First of all I would like to touch upon your mention of the myth "that boats build in the late 70's, early 80's were built a bit better since no-one really had the feel for how much
fiberglass should be used and the older boats tended to be "Overglassed" where the newer boats had a thinner hull." It is really hogwash. The late 1970's through early 1980's was the worst period for
blisters and generally was the worst period in terms of overall build quality since boats were getting lighter but the engineering had yet to improve.
Then there is the old saw that early boat were heavily built because designers did not know how strong fiberglass was. 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 fiberglass 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 fiberglass composite
equipment when he was hired to design the Triton and
Alberg 35) The reason that these 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 than a lack of knowledge of the material. Early designers and builders had hoped to use fiberglass as a monocoque structure with a minimal amount (if any) framing to take up
interior space.
On its own, fiberglass laminate does not develop much stiffness and it is very dense. If you simply try to create stiffness in fiberglass it takes a lot of thickness. Early fiberglass boat designers tried to simply use the skin for stiffness with wide spread supports from bulkheads and bunk flats. This lead to incredibly heavy boats and boats that were comparably flexible. (In early designs that were built in both
wood and fiberglass, the wooden boats typically weighed the same but were stiffer, stronger, and had higher ballast ratios)
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 strength of the hull itself. In simple terms it is the strength of the unsupported hull panel (by 'panel' I mean the area of the hull or
deck between supporting structures) itself, 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.
This fatigue issue is not a minor one. 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) 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. Apparently, there are an increasing number of
marine insurance underwriters refusing to insure older boats because of these issues.
As to the specifics of your question, if you are going to go distance cruising with the goal of doing the Bahamas and then beyond you should be considering boats that are designed for that purpose. There certainly are a number of good choices out there. Neither the Hunter 32 (by which I assume that you mean the Hunter Vision 32 with the freestanding
aluminum rig) nor the Bristol 32 are particularly well suited to your plans. The Hunter 32 is designed to be a good coastal cruiser. It has an
interior layout that makes sense when cruising for coastal cruising from anchorage to anchorage but which is not really suitable for
offshore useage; lacking the kind of
storage, seaberths, tankage, handholds, ventilation,
cockpit design etc. that are so essential to a good
offshore cruiser. Hull form wise, the Hunter would tend to have a quick motion that would be quite uncomfortable on the Bahama banks
The Bristol 32 began life as a CCA era
race boat and suffers from all of the issues that is implicit with the excesses of that era. They were tortured to meet a
racing rule and while pretty boats they are miserable boats to sail in either light or heavy conditions. Thier short waterline length means a very uncomfortable motion combined with limited carrying capacity, cramed quarters and poor performance. A better choice would be the later Bristol 31.1, Bristol 34 or Bristol 35 (with the 1970's era 34 being a real favorite of mine).
Jeff
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