Let me explain something not entirely understood by the casual non boating public. There are many different ways to build a fiberglass boat and most of those ways utilize materials in addition to fiberglass. Boston Whaler has been around for a while now and they pioneered the foam filled single piece hull. This type of contruction is now used in variations by several highly regarded brands. In this contruction an outer hull is layed up in a female mold and an inner hull/sole/interior liner is layed up on a male plug. Then the male plug is set into the female mold and the two pieces are bonded together becoming one single structure. Then foam is injected into the assembly until the interior is completely filled right up to the top of the gunwales. Boston Whaler depends upon the foam to provide structure while other similar brands may also incorporate stringers etc. All good and all resulting in very strong boats that cannot sink. This is an expensive way to build a boat because the assembly has to stay in the mold while it cures.
Now, another way of building a boat, much cheaper--but not always bad---a hull is layed up and popped from the mold and then goes into subassembly process where the hull is dressed out. Generally, especially during the 50 and 60s and 70s and into the 80s this was consisting off glassing in wooden stringers to provide rigidity to the fiberglass shell. Then the interior is dressed out by screwing plywood (usually cheap CDX) to the stringers and then dressing the sides in similar manner and then slathering the entire mess with sheet vinyl and carpet thus hiding the shoddy contruction. Then the top sides are screwed or nailed into place with some marine adhesive and then a decorative molding placed over the joint. Prior to closing the assembly foam blocks are cut and set in place post CG regulations to provide minimal floatation. Now, to be fair, some boats built the above way are not junk and today composite stringers are used in place of wood etc. This is much faster to build hulls because the green hull can be removed from the mold after a short cure and moved to an assembly and finishing area for dressing out.
There are other methods as well, balsa coring for example and as anyone might imagine many variations of marterials and methods within these broad outlines including other composites like carbon fiber, graphite, vinylester resisns in place of polyester resisns and on and on.
Foam filled boats have a weakeness as well, it has been said and to a degree it is true that if the hull is compromised then water can enter into the foam--water logging the boat. This is not entirely urban legend and does seem to happen. Generally, damage that is repaired quickly does not result in a warterlogged boat. Repairing a badly waterlogged boat would be a nightmare. A quality glass and stringer boat could be stripped down and rebuilt--with new stringers if need be--but--opening a single piece bonded hull and restoring the foam--probably not possible. Boston Whaler has been in buisness now for almost 50 years and many of their products are still in use. The same for some of the new comers to foam construction, it is a proven if not perfect method.
The way you keep from spending "gazillions" on a boat is by learning something about what they are and how they came to be. I imagine that Thunderbird is a glass and stringer boat with a topside screwed to the lower hull. Good or bad? You will have to decide.
http://www.pangamarine.com
The panga is usually a rolled edge construction built either on a glass and stringer hull or foam filled lower hull with the single layer rolled gunwale. Naming a boat design with a cute name does not make it immune to the weakness of various construction methods which are used in them as well. Rolled edge boats are a cheaper way of building because the gunwales and decks are simply NOT there. The panga is an efficient design often used in the third world because they are fuel efficient. They are pretty boats but typically not up to US consumers expectations except for those made in the USA.There are other--non panga--rolled edge hulls such as Carolina Skiff etc.
edited to add the Panga Marine link, very nice looking boats and priced well too.
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