Rob:

I gotta tell ya; I don't think there is foam in there! I have a 1990 Hobie 18 magnum and I stuff things in the ports all the time, I've never seen anything like this in the 18s I've dismantled. I do have about four large foam noodles in each hull, though; I originally put them in for floating on when we're in the middle of the lake on a no-wind day with a cold beer in our hands.

Wyatt