Select to expand quote

Mark _australia said..
I think your layup is good as basalt is essentially like S-glass. However, I'd go an extra deck patch rear half, and an extra foot patch.

Stringer won't add strength so leave it out....?

Is the US box made by futures? if so, those tend to break with hi side loading they're only good for SUP and longboard. Get a Chinook if you can. Bonus is you can get one with vent incorporated.

do you think the futures would be weak as a fin box with woodies installed?

Select to expand quote

NicoDC said..

Gestalt said..
Update time.
i've ordered and received a bunch of stuff for the build. the hold up is the bio resin which is out of stock and won't be available till december. the result of covid so things on hold till the resin is available.

what i've got so far..

The eps core above is 100% recycled eps made locally. i've since found out surfboard grade 100% eps it's not available anymore from my local source. future boards will be part recycled.

The cloth is from sanded, and a mix of 4.5oz biax basalt, 4oz basalt and 3oz PET made in Australia from imported materials.
The 3mm end grain balsa being used as the sandwich core is made in NSW from local and imported balsa.

i've never used any of these cloths.
Planned layup is below. no vac bagging.

bottom
4.5ox biax + 4oz basalt + 3oz PET

deck
4.5oz biax + 4oz basalt
3mm balsa end grain
4.5oz biax + 3oz PET

nose
4.5oz biax

feet patches
QLD sourced 0.6mm hoop

rails
basalt rail tape

stringer from finbox to mast track
basalt rail tape

Also have a mix of 5 and 2 screw footstrap plugs made locally
A futures us box for the fin because they are designed to work with layup over the top. (no eco points there)
mast track is a chinook (no eco points there)

Thanks for the info & good luck with the build!
I do wonder why not using a vac?

Here in Europe we have a fabric called "Lin Natural UD" to replace fiberglas. It should also improve the strength of carbon. Ever heard of it?

i'm not sure what fabric that is but am thinking its flax of some description. flax fabric is available in australia but i decided not to use it because i read it soaks up resin and isn't as strong as basalt. seem to be more suited to vac bagging.

i decided not to vac bag because i didn't want to leave a pump going for 6 hours and i'm trying to keep waste down by not using peel ply and plastic bags.

Yes Lin is flax. Lin UD is just uni directional flax. The UD stuff soaks up resin and is furry if you don't bag it or poor man's bag it. The woven flax is easier to use and dosnt need bagging. Again it depends on the brand. Some are really tight and like glass to use and some are still a bit furry.

Select to expand quote

Gestalt said.. do you think the futures would be weak as a fin box with woodies installed?

I really don't know. It would have to be stronger of course but I find the break occurs in a moulding join between the sides and base where the head of the Finn sits. May still be weaker.
btw I deleted a couple of lines by mistake - no vented fin boxes haha haha I was referring to chinook mast tracks just as an aside lol

Bugger about the futures box. I'll use a chinook. Thx for the heads up.

Hi guys,
Some interesting information and links in this thread.
I have a friend who is a hobby shaper and environmentalist. He?s tried lots of this stuff on surfboards. But each time he says it came out far too heavy or it didn?t last and his conclusion each time is that the best way is to make it last. A windsurfboard made with flax and "BIO" resin needs to weigh over 10kgs to make it last half as long. And it still will have EPS, etc to end up in the landfill. Plus all the work that has gone into making it.
Also if you will use just one component that is weaker (including a fin box) which then leads to the whole board to last less long, is the wrong way. Any product is only as strong as it?s weakest component.
Also the so called "BIO" resins only contain 20-40% plant based resin, the rest is still oil based epoxy. But is is also 20-40% (from memory) less strong. An interesting article from people who are selling "BIO" resins themselves: www.seabase.eu/article/epoxy-resin-is-bio-the-right-way/

What I also find concerning is the use of mixed fabrics like carbon-aramid or carbon innegra. Carbon has a far higher modulus and far lower elongation at break. So the carbon will take most to nearly all of the force but there is only 50% of it. And once the carbon has broken, there is also just 50% aramid or Innegra left. Plus to repair it is not really well possible. If you mix materials you need to use materials with similar stiffness so they co-operate or where you do mix materials, you need to make sure that of the stiffest material alone there is enough to take the whole load. If a steel cable is not strong enough to lift a weight, you are not going to reinforce it with a piece of elastic. And you will not combine slicks with off road tires under a car. Just E-glass is as good as carbon-aramid, costs 10% and is far easier repairable. It just doesn?t sound as fancy. And carbon-innegra is even worse.
Dyneema is twice as impact resistant but also considerably stiffer than aramid and the elongation at break is similar to glass. I also chose the resin to have a similar elongation. Where I use carbon for higher compression strength, I place it on the outside so if it does break on impact (**** happens), it is easy to replace. The Dyneema underneath will greatly limit any more (internal) damage. I have repaired boards where a thin carbon was under the Dyneema. Various cracks in the carbon from impacts from the mast, feet and rocks but impossible to repair well as the Dyneema had to be removed over bigger areas to repair the carbon but (like with aramid or innegra) you can?t patch Dyneema again.

Even if a windsurf board is completely oil based, if you make it to last, it is very little compared to what each of us consumes in fuel.
People can and have been trying this in our shop for them selves as well:

^^^^
Interesting stuff.

Select to expand quote

Witchcraft said..
Hi guys,
Some interesting information and links in this thread.
I have a friend who is a hobby shaper and environmentalist. He?s tried lots of this stuff on surfboards. But each time he says it came out far too heavy or it didn?t last and his conclusion each time is that the best way is to make it last. A windsurfboard made with flax and "BIO" resin needs to weigh over 10kgs to make it last half as long. And it still will have EPS, etc to end up in the landfill. Plus all the work that has gone into making it.
Also if you will use just one component that is weaker (including a fin box) which then leads to the whole board to last less long, is the wrong way. Any product is only as strong as it?s weakest component.
Also the so called "BIO" resins only contain 20-40% plant based resin, the rest is still oil based epoxy. But is is also 20-40% (from memory) less strong. An interesting article from people who are selling "BIO" resins themselves: www.seabase.eu/article/epoxy-resin-is-bio-the-right-way/

What I also find concerning is the use of mixed fabrics like carbon-aramid or carbon innegra. Carbon has a far higher modulus and far lower elongation at break. So the carbon will take most to nearly all of the force but there is only 50% of it. And once the carbon has broken, there is also just 50% aramid or Innegra left. Plus to repair it is not really well possible. If you mix materials you need to use materials with similar stiffness so they co-operate or where you do mix materials, you need to make sure that of the stiffest material alone there is enough to take the whole load. If a steel cable is not strong enough to lift a weight, you are not going to reinforce it with a piece of elastic. And you will not combine slicks with off road tires under a car. Just E-glass is as good as carbon-aramid, costs 10% and is far easier repairable. It just doesn?t sound as fancy. And carbon-innegra is even worse.
Dyneema is twice as impact resistant but also considerably stiffer than aramid and the elongation at break is similar to glass. I also chose the resin to have a similar elongation. Where I use carbon for higher compression strength, I place it on the outside so if it does break on impact (**** happens), it is easy to replace. The Dyneema underneath will greatly limit any more (internal) damage. I have repaired boards where a thin carbon was under the Dyneema. Various cracks in the carbon from impacts from the mast, feet and rocks but impossible to repair well as the Dyneema had to be removed over bigger areas to repair the carbon but (like with aramid or innegra) you can?t patch Dyneema again.

Even if a windsurf board is completely oil based, if you make it to last, it is very little compared to what each of us consumes in fuel.
People can and have been trying this in our shop for them selves as well:

Do you have some links with details about how well Epoxies or other resins adhere to the Dyneema fabric?

I agree with the bio stuff but not this combination fabric stuff. Bourke you really know your stuff and I've heard you speak about carbon-innegra and CK before, but it seems that in real world experience it works. The boards with a carbon-innegra deck particulary with wood reinforcement just last. It seems its the impact strength advantage.

The problem is, we can't buy dyneema / spectra cloth anywhere and you're lucky you can. We can't get Textreme. All we have is innegra or recycled PET made for surfboards.
If you can tell me where to buy dyneema cloth in small qty I'd be ecstatic.


Then the other problem is when choosing a factory board from a large manufacturer (which is what 90% of sailors have to do) they don't offer Dyneema and similar..... you get glass and carbon with sometimes other materials. There is a massive difference in glass, the chinese stuff is a LOT weaker than direct sized (non heat treated) E glass made in Australia and USA specifically for surf use. What are we getting in our factory boards? Who knows, but I bet its the cheap ****. But we do know that proper 200gsm carbon-kevlar or carbon-innegra over wood is going to make a bloody tough deck. You can't get fake stuff and if you can see it over the whole board you know its there. No black-tinted resin trickery. So if I was buying a factory waveboard, I know what I'd be looking at.... the RRD / Tabou / Fanatic carbon-innegra construction that lasts. If we could still get it, the Starboard wood-carbon was awesome durability.
Starboard bio stuff now with flax and balsa -no way

Select to expand quote

Mark _australia said..
I agree with the bio stuff but not this combination fabric stuff. Bourke you really know your stuff and I've heard you speak about carbon-innegra and CK before, but it seems that in real world experience it works. The boards with a carbon-innegra deck particulary with wood reinforcement just last. It seems its the impact strength advantage.

The problem is, we can't buy dyneema / spectra cloth anywhere and you're lucky you can. We can't get Textreme. All we have is innegra or recycled PET made for surfboards.
If you can tell me where to buy dyneema cloth in small qty I'd be ecstatic.


Then the other problem is when choosing a factory board from a large manufacturer (which is what 90% of sailors have to do) they don't offer Dyneema and similar..... you get glass and carbon with sometimes other materials. There is a massive difference in glass, the chinese stuff is a LOT weaker than direct sized (non heat treated) E glass made in Australia and USA specifically for surf use. What are we getting in our factory boards? Who knows, but I bet its the cheap ****. But we do know that proper 200gsm carbon-kevlar or carbon-innegra over wood is going to make a bloody tough deck. You can't get fake stuff and if you can see it over the whole board you know its there. No black-tinted resin trickery. So if I was buying a factory waveboard, I know what I'd be looking at.... the RRD / Tabou / Fanatic carbon-innegra construction that lasts. If we could still get it, the Starboard wood-carbon was awesome durability.
Starboard bio stuff now with flax and balsa -no way

From Starboard's website talking about the 2021 Kode. So, this is a good thing?

"WOOD SANDWICH OUR LOWEST CARBON FOOTPRINT TECHNOLOGY Deck is Full 0.6mm Australian Pine Wood on 3mm H100 PVC to ensure durability and comfort in a good weight ratio. The Wood will be less visible this time and protect by a nice blue paint which gives a really nice effect. Let's go back to Starboard origin with Class."

Yep. I wish Starboard would bring back the Wood construction in the slalom/speed range. All my very well used Wood Isonics (some over 10 years old) are still perfectly sound, have held their shapes perfectly and are watertight. Even the 2008 model IS87, where the deck wood has faded quite a bit and the paint is worn off the bottom, is still going strong. The saving a 250 to 500grams of weight is neither here nor there as far as performance goes, even if it as much as a whole KG!! They are also the best damped, most comfortable EPS core boards I have ever ridden. Comfort = confidence = faster.

Show me a well used, high milage full carbon Isonic (circa 2013-4 on?) that is sound, watertight and still going strong without extensive patches and repairs, andI will show you my pet Unicorn.

Select to expand quote

sailquik said..



Do you have some links with details about how well Epoxies or other resins adhere to the Dyneema fabric?

No, I don?t think there is any. I am working with Dyneema since 26 years now and had to find everything out myself. Some 20 years ago I accidentally found a method that bonds very well. By trying to peel it off, you break pieces of PVC out. I also tried different treatments like Corona (a chemical) or Plasma (the fabric is bombarded with electrons) but these treatments only lasted a few weeks and then ended up worse. Expensive experiments if you have a whole roll done like this. I have had people from F1 and other industries like ballistic protection looking for info. Since many years I have my Dyneema (or UHMWPE) fabric specially made for me. Weave type and such also makes a difference. Dyneema can still delaminate because it simply is a whole lot stronger than resin. But to restore the bond is easy by injecting a bit of heated resin.

Select to expand quote

Witchcraft said..
Hi guys,
Some interesting information and links in this thread.
I have a friend who is a hobby shaper and environmentalist. He?s tried lots of this stuff on surfboards. But each time he says it came out far too heavy or it didn?t last and his conclusion each time is that the best way is to make it last. A windsurfboard made with flax and "BIO" resin needs to weigh over 10kgs to make it last half as long. And it still will have EPS, etc to end up in the landfill. Plus all the work that has gone into making it.
Also if you will use just one component that is weaker (including a fin box) which then leads to the whole board to last less long, is the wrong way. Any product is only as strong as it?s weakest component.
Also the so called "BIO" resins only contain 20-40% plant based resin, the rest is still oil based epoxy. But is is also 20-40% (from memory) less strong. An interesting article from people who are selling "BIO" resins themselves: www.seabase.eu/article/epoxy-resin-is-bio-the-right-way/

What I also find concerning is the use of mixed fabrics like carbon-aramid or carbon innegra. Carbon has a far higher modulus and far lower elongation at break. So the carbon will take most to nearly all of the force but there is only 50% of it. And once the carbon has broken, there is also just 50% aramid or Innegra left. Plus to repair it is not really well possible. If you mix materials you need to use materials with similar stiffness so they co-operate or where you do mix materials, you need to make sure that of the stiffest material alone there is enough to take the whole load. If a steel cable is not strong enough to lift a weight, you are not going to reinforce it with a piece of elastic. And you will not combine slicks with off road tires under a car. Just E-glass is as good as carbon-aramid, costs 10% and is far easier repairable. It just doesn?t sound as fancy. And carbon-innegra is even worse.
Dyneema is twice as impact resistant but also considerably stiffer than aramid and the elongation at break is similar to glass. I also chose the resin to have a similar elongation. Where I use carbon for higher compression strength, I place it on the outside so if it does break on impact (**** happens), it is easy to replace. The Dyneema underneath will greatly limit any more (internal) damage. I have repaired boards where a thin carbon was under the Dyneema. Various cracks in the carbon from impacts from the mast, feet and rocks but impossible to repair well as the Dyneema had to be removed over bigger areas to repair the carbon but (like with aramid or innegra) you can?t patch Dyneema again.

Even if a windsurf board is completely oil based, if you make it to last, it is very little compared to what each of us consumes in fuel.
People can and have been trying this in our shop for them selves as well:

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.

Select to expand quote

Mark _australia said..
I agree with the bio stuff but not this combination fabric stuff. Bourke you really know your stuff and I've heard you speak about carbon-innegra and CK before, but it seems that in real world experience it works. The boards with a carbon-innegra deck particulary with wood reinforcement just last. It seems its the impact strength advantage.

The problem is, we can't buy dyneema / spectra cloth anywhere and you're lucky you can. We can't get Textreme. All we have is innegra or recycled PET made for surfboards.
If you can tell me where to buy dyneema cloth in small qty I'd be ecstatic.


Then the other problem is when choosing a factory board from a large manufacturer (which is what 90% of sailors have to do) they don't offer Dyneema and similar..... you get glass and carbon with sometimes other materials. There is a massive difference in glass, the chinese stuff is a LOT weaker than direct sized (non heat treated) E glass made in Australia and USA specifically for surf use. What are we getting in our factory boards? Who knows, but I bet its the cheap ****. But we do know that proper 200gsm carbon-kevlar or carbon-innegra over wood is going to make a bloody tough deck. You can't get fake stuff and if you can see it over the whole board you know its there. No black-tinted resin trickery. So if I was buying a factory waveboard, I know what I'd be looking at.... the RRD / Tabou / Fanatic carbon-innegra construction that lasts. If we could still get it, the Starboard wood-carbon was awesome durability.
Starboard bio stuff now with flax and balsa -no way

wood and fiberglass has been my favorite construction for years now and that combination is pretty much Bullet proof. not hammer proof

Select to expand quote

Mark _australia said..
I've heard you speak about carbon-innegra and CK before, but it seems that in real world experience it works. The boards with a carbon-innegra deck particulary with wood reinforcement just last. It seems its the impact strength advantage.

The problem is, we can't buy dyneema / spectra cloth anywhere and you're lucky you can. We can't get Textreme. All we have is innegra or recycled PET made for surfboards.
If you can tell me where to buy dyneema cloth in small qty I'd be ecstatic.


Then the other problem is when choosing a factory board from a large manufacturer (which is what 90% of sailors have to do) they don't offer Dyneema and similar..... you get glass and carbon with sometimes other materials. There is a massive difference in glass, the chinese stuff is a LOT weaker than direct sized (non heat treated) E glass made in Australia and USA specifically for surf use. What are we getting in our factory boards? Who knows, but I bet its the cheap ****. But we do know that proper 200gsm carbon-kevlar or carbon-innegra over wood is going to make a bloody tough deck. You can't get fake stuff and if you can see it over the whole board you know its there. No black-tinted resin trickery. So if I was buying a factory waveboard, I know what I'd be looking at.... the RRD / Tabou / Fanatic carbon-innegra construction that lasts. If we could still get it, the Starboard wood-carbon was awesome durability.
Starboard bio stuff now with flax and balsa -no way

Well, I have about 12 different spots (most of them with rocks) within a 10 to max 20 mins drive (see a selection here: witchcraft.nu/fuerteventura/spots/) from our workshop and quite a few locals and visitors sailing here are bringing their gear to repair. How much more real world experience do you want? Most brands will not have a repair shop themselves so they will hardly see what is happening with their own gear. There are hardly any locals using production boards unless they can get them somewhere very cheap. But we get visitors and PWA guys with regular production boards bringing them in to repair and this is where we?ve seen carbon-innegra or carbon-kevlar failing. And in the early years working with Carbon-Kevlar myself, I already noticed there was a problem.
Wood is not bad but it is only strong in one direction, impact resistance is far less than Dyneema and it absorbs water. Nowadays you hardly see it in boards anyway. Wood is nice for making surfboards. You can vacuum it in one go between 2 glass laminates. Not too hard to make but lots more durable than regular surfboards. I?ve made Dyneema sandwich surfboards and long boards which are still in use after more than 20 years and lighter than regular boards. But they also cost 3 times as much.It can take a week or 2 to get stuff transported here to the Canary Islands but in Europe everything is available. I understand that in Australia with a far smaller population, you are very limited to what is available.

Select to expand quote

Orange Whip said.. From Starboard's website talking about the 2021 Kode. So, this is a good thing?
"WOOD SANDWICH OUR LOWEST CARBON FOOTPRINT TECHNOLOGY Deck is Full 0.6mm Australian Pine Wood on 3mm H100 PVC to ensure durability and comfort in a good weight ratio. The Wood will be less visible this time and protect by a nice blue paint which gives a really nice effect. Let's go back to Starboard origin with Class."

Yes that's a good thing. Especially 100kg sandwich layer (more often 80kg), and pine is around 500kg. Seems they realised their previous mistake of not enough material over the wood (= sun damage and water ingress) so thats nice
Flip side is it's a real cheap construction so is it cheaper..... or still $3K for a board

Select to expand quote

Mark _australia said..

If you can tell me where to buy dyneema cloth in small qty I'd be ecstatic.

Have a look for a company called Jeely on Aliexpress - I am a noob so cannot post a link. I have bought 125gsm and 90gsm 200 denier UHMWPE fabric. There are many other Chinese companies that produce it. Jeely is actually really quite expensive in comparison, but the quality is better. I have bought it direct from 3 different companies now but have never been able to persuade Dyneema themselves to sell me any. The fabric I have used is tightly woven and needs coaxing to absorb resin. I have found the thinner fabric easier to wet out, but it is much less stable. It is also plain weave so does present some issues going round the rails. You cannot sand laps flat and cutting it cured with a knife is nigh on impossible, it is much more difficult to use than aramids.

I have no idea whether it is anything like Witchcraft's fabric I have never seen theirs in the flesh, but it works just fine. You will need to figure out how to bond it and there are different tricks. I use a different technique to Witchcraft's and I couldn't replicate their very special technique even if I tried.

Select to expand quote

sailquik said..


Do you have some links with details about how well Epoxies or other resins adhere to the Dyneema fabric?

I haven't found any info on this. All my knowledge is empirical. But there is some info out there about the properties of UHMWPE fabric - specifically its tensile strength and elongation at breakage. It is important to remember that UHMWPE is used as a self lubricating plastic in moving parts for a reason, so bonding is always going to be the difficult bit.

UHMWPE is far from ideal for composites, but it does have some very special characteristics and if you can overcome the short comings it is very interesting to use.

To be honest, glass fibre remains the most versatile fabric to use and is actually environmentally not that bad. It is comparable to flax fabric in terms of environmental credentials and requires less energy to produce.

Select to expand quote

Overner said..
To be honest, glass fibre remains the most versatile fabric to use and is actually environmentally not that bad. It is comparable to flax fabric in terms of environmental credentials and requires less energy to produce.

That's what I would have thought, given that is silicon.

basalt cloth has a marginally better footprint than glass from what i have read. that's comparing apples with apples. if anyone can find locally produced glass cloth that may be better.

i found a source for hemp cloth that's australian grown and made.

hempco.net.au/product/100-hemp-lightweight-fabric/

Have you looked into this.
www.sanded.com.au/collections/surfboard-fibreglass/products/pet-surfboard-cloth-3oz-made-from-recycled-plastic-bottles
If you take into the account of growing and processing the flax it has a bigger carbon footprint than glass apparently. I did a innegra then flax bottom on a SUP and it is really ding proof though.
Still can't find basalt in France. Apparently Colan have sent some to a company here but they aren't selling it yet.

I've been dealing with John at Sanded for a few years . He's a nice guy and knows his products . Easy to talk to.
I asked about his fancy stuff and he said , for me , stick with the glass , We were talking of performance for dollar not eco. Even then glass is hard to beat. His glass is the good stuff . If I were to go carbon, cost goes through the roof for little overall weight saving .
Knock a kilo off.
Not to mention fragile.
A stronger longer lasting plain glass and resin board would have to be more eco friendly.

I had a few similar conversations with composite companies in the UK. They said pretty much the same. The carbon footprint of producing glass is relatively small.
I have found some aviation standard glass in Germany that I think i will try next if I can't get basalt.

@tarquin1, I've got the pet cloth from sanded here with me.

on the glass v flax conversation i find it really interesting. i've found snippets of research comparing the 2. i read both being better than the other.

this is one snippet in favour of flax

The existing LCA studies revealed that natural fiber composites have superior environmental performance than composites with synthetic fiber or resin. However, cradle-to-gate LCA studies of flax, as an agrochemical-based material, and glass by Dissanayake et al. [321,322] reported that flax sliver is comparable in energy terms to glass fiber mat, and continuous glass fiber reinforcement appears to be superior from an environmental energy point of view to spun flax yarn.

The extract above refers to traditional farming methods with chemicals, tractors watering etc. not all flax or hemp is grown that way. some is organically produced. it also identifies the way the cloth is made has a big impact.

the other point i've mentioned a few times is locally produced products versus imported. imported raw materials just can't compete against locally acquired. if there is a local supply of fiberglass v an imported supply of flax then flax is far worse. interestingly i also had a conversation with John where i told him i was specifically coming from an eco position. for windsurfers he wasn't pushing flax to me. he did suggest the PET cloth and directed me to testing he had done when it's mixed with glass. he was well across the extra structural needs of a windsurfer as he supplied some manufacturers. glass v basalt he pointed out how either one can substitute the other. my own research puts basalt slightly in front of glass. but both are made from imported yarn in australia.

i'm also interested in working safe. what am i breathing and touching. that is a real issue for me. the more natural the better.

Here is my supply of pet and basalt cloths.

I noticed today sanded has 30" basalt cloth in stock

I like your research and thinking Gestalt.

As alluded to already, I think it important to remember that the integrety of a composite matrix will be very greatly influenced by the adhesion of the resin to the reinforcement. The traditional Glass's, Aramids and Carbons do very well in combination with epoxies. I have not seen any data yet about Basalt and Flax, but they seem to be at least in the ballpark. I am much more concerned with PET and especially Dyneems/Spectra as it's well known that not very much at all will adhere to UHMWPE = Polyethelene = same stuff as Tupperware, rotomoulded Plastic Windsurfers and Kayaks. Try repairing them with Epoxies! No chemical bond. Best you can do is get a mechanical bond, but even that is pretty iffy.

Obviously, Witchcraft has made it work, but I am sure it is not simple or easy.

Gestalt, are Colan glass fabrics made with locally produced glass yarn? I know their surfboard fabrics are among the very strongest, but not always used by surfboard builders who sometimes favour more supple impoted cloths at the expense of ultimate strength.

here's what i was told for cloth from sanded. obviously this was a point in time and may change but forms the basis of why sanded cloth is higher quality than imported cloths.

eglass - germany
sglass - usa
basalt - usa
PET - usa
flax - germany

so currently the most eco product is probably the 4.5oz hemp from WA.

PET cloth seems to bond ok. sanded tested it with their glass cloth and it improved the load before failure. they have a graph on their website that john directed me to when i spoke with him.

yes some surfboard AND windsurfer manufacturers are using the cheaper poorer quality cloth.

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.

This is a paddle blade I made. Cork core,Paulownia veneers and flax. Vac bagged with PU glue. Held its shape and was very strong.
I wanted to do a board like this. But never got around to it. No epoxy.