The boards are 6’ 3" thruster shortboards. !8 1/2 wide by 2 1/8 thick with a deep (nearly 1/4" concave) Custom rockers bent in with stringer glue up (6" nose, 3" tail) with thinned out nose and tails. Rails pretty thin too. Max 6 and 4 deck and 4 bottom glass. Surprisingly they crease and snap and the tails get squashed flat and crack and fail under the back foot despite extra six layers glass wrapped around tail rail heel position.
The maker is not interested in Epoxy or eps or timberflex or compsand etc but will do what they can within the bounds of ordinary PU board building methods. The density of blank is not changeable. We have found a solution to the crushed tails by using a balsa tail. Maybe high density foam on the next one.
What will give us the most benefit?
Crown the deck keeping the desired rails making the board thicker in the stringer line? How much will make a real difference, 1/8"?
Deck channels like the ones Stretch uses just inside the rails? Any benefit on more than one channel?
Extra stringers? Where best to put them and how many?
Other materials that can be hand laminated in a conventional manner? Carbon tape and s glass available. Basalt glass?
There’s no suprises there. You’re making a disposable board then are suprised when it creases and snaps? What did you expect?
“The maker is not interested in Epoxy or eps or timberflex or compsand etc but will do what they can within the bounds of ordinary PU board building methods. The density of blank is not changeable. We have found a solution to the crushed tails by using a balsa tail. Maybe high density foam on the next one.”
Your whole post is kind of funny. You say the maker isn’t interested in compsand then say you found a solution to crushed tails by using a compsand technique (balsa tail). Then you say the density of blank is not changeable but you may try high density foam on the next one?
Why not simplify things and just use EPS/epoxy with the same glass schedule. You’ll get a lighter stronger board and won’t have to change your production methods.
2 1/8" thick with a 1/4" single concave gives you a 1 7/8" thick board. There’s only so much you can do to get around simple physics.
When I was a kid playing baseball there was a time when I had my own Louisville Slugger bat made of wood. I was pretty stoked until it broke one day on what should have been a solid hit.
One of the coaches took a look and snorted in disgust... "Look right here. See that knot? Where'd you get this piece of crap bat?"
Sheesh. Talk about rubbing salt in my wounds.
He went on to show me how to line up my grip so the grain was directed to take the most impact when I hit the ball. He also told me what to look for in a new bat... straight, knot-free grain, etc.
Anyway, the point I'm getting at is maybe selecting your own stringer wood, having it milled and glued up could be a place to improve board break resistance? As with the bat, look for straight, knot-free grain. If you're milling a 1"X6" plank, check which way the grain runs. If you look at the end of the plank, the grain should run with the wide dimension.
Thanks for the repleys. Some are a little dissappointing. The “Surprisingly they crease and snap” was a joke of course. I hoped not to go into too much detail with the backstory on these boards and that I could just give enough information that I could go back with sensible suggestions to the shaper/glasser that didn’t involve for example the misuse of Carbon or the addition of extra stingers in positions that might not do the most good. So to make it clearer. The Blanks are good, the shaping is good and the glassing are exellent, the balsa tails are solid from just in front of the fins and the high density foam will only be a substitute for this. No the boards are not falling apart and no we will not be changing the way we surf because the shapes have evolved under the feet of a local standout power surfer who will put his back foot through any conventional board. The boards have to be low volume to work hence the thin-ness. OK we know the materials and methods are innappropriate. With another shaper/glasser I went in and did my own Epoxy Glassing of the shapes he did for me. This isn’t an option in this case. A small shaping and glassing shop doesn’t have the time or money or inclination to start bagging compsands for 2 or 3 riders.
So to get more specific.
Carbon. Where and how much? I understand that as the carbon is stiff (especially without a flexy epoxy) then it takes all the load (whilst the normal glass stretches) which can leads to a weakening of the structure.
Deck channels. If one channel 2" from the rail gives strength is it worth putting additional channels. One big channel or several thinner ones?
Stringers. My latest has a 1/4" ply and is holding up well. We can specify double or triple stringers when the custom rocker is bent in and glued up. Are exotic patterns worth it?
I am not sure we really care about engineering in flex. The boards are thin enough they are going to flex even under a heavy glass job but I don’t think the extra weght will be wanted. I wonder about a slightly higher volume board and reducing the buoyancy with multiple layers of glass. I liked a board with 3x4oz rather than 2x6oz but that was epoxy and it wetted out OK. I think it would be harder to get Polyester resin throught the layers. Not seen Impact or X glass etc here but I guess its available outside of surfboard manufacture so will see what I can find in the UK.
OK any small simple things within normal PU surfboard building methods to give us a bit more life from our boards?
Mark, thicker stringers (one down the middle) for snap resistance have been the conventional wisdom in HP guns in Aus for decades and seeing as your boards are conventional that makes sense if your boards are subjected to extreme loads.
Doming/deck roll on a board is good for stiffness and it seems that stiffness is good for resisting creases in particular. However the board that I had worst tail collapse on was a foiled out/domed out professionally built custom hybrid where the tail was domed out too - I suspect doming takes out the harder outer part of the foam. Also rolling the deck is more associated with rail preference than structural preferences? Unless you are prepared to compromise with extra foam thickness in the stringer region? My 6’ 3" Bushman chip has a very rolled deck and rails fairly pinched in the main body although the “stringer line” has 2 1/2" of foam at its thickest point. So it looks nothing like say my chunky 2 1/2" thick flyer and gives the appearance of a thinner board (and almost certainly works like a thinner board too). I’m just mentioning that in case it is an option.
Most of the potato chips I see in the water in West Vicco come out of the BASE shapers cooperative and are made in PU/PE. I’m not seeing anything exotic in the way of stringers - they are all just one down the middle. I’m not seeing any lengthwise carbon strips either like K Slater’s board. However a minority I see (but enough for me to notice) do have semi circular carbon patches in the tail region, but I’m not sure what they are for.
maybe you can explore what their custom glass options mean - it seems they do diagonal glassing, but I don’t know what that means (maybe the weave direction?).
[img_assist|nid=1047084|title=Carbon tail wrap|desc=|link=none|align=left|width=640|height=198]The carbon tail wrap was tried but failed also.[img_assist|nid=1047084|title=Carbon tail wrap|desc=|link=none|align=left|width=100|height=31] The foam gets squashed flat between the top and bottom of the wrap. Doesn’t help that there are now channels in the tail bottom so very little foam left. Any carbon railed boards in the water? I think I saw some JS ones advertised somewhere.
I am going to pick up a Sunova tomorrow. [img_assist|nid=1047085|title=Sunova|desc=|link=none|align=left|width=338|height=640]Hope it is a good shape and I surf it well and it gets local shapers thinking about these materials but at the moment its probably too much of a leap.
Anyone done 3 or more layers of 4oz E glass in one go with Polyester resin? Can it be thinned with styrene for example to get it through the cloth easier?
Wow! there must be some serious power surfing going on. Yes thats the wrap I have seen.
Yes I saw one on the weekend, but I don’t see many and I think they are epoxy. Conventional JS is possibly the next most popular chip brand to BASE here. I know from looking at their website that JS do a conventionally contructed EPS/epoxy which would look like a PU/PE called “Solite”, but I’ve no idea if the JS boards I seen were made of that. JS say that the light weight Solite is suited to smaller waves, but from what I’m picking up here on Swaylocks from Mike Daniels and Surfding is that the pros ride lighter than “shop standard” PU so maybe the small wave suggestion for Solite is just marketing? I know I like really light boards coz I ride oversize boards and need to be able to throw them around so Solite appeals to me more than their PU in all size waves.
yes I know the new board order anticipation, its all a gamble isn’t it!
Backyard guys can easily reinforce the stringer with roving laid in along both sides of the wood on both the top and bottom of the board. It’s a simple process that adds strength without an extra step, and for litteraly about a dollars worth of material… just take a utility knife and remove a long sliver of foam on either side of the wood, then wet out long strands of roving and lay them in the channel. Glass right over the top.
Other than that, high density foam under the stop area of the back foot, with wood over that.
Thanks nice simple stuff that uses the usual PU/PE materials and methods will meet with little resistance. I remember now Herb using something like this. Wood unless in an obvious way (solid balsa tail) meets with resistance.
Considering just the creasing aspect, if I were to reinforce an area with more glass fabric should we put it on the rails or above/below the stringer?
I think if the entire tail was wrapped rather than just patches like the Base board we would have a better chance of stopping the crushing.
I have never seen anyone crush tails like this surfer. Powerful surfer with tiny feet and a board that needs to be driven hard. Not me but I am enjoying the late drops and despite the lack of paddle speed they catch waves well considering their low volume and high rocker.Now I just have to put the effort in and learn to get the most from them.
Clark did a lot of research on board strength - his conclusion - the strength is in the blank density not the glass job. Also the really stiff plywood stringers are more likely to contribute to snapping than single laminate basswood. My best luck has been the blue density ( Clark, now S.A.) with 3/16"basswood. Superlight pu boards are the most likely boards to snap and so far there is no getting round it. Regarding the crushed tails I think the balsa or high density foam inserts is the best idea so far.
Also, strength comes from the total glass on the deck and bottom......not rail wraps, or patches, or stringers.....well maybe stringers. but stringers will increase stiffness faster than anything else...well maybe carbon fiber rails...thats pretty stiff too. My advice would be to add a layer of 4 oz on the entire glass job, or re caculate the way the oz of cloth layout. And change the type of cloth.
So your saying it's a 4 x 6 top, and a 6 bottom. Make it a 3x4 top, and a 2x4 bottom. Use impact glass or something with a tight weave, not crappy S or E glass. The laminate will be as flat and light as a regular glass job. There are a million different types of fiberglass, 99.9% of them better than the surfboard glass we are custom to using.
Make the board just like you always do...use better / higher tech glass.....use epoxy
And use Epoxy with the poly blank..............that's not so high tech?
I agree… the strength is in the core… the foam density (crush/dent resistance) and the stringer (flex/failure characteristics) matter much more than the skin strength when it comes to standard construction. You can add to that the BOND between the skin and core… the stronger the bond, the more snap resistant the board. Ideally, you want a structural gradient from the skin to the foam beneath the skin. In other words, a tight lamination, with a gradient of resin penetration into the foam. I’m no engineer, but I’d bet that can help make Epoxy/EPS boards so much stronger than PU/PE, and why you don’t want a skin-like seal on the foam beneath the lam. You want partial absorption of the resin into the foam. The difference in weight is negligable, and the bond is exponentially stronger.
I don’t understand this logic. If the strength is in the core, why do we put glass on the outside, why not just waterproof it with polyester? How many 3x6oz deck, 2x6oz boards with conventional construction break? If you add anyweight to a conventional board, ounce for ounce, pound for pound I think you get more strength for the weight by adding it in glass instead of foam density. The problem is with the 2kg goal of a hp shortboard you cannot really add anything.
