Never got to try one suggestion I read that sounded good - take a regular spade bit - maybe a 1" size to start with? Cut/grind off the point, chuck it as usual in a variable speed drill, and essentially "drill" out the foam. The flat part of the spade bit without the point prevents major hull/stringer damage, but the shape/edge on the spade bit eats thru the foam. Let us know how that works if you try it.
Yes the foam is wet at bottom. I left the boat uncovered over winter after i took the hardtop off knowing that I would be replacing the foam. I plan to replace it with rigid foam....By the way, is that foam wet?