his own gear, has experience in repairing different boards and has good technical knowledge, would use it for his own boards.

Another example is masts, in the 80?s we were using 100% glass fibre masts. Then when carbon came up the engineers of No Limitz and Powerex said that carbon is on paper a better material but with very different properties which do not work really well together. So you either use a high % glass or carbon. And when using carbon, to get the same bend characteristics, you need to reduce the diameter and increase wall thickness. For a composite engineer quite easy to calculate. I had a chat with the people of No-Limitz on the BOOT D?sseldorf fair in Germany in ?89 where they explained this. So after moving to Fuerte in ?93 and breaking 8 to 12 masts of various different types and brands each year during the first years, I remembered this and I had a friend who went to the US and asked him to bring back some RDM Powerex masts as they weren?t available in Europe yet. Those first masts (still a 460 mast for a 5.3 in those days) lasted over 2 years. Never touched an SDM mast again. But since RDM masts became popular you see brands bringing out 60% Carbon masts to make them cheaper (and last less long?). That is putting the horse behind the wagon. Unless the same amount of carbon is actually still there and they just added extra glass which mainly just would add weight. But then you could ask why they can be cheaper.....So for the mere bending forces on masts, there is no point for glass if you use carbon. However glass does help for impact resistance which is usefull as carbon is brittle. So a 10-15% glass fibre content added on top of the carbon is useful. On F16 fighter planes made out of carbon, if an engineer drops his wrench on a wing, the wing is scrapped. This costs a million or more.

as a punter, it appears to me that sven is practicing what he preaches. admirable stuff.

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Gestalt said..

i was wondering if your polystyrene comments are due to foam density. whilst i don't have the experience of most in this thread i have found i prefer shaping denser eps. the lighter stuff just sands away too fast. the denser stuff makes me feel like i'm crafting something. the process is slower so i can stand back look at shadows, take a bit more etc and not just sand a flat spot into the blank.

I used to shape polystyrene boards, but have always been unhappy with the outcome. either the weights weren't as good as being promised (using 30kgm3 Polystyrene) or the shape hasn't quite looked as I had planned - i.e. over shaping.

So, I have been using 34kgm3 PU foam (Orange density from US Blanks) for a couple of years and have made some nice boards. But their weight is too high - 8kg for a 90 litre sandwich freewave board. The shapes are nice, but the weight is just rubbish.

So I got myself another block of polystyrene and started hotwiring blanks out of that. With the first blank, I over shaped the outline on one side trying to true up the rail... ruined hours worth of labour. Polystyrene is just the worst to shape. So back to the drawing board!

What are other core options between 13 to 20 kg ? It's fine to go heavier on a smaller waveboard , ( better ? ) but what about larger boards .They would end up too heavy . I believe 13 is industry standard . I know 13 is a bit soft and rubbery but 19 shapes nice.

My last board was 24 and this eco board is 13.
13 and 100% recycled for use as a board cores.

Pu feels similar to higher density eps to me.

Ends up being swings and roundabouts to a certain degree. Higher density doesnt need sandwich construction for normal use where as lower density does.

Lower density is significantly cheaper.
Then there is the graphics. The foam and layup all enable different graphics.

The people i get eps from have 16kg density too.

Isn't PU a lot heavier ?
I remember it being nice to shape especially fine edges .

Yeah its 32-36 but you can get lighter / different densities like with eps.

www.sanded.com.au/pages/core-basics

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Overner said..

Gestalt said..

i was wondering if your polystyrene comments are due to foam density. whilst i don't have the experience of most in this thread i have found i prefer shaping denser eps. the lighter stuff just sands away too fast. the denser stuff makes me feel like i'm crafting something. the process is slower so i can stand back look at shadows, take a bit more etc and not just sand a flat spot into the blank.

I used to shape polystyrene boards, but have always been unhappy with the outcome. either the weights weren't as good as being promised (using 30kgm3 Polystyrene) or the shape hasn't quite looked as I had planned - i.e. over shaping.

So, I have been using 34kgm3 PU foam (Orange density from US Blanks) for a couple of years and have made some nice boards. But their weight is too high - 8kg for a 90 litre sandwich freewave board. The shapes are nice, but the weight is just rubbish.

So I got myself another block of polystyrene and started hotwiring blanks out of that. With the first blank, I over shaped the outline on one side trying to true up the rail... ruined hours worth of labour. Polystyrene is just the worst to shape. So back to the drawing board!

I have always used 15. When hand shaping or since 2007 by CNC. The trick is to first just shape the bottom and vacuum the PVC on the bottom. That gives added stiffness to shape the deck. The board and especially the tail and the nose get far too thin to shape without the PVC.
I see the EPS as a material to give shape to the sandwich construction, not something that will/should take much force itself. EPS is a pretty poor material and suffers from fatigue. Any deformation over 2 to 3% is permanent. witchcraft.nu/strength-analysis-of-witchcraft-sandwich-composite-boards-david-cadel-compares-heel-area-and-bottom-areas/

The reason why surfboards have stringers is to be able to shape the blank without it bending too much. Once it is laminated the stringer hardly makes a difference in strength.

For boards without a sandwich lay-up I use 20 or 25kg/m?.

Would be nice if there was some material similar to say 15-20 density EPS which either could be heated to say 70C to become liquid or was made of some food starch. Imagine you CNC it, build a board then flip the board and heat it up and the entire core is drained leaving a hollow board. Plus the drained liquid can be re-foamed. Or in case of some starch-like material you open the pressure valve, put the board in an anthill and a week later, you get a hollow board.
I think that if the EPS core can be easily removed, it will make all boards about 1.5-2kg lighter and eliminate the problem of water in the core.

Maybe it could charge your electric car at the same and the waste product is beer.

Once you drink all the beer out of it , I'd like IPA please , the board would collapse like a crushed beer can . To stop this happening you could fill it with a lightweight foam .

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leto said..
Would be nice if there was some material similar to say 15-20 density EPS which either could be heated to say 70C to become liquid or was made of some food starch. Imagine you CNC it, build a board then flip the board and heat it up and the entire core is drained leaving a hollow board. Plus the drained liquid can be re-foamed. Or in case of some starch-like material you open the pressure valve, put the board in an anthill and a week later, you get a hollow board.
I think that if the EPS core can be easily removed, it will make all boards about 1.5-2kg lighter and eliminate the problem of water in the core.

Dissolving the core after sandwich laminating has been tried before as I recall. Just pour styrene monomer into it an dissolve, flush out the EPS core. It didnt catch on.

I used this stuff once. Thinnest is 5mm though.
local.armacell.com/en/armaform-pet-foam-cores/products/armaform-core/

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Witchcraft said..
The reason why surfboards have stringers is to be able to shape the blank without it bending too much. Once it is laminated the stringer hardly makes a difference in strength.

For boards without a sandwich lay-up I use 20 or 25kg/m?.

Finally somebody else said it!!! (not stronger, that is) The surfboard guys seem to still cling to it though.

I use 28kg EPS for kiteboards and shape all in one go down to 2" centre and 1/4" ends with no problems. Yes it bends but it just needs care.
Once the bottom is glassed, then vac the deck with a rocker spine. Nobody needs stringers, and some are putting mega effort into halving EPS blanks to glue in divinycell stringers etc. Painful.

Agree with the WS boards - bag bottom first then shape deck. I've seen some instructionals that show a full shape then making a rocker table and bagging the bottom on using the table. OMG wayyy too much unnecessary stuff.

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Mark _australia said..

Finally somebody else said it!!! (not stronger, that is) The surfboard guys seem to still cling to it though.

It is quite easy to understand this as well. The stringer still is more flexible than glass and will not take force until the glass is broken. And when the glass has broken, the stringer will also easily snap. A stringer standing upright seems stiff compared to a flat lying sheet of wood. But that is the wrong comparison. Even upright it actually still is pretty easy to bend. But I do understand that without the stringer, the blank is a lot more flexible and much harder to shape accurately, either by hand or CNC. To then claim it is for strength is BS, but that doesn?t change the fact it is needed for shaping and stays in the board anyway.

I used to think a stringer would help in strength but see the light . I still use a very thin 3 ply pine stringer for shaping purposes . I'm strange , I start with the stringer as a finished sized template . Easy to get the rocker perfect . It makes shaping the bottom easy . It helps get the V or concaves perfect down the centreline , ( no overshaping ) . It also helps to get the tips right . So for me as a hack bacyarder , it definitely helps , I'm ok with the slight weight .
ps , that super lightweight honeycomb sandwich panel looks interesting . Probably not fun for repairing . I've fondled it and it's so stiff and strong and has no weight . Is it a option ?

i guess everyone has their own method. one mate uses a stringer to stop the board loosing rocker during vac bagging. another uses a spine.
both have told me you don't need a traditional stringer but are in favour of a carbon tape stringer on the rails.

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Gestalt said..
both have told me you don't need a traditional stringer but are in favour of a carbon tape stringer on the rails.

It's going round and round in circles . Some say it's pointless mixing carbon with glass. Carbon will break before glass . Kinda like the board breaking before the wood stringer adds stiffness .So wouldn't it be the same with carbon rails , unless you make the carbon rails thick enough with carbon to take all the strain ? Then the glass on the rails only adds weight . I'm even wondering if carbon patches under heels is better than glass . The science says no. I suppose in this instance , do fibres break with heel indentations ? If they do then carbon doesn't make sense. Unless you have enough carbon layers to take all the strain . If fibres don't break and it's about the lam flexyness , how much less flex in a layer of carbon vs glass . I'd think if you laminated a 4 oz layer of glass and carbon test piece by itself , bending it in your hand would be similar . I'm not talking of bending it at right angles ( they would feel different ) but just slightly bending a couple deg like a heel indentation would be .So how does this make sense under heels ? It obviously does because everyone does it , including me , but science still says nooo. To me it seems thickness of layers giving a thicker resin block doing the work under heels apposed to what type of cloth . I must be missing something . ???