I apologize for exerpting this from articles that I had written for other purposes but this thread contains two very important points of view that I strongly disagree with. The first has to do with the strength of older boats.
"One statement you see a lot is “Early boat builders did not know how strong fiberglass
was and so made it very thick.” Horse Feathers! This is just plain bunk. The federal government
had done a lot of research
during WWII and in the years following, and the information was widely available by the late 1950's and early 1960’s. As a kid, I had literature on fiberglass that pretty clearly analyzed its properties. Guys like Carl Alberg
, who was working for the government
designing fiberglass ammo boxes and other composite structures when he was hired by the Pearsons to design the Triton, knew exactly what fiberglass would do. They knew that the e-glass of that era was pretty poor quality and was especially prone to flexing and to fatigue. Designers of that era attempted to design fiberglass boats to be as stiff as wooden boats of the era. That took a lot of thickness since F.G. is very flexible compared to wood. This was especially true on a pound for pound basis.
They also knew that the fiberglass resins and cloths of that era were extremely fatigue prone, and so if the boats were not as stiff as wood, there would be major fatigue problems. This put early designers in a bind. If they made the glass boats as thick as a wooden planked hull
they would be impossibly heavy. If they did not, fatigue would condemn them to a short life. They mostly chose to compromise. By that I mean they chose to do boats that were not as stiff as the wooden boats they replaced but were heavier. Early glass interpretations of wooden boats were generally heavier and carried less ballast than their wooden counterparts. They were much stronger in bending but not as stiff. As fatigue took place some of these early glass boats became even more flexible which leads to more fatigue, which can lead to a significant reduction in strength."
It is extremely wrong to say that the marine insurance
industry does not know what it is talking about when they refuse to insure older boats. They see thousands of claims in any year and they are pretty vigillient in looking at trends and trying to understand why they are occurring. In the late 1990's the marine insurance
industry noted that claims made on older boats seemed to be disproportionate to the source of the damage. (To quote from of my article again)
"In a study performed by the marine insurance industry looking at claims on older boats and doing destructive testing on actual portions of older hulls, it was found that many of these earlier boats have suffered a significant loss of ductility and impact resistance. This problem is especially prevalent in heavier uncored boats constructed even as late as the 1980's before internal structural framing systems became the norm. Boats built during the early years of boat building tended to use a lot more resin accelerators than are used today. They also would bulk up the matrix with resin rich laminations (approaching 50/50 ratios rather than the idea 30/70), and non-directional fabrics (mat or chopped glass) in order to achieve a desired hull
thickness. Resin rich laminates and non-directional materials have been shown to reduce impact resistance and to increase the tendency towards fatigue. The absence of internal framing means that there is greater flexure in these older boats and that this flexure increases fatigue further. As a result of finding that a small collision
will do disproportionate damage, there are an increasing number of marine insurance underwriters refusing to insure older boats."
Beyond all of that that these early laminates started out with less inherent strengths. While Insurance industry testing of older boats has shown that these heavy solid hulls did not have the strength of newer lighter hulls, the failure mode was not completely understood. As mentioned above, it was generally believed that the issues were inferior resins and fibers, poorer handling of the materials, poor resin ratios, and the extensive use of accelerators and fillers. What is learned in testing performed by the U.S. Naval Academy is that the problem may also lie in the extensive use of non-oriented fiber type laminates (mat). These old heavier so-called solid glass hulls actually used an enormous proportion of non-oriented materials which greatly reduce their impact resistance, stiffness, and tendency to resist fatigue.
So while these older boats may be less desirable because of their inferior sailing characteristics, they are also comparatively fragile when compared to better built, equally well maintained newer boats.