Fleet # 7 of the S2 7.9 Class has a website with information about their boats. On it they've posted a 10 page letter from S2 about the 7.9 construction, etc. Pages 8-10 also have information about the 6.7 and 6.9.
It also identifies in earlier pages the type of epoxy used in later 7.9 (and 6.9) hulls.