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Planking
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Bottom Planking
The most important aspect of wooden boat restoration is a sound
hull. It does not really matter what kind of bottom construction
you choose, except with regards to longevity. Remember, the bottom
planking is not, in any way, meant to hold the framework together,
quite the opposite is true.
When doing a standard bottom restoration, the hull is turned over, the
bottom planks and top sides chine strakes are removed, and the framework
and fasteners properly addressed. The original planks are saved
for patterns only, as a standard bottom job includes all new mahogany
planks; the labor to save the weakened old wood is more expensive than
replacing them with new and the benefits are obvious.
As I have stressed repeatedly, it's critical that you eliminate
weaknesses in the framework and fasteners in order to minimize failure
rates in the bottom planking. The hull is brought plumb and
level. The gripe, keel, chines, and lower transom bow are removed
from the boat, degreased, inspected, replaced if necessary, sealed,
bedded, and re-installed with new silicon bronze carriage bolts.
While these components are out, the bottom frames are likewise
degreased, inspected, replaced if necessary, sealed, and bedded, and all
fasteners, including the carriage bolts in the bilge stringer, are
removed and replaced with silicon bronze.
If the hull is not straight, plumb, and level now, it never will be
after it is planked---the planking will secure whatever shape the
framework is in now.
Check carefully for all things that are easy to get at now before the
bottom is applied. Make sure that all of the weep holes in the
frames alongside the keel are adequately sized and sealed. The
sides of the bottom frames are easiest to paint now. Surfaces in
the bilge areas should be sealed with CPES and a light coat of bilge
paint, usually an alkyd enamel. Too thick of a coat can keep
excess moisture from gassing. I make quick work of it with a
6-inch paint roller and a 2-inch brush in the corners.
I favor double planking with a bedding compound between the
layers. The size and placement of the planking layers should
be as close as possible to the original factory construction, with one
exception. I use sheet plywood in place of the original inner ply
of 6-inch diagonal slate, which are notorious for collecting dirt,
debris, and moisture inside the bottom construction. Some
manufacturers, including Chris-Craft, switched to plywood for the inner
layer sometime in the 1950s. If you do not want to upset the
judges, scribe diagonal lines on the inner face of the plywood and
re-install the little pan head screws wherever the inner bottom can be
seen through hatches. The size and placement of the fasteners
should be as the factory installed them. The original brass
fasteners should all be replaced with silicon bronze.
Bedding Compounds
The real debate is what kind of bedding compound to use.
Originally, builders used linseed oil-based boatyard bedding compounds
with a layer of absorbable canvas to hold it from being washed
away. This method does have its problems, however. While
some believe that it will leave the bottom planks easy to repair, it is
still the same six-year lifespan bottom construction delivered by the
factory. Even if the inner ply is bedded in rubber to keep
the bilge dry, water will still exist between the planking layers.
This type of bottom will experience expansion and contraction every
season, elongating fastener holes and eventually cracking frames and
planks. Compressive set at the edges of the planks will create
successively larger gaps each year. This type of loose
construction invites dirt, debris, and rot spore. The vehicle of
the bedding compound (mineral spirits) eventually evaporates and the
bottom must be re-done.
Some restorers favor "epoxy encapsulation," in which the plank
layers are glued together with a hard epoxy resin mixed with thickening
agents. All surfaces of wood components are encapsulated in a hard
epoxy resin coating meant to stop any moisture movement at all. In
my opinion, this material should only be used in new construction with
much thinner planking material. Professionals with temperature and
humidity-controlled shops can re-design and build long term vessels with
this technology using methodical procedures.
No moisture at all can be introduced to any part of the structure or
enough wood expansion will simply tear surface fibers off, leaving one
face of the joint bare and un-bedded. All surfaces, inside and
out, must be encapsulated and maintained against trailer scratches or
minute surface cracks caused by expansion and contraction due to
temperature differences or an inflexible hard ride. And, as
discussed previously, encapsulation of wood does not allow it to dry out
if moisture does get in. This can incubate rot spore, causing it
to grow at vastly increased rates. Plank replacement requires
routing the damaged plank out.
A third option might be called "enhanced traditional" bedding,
in which all wood is sealed with a flexible penetration sealer
that significantly slows the movement of moisture but does not completely
stop it. All wood-to-wood joints are bedded with a flexible marine
adhesive sealant that flexes with the movement of the components to
maintain the seal. The bottom is coated with an underwater barrier
coat primer to keep moisture out of the planks, thus diminishing
expansion and contraction. With this method, plank replacement
does require routing the damaged plank out. To achieve long-term
results, the encapsulation, albeit flexible, should be repaired if
damaged by component movement or trailer scratches.
Top Side Planking
Retaining Original Topside Planking
With the bottom sides complete and painted, it is time to flip the hull
upright and address the topsides, the area of the hull between the chine
and the deck at the shear. If you intend to strip the topsides
varnish it is easiest to do this while the hull is still upside
down.
At this time I recommend removal of the deck. This is an
opportunity to make your deck framework--and thus the boat-- straight,
tight, and secure from existing rot conditions. Address the deck
beams before re-planking the hull topsides.
I recommend that you replace your topside planks with sound, new
wood. It will cost less in the long run and last longer then
re-using the dried, brittle, cupped, and cracked wood that originally
came with your boat.
If your determined to preserve the brittle, cupped, and cracked original
wood, use the following procedures. I rarely re-use the old wood
unless the customer requires it after fully understanding that he is
getting a product substantially inferior to new wood at a cost, due to
labor, from removal to fairing, that is at least twice the cost of new
wood. Remember, however, at the very least you must expect the
original wood to react differently than it did when it was new; you must
expect unsightly surfaces and occasional repairs.
New Top Side Planking
The Router Method
The Router method of fitting new planks is an ingenious blend of new
technology with old material procedure. It is the one innovation
that makes planking a hull with new wood. In the end, you have a
far more sound and usable hull.
I first read of the router method many years ago in both Classic Boating
and WoodenBoat magazines and was immediately impressed by its speed
and accuracy. One no longer needed years of experience tediously trial
fitting planks with a hand plane.
The basic concept of the procedure is that a fence attaches to the
router base and rides along the top edge of the chine or previously
installed plank and trims the bottom of the next plank to an exact
fit. An added benefit is that the base of the router follows the
router bit to cut the correct bevel edge for a dead-tight fit, plank to
plank.
Before starting this procedure, complete all frame, plank batten, and
deck beam repairs and have a thoroughly secured hull that is plumb and
level. The hull should be blocked up high enough so that you will
be operating the router in a comfortable position in front of you.
Temporary bracing from the chine to floor will help hold the hull in
shape while you are working on it. Take diagonal measurements of
the transom to insure it is square. Half-breadth measurements,
outboard from a taught centerline with plumb-bobs to the keel, should be
taken at every frame station. The hull should be square, plumb,
and level and all frames, including deck beams and plank battens, should
be properly sealed, bedded, and re-fastened before the topside planks
are installed.
At the risk of sounding redundant--but I cannot stress this
enough---once these planks are
secured, they will hold whatever shape the hull frames were in, straight
or not. Make sure that your work area allows for planking both
sides of the hull at the same time. If you attempt to plank the
hull one complete side at a time, the weight of the planks as well as
the tension created by thousands of fasteners will pull the topsides out
of shape. This will cause the boat to always want to pull to one
side when underway and look noticeably crooked at the stem or stern.
A serious buyer would consider such a hull no more valuable than a gray
boat.
Deck Planking
The deck of an antique or classic boat has two great enemies in the struggle for survival---the wind and the sun.
Because of its exposure to the elements, the deck planking does not remain long at or
above moisture saturation levels, which can host rot spore.
Decks
may rot, but they do it from the inside out where moisture can accumulate
between joints of un-bedded planks and frames. The weather can
make wood look good at the surface while it is devastated below.
Given that the value of these collectible craft has risen so greatly, so
recently, the most visible part of the commodity, the deck, is easily
recognized as the first place to invest cheaply, if one's personal
values could allow this. "Mop & Glow" is one
industry term for a "restoration" that involves varnish,
chrome and little else. But as with the rest of the boat, the
important parts that exist below needed attention as well--I highly
recommend at least the removal and replacement of all deck planking.
The outer covering boards are the place to start, especially with the
large, thicker post war covering boards. These were normally
mounted on a horizontal sheer shelf, very often made of pine, which was
used in place of the earlier vertical sheer clamp. Water finds its
way down the sides of the deck and underneath the metal rub rail at the
sheer. This water then wicks its way sideways under the covering
boards. Being protected from the wind and rain, these areas
do not dry as exterior surfaces do. Since the factory did not seal or
bed these interior surfaces prior to assembly, the aged bare wood
surface draws in this moisture like a sponge. Even if rot has not
gained a foot hold here yet, this moisture is drawn up to the underside
of the surface varnish coats by the heat of the sun. If
the surface gets hot enough, the moisture vaporizes and expands, causing
varnish coats to bubble from the surface.
The live seams between the individual deck planks also admit water that
collects between the planks and plank batons below them, causing the
same problems to occur. Likewise, hardware fastener holes
and crash pad upholstery edges will will do the same. It is for these
reasons that all deck planking, either new or old, should be well sealed
and bedded to protect from moisture incursion. Ignoring such areas of
known trouble spots will cause a great deal of future expense in money
and time involved with maintenance and repair. |
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