I have Betty Cook's 2nd Larry Smith Scarab, KAAMA. Kevlar/epoxy with Carbon fiber reinforcements. Larry indicated the boat is around 8,000 pounds dry. He said the first boat was some 1,200 pounds heavier.
The deck flexes when I walk on it, but the bottom is very thick judging by the transom drain. It is about 3 inches from the bottom, outside, and nearly touches the bottom on the inside- Larry said about 2-1/2 inches thick in that area. There are 3 full length stringers and has 2 more in between from the engine bay bulkhead forward. The stringers are about 16 inches deep along most of it's length.
The stringers are placed directly above the lifting strakes for direct load transfer. As I recall there are 11 bulkheads total. I think Larry Smith put all the beam stiffness he wanted in the bottom from the chines down, and the rest is as we say- laginappe.
There are no signs of stress cracks, and that is significant considering Betty raced her for 4 years and Ron Hirschberg a few more. He raced it as Revenge, and is in the 1985 Apache Offshore Challenge video. He retired when someone on board broke some ribs in the 12 footers. To be continued....