> For example, if you take a board and cut off 1/8" directly across the
> grain, the fibers are only 1/8" long and can be broken (separated)
> very easily. If you would cut an other 1/8" strip exactly with the
> GRAIN (not necessarily along the length of the board because the board
> will probably not be cut "straight" to the tree's growth) the
> strip, with all the fibers intact will be many times stronger.

Cutting with the grain (flat-sawn) will result in a strip that is pretty strong when it's sitting by itself on your workbench, or being stapled to the form. However, you need to have vertical-grain strips to be strongest in the glass/wood/glass composite member. Remember that the wood in the center ply is not taking any tensile stresses that would tend to break the wood between the stronger bands of summerwood. (or is that spring wood...anyhow...) The wood is in compression and shear, but not tension. For compression, you will get your best strength when the grain runs perpendicular to your boat's surface. For shear, the forces run somewhat diagonal to the normal surface of the panel, so the exact orientation of the grain isn't as critical.

> chance there will be that the grain will run out (cross from top to
> bottom). That is why plywood is so strong, with the layers glued together
> there is not a single grain path through the material.

Grain runout isn't so much of an issue with wood-composite boats, as the fiberglass-resin matrix is carrying the tensile forces that would have ordinarily torn the wood apart. Fiberglass, for its weight, is generally a lot stronger in tension than wood. Wood, per weight, is generally a lot stronger in compression than glass.

> Why my infatuation with grain patterns? I make "primitive"
> wooden bows out of logs - if you violate the grain the bow WILL fail. Some
> of my "character" bows look really weird because the limbs of
> the bow twist and curve to follow the grain - but you should see them
> shoot!!

Cool--that is also why "primitive" kayaks are be built with frames that minimize grain runout. That's why chines, keels and stringers are often hand-split rather than sawn, as the split will follow the grain where the saw doesn't. Wooden-framed snowshoes too, I understand.

Shawn