I had a pair of H14 hulls that had soft spots so I cut them up today for disposal. They had matching 1979 hull numbers, but the interior foam blocks were completely different. One was a two piece type that matched the shape of the hull pretty good. The other hull had a squarish block in it which was tapered at each end. The hulls haven't been in the water for 15 years, but there was some moisture from condensation inside. The lower block of the hull shaped foam probably weighed 10 lbs, as it was completely waterlogged. Here's a couple photos.
BTW: A reciprocating saw with a coarse metal blade cuts through Hobie hulls like butter.
Jack