I like your crude spring flex method/research George. Reminds me of a method a street luger said he used for finding the 40/60 weight distribution point when making his rigs – one end on a bathroom scale and the other end supported at the same height in a static position.
I’ve wanted to do crude (static) G-Force tests on surfboard flex. Measure deflections in height at critical points with a wieght representative of a surfer’s weight, 2x weight and 3x weight placed on the deck of a surfboard, with saw horses at different positions relative to the weight. Fun research but I do not have the weight set needed or a good supply of surfboards to test. Maybe some sunny day…
I had a Hansen Stratoglas. the air vent hole had a plug similar to that for a squirt gun. I would pull the plug and let it sit in the water for awhile and then put the plug back in. The Hansen had a fairly solid glass shell. Forgot to pull the plug after setting it on the beach one day. A bit later when I came back to the board the plug had blown and was long gone. After that, my quick fix was to plug the hole with surf wax after air temp had acclimated to water temp. New plug every trip.
Before I bought a Morey-Doyle years ago to ride crowded breaks, I was unaware of the possibility of desirable flex. That was a fun board to ride. Variable flex is my latest quest.
Clearly foil, max thickness, foam density, shape (etc.) affect flex. Like you, I think there is a (quantifiable?) “flex” pattern that creates preferred performance.
Satisfaction is in the quest.
Bill