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Posted: Sun Feb 27, 2005 2:49 pm
by zfennell wrote:They're 3/4" just like your H80.

I use 1/8" H80 for the top and bottom and 1/2" eps foam.

EDIT: Forgot to add, the biggest advantage is strength and the weight difference. The only disadvantage is it's a longer process and you need more equipment to do this compared to other ways...

I'll tell you what... once I get my DBA and tax forms I'll loan one of you a board to make a review on... gimme an email at or

If you like the board after riding and reviewing it, you can buy it for cheap... otherwise send it back, etc etc.

is it just me, or does the quote feature totall suck?

but anyway.
thats a very kind offer.

do you believe boards built this way are actually stronger (stiffer) or perhaps more flexible and (maybe) durable ?

one the cons of H80 is that it is brittle.
despite having higher strength and modulus compared to similar foams. the max elongation is relatively low.
especially, in shear.

EPS, on the other hand, has all the strengh of oatmeal. but will permit alot of deformation/elongation before failing.
i'm guessing ( along with the fact, it works in surfboards)..
By using the H80 in the skins only, the shear strain is kept to a minimum.
the EPS will allow the board to flex until the skins can absorb all of the flexure loads.

sorry for my rambling.
i was just wondering if you do anything special to account for those nasty compressive loads from your feet? is the EPS strong enough to maintain spacing between the top and bottom skins?

thanks again,

Posted: Sun Feb 27, 2005 3:10 pm
by not annonymous
From what I understand eps is pretty good in compression, it just can't take shear forces well.

If you are not putting any reinforcement between the EPS and the H80, how can you possibly get any increase in strength or stiffness over solid h80?

All you are doing then is replacing strong foam with a weaker (but lighter) one.


Posted: Sun Feb 27, 2005 3:43 pm
by zfennell

i haven't actually done the math, but its hard to argue with the success other folks have had with surfboards.

i agree, its hard to believe swapping core material with something softer will improve the strength/stiffness. But, it may allow the board to withstand higher flexure limits

almost out of necessity, thin boards are required to flex alot.
the more the flex the greater the shear and related shear elongation.

even though we design the skins to carry all of the associated tensile/ compressive forces of a flexible board its still possible to exceed the flexure/shear limits of the core.
possibly, the shear stress is not too high for the H80 but the required shear elongation is.

i think this may also be related to some folks having better success with more elastic Airex cores. In particular, when using lighter layups.
maybe that is a much simpler solution than a full sandwich layup?

there is a pretty cool thread talking about what others are trying. ... ost=183391

lastly, i should appologise for completly hijacking this thread.

Posted: Sun Feb 27, 2005 9:43 pm
It is actually (I believe) stronger then just H80 because of the layers of epoxy (or glass if you choose to use it) between the Foams.

Just trust me, it's a lot stronger... I guess one of these boards will go around a few people for testing... keep in mind I don't want to send out a demo board quite yet, since I'm only 16 (17 in april) and money doesn't come too easy for me... give it a week or two and I'll look into sending a demo board to whomever emails me first...

After someone tests it out, I guess we'll have a more unbiased opinion.

EDIT: Your link, that's exactly what I do... but I didn't find it there... I actually found it about a year ago (not exactly the same foams that I use) but in a boat building book, and I came up with the idea of using polyeurathane or expand foam and balsa on the outside. Then I came across swaylocks and that forum and used that exact process for a surfboard, and now I'm incorporating it into kiteboards (made a few already and I've been riding/abusing one to see what it can uphold to.)

Posted: Sun Feb 27, 2005 11:25 pm
by sq225917
take a cigarette, roll a ten pound note tightly over it and then bend it to touch the tips together.

then unroll the ten pound note, and try to bend the cigarette without rolling it up in the ten pound note first.....

we all know the result...

Posted: Thu Mar 03, 2005 10:13 pm
by Guest
A non-homogenous core need not be made just in layers. -Hein

Posted: Thu Mar 03, 2005 11:56 pm
by zfennell
i'm guessing that you mean the core may be varied laterally.
i.e. stringers and rails.

but you should probably just spell it out.

Posted: Fri Mar 04, 2005 6:37 am
You can add a stringer quite simply, but the Side being H80 will make up for that... at least... actually... I don't know. I guess I'll try that one out and tell you guys about it later...

Being 16 and starting a business sucks is all I've got to say... I'm already broke as it is and now I'm getting broker doing this... and I have a girlfriend which makes me twice as broke as I was... damn I'm poor as hell now... I really hope these boards sell.

BTW nobody ever emailed me about testing a board out... Just email me and I'll get you a board out asap.

Forgot to mention... what would you pay for these boards? Before a review? After a good review? I'm hoping to put them out for like $350-$400 without straps and probably $400-$450 with straps. Any suggestions on pricing? Come with 6 Month warranty unless used on sliders or broken in any way other then just riding. (like dropping off of something onto concrete going at highspeeds)

EDIT again: Forgot to mention the site hasn't been updated in a while and I changed board design and etc. Whole site's due for a makeover soon so just ignore that incase you check it.