I appreciate the sophistication of your testing methods. However, because I am old and fat and have fused vertebrae and bad knees so I can't get in or out of a kayak I use the bottom of my double paddle canoe for impact testing. I paddle at flank speed at 90 degrees to a nice rocky beach and drive the canoe on to it as hard as I can until I can just stand up on the bottom of the canoe and step out. If no rocks grow up through the bottom---and none have to date--- the impact test has been successful and I know the canoe is light enough because I can carry at least 100 meters over my shoulder back to the car with only one rest stop. The bottom of this canoe is hot moulded from 5 layers of mahogany that total .2 inches with a layer of 6 oz cloth inside and out. If the impact test failed I would fix the hole and add another 4 oz layer in that area and successive layers until no more rocks appeared.

BTW, is your glass/wood ratio of 66/33 covered on one or both---33/33/33---sides? Also, just how good a model is a flat sample when every square centimeter most strippers, etc, is convex?

My problem was not with the speed. My problem was that no claim were made. No
: claim was made that 12oz of glass was sufficiently stronger than 6oz to be
: called an "expedition" layup or tht 4oz glass was sufficiently
: strong and light enough to be called a "lightweight" layup.
: (That was a claim I expected to be made.) No claim was made that the cross
: grain testing was more suitable than the more obvious along the grain
: testing. (Another claim I expected.)

: One could modify the standard impact test to: use a (3# or 8#) hammer with a
: hole drilled in the handle for a pivot, and a (6" or 12") square
: sample supported along the edges. Drop the hammer from a set if increasing
: heights until the panel breaks.

: Remember, I don't do experiments. I do my math and I believe the results. So
: I simply look up the solution of a point load on a plate (the glass/epoxy)
: on an elastic foundation (the wood).

: If I limit myself to identical layups on the interior and exterior, I believe
: the math shows that the optimum glass/epoxy:wood ratio near 66:33.