He might be asking about the use of wood in fiberglass boats, rather than
wood boats. Commonly the use of plywood for floors, transoms, and interior
pieces. As to the why, it's because plywood is cheap.



Cheaper. Lighter. More easily fabricated.
Can be the best choice in certain applications regardless of cost savings., but
in most cases it is a matter of building a boat that the public can afford to
buy.

Like our cars, homes, and other possessions- every manufacturer knows of ways
to make any product "better", but if the difference ultimately results in a
near-perfect product that 1 or 2 percent of the population could ever
contemplate affording or an extremely serviceable product available to a far
greater number of folks, there are a number of factors to consider.

The good news is, buyers who want a boat built without a sliver of wood in the
hull can find them. In some cases, they will be more expensive. In others,
(such as welded aluminum), they will not be more expensive but may have other
issues to deal with beyond potential wood rot.