Anyone done the calculations??

General Discussion
1

As a frequent browser and occasional contributer to this great site I’m always interested in the persuit of lightness many so assiduously follow. The comment about the small difference in weight between some boards as a percentage of the overall weight with surfer included is very important. I see a post about the merits of Spectra (high specific strength) but what warrants its use?

Has anybody got figures for weight of shaped but unglassed blank and the weight of the board when it is finished, combined with glass schedule and resin schedule. My feelings are that there is little that can be gained weightwise that hasn’t been covered in these pages by a materials solution alone. The persuit of hollow boards must surely be the way forward (and there is some GREAT stuff going on there).

I’m sure many of the shapers out there keep a record of these details. Fancy sharing them? It would be interesting to put a database together of weights, construction etc…

I’m desperate to do another board but cannot decide what or how (wasn’t it the Nowhere Man in Yellow Submarine who had similar problems?). I really fancy going for a super lightweigth just for the hell of it…

What think the world?

2

hey Rikds

my latest was 4.7 pounds with plugs ( thats a 6 4")

mikes lightest to date is a tad under 4 pound (1.8 to 1.9kg i think)

these are strong almost unsnappable boards

neither board is hollow

i dont think that hollow boards are the way forward wrt weight

eps is 90 odd percent air anyway

prolly less material volume then ribs on a carbon hollow

not only that carbon is expensive and stiff

3

There definitely is potential with hollows.

Compsands can be said to be semi hollow anyway.

Ribbing such as foam ribbing is being done more and more.

On my boards, there is the potential to save another 500 grams by removing the foam core - this can be directed in the shell to make it even more durable!

Getting them to flex and ride well would be the hard part, as i’m sure Kendall will vouch for!

But definitely potential…

Just gotta decide if it’s worth it.

The jump from traditional materials to compsands is huge, with relatively little work. It’s not easy, but allthe info is here on sways.

Building a hollow that out performs PU/PE and compsands will be a bloody big task, and the jump in performance may not be quite as pronounced! Not worth it for me at least. Got my hands full with the current obsession.

I wish I had all the time in the world and an unlimited R&D budget, because there is an answer out there.

Kit

4
Quote:

The persuit of hollow boards must surely be the way forward (and there is some GREAT stuff going on there).

I couldnt disagree more. Hollows require extra reinforcements, adding significant amount of weight. That recent hollow thread the board finished at 9 pounds. When you add up the cost of carbon cloth, that was one heck of an expensive ‘failed’ experiement. Sure you can make them light, but not without routine failures or astronomical costs. In short, core material is your friend. Has anybody got figures for weight of shaped but unglassed blank and the weight of the board when it is finished, combined with glass schedule and resin schedule. For shortboards: A light Clark shaped (AROUND 3 pounds) would be about 50-60% of the finished board. 5-6 pounds finished. A #2 eps shaped blank (AROUND 2+ pounds) is about 45-50%. 5-6 pounds finished. An epoxy wetted 6oz layer is about 3/4 pound. 4oz less than that. Hot/fill/sand coats add sig amount of weight. Fin systems add weight too. Compsand is another world thats more complicated depending on build, with a finish range of 4-6 pounds, avg around 5 for shorties. But much higher surface durability and much slower board fatigue. Sorry I cannot get more precise than that.

5

Small point of order: Light boards suck, and calling a 9 pound board a failure is ridiculous, 9 pounds is an improvement on 4 pounds by approximately 25 Newtons of thrust, and a lower centre of effort and gravity.

Talking about light boards being the way ahead is like being stuck in the dark ages, or wearing your wetsuit back to front, ok if you are into it I suppose.

<

6

Surely merely saying “each to their own” would be a nicer way of putting that!!

Small point of order: Interesting mix of units pounds and Newtons, surely one’s imperial and the other metric? Where exactly is the centre of effort of a surfboard? So far as the lower centre of gravity is concerned, that would depend on the thickness of the board assuming the rider doesn’t bend his legs. I’m probably wrong, “O” level physice was a long long time ago!

But let’s not go there, I was merely interested in the numbers, not an unedifying argument about the merits of weight.

7

6’0x2.25x18 Vac formed corecell

polystyrene 0.35 epoxy resin 0.275. two oz cloth 0.150. Shell corecell 0.2. corecell rail 0.030 4 oz cloth 0.100 Polyester 0.750 fins 0.162 plugs and resin 0.008 Total kg 2.025

8
Quote:
Quote:

The persuit of hollow boards must surely be the way forward (and there is some GREAT stuff going on there).

I couldnt disagree more. Hollows require extra reinforcements, adding significant amount of weight. That recent hollow thread the board finished at 9 pounds.

craftee, have you felt the weight of an Aviso? There are some great fabrics out there that I feel could be used in place of carbon in regards to surfboards. Not to demean that project but the support structure was unneeded. I feel a good sandwich skin without the support is enough. Good infusion can make one of the best sandwich skins.

rikds, I say go for making a hollow. Learn to do your tooling to make the rail joggle. Contact airframe for suggestions. Research your fabric and core and Infuse it.

9

Ultimately I plan a hollow board infused with a bladder inside (hard to get out but could use the vent hole). Time (and some dosh) is all that holds me back at the moment.

10

The weight savings with hollow boards happens as the boards get bigger in size.

At Hydro Epic, the lightest we could make Kelly Slater’s 6’1" and still have it reasonably strong was 4.5lbs. That’s what his PU/PE competition boards weigh… of course he breaks one every four days - that’s 85 a year (!) Production models are around 6lbs.

Our 9’1" longboards were strong at 9.5lbs. I think the production models are coming out around 11lbs. That’s a huge weight difference from traditional boards. Believe me, you can feel how light they are when you’re surfing them.

Hollow boards have almost all of their weight in the skin, and consequently the skin weighs more than a standard glassed board. The amount of foam you lose on a shortboard isn’t that great, so loosing the foam doesn’t save that much weight. Figure a 6’1" poly blank weighs around 3lbs. The extra material that goes into the skin negates the weight savings from loosing the foam. On the other hand, the amount of foam you loose on a longboard is much greater. To put it into perspective - Hydro Epic’s 9’1" is three feet longer, 3"+ wider, and about an inch thicker than the 6’1" K model, plus it has a big Bahne center fin box, and it only weighs 3lbs more.

Hollow boards require more than the skin to make them strong if your goal is shedding weight. You need some kind of internal reinforcement. One thing I learned while testing hundreds of hollow boards is that waves put all kinds of stresses on the board that are hard to replicate in a lab. While you may not need ribs or stringers, you at least need something that will keep the rails from deforming. Nearly 100% of all failures I experienced - and I’ve experienced a lot - were related to the rails compressing and allowing the board to fold.

And Roy… some people actually like light boards. They surf differently for sure. If your goal is to make as many turns on a wave as you can, or you want to make sudden direction changes, then a light board will help. They don’t plow through chop as well, and they don’t have the same glide, but different strokes… I loaned one of our 9’1"s to a kid at Hookepa, and he was sticking 360 airs on it. Do that on a heavy board - and don’t tell me that’s not performance surfing.

We’ve had feedback from a lot of pros that said they had their best rides ever on our hollow boards. Other than the light weight, hollow boards can be built more lively - since the foam doesn’t absorb the feel - and they can be tuned to flex where and how you want them to. The downside is - hollow boards surf like crap if they get water inside (and there’s no such thing as a little leak), they’re way harder to make, and the materials to make them strong and light are really really really expensive.

Oh… about the bladder… You can get super thin bladders that you can just leave in the board when you pull it from the mold. I think that’s what Alviso does. The plus side of building boards like that is you’ll end up with a finished product right out of the mold - no seams to deal with. The downside is you can’t add fancy reinforcements inside the board to add strength or control flex. In that case you have to rely entirely on the skin for everything.

11

I always liked the idea of using a foam core as the male mold, then disolving it away with solvent when your ready.

That could easily be done through the vent plug.

And it allows any ribbing or other internal re-inforcements to be put it place - as long as they don’t disolve as well :slight_smile:

I like light, especially when it come to women

12

Sorry mate I was on surfermag and forgot to change my settings

The centre of effort of a surfboard and rider is the same as the centre of gravity btw, and the newtons estimate was via kilograms.

You are right though, let’s not go there, no hijack intended

13
Quote:
Hollow boards require more than the skin to make them strong if your goal is shedding weight. You need some kind of internal reinforcement / While you may not need ribs or stringers, you at least need something that will keep the rails from deforming. Nearly 100% of all failures I experienced - and I've experienced a lot - were related to the rails compressing and allowing the board to fold.

Oh… about the bladder… You can get super thin bladders that you can just leave in the board when you pull it from the mold. I think that’s what Alviso does. The plus side of building boards like that is you’ll end up with a finished product right out of the mold - no seams to deal with. The downside is you can’t add fancy reinforcements inside the board to add strength or control flex. In that case you have to rely entirely on the skin for everything.

My comment was in a bit of haste before rushing off to work. And this is all speculation of course. Yeah, for sure I think it would be best to have more than just a joggle at the rail seam. Especially if the core did not wrap the rail. Back in the archives there are some good comments by Bert and Greg on Perimeter Stringers as to board strenght when they first started talking about them here on Swaylocks. If you could incorporate something like the blasa perimeter stringer into the rail of your hollow board. Basically building your hollow as a Compsand (as we here know them).

If I’m not mistaken I think what Ken was doing was just a joggle, where the honeycomb ended short of reaching the rail area. I wonder if he learned anything from any broken boards regarding that. I had a good look at his shop a couple of time at all the various tooling he used to make a board. It is a complex process for sure. And I thought I saw a comment by Ken here that he thought Hydro Epic was just a joggle at the rail seam.

So maybe best would be to incorporate in the hollow board a good perimeter support.

Kendall, what do you think Aviso does with the rail? I’ve looked in that plug in the tail and as far up as I can see there appears to be no internal supports. And I see no support in the rail area of the tail either. Aviso short boards seem lighter than a typical pu/pe off the rack. Do you know of their durability history? Your seeming to say that you think Aviso is just sandwich composite skin with no support like you recommend against? Do you know what type of core they use. And if the core wraps the rail?

Have there been any pictures of a broken Aviso floating around?

14

Aviso was just coming on the scene when I left Hydro Epic. I haven’t paid super-close attention to what they’re doing, but I have some idea. I think they use PVC foam sandwiched between layers of 7oz carbon fiber. This skin is formed in a female mold as a one piece structure using a bladder to form the inside. I’m not sure if they leave the bladder in, or pull it from where they put the plug. I think the skin is the same all the way around - including the rails. Because of the way they mold their boards in one pass, and since they don’t have access to the inside, it’s not feasable to add things like stringers, ribs, or other internal features. They can make their boards strong, but they can’t fine tune the flex.

I haven’t ridden an Aviso yet, but I’ve heard they’re much stiffer than Hydro Epics. I’ve only talked to a few guys who have tried them. The stores I know that carry them haven’t actually sold any and don’t have demos.

I’d love to try a few.

15

A friend of mine has a 9’ performance board. It weighs about 14-15 pounds. Pretty heavy to me, I’m riding the same size board at 7.75 pounds. (compsand) -Carl

16

Glen,

I say put your money where your mouth is by making one.

And please dont forget to let us know how much effort and expense you went thru.

Here are the ‘facts’:

Hydroepic has spent million(s) in this pursuit. I wish them well wrt sales, but I’d/we like to know how thats going.

Ive seen Aviso up close. Awesome. But Im not prep’d to take out an equity loan to buy one.

Swaylockers with excellent composite skills have made some. All heavy and likely to fail easily. Sure, with some good engineering, they can be made light and strong. But may I remind you, CF costs about $50/yd…if you can find some.

You can argue all you want about the merits. But the fact is, you gotta plunk some serious dough in this pursuit. So I say, go for it!

But hey, just one man’s opinion. Kendall is the real king of hollows around here, so if it doesnt bother him, I’ll post this quote:

We’ve had feedback from a lot of pros that said they had their best rides ever on our hollow boards. Other than the light weight, hollow boards can be built more lively - since the foam doesn’t absorb the feel - and they can be tuned to flex where and how you want them to. The downside is - hollow boards surf like crap if they get water inside (and there’s no such thing as a little leak), they’re way harder to make, and the materials to make them strong and light are really really really expensive.

You cannot get a more balanced opinion.

So there you go boys and girls. Dive right in!

I definitely want to see more hollows being built. But I’ll just take a wait and see approach. Have fun Glen, keep us posted on your progress.

17

Soluable cores would be great. Trouble is I don’t fancy the slurry that you’d pour out! Petrol and acetone both dissolve polystyrene. Fishermen use a water soluable foam to control the rate of sink of the bait. I’ve been trying to buy a board sized block for ages but all the suppliers think I’m nuts and do I ever want my bait to sink! There is also a very slick (and therefor probably expensive) water soluable ceramic material. It machines and shapes like plaster of Paris. Use it as a core, layup the fancy skins and wash it out…I need to sell the house to buy a block and seem to be meeting some resistance from the other inhabitants (the wife anyway, the son fancies a light board and say’s he’d settle for a tent for a bit…)

18
Quote:

Soluable cores would be great. Trouble is I don’t fancy the slurry that you’d pour out! Petrol and acetone both dissolve polystyrene. Fishermen use a water soluable foam to control the rate of sink of the bait. I’ve been trying to buy a board sized block for ages but all the suppliers think I’m nuts and do I ever want my bait to sink! There is also a very slick (and therefor probably expensive) water soluable ceramic material. It machines and shapes like plaster of Paris. Use it as a core, layup the fancy skins and wash it out…I need to sell the house to buy a block and seem to be meeting some resistance from the other inhabitants (the wife anyway, the son fancies a light board and say’s he’d settle for a tent for a bit…)

You need to break out of the 50 year foam fiberglass plastic mental rut for this thought exercise. No reason why the male mold should be any such material, nor the removal toxic. Consider the “lost wax” metal casting method (not literally, just for a concept shift) What you need is a material that you can cast or craft with shape fidelity, that will hold up while the shell is applied, and can be persuaded to lose it’s structural integrity (turn to liquid or powder on demand) Without putting a lot into it, how about that cornstarch foam material used for some shipping peanuts? It dissolves in water. I’ll bet there are (at least) a dozen reasonable alternatives to the aromatic hydrocarbon based solution…

-Samiam

19

not to mention if you get a ding way out on a reef on a big cold day and your boards slowly filling up with water as youre paddling in

at least a wood hollow would still float good

take a copper pipe and bend it

the wall will collapse

fill it with a sand or wax or foam and you can bend it 90 degrees and back again

its really that simple

i must say though

i like the hollow woods

and it looks to me there is generally a fairly substantial solid perimeter

with overlapping skins

20

Hi Guys,

It seems like people that have made and ridden hollow boards unanimously say that it is more ‘lively’ because it seems to resonate with the wave like a finely tuned guitar. They usually attribute the board’s liveliness to the fact that it doesn’t have a foam core to absorb the feel. But isn’t air more of a dampening medium? wouldn’t air absorb more of the feel since it can be thought of a less dense core? But, I don’t doubt the statements that the boards are more lively and less dampened though. I was thinking that maybe it isn’t the lack of a foam core that’s the reason for the board’s liveliness but maybe the rib structure or the skins are built very rigid that they transfer the energy quite effectively.

Rio