Regardless of what you might think of George's interpersonal skills or ability to design the shape of a kayak, I am a supporter of his engineering analysis. Here are a couple of work-related, though not kayak-related, examples. The point is to debunk the "stiffer is stronger" thinking:

Dodge Viper Inner Door Handle: I work for a company that supplies automotive interior components (door panels, headliners, etc.) including the whole interior for the Dodge Viper. During a test of the inner door release handle, we found that the handle was breaking before maximum load. We used our CAD data to run a finite element analysis (FEA) of the part to do a virtual test of the failure. We then decided to "beef up" the handle in CAD by thickening the plastic wallstock and adding gusseting ribs. We ran the analysis again, and found that our efforts actually made things WORSE. Overall, the stress on the handle was lowered, but the stiffening had increased stresses in what we call "hot spots" that show up on the analysis in bright red. These are places where the stress exceeded the ultimate stress of the material, and we would expect to see failures there. If memory serves, we ended up conceding that the handle design we had was poor, and could not achieve the 30# load that we were testing to, but it went to show that "stiffer" was not "stronger."

Boeing Cargo Net: One of my co-workers worked at Boeing and told me of a problem that they had with a cargo net. (This subject came up during the Viper handle test.) They were using FEA to study the loads on a cargo net that holds cargo in the lower deck of a plane. They found that the corners of the rectangular net were over-stressed under load. Common sense told them that they needed to "beef up" the corners -- to reinforce them. They did and it still failed. The problem was solved when they WEAKENED the corner attachment areas, which allowed the attachment areas along the straight sides of the net to take up more of the load.

Hopefully you can draw some parallels to a kayak hull parked on top of a rock -- that if it flexes, the stresses are less concentrated in the area of contact with the rock, and that failure is less likely.

In the words of the old jazz standard, "somethin's got to give, somethin's got to give, somethin's got to give..."

End ramble.

Dean