|Mr. Vaitses was a successful wooden sailboat builder before fiberglass took over. As fiberglass became popular Allan developed skills in the use of that material as well. At about the same time many failed attempts were being made to save rotting wooden boats by covering them with fiberglass. Most of these attempts actually accelerated the rot. Because Allan had an understanding of both wood and fiberglass construction he developed a successful technique for covering wooden boats with fiberglass. A book “Covering Wooden Boats with Fiberglass” was published in 1981 by International Marine Publishing Co. Allan has also written books on wooden boat repair, fiberglass boat repair and marine surveying.
The reason that Mr. Vaitses understanding of covering wood with fiberglass is so relevant today is because many boat manufacturers still imbed a lot of wood in their fiberglass laminates. Marine plywood is imbedded in structural members such as the grid surrounding the keel, stringers, motor mounts, chain plates and transoms. Also wooden cores are used almost everywhere in a boat hull/deck above and below the water line. Finally, wood is common in bulkheads, cabin soles and cabinetry. To appreciate how much wood is still used in today’s boat construction, it is interesting to note that one of the worlds most prominent fiberglass boat builder promotes themselves as a wooden boat builder with a fiberglass hull.
Although there are many lessons to be learned by reading Mr. Vaitses’ books there are two lessons that have served me well.
- Dissimilar materials bonded together will eventually shear or the stronger material will break the weaker. By dissimilar Allan means materials that expand and contract at different rates. For example, Allan suggests that epoxy laminate bonded to steel will sheer quickly. But more surprising is Allan’s theory that fiberglass laminate bonded to marine plywood will eventually shear. How long it will take a laminate to shear will depend on the difference in expansion and contraction for various temperature changes.
When wood is imbedded in fiberglass, more than temperature will be at work in the shearing process. Moisture in the wood can have a stronger effect. Water makes wood swell. And water without air makes wood rot. Finally, when wet wood freezes, it expands. All lead to delamination. Moisture may be present in the wood because it was trapped when the wood was covered or from water that finds its way in from the outside. Holes drilled in the laminate or any imperfections in the laminate can allow water to enter. Water in a bilge has 24x7 to work its way into a wooden core.
To avoid wood rot, wood needs to breathe, breathe, breathe. Mating surfaces of wood that cannot breathe need to be bedded with a flexible sealant. Make as few joints as possible. Drill as few holes in the wood as possible. Use good marine grade woods with natural resins such as cedar. Fresh water is worse than salt water.
Using Allan Vaitses’ rules you can quickly conclude the following. If you want to create a wood rot factory, you should cover wood with fiberglass so that it cannot breathe, drill some holes in it and submerge it in water so that moisture can get in but not get out. Then you can accelerate the shear/rot process by using fresh water normally found in a bilge and by allowing the water to freeze and thaw. To accelerate the problem even faster, use plywood that will absorb water in two directions. Another good way to create a potential rot factory would be to imbed a wooden core in a boat deck and then drill two thousand holes in it for a teak overlay. In other words, much of today’s boat construction may fail prematurely.
You might be wondering how Allan devised a successful method to cover wooden boats with fiberglass. How did he avoid shearing or rot problems described above? The answer was that (1) he did not attempt to bond the wood to the fiberglass. He used mechanical fasteners (staples) so that the dissimilar materials could freely expand and contract. And (2) Allan proposed building a new fiberglass hull that was stronger than the wooden hull so that, in effect, the wood could be taken out and the mold could be thrown away. The fiberglass was not just covering the boat.The fiberglass was the boat. Allan assumed the wood would eventually rot.
Vaitses’s theories applied to a 51 ft. cutter
I applied the theories of Alan Vaitses to problems found on a 1987, 51ft fiberglass cutter. These problems include wasted wood in bulk heads, the keel grid, motor mounts and cored deck. Almost all of the wood in this boat that was adjacent to water was in trouble.