I think you have this backwards- Kevlar on the outside and carbon on the inside. Otherwise the carbon is doing ALL the work as it's the stiffest of the three.
With a Kevlar/Wood/Carbon lay-up, the Kevlar distributes the load to the wood, which in turn distributes the load to the carbon.
First, a practical matter, It is very hard to sand and fair Kevlar, it fuzzes. So you put it on the inside so you don't have to finish it. You can cover kevlar with glass or microballon epoxy to fair it but that is dead weight
Second, Components of a laminate do not take load individually. It is the strength of the whole. Once you exceed the strength of the whole, it starts delaminating, becomes about as strong as wet cardboard and and the whole thing falls apart.
Third a Carbon/wood/Kevlar can be made lighter and cheaper than a carbon/wood/carbon. Plus Kevlar has great impact resistance and tension strength. In case of a sharp impact, like a collision, there are a lot of cases where the carbon would break but the wood/Kevlar will flex or not break clean so the hull would hold long enough to go home and fix it. That is the theory plus panel testing plus hear say from white water kayaks anyway.
Fourth, for a homebuilder Kevlar is easier to laminate and a lot cheaper. I have bought it for as little as $2/yd on eBay. Carbon is ridiculous on eBay. To make carbon junk for their car, people are paying more than they could buy it from a real dealer like Fiberglass Supply Company.
Carl
