To get to the original, question, the Morgan 34 was a really nice boat for that era. They were better built than later Morgans, sailed well for the day, and with their shoal draft still make good coastal cruisers in venues with shallow waters to explore. The keel/cb arrangement is a nice feature allowing the boat to go to windward well with the board up, Run pretty well with the drag reduced by raising the board, and allow the helm to be balanced by partially raising the board. They have a very usable interior layout.
But to some of the points above,
When fiberglass was first used nobody knew the lifespan so everything was overbuilt, certainly not a bad thing. Engineering was just different back then.
That is a myth that has little bearing in fact. I explain this in more detail below, but by and large boat designers and builders new exactly how strong fiberglass was. They also knew that fiberglass was way more flexible than wood when compared on a pound for pound basis, so they looked for a compromise to get closer to the stiffness of a wooden hull without getting so wildly heavy that the boats could not sail well. The bulked up the hulls with larger proportions of mat and resin than is ideal from either a strength or durability standpoint. So while glass hulls of that era were often slightly thicker than the boats that followed they did not necessarily start life stronger and they are more prone to fatigue than later designs.
They used a lot more resin, so osmosis blistering less common. Hulls heavy and thicker than they would today. Usually no wood or other cores in hull, but deck is likely cored, so need checking for delamination.
Using more resin has no impact on the likelihood of blistering. In fact its the resin which is the primary originator of blistering. Osmosis blistering was less common in some of these earlier boats since they used a different resin formulation before the Oil crisises of the 1970's. Boat builders began using the reformulated resins around 1973/74 and they were ubiquitous by the late 1970's. As the problem became readily apparent by the mid-1980's builders began moving towards boat building techniques which minimized blisters even more effectively than the early pre-reformulation resins.
Fiberglass boats had wooden cores almost from day one. Some of the earliest boats used materials like Masonite which is a disaster, and plywood which is not much better. By the very early 1960's most production builders had moved to using balsa coring because it is lighter and less prone to rapidly rotting than plywood. There have always been a limited number of companies which did not core decks, and the British in particular preferred closely spaced frames to coring, but boats built with un-cored decks are the exception for any period in fiberglass boat building.
Whenever this topic rolls out, Gary likes to role this link out. This link supports some of what I am explaining below. The testing done on the Coast Guard boats is interesting. These boats show how durable a properly built Fiberglass boat can be. In this test, the hull has retained all of its tensile, compressive, flexural and roughly 90% of its sheer capacity after 20 years of hard service. But as the article notes: "These were Single skin FRP construction was reinforced by transverse aluminum frames, a decidedly conservative approach at the time of construction.
Laminate schedules consisted of alternating plies of 10 ounce boat cloth and 1 ounce mat" (bold and underline added for emphasis)
The Coast Guard boats represent a wildly unusual and superior construction to the typical production sailboat of the era. In the description these boats had less than 10% of their reinforcing in mat. Production sailboats of that era often approached 25% ratios. Mat starts out weaker and factigues much more rapidly. Mat is particularly poor in impact perpendicular to the laminate and horizontal sheer and delamination of the mat layers are general the failure mode in impact.
This is what the article is referring to when it says, "The reason solid skin laminate were 3/8 to ¾ inches thick was because the laminates of the time had what we would today consider to be poor mechanical properties."
Beyond that, these boats had aluminum frames which greatly limit flexure, especially as compared to typical pre-mid-1970's era boats which had almost no internal framing to control flexure. Flexure is a major cause of fatigue which in turn greatly reduces impact resistance, stiffness and resistance to bending capacities.
The Shields is another atypical boat of that era being the pet project of Corny Shields, the then owner of Chris Craft who personally supervised every aspect of the design and construction of these boats. Quality control was extremely high on these boats since as one designs, they were expected to roll out the door with in an extremely tight weight range. While the article does not comment on its structural condition, I would expect that the Shields would be in unusually good condition for a boat of that era.
Anyway, here is a draft article that I wrote on this topic quite a few years ago. (As was pointed out the insurance study mentioned in the article is no longer available online.)
I would not think that a well- constructed fiberglass has a life span per se. Neither concrete nor fiberglass inherently breaks down or loses strength simply on their own without other factors coming into play. They require other causes. In the case of fiberglass loss of strength can result from one or more of the following,
-The surface resins will UV degrade.
-Prolonged saturation with water will affect the byproducts formed in the hardening process turning some into acids. These acids can break down the bond between the glass reinforcing and the resin.
-Fiberglass is prone to fatigue in areas repetitively loaded and unloaded at the point where it is repetitively deflected. High load concentration areas such as at bulkheads, hull/deck joints and keel joints are particularly prone.
-Salts suspended in water will move through some of the larger capillaries within the matrix. Salts have larger molecules than water. At some point these salts cannot move further and are deposited as the water keeps moving toward an area with lower moisture content. Once dried these salt turn into a crystalline form and exert great pressure on the adjacent matrix.
-Poor construction techniques with poorly handled cloth, poorly mixed or over accelerated resins, and poor resin to fiber ratios were very typical in early fiberglass boats. These weaker areas can be actually subjected to higher stresses that result from much heavier boats. It’s not all that unusual to see small spider cracking and/or small fractures in early glass boats.
-Of course beyond the simple fiberglass degradation there is core deterioration, and the deterioration of such things as the plywood bulkheads and flats that form a part of the boat’s structure.
Earlier boats had heavier hulls for a lot of reasons beyond the myth that designers did not know how strong fiberglass was. Designers knew exactly how strong the fiberglass of that era actually was. The US government had spent a fortune developing fiberglass information during WWII and by the early 1950’s designers had easy access to the design characteristics of fiberglass. (Alberg, for example, was working for the US Government designing F.G. composite items when he designed the Triton and Alberg 35) The reason that the hulls on the early boats were as thick as they were had more to do with the early approach to the design of fiberglass boats and the limitations of the materials and handling methods used in early fiberglass boats. Early designers and builders had hoped to use fiberglass as a monocoque structure using an absolute minimal amount (if any) framing which they felt occupied otherwise usable interior space.
On its own, fiberglass laminate does not develop much stiffness (by which I mean resistance to flexure) and it is very dense. If you try to create the kind of stiffness in fiberglass that designers had experienced in wooden boats, it takes a whole lot of thickness which in turn means a whole lot of weight. Early fiberglass boat designers tried to simply use the skin of the boat for stiffness with wide spread supports from bulkheads and bunk flats. This lead to incredibly heavy boats and boats that were still comparably flexible compared to earlier wooden boats or more modern designs. (In early designs that were built in both wood and fiberglass, the wooden boats typically weighed the same as the fiberglass boats but were stiffer, stronger, and had higher ballast ratios)
The large amount of flexure in these old boats was a real problem over the life of the boat. Fiberglass hates to be flexed. Fiberglass is a highly fatigue prone material and over time it looses strength through flexing cycles. A flexible boat may have plenty of reserve strength when new but over time through flexure fiberglass loses this reserve. There are really several things that determine the overall strength of the hull itself. In simple terms it is the strength of the unsupported hull panel itself (by 'panel' I mean the area of the hull or deck between supporting structures), the size of the unsupported panel, the connections to supporting structures and the strength of the supporting structures. These early boats had huge panel sizes compared to those seen as appropriate today and the connections were often lightly done.
This fatigue issue is not a minor one. In a study performed by the marine insurance industry looking at the high cost of claims made on older boats relative to newer boats and actually 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. The study noted that boats built during the early years of boat building tended to use a lot more resin accelerators than are used today. Boat builders would bulk up the matrix with resin rich laminations (approaching 50/50 ratios rather than the idea 30/70), and typically used proportionately high ratios of 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 further 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. Apparently, there are an increasing number of marine insurance underwriters refusing to insure older boats because of these issues.
I have been looking at a lot of older fiberglass boats in the past few years. One thing that has struck me is the sheer amount of noticeable flexure cracking in areas of high stress, such as bulkheads, chainplate attachment points, hull to deck joints, cabin to deck lines, engine beds and rudder posts, and other high load hardware positions.
There are probably other forms of hull degradation that I have not mentioned but I think that the real end of the life of a boat is going to be economic. In other words the cost to maintain and repair an old boat will get to be far beyond what it is worth in the marketplace. I would guess this was the end of more wooden boats than rot.
In most cases the prices of these older boats are somewhat constrained by their obsolescence. Sailors who buy modern boats have certain expectations that these older boats cannot or do not deliver. These factors can be faddish or fashion, but many are simple functional matters. Newer designs potentially offer more space, better performance and ease of handling, bigger engines and more robust electrical systems to power all the conveniences of home. While there are clearly people out there who prefer the older styled boats, for better or worse, in the marketplace there is a sense that they are simply worth less. And it is that market value which sets a ceiling on how much a boat is worth, no matter how perfect a condition it is in.
I can give you a bit of an example from land structures. When I was doing my thesis in college, I came across a government statistic, which if I remember it correctly suggested that in the years between 1948 and 1973 more houses had been built in America than in all of history before that time. In another study these houses were estimated to have a useful life span of 35 years or so. As an architect today I see a lot of thirty five year old houses that need new bathrooms, kitchens, heating systems, modern insulation, floor finishes, etc. But beyond the physical problems of these houses, tastes have changes so that today these houses in perfect shape still has proportionately small market value. With such a small market value it often does not make sense from a resale point of view to rebuild and these houses are therefore often sold for little more than land value. At some level, this drives me crazy, since we are tearing down perfectly solid structures that 35 years ago was perfectly adequate for the people who built it, but today does not meet the “modern” standards.
The same thing happens in boats. You may find a boat that has a perfectly sound hull. Perhaps it needs sails, standing and running rigging, a bit of galley updating, some minor electronics, a bit of rewiring, new plumbing, upholstery, a little deck core work, an engine rebuild, or for the big spender, replacement. Pretty soon you can buy a much newer boat with all relatively new gear for less than you’d have in the old girl. Its not hard for an old boat to suddenly be worth more as salvage than as a boat. A couple years ago a couple friends of mine were given a Rainbow in reasonable shape. She just needed sails and they wanted a newer auxiliary, but even buying everything used the boat was worth a lot less than the cost of the “new” parts. When they couldn’t afford the slip fees, the Rainbow was disposed of. She now graces a landfill and the cast iron keel was sold for scrap for more than they could sell the whole boat for.
Then there is the issue of maintainable vs. durable/low maintenance design concepts. Wooden boats for example represent the difference between a maintainable construction method versus a low maintenance/ durable method. A wooden boat can be rebuilt for a nearly infinite period of time until it becomes a sailing equivalent of ‘George Washington’s axe’ (as in “that’s George Washington’s axe. It’s had a few new handles and a few new heads but that is still George Washington’s axe”.) The main structure of a fiberglass hull is reasonably durable and low maintenance but once it has begun to lose strength, there is nothing that you can do.
The best deals on older used boats are the ones that someone has lovingly restored, upgraded, and maintained. Over the years they have poured lots of money and lavished lots of time into maintaining the boat in reasonably up to date condition. No matter how much they have spent the boat will never be worth anything near what they have in it because there is a real ceiling to how much an older boat will ever be worth and they will often have several times that ceiling invested.
And finally if you buy an old fiberglass boat, paint the bilges white. It does nothing for the boat, but if you ever have to sell the boat, then someone may look in your bilge and say “Lets buy her because any owner who would love a boat so much that he went through the trouble to paint the bilge white must have enjoyed this boat and taken great care of her no matter what her age.”