has anyone seen this?

I tore out my flooring today.Thanks for the sawzall tip it made life easy!! I have a 74 southwind and I believe that I am removing stock flooring! on the sides the floor is sectioned off into squares.These squares were filled with foam and had 2 4 inch or so strips of wood running down the middle.The floor sat on top of that.These square cavities are pristine!Minus the wood! There is only a veneer left stuck to the glass.This system just does not look very strong??Any suggestions for improvements?The cavities are also watertight my boat has been inside for several weeks and these boxes had quite a bit of water in the bottom.The foam was a little wet as well.Thanks for any help or suggestions,this is my first attempt at this and I like my boat too much to do a half a-- job!Yes I have drilled many holes in stringers and the wood is great.Top and bottom. Thanks again guys.Kevin

Here is a link to a website that has a good assortment of blades & their use. I just buy mine locally, but this does show what there is.
You can get a general purpose blade that works
for several materials.


Blades