either your photo is a very old one, or your dreaming. i worked in hong kong back in 1971 and visited the yard often. had a cadet back then. later, in 1986 back in u.s. we cut up an old cl-40 after it was gutted by fire. the decks were solid glass with channels filled with continuous solid teak. no end grain balsa anywhere. not even sure back then it was used by any asian yard. yes, ply was used as embedded backing plates for high load area.