Like 2.5# or 3#? I’m trying to get a feel of where lies the point of diminishing returns between core and skin.
For instance, if I would normally do 4+4 on the bottom and 4+4+4 on the deck with a 2# core would bumping the density to 2.5" be enough to offset cutting back some on the lamination? Or is the difference in density not enough to offset what the additional fiberglass adds?
I would think that if you go to 2.5 pound density core, you could go to a single 6 bottom and a 6+4 top lam. I’m speculating here, but that is how I would address the issue. You could always do some drop tests using some foam and glass pirces, with the different densities and glass schedules. I’m sure Everysurfer has probably done some tests of that nature.
Bill
Hi Bill, not on EPS. but I’m thinking if Gdaddy tested the EPS vs PU without glassing under a drop test it would show the isolated difference of the foam.
I made 4 boards from 2.5# blank. I glass them with same schedule than 2#, no weight problems, guys who use them are heavy babies 85 to 105 kg. Those boards were (are) really durable. Increase foam density increase skin buckling resistance so it increase snap résistance of board but not so much denting résistance. Réduce skin thickness will quickly reduce board durability, far more than going from 2.5 to 2 blank density.
Hi gdaddy -
I’ve done some experimenting and have made boards from various density EPS foams. All foams were not the same manufacturer so there may be some differences related that but the higher density foams can obviously be glassed with lighter lamination schedules and maintain some degree of durability.
Everything is relative though… some guys prefer boards that cave in on the deck. I’ve heard it described as 'breaking in ’ like a baseball glove. Others, like myself, consider this too weak. I like to get lots of mileage out of my boards.
In any case, it might be worth mentioning that the higher density EPS foams tend to be less ‘springy.’ By that I mean a dent tends to remain dented where as a light density EPS tends to be more spongy and springs back.
On this subject: http://www.swaylocks.com/groups/why-have-i-not-seen-3-lb-eps-blanks
Very informative feedback, gentlemen; especially the 2007 thread referenced above.
The other approach I’m considering is using Warp + my regular epoxy for the primary lamination layers and swapping the deckpatch out for some S-Glass laid at the diagonal and lammed with a stiffer resin. I don’t want to stiffen the entire board, just the contact area on the deck.
For a long while now I’ve shaped my personal boards in higher density eps with balsa stringers. I’m sure that somewhere in the archives I’ve explained it in great detail, but basically I found that getting my densities up a bit allowed me to approach the riding characteristics of my pu boards, without loosing drive and inertia, and noticably cut down on chatter (the balsa stringers really do help here as well) - all the while giving my a 15-20% weight reduction. Floaty but not too corky, and pretty reactive.
Almost counter-intuitively, you’ll get more indentations with the higher densities as they have less springback and flex. If you get a dent it’ll stay whereas with really light densities and a fairly flexible resin you’ll have some elasticity that avoids this. Your glass schedule and technique can help make up for this.
Enjoy