Yes, provided that the skins in both cases are supported sufficiently to prevent buckling, and that the skins are identical in both cases.

It's not necessary for me to obtain experimental data for this, it's physics 101 but if you wish to test it just make two identical boards, one with stiffer foam and then measure the difference in deflection under load. The difference will be negligible.

I'm too busy with investigations into the effects of water temperature on Reynolds numbers and what this means for fin design to bother proving what I already know, but you might have fun with it.

Roy Stuart]

[quote wrote:

.Foreday rider: thickness will be determined by the core's buoyancy.......the often quoted "volume" will give different flotation if the core density is changed...as in EPS core instead of poly blank.

... clearly that's not necessarily the case, since core density does not determine finished board density.

Furthermore neither core density nor core stiffness determine finished board flexibility.[/quote]Considering the thread is about the virtues of Varial foam blanks , to be shaped and glassed with either poly or epoxy , you're remiss on all counts Roy.......less flexible core will produce less flexible board , and vice versa.....every time.....in HP shorties that are often built under the 5lb mark , all aspects of performance are quite noticeable , and almost nothing escapes the test riders.

"Float:
Varial has a nice float to it without feeling too ‘corky.’ More buoyancy? Tough call, but if we had to decide, we’d say the Varial is a touch floatier. To gauge if this was all in our heads, we asked Biolos about the difference in float and materials: “Whatever is more light of two exact objects will be more buoyant,” he says. “So, in general, boards built with lighter cores like EPS, XPS or Varial, tend to feel floatier.” Thank you Matt."

"Varial convert Ian Battrick said he goes a shave thinner in his dims when ordering a Varial board compared to a PU board"........ergo= lighter core = MORE (edit) float=thickness reduced accordingly......nothing new .

I liked the concept behind the "geodesic" blanks.....not sure if they ever got them to market , but they provided some interesting possibilities .

foreday rider wrote:

I liked the concept behind the "geodesic" blanks.....not sure if they ever got them to market , but they provided some interesting possibilities .

Yeah, they're starting to slowly filter into the market now. I spoke to Guy Walker, the fella behind them, a while ago and he said he was happy to take things slowly and keep consolidating along the way.

https://www.geoblank.com/ 

Also, keep an eye out for an article on another type of blank technology. Called X-Core Reactor it's similar to Geoblanks in that it has internal stringers yet is a simpler design, and it has a few shapers, incl. Greg Webber, very excited.

Article should be ready late today/tomorrow.

foreday rider wrote:

less flexible core will produce less flexible board , and vice versa.....every time.....

Not significantly (i.e. noticeably) it won't.

Don't you understand the physical principles involved? ... they are pretty simple.

.

Trying to compare the effect on flexibility of two different foams by comparing boards which are glassed with two different materials will only be testing the effect of the differences in glassing so in that respect the experiment is ill conceived. Epoxy is more flexible so it is no surprise that the epoxy board feels 'springier' but this says nothing about the blank.

Re. buoyancy the pu glassed board is 25% heavier so will have 25% less buyoancy... if test riding is as accurate as foreday claims than this should be more noticeable than the "More buoyancy? Tough call" test result would suggest.

In order to test the effect of blank flexibility on finished board flexibility two identically glassed boards need to be compared. PU resin is much stiffer than epoxy, so this will skew the results.

foreday rider wrote:

lighter core =less float=thickness reduced accordingly......nothing new .

Presumably you meant to write that: lighter core equals more buoyancy (all else being equal) but that the lighter core can lead to a thinner board if buoyancy is to be kept constant, and this can lead to greater flexibility due to reduced thickness.

I presume so, because "lighter core =less float" is obviously incorrect.

.

if the same test could be run with stringerless blanks vs varial stringerless it would be interesting

You right Roy, I wish that the pasted link below can help others to what are you saying.

https://en.wikipedia.org/wiki/Euler–Bernoulli_beam_theory#Static_beam_equation

Sorry that link is rotten.

Sorry that link is rotten.

bamboo boards- can anyone tell me what they are like? Can they use any type of blank. Also can they be made thinner as I would think the bamboo has it's own floatation capacity?
I know adi was trying them but they were bulky big buggers and i think he is on kanga island now. also are they too floaty to duck dive easily. one last question, has anyone come up with a board that can paddle like a 7'6 but surf life a 6'1?
maybe off with the fairies but on a high as the hawthorn hawks and nth qld cowboys are both in grand final so i am on avery big high at the moment.

A 6'1 that paddles like a 7'6.....these do Dave -Stealth epoxy [firewire copy] with a bamboo deck...just happens to be one on gumtree @ the goldy a 6'4 for $195 ,a bit battered but be ok for a $100-120.

thanks udo, see surgeon on wed, so if he tells me im shithouse, gunna go out in style- really missing my surfing, will change diet, become yoga stretching addict and get out there, tubes, cant get them out of my mind- just love them to death.

I see Roy is really trying hard to cut through the endless bullshit and ignorance that seems to prevail here whenever these types of articles come up.Good on you Roy You must be a patient Man.He is of course right,as any of the Professionals working with modern foam construction [Boatbuilders] will verify.

After eleven years, Varial foam are shuttering their operation owing to supply issues - explained in this article on Stab:

https://stabmag.com/news/this-aerospace-inspired-board-builder-is-closing-down-in-three-weeks-varial-foam/

Need Stab premium but the gist of it is Varial foam leans heavily on aerospace tech and aerospace is booming, so the little niche product off to the side gets clipped.

I didn't realise they didn't own the tech, they were simply siphoning off blanks from an already existing aerospace technology under license.

Anyone here try one?

I went close to pulling the trigger a few times, but could never quite swallow the price premium.

Just looked at their site the resin infusion looks neat...