Flex and Fiberglass

I’ve been glassing boards by pulling down the cloth over the board, and havent seen or heard to do any different. But what would happen if I layed the fiberglass ACROSS the board, instead of parallel to stringer?? Would this affect flex? it seems it would, just curious to see if anybody else has ever tried. Thanks;

Jim Banks used to lay glass diagonally ,reaconed it was stronger???

thanks… I thought it would have some effect, but wasnt sure. I’ve seen this idea applied to snowboards, and figured it would work for surfboards as well…

I was once taught fiberglass techniques by an old timer who used to build boats. Sounds like Jim Banks must have figured it out too. The pros would lay their cloth diagonally on boats for strength.

ive seen many boards from a certain factory here that were glassed diagonally! they snapped diagoinally too! i guess it could be that the jury is still out in deciding strength! however im sure it has some affect on the flex, which inturn would affect the performance according to rocker. i wonder if KR has had two identical rocker boards glassed differently? some of the factorys he has worked in here on the gold coast use both methods. im aslo thinking that the board may or may not twist a little easier too! http://www.feraldave.com

Snowboard have glass with the usual ‘crossweave’(I don’t know the correct term) and diagonal weave. Usually a combination in one cloth. Triaxial is normal with snowboard with weave in the length direction and both diagonal directions. It’s mainly used to keep the board from twisting too much(torsional stiffness) and wash out on hard turns. Such cloth is propably more expensive and hard to work with hand laminating a surfboard than normal glass. regards, Håvard http://www.earthlife.net/birds/flight.html

I think the general principal is that a board will flex more, and break, along the weave. So if you turn it, say 45 degree for example, now your “fault lines” are running diagonally across the board, which makes the break line longer and less prone to snap… I’m sure they still break, but I would be curious to see the difference in flex. Actually I’d like to see how the flex affects performance. I couldn’t say that I’ve ever ridden a board that was noticably very flexable or in-flexable. It doesn’t seem an aspect that is explored very much. Has anyone ever made an extra-flexable shortboard? …maybe with a small ceder stringer or some plastic? …I’d be interested in how that rides.

right now i am making a 6’0 single fin egg with a flexible tail. it has no stringer in the back 2 feet of the board. it will have a flexy fin glassed on as well. Rusty makes/made a CJ Hobgood thruster shortboard kind of the same way with no stringer in the tail. I have heard those bamboo boards are really flexible - they have no stringer. Some say its good, others bad, probably just different. The solomon S-Cores are being engineered to have specific flex patterns.

I would think that laying the cloth diagonally would only have a strength advantage if you used two layers. A single layer would still have most of the same stresses as a “staight-layed” lamination, and it seems, as was stated before, it would snap on the diagonal. But if you had one set slightly diagonal and another layed diagonal in the other direction, the stresses would be spread out more. Maybe two layers of 4oz. on the bottom. I think I’ll try that on my next board and see what happens. Thanks for the brain stimulation guys! Doug Schuch

Another cloth type worth checking out is the clothes that isn’t woven. It has the fibers for each direction in layers, only lightly stiched together. Because there is no weave it lays down flatter and uses less resin, improving strength to weight ratio. There was also something about the weave creating small point load which fails at less stress than a straight fiber. Con is it’s harder to work with such a cloth with a squeegee. regards, Håvard

Remember that cloth is weakest in the direction of the thread, which for normal cloth runs in both directions, rectilinear. I don’t think that laying two opposing layers will matter as much unless your using a biased cloth that has more yarn in a particular direction. I usually use the cheep stuff, “E” I think, so the diagonal will go in both directions, if you layed it at 45 degrees, which would probably be impossible with 27" width cloth. Hey Richard, let us know how the flextail works out, and the board in general… I was curious of making one of those single-fin mini-eggs as well. Though I am more curious of how the flex would apply to more vertical surfing, on a shorty.

I don’t agree with you that the cloth is weakest in the direction of the thread. That would mean that warp cloth which has more fibers running lengthwise on a board should be more prone to breaking. I still think I get your point though. How about this for a semi-diagonal layup: Cut your normal cloth to length, maybe a little oversized and use a wide cloth. lay it out with one corner on the nose and one corner on the tailLay the next layer wise versa. Bdw. Another advantage of the non-woven cloth would also be the very thight ‘weave’. Since there is no weave there would be less ‘resin pockets’ in the lam that consist of just resin. regards, Håvard

No… you kind of missed my point, though I guess my word choice was poor. In a weave, you have two sets of strands, running perpendicular to each other. The break is least likely to occur across the nodes, i.e. diagonal, it will follow the strands, or actually, the space in between two strands. As far as the cloth is concerned, that break is just as likely to go across a longitudinal line as it is latterally - it’s the fact that most surfboards are 4 to 5 times as long as they are wide that keeps them from breaking nose to tail.

I’m really glad to be getting all the ideas, two heads are better than one, multiply that by 100 and you have swaylocks. Thanks for the info on triaxial weave, my snowboarding instinct must be a little rusty, but pleanty of time to work on that. For my next board, I may either : A) Both sides diagonal weave, most likely two layers of four ounce to accomplish this, and being sure to add a strip of cloth over any place i may have to lay cloth next to each other. B)Bottom glassed as regular, the top glassed with the diagonal weave. I’m not sure , but I’m hoping this will let the board have more of a “true” flex,something that would respond more to the wave and not the riders weight ( HOPEFULLY!) the only problem I can find is that I wouldnt be able to overlap fiberglass in one area more than another on the deck, as this would affect the flex. great ideas guys, keep em commin

Make a couple pieces of cloth; one diagonal cut,one square cut. Make them both the same size, lets say 2" x 6". Laminate them using the same batch of resin, maybe on top of a piece of waxed paper. Use a scale and maybe some small wood blocks to see how much push it takes to deform/bend them to a certain amount, say a half inch or whatever works for ya within the limits of the scale you’re using. That oughtta answer the question, for the particular cloth and lamination technique you’re using. Me, I’ve found, all other things being equal and bending a piece of laminated cloth from a busted board, it doesn’t much matter, with the weave or diagonal to the weave, they bend pretty much the same. You have to get into more exotic cloths before it really starts to show up. doc…

I am with Doc.If its standard glass and resin the blank (core) is going to be the deciding factor.But I am not an engineer so its only my opinion.

I thought about glassing a longboard this way, but decided it more trouble than it was worth.I think you still need the 0/90 particularly the 0 which needs to be on the bottom (in tension).So that only leaves the deck for the 45/45. With the deck in compression most of the time I dont think it would make that much difference what way the glass is orientated on the deck. Also laying the glass at 45 degrees you are going to have to overlap the joins leaving high spots at the joins, then you end up sanding them off and get weak point at each join.I use triaxial and double bias glass alot at work, it is the way to go but I dont think it is available in light enough weights.David.

Rook wrote: “it’s the fact that most surfboards are 4 to 5 times as long as they are wide that keeps them from breaking nose to tail.” That and the fact that since they are rockered and long, the load is on the lengthwise axis. regards, Håvard http://www.earthlife.net/birds/flight.html

We tested a heap of diagonal weave lay ups when i worked at pipedream, yep some came back broken on some weird arse angles and the flex did seem to roll accross the board on an angle, insted of straight accross but in general the feedback was good for strength, I think that it is good for team guys who get 1 deck layer of 5oz, I’m pretty sure that Murray is still pumping the theory to most of his team riders and I know that Rod Dahlberg believes in it aswell, I guess the only way that we will ever know is to do some proper equivelentsy tests in the lab, anybody got one handy??? My multi national bankroll for inderpendent surfboard studies has gone amiss. I guess that they finally woke upto the fact that I am not a well respected aero-nautical scientist, just a long haired surfy bum that recons that he knows what feels good to him. As for flex of boards, I am currently riding a stringer less board that goes nuts. I made myself one about 20 years ago but made the mistake of putting my normal rocker in it, it went good until you started applying heavier force due to wave size, then it would over flex and the rocker become to curvy and you would basically come to a hault until you backed off the pressure, With my new ones I flatten out the rocker radically compared to normal so that when you are light footed looking for speed the rocker is at maximum flatness and when you apply the presure for manouveres the flex kicks in and the baord bends into the curve of the wave better, INTERESTING THEORY, Neal purchase ‘senior’ and ‘junior’ have tested these to the max and most of the boards that I see ‘senior’ shaping are stringerless, watching junior surf his boards is something to behold, its like he is surfing on a rubber band, he will spring out of a cutback at such a rate it looks freakish (but then again junior is a freak)He looks like sheriff "ping ping ping " ricochet rabbit. More research in this department is a definatly must. Sorry for the long post, practising typing for Uni next year, old fart division. KR http://groups.msn.com/MyKRSurf/krcomweb.msnw

TO ALL YOU NON BELIEVERS, As the owner and shaper of pipedream surfboards Gold Coast Australia I can tell you that I have been using 60 inch cloth and cutting all my glass for my team rides out diagonally for over 5 years now and I am probably the certain factory that feral dave is referring to only his assumption that they all break diagonally is bullshit!Extreme shock like a 6 ft thick lip at low tide speedies at G- land on a 4x4 diag did just that and in deed it was an amazing force that did that damage, however in 6 years of laminating this way I have only seen this happen on only a few occasions and with guys with gonads like Tony Ray and Zane Harrison riding them its not like they have not been put through their paces. In fact the most common way they break under slightly less forces than the one described above is the shark tooth pattern where the glass begins to break along the thread line then turns tack and follows the opposite line and so on until the the break finally zig zags to the opposite rail and it is all over.Concluding they do not twist and since introducing the system my team snaps are down by 70% .Murray Bourton