According to a boatest.com reviewer, the hull of the Cutwater 28 is solid fiberglass, with no coring: http://www.boattest.com/boats/boat_video.aspx?ID=2491
However, the decks are cored with Divinycell PVC foam. Is this rub rail right at the hull-deck joint?
USNA81, are you confident that moisture is staying where it shouldn't? Any visual evidence, on the inside or outside of the hull?
The CW 28 is a relatively recent design with lots of interesting features.