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Mark _australia said..
It doesn't matter that the bottom is nearly flat Bourke!! the board in cross section is much closer to a cylinder than a piece of flat wood or foam is
that gives it rigidity, and it IS a cylinder in engineering terms. Not a perfect cylinder, but structurally it is more like a cylinder than a flat foam blank is - due to the sandwich layer.
bit like how corrugated steel works - and it matters not that it is almost flat. It still stronger and stiffer. so not it is not perfectly round but it does have qualities closer to a cylinder than a bit if flat foam. That's the point

And the longitudinal curve (rocker curve) adds some stiffness to a nearly flat cross section bottom. Add sandwich to that in it can be super stiff.

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Mark _australia said..
It doesn't matter that the bottom is nearly flat Bourke!!

Yes, it does. For the durability of a board it does matter. A corrugated sheet of steel has many times more shape than the bottom of a windsurf board. As I explained extensively before, it is because of the bottom flexing inward that boards break. And because it hardly gets any flexural strength/stiffness from a cylindrical or other type of profiled shape, it needs to be made stiffer in another way. But have it as you want it if you think it is otherwise. I was trying to give some advice for building a more environmentally friendly board, which I always think is a good initiative. Have you actually noticed that I give 3 years guarantee on our HDD construction and the weights of these boards?

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Bouke-Witchcraft said..

Mark _australia said..
It doesn't matter that the bottom is nearly flat Bourke!!

... Have you actually noticed that I give 3 years guarantee on our HDD construction and the weights of these boards?

I was wondering when the sale pitch would start, this sounds familiar! But besides that, of course adding a flat surface to an open beam of any shape or material would add structural strength! Take a rectangular tube, cut off its bottom, and compare. Take a sailboat, cut off its very flat deck and see what happens.

It makes no sense to think about the bottom and top of a windsurf as separate entities. We are effectively riding a rocker-ed and tapered cylinder-oid, and any navigational stress distributes on its entire 3D surface. It would be the ideal form for hollow construction if it wasn't for the small size ... if we could only enroll elfs to help building it! Where's Dobby when you need him?

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duzzi said..

Bouke-Witchcraft said..

Mark _australia said..
It doesn't matter that the bottom is nearly flat Bourke!!

... Have you actually noticed that I give 3 years guarantee on our HDD construction and the weights of these boards?

I was wondering when the sale pitch would start, this sounds familiar! But besides that, of course adding a flat surface to an open beam of any shape or material would add structural strength!

Sorry, I didnt know how else to convince him that I know a thing or 2 about board making. Off course in Australia it is common to get 3 years guarantee.
Yes, just untill the flat surface collapses-folds-buckles-creases inward in between the 2 vertical "webs" (rails) because of a local perpendicular force. When that happens, all the force goes to the outer edge of the web or rail, which isnt enough and also buckles. How many broken boards have you examined or repaired? Just already each summer when the PWA lands here, during a few weeks training and then competing, the PWA guys take turns in driving up to bring broken boards and to collect repaired ones. Either with broken heel areas or creased bottoms. When the inside laminate hasnt broken, what we do is to fill up the folded inward area and concave jumping side with various layers of alternating carbon and glass to add stiffness and bring back the shape to its original state. That can be 10 to 20 layers to fill up various millimeters, the biggest first than each layer a bit smaller. We do the same with slalom boards that have gone concave with a negative rocker and become slower as a result.

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Bouke-Witchcraft said..

duzzi said..

Bouke-Witchcraft said..

Mark _australia said..
It doesn't matter that the bottom is nearly flat Bourke!!

... Have you actually noticed that I give 3 years guarantee on our HDD construction and the weights of these boards?

I was wondering when the sale pitch would start, this sounds familiar! But besides that, of course adding a flat surface to an open beam of any shape or material would add structural strength!

Sorry, I didnt know how else to convince him that I know a thing or 2 about board making. Off course in Australia it is common to get 3 years guarantee.
Yes, just untill the flat surface collapses-folds-buckles-creases inward in between the 2 vertical "webs" (rails) because of a local perpendicular force. When that happens, all the force goes to the outer edge of the web or rail, which isnt enough and also buckles. How many broken boards have you examined or repaired? Just already each summer when the PWA lands here, during a few weeks training and then competing, the PWA guys take turns in driving up to bring broken boards and to collect repaired ones. Either with broken heel areas or creased bottoms. When the inside laminate hasnt broken, what we do is to fill up the folded inward area and concave jumping side with various layers of alternating carbon and glass to add stiffness and bring back the shape to its original state. That can be 10 to 20 layers to fill up various millimeters, the biggest first than each layer a bit smaller. We do the same with slalom boards that have gone concave with a negative rocker and become slower as a result.

no one is questioning your experience making boards or respect in the industry Bourke. for sure you have added a massive amount to this conversation bringing a different perspective. what's being questioned are the theories you are putting forward to explain your findings.

like the others have said i think it is still within topic talking about non eco boards and construction ideas. Comparing materials and techniques is vitally important.

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Mark _australia said..
It doesn't matter that the bottom is nearly flat Bourke!! the board in cross section is much closer to a cylinder than a piece of flat wood or foam is
that gives it rigidity, and it IS a cylinder in engineering terms. Not a perfect cylinder, but structurally it is more like a cylinder than a flat foam blank is - due to the sandwich layer.
bit like how corrugated steel works - and it matters not that it is almost flat. It still stronger and stiffer. so not it is not perfectly round but it does have qualities closer to a cylinder than a bit if flat foam. That's the point

this is a great comment mark. same goes for metal flashings. folds and creases are used to add strength and prevent oil canning.

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Bouke-Witchcraft said..

Mark _australia said..
It doesn't matter that the bottom is nearly flat Bourke!!

Yes, it does. For the durability of a board it does matter. A corrugated sheet of steel has many times more shape than the bottom of a windsurf board. As I explained extensively before, it is because of the bottom flexing inward that boards break. And because it hardly gets any flexural strength/stiffness from a cylindrical or other type of profiled shape, it needs to be made stiffer in another way. But have it as you want it if you think it is otherwise. I was trying to give some advice for building a more environmentally friendly board, which I always think is a good initiative. Have you actually noticed that I give 3 years guarantee on our HDD construction and the weights of these boards?

when you say "stiff in another way." would a more eco friendly method to be to add a stringer. the problem with carbon fiber is it is excessively bad for the environment. there are moves globally to remove carbon fiber from land fill sites because it just does not break down. add to that it being made from oil and it's probably the worst material you could put in an eco board. whilst i can't find the data i'd guess dyneema is on the same page.

making boards to last doesn't really help either. after 30 years a boards design is past tense and it will end up at the tip, in the landfill, and never breaking down if made from plastics.

It's common thought that boards made with eps, non bio resin, carbon fiber and dyneema are about as bad as we can get when it come to the planet. it would be great if anyone knows sven rasmussen or any of the fanatic guys if they would be able to come and add their experience building more sustainable boards.

below are some embodied energy figures.

Building a board yourself and trying to be environmentaly friendly and companies mass producing being environmentaly friendly are very different.
I think you have the right idea to source locally and build a board. Don't make it too complicated.

The carbon footprint of our sport is practically zero compared to the damage we all spew out on a daily basis .
There are much better ways to save the planet. The thing is , almost nobody cares . I want a clean planet but I drive a big old car , so who am I to point a finger . When I produce two rubbish bins full of crap making a board it makes me sad . But the fact is , I fill my bin every week with general crap anyway . If I made a board with eco materials I still make the same two bins full of rubbish , only fractionally healthier rubbish ?
I want the idea of eco healthy , and it has to be talked about , ideas thrown around , but to me , at the moment , the maths doesn't add up . In lots of cases actually goes in reverse in the name of saving the planet. For instance , producing cork sheet is way worse than fizzing a matchbox full of petro chemical to make foam sheet . And as far as cork vs foam in landfill , there is no difference once saturated with whatever resin .
We are on a one way road to killing ourselves . Sadly , we're stuffed , I don't think we will better things only slow it down a little .
Sorry about the downer .
I need to go sailing to make me happy again .

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Imax1 said..
The carbon footprint of our sport is practically zero compared to the damage we all spew out on a daily basis .
There are much better ways to save the planet. The thing is , almost nobody cares . I want a clean planet but I drive a big old car , so who am I to point a finger . When I produce two rubbish bins full of crap making a board it makes me sad . But the fact is , I fill my bin every week with general crap anyway . If I made a board with eco materials I still make the same two bins full of rubbish , only fractionally healthier rubbish ?
I want the idea of eco healthy , and it has to be talked about , ideas thrown around , but to me , at the moment , the maths doesn't add up . In lots of cases actually goes in reverse in the name of saving the planet. For instance , producing cork sheet is way worse than fizzing a matchbox full of petro chemical to make foam sheet . And as far as cork vs foam in landfill , there is no difference once saturated with whatever resin .
We are on a one way road to killing ourselves . Sadly , we're stuffed , I don't think we will better things only slow it down a little .
Sorry about the downer .
I need to go sailing to make me happy again .

to be fair. whilst this may be true for some it isn't the case for everyone and especially not me

for example,

i drive a car that i bought because it had the best fuel economy i could find and afford at the time and i use e10 fuel
i buy second hand gear regularly
fix broken gear
i recycle, reuse and compost in my every day life,
catch public transport daily.
use 100% green power at my home
buy organic food
have reduced meat consumption significantly
harvest rain water for plants,
grow my own veggies from time to time
started replacing garden tools with battery powered
used rechargeable batteries around the house
i don't remember the last time i had a new phone. i use all the second hand hand me downs.

etc etc etc..

reality for me is i have taken systematic and deliberate steps in changing my footprint.
and you've met me,... do i look like a hippy...
is there more i can do... yep lots.

What your doing as a whole is great ,and your definitely doing your part . More people including myself should think that way.
But in the board building , we need to come up with way better options for it to make a difference . Im just throwing in my view the way I see it . I have been wrong before . As I said , it needs to be discussed and this thread definitely throws around some good ideas . But the feel good sea plane guy ,chopping , sorting and re wieving offcut Carbon fibres is doing diddly squat . Looks fancy though , but that's about it . If Starboard gave accurate , total , carbon footprint figures between their eco and normal boards , Id bet there would be little if any difference. Yet they make a big point of it .Eco is trendy . It seems there is a lot of grey area around the eco branding . Because it is important , there should be a law that selling something , has to actually be proven eco by a margin to use the word eco. For instance , as someone else mentioned, If eco resin is 30% bio but 30% weaker so you need 30% more , that doesn't count. So your actually using 30% more also of the bad 70% resin . ( my brain hurts ) . If you know what I mean . So that gives me doubts about eco resin .
Hopefully there will soon be truely eco materials to use . If there as good and cheap , I'll use it .

ps , don't let me discourage your way of thinking , we need people like you to save us

did you get a chance to listen to the Sven interview on windsurfing TV. he talks specifically about eco branding and what starboard are doing. he acknowledges the issues with eco construction and identifies past technical problems and goes on to talk about how he has had to accept some of the waste and how he has offset that in his personal life and at starboard as a business.

Is it amongst this forum ?
We absolutely have to try to go in the right direction .
Hope we can do enough .

WOOD!!!

yes to wood. sustainable....

p.s. im waiting for the tide to turn so i can go catch some waves....

on the bio resin note. this is the resin i used on the last board i built. i found it to be runnier than non bio based resins. not sure if all bio resins are like that.

anyways. 77% bio based. the 77% that is bio is made from bio fuel waste. double word score their. plus an ozzie company..
Surfing Green.com.au/collections/shaping/products/change-climate-bio-epoxy

Bourke nobody is criticising your boards or your massive experience. Good on you for 3yr warranty, nobody else does. However you clearly missed something or simply didn't know what you're talking about when you said the board is nothing like a cylinder. No it isn't perfectly round of course, but the curved deck bonded at the perimeter to a flat bottom does make a more rigid structure. I think the best analogy here was whoever said to take the flat deck off a sailboat and see what happens. It would be more bendy. Put all the missing deck material in the hull sides, and it will will still be more bendy than the original sailboat with a deck.
Because the first one with a hull and flat deck was a cylinder. Misshapen cylinder, but in engineering terms it is behaving like a cylinder.
Windsurf board- same.

And sailquik is onto it- wood.

Good ol' 500kg/m3 unidirectional australian pine.

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Mark _australia said..
And sailquik is onto it- wood.

Good ol' 500kg/m3 unidirectional australian pine.

yup. here is my spreadsheet. i've kept a track of everything with tech spec, point of origin and supply chain details.

Years ago I designed and built a hollow wood SUP kit. The idea was for people to be able to make a simple board easily with very few tools. I worked with a kit company in the U.K. They do kayaks,boats everything. They said the thing that worried people the most was the glassing stage.
So to build a hollow wood board and not glass it is quite risky and getting away from the idea of a simple kit. Just make it out of ply is the easier answer but I didn't like the look. And don't do easy.
I wanted to make panels. So I did lots of testing. Home testing nothing scientific. Paulownia was the best of the woods I tried. This is well known in the wooden surfboard world. So I vac bagged 0.6 mm bamboo veneer at 45 degrees to a 4 mm Paulownia panel I made. It added a huge amount of strength. Allowed the panel to flex more and is very impact resistant. I also added a very light layer of flax and this added more strength.
I was also in touch with Grant Newby on the Gold Coast. He make surfboards by vac bagging Paulownia onto cnc cut blanks. He uses PU glue and doesn't glass them.
You might be able to use a combo of Paulownia and Bamboo vac bagged onto a blank. Both available in Oz.Maybe solid wood rails. Grant has loads of vids of how to build boards. He is also happy to help people and share what he has learnt.

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Gestalt said..

no one is questioning your experience making boards or respect in the industry Bourke. for sure you have added a massive amount to this conversation bringing a different perspective. what's being questioned are the theories you are putting forward to explain your findings.

Yes maybe it is hard to explain in words. Lets try this way: How rigid against flex would a sheet of the same thinkness of steel be if it wasnt corrugated but had the shape of the bottom of a board? Hardly. And the distance between the rails is quite big, leaving a big area in between to flex inward and buckle.

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Mark _australia said..
Bourke nobody is criticising your boards or your massive experience. Good on you for 3yr warranty, nobody else does. However you clearly missed something or simply didn't know what you're talking about when you said the board is nothing like a cylinder. No it isn't perfectly round of course, but the curved deck bonded at the perimeter to a flat bottom does make a more rigid structure. I think the best analogy here was whoever said to take the flat deck off a sailboat and see what happens. It would be more bendy. Put all the missing deck material in the hull sides, and it will will still be more bendy than the original sailboat with a deck.
Because the first one with a hull and flat deck was a cylinder. Misshapen cylinder, but in engineering terms it is behaving like a cylinder.
Windsurf board- same.

OK, the thing is, the bottom of a board flexes a whole lot more under the load it has to take than the deck of a boat. If the deck of a boat was flexing as much, the boat would break in heavy weather as well. Yes, the deck of a board alone alone would be half as stiff if there was no bottom. But the bottom itself flexes inward from water pressure and is under a longitudinal compression load. Like the example with the batten, under a compression load, once it starts flexing just a little bit, it is easy to break. And a batten is a solid material, the bottom just has 2 thin sheets of fibre with a softer PVC foam in between.

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Gestalt said..

when you say "stiff in another way." would a more eco friendly method to be to add a stringer. the problem with carbon fiber is it is excessively bad for the environment. there are moves globally to remove carbon fiber from land fill sites because it just does not break down. add to that it being made from oil and it's probably the worst material you could put in an eco board. whilst i can't find the data i'd guess dyneema is on the same page.

making boards to last doesn't really help either. after 30 years a boards design is past tense and it will end up at the tip, in the landfill, and never breaking down if made from plastics.

It sure does, if a board lasts 4 times as long means 4 times less boards end up in a landfill. That is far more than what you can achieve by using 30% "BIO" materials in a board, which than last 30% less long and still can?t be recycled. And if you can achieve that by using for a small part of the whole board Carbon and Dyneema, isnt it still easily worth it? And it is not just the environment that profits from it. Less missed time on the water, less repairs or driving to take a board to repair, less transport of boards from factory to end user.

Well made full carbon masts last a lot longer than glass fiber masts as well.

How long do you think a "normal" production board lasts in a rental environment in Pozo? Howling winds, lots of jumping, round slippery rocks and partly careless, clumsy rental customers.

Yes, we are still far away from a sustainable planet. But so far using "BIO" or "ECO" materials, if boards end up lasting less long and still can?t be recycled and use up valuable resources that can better be used elsewhere, it still isn?t the better way.

And actually, my guess is that sails are worse than boards. There is no way around it to use 100% oil based material and they last a lot less long. Still many people choose lighter sails which last even less long.

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Gestalt said..

when you say "stiff in another way." would a more eco friendly method to be to add a stringer.

What for? Didnt we agree a stringer does not add anything but for shaping? That is a trick question.

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Bouke-Witchcraft said..

Gestalt said..

when you say "stiff in another way." would a more eco friendly method to be to add a stringer.

What for? Didnt we agree a stringer does not add anything but for shaping? That is a trick question.

nope not a trick question. for me the jury is still out on stringers.

if we assume as was suggested previously that the bottom of a windsurfer is a flat plate, then adding a stringer halves the span of the flat plate and also makes it continuously supported. which from an engineering position makes a difference. adding in a stringer also reduces the load to the rails, as the stringer is supporting half the span and the rails are now supporting 1/4 the span.


now if we also add a stringer across the board we can improve the bottom laminate stiffness further.

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Bouke-Witchcraft said..

Gestalt said..

when you say "stiff in another way." would a more eco friendly method to be to add a stringer. the problem with carbon fiber is it is excessively bad for the environment. there are moves globally to remove carbon fiber from land fill sites because it just does not break down. add to that it being made from oil and it's probably the worst material you could put in an eco board. whilst i can't find the data i'd guess dyneema is on the same page.

making boards to last doesn't really help either. after 30 years a boards design is past tense and it will end up at the tip, in the landfill, and never breaking down if made from plastics.

It sure does, if a board lasts 4 times as long means 4 times less boards end up in a landfill. That is far more than what you can achieve by using 30% "BIO" materials in a board, which than last 30% less long and still can?t be recycled. And if you can achieve that by using for a small part of the whole board Carbon and Dyneema, isnt it still easily worth it? And it is not just the environment that profits from it. Less missed time on the water, less repairs or driving to take a board to repair, less transport of boards from factory to end user.

Well made full carbon masts last a lot longer than glass fiber masts as well.

How long do you think a "normal" production board lasts in a rental environment in Pozo? Howling winds, lots of jumping, round slippery rocks and partly careless, clumsy rental customers.

Yes, we are still far away from a sustainable planet. But so far using "BIO" or "ECO" materials, if boards end up lasting less long and still can?t be recycled and use up valuable resources that can better be used elsewhere, it still isn?t the better way.

And actually, my guess is that sails are worse than boards. There is no way around it to use 100% oil based material and they last a lot less long. Still many people choose lighter sails which last even less long.

just because your board lasts 4 times as long doesn't mean it won't be put aside after 2 years and sent to the tip.

again, 30% bio is old tech 77% is commercially available and 100% is being worked on. also bio resins can be biodegradable.

boards, sails, fins etc etc. your bias is that it's not possible, it can't be done and there is no way round it. yet here i am building an eco board and providing you with page after page of evidence that prove otherwise.

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Bouke-Witchcraft said..
What for? Didnt we agree a stringer does not add anything but for shaping? That is a trick question.

Snapping in half resistance and bending/flexing resistance (stiffness) are not nessasarily the same thing

The durability of wave boards in your Tropical island wave sailing and rental bubble is a specific case. Most wave and freeride boards in many other parts of the world have a much easier life and often outlast improvements bought by newer designs. In other words, they are discarded by their owners before they are no longer servicable in favour of a newer, faster, easier, better design. My wave sailing friends here mostly change their boards because they want to try a new design or something different, not because they destroy their boards. There are no reefs around here.

Sadly, slalom boards have become very fragile and are often trashed and waterlogged before they are outdated. For the sake a a few hundred grams they could be a lot stronger with no practical performance detriment. There is a very unhealthy emphasis on saving the last few grams of weight in slalom board construction in some completely misguided belief that a sailor with a 500gm lighter board will go faster and win races. Like the old saying says: 'Its the Indian, not the arrow". I would always buy the 500gm - 1Kg heavier one with the extra layers of reinforcing and strengthening patches if they would build it for me, which is why I might favour a custom builder rather than a off the shelf model.

About the only thing I can save and recycle from older trashed or worn out sails are the carbon and fibreglass battens. But they often only replace others I have snapped and sent to the trash anyhow.

When it comes to the design and testing process, there can be a LOT of waste landfill. Many of the bigger brands build quite a few prototype boards and sails, most of which end up in landfill in very short order. Virtually none are sold to consumers for various reasons, and many proto boards I have seen would not last more than a few sessions anyhow. They are only constructed to prove a concept or compare a shape/feature. Prototype sails especially (but also boards) are usually made without the branding logos and screen printing graphics so the designer certainly does not want them out in the wild, especially if they are not as good as the evolved final design.

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Gestalt said..


just because your board lasts 4 times as long doesn't mean it won't be put aside after 2 years and sent to the tip.

No, if people want something new, they get sold on or traded in and maybe 3-4 times after that. Who is going to throw away around 1300 Euros (2100 AUD) of value? Such a board is still a lot better than any brand new "normal" board. I could sell 5 fold of used boards if I had them.

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Gestalt said..

again, 30% bio is old tech 77% is commercially available and 100% is being worked on. also bio resins can be biodegradable.

If they are mixed with fibres, foams, how much use is it if the resin is biodegradable. I am not saying they should not research all this but so far it isnt good enough. I have a good friend who is an environmentalist and has made various boards using as much BIO material as possible in different ways. He asks me for advice at times (sometimes too late) but if I tell him that I think it will not work, he goes ahead and does it anyway. But he says that so far he hasn?t had much succes with his experiments so that he has more or less gone back to oil based products if he really wants something that lasts longer. In between he keeps experimenting but with more thought. Recently he tried to build a hollow surfboard which went wrong. He told me he was following this thread as well but I presume he has not found he could contribute anything so far.
It is like with electrical cars, no emissions from the car itself but what is up with the batteries and where does the electricity come from?
What I do like and seems to work quite OK in surfing is those hollow wooden boards that you can buy as a package to put together yourself. Off course you still have to be carefull with impacts but even if I have not seen one in the flesh, I would think the longevity and performance is OK. Another friend of mine has built various wooden windsurfboards in the 80s and 90s but not for use in waves. They were OK for their weight and longevity as well but he was a bit limited with the shape. One time he made a fully round deck from plywood, which as a result had to be straight from tail to nose. Or he had square rails. Now with CAD and CNC, this has become a lot better.

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Gestalt said..

boards, sails, fins etc etc. your bias is that it's not possible, it can't be done and there is no way round it. yet here i am building an eco board and providing you with page after page of evidence that prove otherwise.

It is interesting and I hope you will succeed but you have not proven anything so far. First see what it will weigh and how long it will last.

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sailquik said..
Snapping in half resistance and bending/flexing resistance (stiffness) are not nessasarily the same thing

Exactly, they arent the same. That is what I said it is a trick question.