: 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~

I'm a big fan, recently, of polyester fabric in a composite layup, works well, actually mimics (sort of) Kevlar for a heck of alot less money and aggrevation. I'm not a great fan of Dynel because it sucks up gross quantitites of resin and results in a very heavy layup.

Btw, the primary reasons production builders shy away from epoxy other than the cost issue is that it takes so darned long to set up and slows the building process to the point they're not making any money. Also there are bonding issues with most gelcoats, most require and intermediate step(s) between the gelcoat and the resin which also slows production. Waiting even 4 or 5 hours for a heat set epoxy is wildly different than waiting 15 minutes for vinylester to cure.

Bill H.