The Smith Method Starting back about 1972 I was selling a variety of adhesives,
sealants and coatings in the San Francisco Bay area from my one-man business there,
and was doing no advertising at all, being only a chemist and engineer and knowing
nothing of marketing. I was an aerospace electronics engineer and this paint-and-glue
business was really a sideline, a sort of hobby for me. People with various
kinds of boats heard about me and came to my shop with their problems. I often
went to the local boat yards and looked at their boats with various afflictions,
and occasionally concocted something special. Some of these eventually became
standard Smith & Co. products.
In the middle seventies, blistering of Glass-Reinforced Polyester
[GRP] boat hulls was common, and I was the one who identified the fundamental cause
[water decomposes esters, and polyester is that kind of resin] and invented the
moisture-diffusion-barrier-coat that everyone now uses to repair osmosis-blister
damage and prevent it from happening. The details of how and why this works and
how to treat your GRP hull is too long to go into here, but anyone who wants to
know more can e-mail me or call my factory at 1-800-234-0330; the procedure is
now posted on the website.
Anyway, I had identified products and technology that kept water
from getting into a GRP boat hull, and between reducing the rate of water uptake
from the side of the GRP hull in the water, and facilitating evaporation of water
off the inner hull surface [improved ventilation, dealing with integral tanks,
etc.], I had created a situation where the hull stayed dry, even when floating
in the water. It was not uncommon for a GRP hull redone with my procedures to
float several inches higher a year later, as the water-saturated resin laminate
slowly dried out from the now-ventilated inside even while floating. This same
result would eventually be attained with wood hulls.
In the early eighties some friends of mine from Sweden were visiting
me in America because I was one of the founders of an international franchise
that used certain magical primers I invented.......I can't say what it is but
many people have one in their home, mainly in the U. S. These folks were the
European Master Franchise holders. Looking for more of my products to market,
they got interested in the GRP blister repair technology. They licensed it,
set up franchises in Europe to apply the coatings and actually had a warranty
on the result that was backed by Lloyds of London.
You're probably wondering how wood boats got into the picture,
and it came about this way: In spite of my having had MANY wood-boat-owners for
customers over the previous ten years, I only had Clear Penetrating Epoxy Sealer
for restoration of aged wood and 2-component Polysulfide rubber for sealing the
seams. People commonly applied antifouling paint on top of that. Some applied my
High-Build Epoxy Paint moisture-diffusion Barrier Coating on top of the wood and
before the antifouling paint, but I never really appreciated the significance of
that entire coating system at the time.
My Swedish friends, having gotten the GRP repair business
established, began to look further for other things that could be done with these
materials they were importing into Europe. They told me of the typical Swedish
wood boat, which is hauled out for about six months of the year, the wood dries
out, the planks shrink, and the seams open. Then, when launched in the spring,
it takes about three days for the wood to swell and sort-of-seal the seams, during
which time fantastic amounts of water leak into the boat, requiring constant
attention lest the vessel sink. They asked me what I had that could be done
and whether this represented a market for my products there. Having now clearly
understood the function of the moisture-diffusion-barrier-coating from the work
with GRP hulls, I thought to apply the same technology to solve the problems of
leaking seams in wood boats, and began to work out how to do it.
The fundamental difference between wood and GRP hulls was that
wood hulls had seams, and planks that changed in width with variations in weather,
in-and-out-of-the-water, and temperature. I realized that putting anything in the
seams was going to be a problem, as the planks would try to compress the solid
material or even rubber, and stretch the screws, probably breaking or tearing-loose
some, and in extreme cases of packing solid rubber in the open seams of a dried-out
-hull, when the wood swelled it could literally jack-out the chines, which is
kinda destructive. This would not be good.
Wood was stronger when not waterlogged, and so there seemed to be
two stable states for which to strive: Wood in equilibrium with the moisture in
the air and wood in equilibrium with the moisture in the water. The latter seemed
less desirable, and if the seams could be sealed while allowing small movements
of the planks, then there was the potential for a wood boat with a planked hull
to actually float in the water with a dry bilge. The unheard-of would eventually
become commonplace.
My thought at this point was to pilot wood-boat-restoration in
the U. S., where I could observe more closely how this worked before releasing
the technology for use half-a-planet away. The problem to solve was how to keep
water from leaking through a seam between two planks in spite of variation in
the seam width from e.g., zero-to-an-eighth-of-an-inch]. The problem was that
no elastomer could stretch from zero to anything.......that being infinite-percentage
elongation. I thought to vee-grove the outer part of the plank [imagine putting a
chamfer on the outer plank edges before installation], thus creating a minimum
seam width of at least equal to the plank movement. With this arrangement, the
elastomer would only need a two-to-one elongation capability, which is referred
to as 100% elongation, meaning going from one-eighth inch to one quarter inch.
A vee a quarter-inch wide, and about 3/16" deep, would easily
accommodate a quarter-inch movement with a suitable elastomer.
At that time I was selling a two-component polysulfide rubber
sealant which would easily stretch to accommodate this much movement without
creating so much stress at the wood-sealant interface as to tear the sealant
off the wood. 3M makes something similar, 5200, a one-component tough
synthetic rubber adhesive sealant. that stretches easily, thus accommodates
wood movement while maintaining a watertight seal. The moisture-diffusion-barrier-coating
Epoxy Paint would go on top of sealant and wood-treated CPES, and that was
the proposed coating system. The epoxy paint would of course develop many
fine cracks when the sealant stretched, but it was still all glued to the
sealant and the cracks would only go through the paint to the sealant. No
water would leak in, and mechanical integrity would not be jeopardized.
The fundamental design of the wood boat would be unchanged , and the fasteners
would carry the load of the individual frames and stringers and planks as the
original designer intended. My design modification only was intended to solve
the water-leakage problem, not change any significant engineering characteristics.
I proposed this design to various boat-customers over the next
year, and some thought it a great idea and did it. Others were highly offended
that I would propose mechanical alteration of the vessel, even so minor as
chamfering plank edges. Nevertheless, enough adventurous souls did buy into
my [at that time] radical ideas, and do it, thinking as I did that it would
work and solve this classic problem of all planked wood boats. I had created
something based on engineering principles, designing something to work, using
modern materials and modern engineering technology.
Over the following few years I heard from these customers from
time to time, as they came back for various supplies, or just to visit and
report on how things were working. The consistent result, which amazed every
wood-boat-owner, was that this kind of "restoration", done as I have described,
consistently resulted in a dry bilge and a mechanically stable hull regardless
of whether the boat went in and out of the water or stayed in the water. This
led me to write two short essays, "Wooden boats and wet wood" and "Wooden boats
that go in and out of the water", which are part of the basic boat-related
literature package sent to anyone who requests one [by reply email or phone
to 1-800-234-0330, as we need a mailing address].
After some years and a few dozen instances of successful
application it was clear to me that the solution I had invented really was
a workable solution to the problems of planked wood boats, including some
runabouts that were truly antiques and one commercial fishing boat I
particularly recall, about a hundred years old [Fish & Game registration
number 27].
I began to promote this more widely and in my literature
as I learned more about marketing, and found over the following years
that many of my old [earlier] customers had done pretty-much this sort
of thing but in some cases actually bedded the outer layer of planks of
a double-planked hull in my 2-part polysulfide rubber, behind the planks
as well as in the seams. This, using today 5200, has come to be known as
the Danenberg bottom, after Don Danenberg who [somehow] found out about me
and CPES roughly 35 years ago. I [ever modest] never called my bottom-restoration
method a Smith bottom until this subject came up in the middle-nineties
on the Chris-Craft list, and [as I recall] someone got Don's method and
mine mixed up and I wrote something to clarify our different approaches.
I never heard of one that had a problem or needed a plank replaced, with
either method. It is noteworthy that even though many of my customers are
professionals such as Don, the vast majority are amateurs or hobbyists,
and virtually all have, to my knowledge, been successful in restoring
their boats by either method.
The procedure for doing this would be, first, to sand or
heat-gun-and-scraper clean off the old paint. I'd prefer you not use
chemical strippers, as some can leave a residue that screws up adhesion
of subsequent things. Next, sand or scrape or cut a vee or chamfer where
the seams are. Given a guide-strip, you could use a router or a small
rotary saw. The idea is to have a gap everywhere the external seams are.
It does not have to be a very large gap...and it does NOT go all the way
through; it is a Vee. Friction between plank sides contributes to overall
longitudinal strength of the boat, and is part of the original design of
the boat.
Next, apply CPES to saturate the wood. This will take
anywhere between 20 and 200 square feet per gallon, depending on the condition
(porosity) of the wood. For example, the typical 16-foot runabout in decent
condition takes a two-gallon kit to do the outer part of the hull below the
waterline...very occasionally two 2-gallon kits of CPES. The stuff runs like
water, and really soaks into abnormal porosity of old wood. Next, apply
masking tape on each side of each seam, fill with 5200 and squeegee flush,
and remove the tape before the sealant jells. This gives really neat seams,
and finally a couple-three coats of my Barrier Coat, an epoxy paint I make
that offers really high resistance to diffusion of moisture.
Whatever final bottom paint is desired may be applied over
that. The same procedure, pretty-much, is done for lapstrake hulls, except
that one does not vee-groove anything but instead puts a neat fillet of 5200
on the inside corner where each plank laps over the other on the outside.
It usually isn't even noticeable.
Circa 2003 I was at an ACBS annual meeting and found myself
sitting behind Chris Smith III on the deck of a boat touring around the
Mackinac islands of northern Michigan. He told me the method used in boat
construction by his grandfather Chris Smith (the first) was a few coats
of enamel paint on the outside and a color-wash of the same paint, thinned
50-50 with turpentine, on the inside. What this gave was a moisture-diffusion-barrier
on the outside and an inner coating that could "breathe" so water that
got into the wood could easily evaporate off the inner surface.
That's why Chris-Craft boats had such longevity, and the
Hackers and Hunters and Garwoods mostly rotted-away over the decades
because both inside and outside were painted, thus trapping moisture
in the encapsulated wood. I had in the early seventies independently
invented the same thing to cure and prevent osmosis blistering on
GRP hulls. See http://www.smithandcompany.org/GRP/GRP.html.
So, here's the wood-boat restoration process in a
nutshell: Put a moisture-diffusion barrier coating on top of CPES
on the outside and CPES-alone on the inside; the wood can still
"breathe", as CPES is permeable to water vapor.
Well, that's about all I can remember. Please feel free
to ask more questions if you have them, and the 800-number previously
given is good for ordering products also. Smith & Company products are
available on-line from the Smith & Co. website as well as on the shelf
in many stores around the country; the office staff can tell you if
there is a store near you, and even provide handout information you
can take into your local hardware, paint, building supply store or
marina to induce them to stock product for you locally, should you
wish to go that far. Here's that number again, 1-800-234-0330. I have,
after all, learned something about marketing.
Steve Smith
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