: In a conventional composite layup you'd want the Kevlar where you had it
: initally, but this isn't a conventional composite layup, it's wood cored.
: If the layer right at the wood/composite junction breaks free from it's
: bond to the wood the entire layup is then compromised, so you have to
: insure that this doesn't happen.

: Bill H.

Ok, I'm seeing where you are coming from now. In essence, the stiffness of the Kevlar right against the wood is hurting itself more than it is helping. Hmmm...

Ok, I see your logic of moving the Kevlar to where it could do the most good (not against the wood). But what about moving the Wood to where it can do the most good? The benefits of having a core material are that you increase the thickness of the laminate, which increases stiffness, while also transferring the inner and outer layers more truely into Tension and Compression (as far as I understand). So would it make more sense to move the Wood more to the inside and surround it with Polyester...? I'm mentioning Polyester instead of Glass because it is more Flexible (Poly has an elongation of ~14% instead of the ~4-6% of any of the Glasses or Aramid fibers). This would give it more flexibility to use the max elongation of the MAS epoxy (~10-12%), while also maintaining the benefits of the core-

I originally placed the wood so far towards the interior of the laminate because I wanted to protect it from damage of point impacts, but perhaps I should be more worried abouts its position relating to delamination from shear stress? My worries of delamination were originally subsided when regarding that Epoxy resin has interlaminar fracture toughness considerably greater than that found in Vinylester resin, which is what is commonly used in whitewater composites. Most of the pro builders shy away from Epoxy to cut costs, and only use it for bonding applications- I figured using Epoxy over Vinylester should lighen my concerns of delamination of any bonds.

Bill, your insight is greatly appreciated. You provide a lot of great responses on this forum, and I know that myself as well as others are quite thankful~

So if my initial layup (from outside to inside) was the following:
Dynel : S-Glass : Poly : S-Glass : Poly : E-Glass : 4mm Okoume : Kevlar

Perhaps now I am proposing something like this:
Dynel : S-Glass : E-Glass : Poly : S-Glass : Poly : 4mm Okoume : Poly : Kevlar

I mean, there are so many combinations possible... I would really love to make a bunch of test panels and really give them some testing. But even with that, its hard to translate any standardized test into the forces applied in a whitewater environment. I remember reading in the "Boat Builders Manual" that a number of the laminates didn't do well in testing but worked pretty well in actual application. Thats part of my current boat building project is to take a wood cored laminate and see how it actually works out in a whitewater environment. But I also don't want to kill myself in the process. So I'm definitely trying to use as logical of a Lamination schedule as I can come by with a wood core~

~Johnathan

p.s. brevity is not my strength~