Mark,
If I am reading you correctly, someone (probably previous owner) replaced  
the stringers with pine and hoped that the fiberglass would seal them in.  The 
factory stringers were fabricated from marine grade plywood.  Again, it's hard 
to comprehend why someone had to replace them.
If you have a digital camera or a good quality cell with camera, this  would 
be the easiest way to post the pictures to the list.
 
Rummy