2004 and thereabouts was a turning point for the boat building industry. The manufacturers who used wood and desired to stay with wood went to KDAT types of plywood . . . product names like 'Perma Panel' and 'Greenwood XL' may appear in their promotion materials. Their products are pressure treated plywood and Kiln Dried After Treatment (ie. KDAT) making them suitable for use in fiberglass boat construction. They exhibit rot resistance as regular PT lumber does.
Other manufacturers began using foam coring instead of wood for their stringers and structural components, and others began using molded fiberglass stringer 'grids'.
Many boat manufacturers are fairly vague about the details in how their boats are built . . . otherwise you would not buy them
Many boat owners do not have a good understanding of how their boat was built
.
I have found that factory tour pictures and videos are a decent source of information as to how a boat was built. Additionally, you can look well into a boat's structure to get an idea. You can also find some boat review articles that mention construction methods or materials.
You can also find boat restoration threads (here on iBoats) that reveal the guts of a boat. We know for example that
@Friscoboater 's 1995 Sea Ray had lots of wood in it. As to if/when that changed, some research is probably needed.
The challenge would be to find out what was used in 2004 . . . vs in the 1990's vs. what is used today.
