Could the book title possibly be

Covering Wooden Boats With Fiberglass
by Allan H. Vaitses

Allbookstores.com shows it was printed in a revised edition and in paperback in September, 1989

: Don't know if this has been answered but here goes.

: All fiberglass may eventually delaminate from wood depending on which system
: is used and the use and state of the wood adhered to. Epoxy seems to be
: the best for direct wood adhesion but all systems will work better if
: mechanically fastened to the hull. I read a good book on this called
: "Fiberglassing wooden boats" or "How to Fiberglass Wooden
: Boats" which is now out of print but I got in the library. The author
: had quite a bit of experience saving wooden hulls (mostly larger boats)
: using fiberglass and had seen much of the delaminating of fiberglass jobs.

If you compare salvaging old hulls by using fiberglass materials with new construction you may find that some of your comparisons are not based on equal situations. If you generalize exclusively from old data, you will certainly be excluding new data. At the moment, the opinion on whether fiberglass must be mechanicaly fastened to the wood seems to be in the opposite direction from what this author suggests.

I am certain that the author of the book you read saw many delaminations. Polyester resins applied to old wood hulls have had a history of delaminating -- a history that I am sure this book documents well. But that is old news. We now understand that moisture, in the form of watervapor, can penetrate polyester resins by traveling through microscopic "tunnels" formed by the evaporation of solvents used in the manufacture of those resins. The amount of moisture may be minuscule, but it is enough to sustain the growth of mold and the spores that lead to rot. Further, moisture trapped behind the fiberglass will turn to steam when the area is exposed to heat and direct sunlight for a period of time. The steam does a wonderful job of lifting the fiberglass layer away from the wood!

: One of the delaminations he saw was an epoxy job that had taken some of
: the wood with it. The cause being the deterioration of the wood beneath
: the fiberglass. Evidently, water getting behind the fiberglass can start
: this.

If the fiberglass comes off pulling wood with it, then you do not have a delamination. The evidence is that the wood itself had to split somehwere in the interior of the board so that some could come away with the fiberlass. You have failure in the wood, not in the bond between epoxy and wood.

While epoxy can encapsulate wood, and polyester cannot, water can easily get past either barrier if there is impact damage which penetrates the materials. This happens a lot with boats used in rapids on rivers -- they are always bouncing into rocks. Such damage does eventually cause delaminations, but the areas affected are usually very small ( a few square inches) and rapidly detected as most of the small boats we build are taken out of the water daily, and inspected frequently. Larger boats such as the book you mention dealt with were probably put in the water and left there until a winter pull-out, or an annual inspection.

: The method used may not work for kayaks, but the minimum he used on
: a regular boat were 1 layer of mat, 1 layer of rove (for bidirectional
: strength), then mechanical fastening such as staples or nails while the
: first two layers were still in the plastic stage (might be kind of hard on
: a thin kayak). Followed by two more layers of mat.

MAMA MIA!

I checked with the catalog pages at Defender Industries (www.defenderus.com) and found that they sell fiberglass roving and fiberglass mat. It is very heavy stuff. The glass roving comes in two weights: 18 ounces per square yard, and 24.5 ounces per square yard. By comparison many kayaks are being built with coverings of fiberglass cloth that weighs 3.1 ounces per square yard, or 1/6th to 1/8th the size, and thickness of just one of the materials mention. Few kayaks go beyond two layers of 6 ounce fabric, or a total of 12 ounces of glass.

The mat sold by defender came in three weights, and was listed as 3/4, 1.5 and 2 ounce material. This seemed fairly lightweight, until I realized that these listings were for the weight of the cloth in square feet, not in the more common measure of weight per square yard. Multiplying these numbers by 9 to convert them to a common base (that is, square yards) it appears that these would be 6.75, 13.5 and 18 ounces per square yard respectively.

At the extreme, putting two layers of 18 ounce mat over a layer of 24.5 ounce roving would give you a layer of fiberlass that contained 60.5 ounces of glass in every square yard. Assuming a nearly ideal fiberglass mix is a 50/50 blend (by weight) of resin and glass fiber, an equal amount of resin would add another 60.5 ounces to each square yard. that would make each square yard of fiberglass covering described by this author weigh in at 121 ounces, or a little over 7 1/2 pounds. A kayak uses about 10 square yards of fabric to cover the exterior, and about the same for the interior. If built to these specifications it would be extremely heavy! At about 150 pounds for the fiberglass work, plus the weight of the wood core (about 25 pounds) the kayak would tip the scale at about 175 pounds.

In fact, many solid fiberglass canoes are not built as heavily as these specifications for sheathing a larger boat.

: On a properly built
: kayak, I suppose, one layer of mat with mechanical fastening followed by
: another layer of mat or cloth would work.

So much for extrapolating from this author's work. while I can see how you might be lead to these conclusions, in fact experience and lab testing has shown that the mat is not necessary, and that considerably thinner and lighter weight glass cloth is plenty strong.

: Unfortunately, mat may not look
: as good as fiberglass cloth but fiberglass cloth allows the resin to crack
: between weave, allowing water to penetrate. Mat has multidirectional
: fibers and has better resistance to water penetration because of it.

A few concepts here. Mat CAN be extremely good looking. If it wets out clear the random orientation of the fibers avoids the texture of the woven pattern of cloth. There is no weave pattern to "kill" by the application of additional layers of resin. It may not lay very smooth, and it tends to absorb resin more like a sponge, though. So, using mat alone you are unlikely to get a glass to resin ratio near 50:50 unless you go with vacuum bagging. the shorter fibers used in mat give a finished material that is considerably weaker than cloth of the same weight. It is like comparing heavy canvas with felt.

People tend to cover mat with a thin layer of cloth for easier finishing, or layers of heavier weight cloth for strength. In solid fiberglass canoes the mat is usually a core, sandwiched between layers of glass cloth. In wood canoes and kayak, the core is made of the wood, which is far lighter in weight. in either case the strength of the compsoite is mostly determined by the interplay of forces in the fabric which is furthest from the center. The core (whether of glass mat, expanded foam, honeycomb or wood, adds relatively little to that strength, but it can affect stiffness.)

Polyester resin is more rigid and brittle than epoxy. With the wide weave of the heavy roving I can see how a less-flexible polyester resin might develop cracks over time if it was allowed to flex -- but with the thinner coats of the more flexible epoxy resin on thinner fabrics this is just not a problem. Unless you whack it with a hhammer.

The woven strands in glass cloth do serve as a wick. If the fiberglass should be damaged enouh to expose the layer of glass fibers, then moisture can enter through the damaged area and the wicking will bring moisture deeper into the fiberglass. But, if a sealing coat of epoxy resin has been applied to the wood before the glass is applied, that water will not enter the wood. It will remian trapped in the fabric, which is sandwiched completely between layers of plastic resin.

Actually, it is more likely that an impact will go deeper and totaly penetrate the layer of fiberglass, allowing water to enter the wood under it. This is a bigger problem, and far more common, and easily repaired. In this case the injury is shown by the delamination itself! The loosened fiberglass is easily removed as it does nto stick any longer to the surface of the wood, and it is replaced with a patch of new fiberglass cloth and fresh resin. Such delaminations are usually small areas of only a few square inches around a puncture, and a long scratch will usually have all the damage contained within a few inches to either side of the scratch. Usually this damage can be temporarily repaired with a patch of duct tape.

: I
: have no idea what could be used for mechanical fastening on a kayak but
: the fasteners should not go through the hull. The next step is to either
: encapsulate the interior to keep water from getting behind the fiberglass,
: or never get it wet! The authors shop had customers that had wooden boats
: fiberglassed by his shop that did not have the delamination problem after
: 20 years.

Glad to hear there is some hope that we might go for 20 years without delaminations, too I think the current construction methods are superior to those used in the past because we have learned from the mistakes made by those who came before us -- such as this author -- and because we are spending a bit more money to obtain the better and more durable materials. Certainly polyester resin is still out there, but most builders are going with epoxy.

: Hope this helps some.

Thanks for the report. Besides being a historical perspective, it reminds us to stay us on our toes and use the best materials for the job.

PGJ