http://www.acmanet.org/cm/historical/do ... rt%201.pdf
Despite the myths of fiberglass boats being 'overbuilt due to ignorance of fiberglass strength' that we have all heard so much about, the article mentions Everett's engineering perspective and the fact that they actually knew quite a bit about what they were doing.
Here is an interesting quote (to me) I knew the early Tritons didn't use end grain balsa but this fills in some of the blanks.
When we first started with Triton, we
didn’t know how to stiffen the deck.”
Pearson explains. “We’d take the three-inch
diameter cardboard tubes the fiberglass
came in on, slice them in half, place them
over the deck, and lay fiberglass over them.
But it became difficult to get a nice interior
finish, so we started using longitudinal
strips of balsa as our core material.”
First the trial, then the error. Pearson
found that if water seeped through a deck
fitting, it migrated along the balsa grain
and delaminated the bond. He then took
several pieces of balsa, glued them
together and sliced off the ends to make “end grains,” so the
grain ran perpendicular to the laminate. This blocked water
migration. A salesman from the balsa supplier, Baltek, spotted
the paste-and-cut procedure one day while visiting Pearson’s
plant. He took the idea back to Baltek, and the company started
producing end grain, contoured core.
But by the time Pearson was approached to build the infamous
J/24s in the mid ‘70s, and even though he’d amassed a wealth of
knowledge in mechanically testing mostly industrial FRP parts,
not everyone was convinced balsa was a panacea for stiffening
fiberglass hulls. In fact, there was still a lot of resistance and
concern for water migration and rotting. But, “for impact resistance
and stiffness, balsa wood wins hands down,” Pearson
proclaimed. And he set out to prove his point. He made up an
end grain panel, drilled a few holes through it, anchored it to
some blocks, and submerged it in the Kickemuit in front of his
house. During low tide, the panel came up for air for about an
hour. Three years later he pulled the panel out of the river and found virtually no water penetration.