Maintenance:  Taking care of your
strip-planked canoe or kayak
You are now the proud owner of a Sanghalei strip-built canoe or kayak.  
You want to get it out on your favorite waterway as soon as possible ....
to put it to its intended hard use, and to enjoy it to the fullest.  This is as it
should be !!

However, keeping your hand-crafted beauty in top shape will require that
you commit yourself to a certain amount of effort and TLC.
Your hand-crafted canoe or kayak is a work of art to
use and cherish . . . BUT it is not indestructible . . . it
is especially vulnerable to abrasion, weathering, and
the ultraviolet rays of sunlight.
The hull of your canoe or kayak is constructed of thin natural wood strips
closely fitted and edge-glued with epoxy ... the strips are then sandwiched
both inside and outside with a bonded layer of epoxy resin and woven 6
oz. "e-type" fiberglass cloth.  The clear fiberglass and resin allow the
beauty of the natural wood to show through.

A high quality spar varnish (alkyd-based) is then applied in repetitive coats
to further enhance the attractiveness of the natural wood and to provide a
deep, glossy sheen.  Finally, an automotive-type clear coat is sprayed
over the varnish to add additional sheen and to provide extra protection.  
VERY IMPORTANT ... the varnish and clear coat protects the epoxy,
fiberglass, and wood from the deteriorating effects of weather, abrasion,
and especially the damaging ultraviolet rays of sunlight.

Please keep in mind that all unprotected clear epoxy resins deteriorate
rapidly with direct exposure to sunlight (UV), causing the resin to become
brittle, whitish in color, and to form surface peeling and blistering.  Direct
and continuous daily exposure to the sun will completely deteriorate an
unprotected layer of epoxy resin in as soon as three months.  Unprotected
fiberglass fiber will similarly deteriorate with exposure to UV sunlight.  
Bare natural wood will also discolor and weather if it has lost its protective
coating, and will absorb moisture ... which in turn will cause the wood to
alternatively expand and contract, breaking the bond between joined wood
sections and, most critically, the bond between the wood and the layer of
epoxy resin/fiberglass fiber.
Normal abrasion, weathering, and exposure to
sunlight UV will rarely require more maintenance
effort than a periodic light sanding and applying
additional coats of varnish.
The first and most important point to make in maintaining your new
strip-planked canoe or kayak, then, is that the protective varnish coating
must be maintained and renewed on a regular basis.  It is also a great idea
to keep your treasure covered or at least away from direct sunlight as
much as possible.
It is a great idea to cover you canoe or kayak and to
keep it out of direct sunlight as much as possible.
Now for the nitty gritty of how to take care of your canoe
or kayak.

1.  Re-varnishing:

a.  Use about a 100 grit to take off any deteriorated varnish or surface
discoloration.  I personally like to use 80 grit for this, but I am somewhat
aggressive.

b.  Then sand with a finer grit to reach a smooth and scratch-free surface.
 The choice of grit is up to you, but keep in mind that scratches will likely
be visible after varnishing with any coarser grit than 220.  I recommend
that 220 grit be your final choice ... but some folks will prefer to take it
further, to a 400 or even 600 grit.

c.  Now ... this is very important ... avoid "finger-sanding" !!  What is
meant by finger-sanding is folding the sandpaper into small sections and
then sanding with the ends of the fingers only.  This is effective and often
necessary when sanding out gouges and deep scratches, and it is OK at
the final step when you are using your finest grit.  It should not be done at
any other time, however, because it will create undesirable high and low
spots.  It is good practice to use a sanding block as much as possible ...
this method will maintain the surface "fairness", and may even improve the
fairness.  A standard 3 in. by 4 in. rubber sanding block from your favorite
hardware store or auto parts retailer works fine.  A larger surface sanding
block typically used by dry-wallers is even better.  Or, you can use a
belt-sander belt mounted on a hand-cut wood block as another good
option.  This is the preferred hand-sanding block used in our shop, using 4
in. by 24 in. sanding belts.  We finish with a 4 x 5 rubber block, however.

d.  So ... you have taken off the discolored surface varnish, and perhaps a
little wood on the areas not covered with fiberglass (the gunwales, thwarts,
seat framing, or cockpit combing), and you have finished fine-sanding with
220 grit or finer ...
now for the varnish.  It is assumed that you do not have
access to spray equipment nor the expertise to do a good spray job ... you
are limited to brushing and have mastered an acceptable "brush stroke".  
The varnish of choice should be a good quality "spar varnish".

Most spar varnishes are surprisingly similar ... they are oil based (alkyd
based) and naturally provide good UV protection.  The actual brand choice
is a matter of personal experience or "who you talk to".  Some brands
indicate that their varnish has enhanced UV protection, and/or a harder
finish.  Good advice is to stick to your better known yacht grade spar
varnishes.  Z-Spar is a great choice.  But I have had good results with even
the spar varnish sold at your near-by Ace Hardware.

Please ... do not use standard one-part polyurethane varnish !!  
"One-part" means that the varnish is used as it comes out of the can, with
no second-part additive.  These one-part polyurethane varnishes
may be
able to provide superior UV protection, and
can look better than
alkyd-based varnish, and
can also be harder ... BUT ... one-part
polyurethane varnishes usually deteriorate to a whitish, peeling, and flaking
layer which
must be aggressively sanded off completely before a fresh
coat can be applied.  Spar varnish does not require such drastic action.

A special note here ... we are currently finishing our craft with a two-part
polyurethane, automotive type, "clear coat".  This is applied as a final one
or two coats.  The ability of this finish to enhance UV protection is not yet
proven ... we apply this clear coat only to provide a final harder, more
abrasive resistant surface.  We advise that these coatings not be
attempted unless you have access to quality spray equipment and can do a
good spray job.  As a rule of thumb we recommend that you stick to a
good spar varnish.

Now, how to apply your varnish coating.  Once again, if you have the
resources your varnish can be sprayed on, which will normally give you
better looking results.  But application by brush has the advantage of
simplicity and the ability to lay on thicker coats.  Using an inexpensive foam
brush is a good route to go ... no bothersome brush hairs and greater ease
in laying on a smooth coating.  The foam brushes also tend to make less
air bubbles and less brush-stroke marks.  But I am sure you old-timers will
strongly disagree with me, and insist that a good quality varnish brush and
the simple mastering of an acceptable "brush stroke" cannot be beat !!

There are plenty of sources for instructions of how to do a good job of
brushing on varnish ... especially from yachting supply stores.  The basic
idea is to use long, slow strokes to spread your varnish smoothly, evenly,
and without bubbles.  Keep your coats thin to avoid runs.

Remember . . . the more coats you apply, the deeper the sheen and
the greater the protection
...... to a common sense limit, of course.  A
good guideline is that a total of 3 thin brush-on coats will provide good
sheen and reasonably long-lasting protection.  Six coats is about max.  If
you are spraying, 5 or six coats will normally be about equivalent to 3
brush-on coats.


2.  But maybe you haven't kept up with periodic maintenance, or you have
deep scratches or even gouges ... but the fiberglass hasn't been damaged.
 This will warrant more intensive attention ... you will need to remove all
varnish in the damaged area and apply additional epoxy resin.  Removing
all the varnish is essential, as the varnish will interfere as an inferior layer
and a weaker bonding medium ... you want to be able to bond the new
epoxy directly to the scratched or gouged original epoxy.  You need to
apply the new epoxy as a filler.  It will be desirable to place your boat so
that the worked-on area is horizontal and level.

Almost all epoxies will bond to each other, and the choice of epoxy for
small surface repairs is not critical.  It must be clear epoxy, however.  Even
the two-part clear epoxy tubes from your hardware store will work fine.  
Once the filling has been done successfully, sanding and varnishing can
proceed.


3.  The next worst damage would be that the fiberglass layer has been
penetrated by impact or removed by abrasion, but that the underlying
wood is still intact.  This degree of damage will require that a fiberglass
patch be made.  Again it will be essential to remove all surface varnish in
the affected area, and to sand out the damaged fiberglass.  Sand to the
bare wood only where necessary.  Then, cut a patch of fiberglass cloth
which will extend beyond the damaged area about 3 inches on all sides.  
Next apply the cloth patch with epoxy resin, saturating the cloth with the
resin and with the cloth tight against the underlying surface.  The fiberglass
may want to
float in the resin, causing air bubbles to form underneath or to
form blisters.  It is therefore essential that all excess resin be squeegeed
off with the first application.  If done correctly, the cloth will be fully
saturated, will be tight against the underlying surface, and the "print" of the
cloth will be visible.  A second coat of resin is then applied, and a third if
necessary, covering or "burying" the cloth print and providing a smooth
surface.  A throw-away brush can be used for brushing on the resin.  Your
squeegee can be the common plastic ones used in automotive body-work
and available at your hardware store or auto parts retailer.  Softer ones
used in the surfboard industry are better, but not necessary.

Aaahh !! . . . this is a little more difficult.  But not really !!  

Your choice of fiberglass cloth is important.  We use untreated 6 oz. (200
grams/sq.meter) woven cloth, type "e", for all our canoes and kayaks.  Do
not fool around with any other type of fiberglass cloth, such as "s" cloth or
"c" cloth.  These other fibers usually have chemical treatments or coatings
that interfere with resin saturation and clearness.  You need to ask your
supplier to make sure that your cloth is type e, is compatible with epoxy
resins, and
has not been chemically treated.  Untreated cloth is typically
very white and soft to the touch, versus treated cloth tends to be stiff and
slightly discolored.

The choice of epoxy resin should be based on it having a low viscosity
(thin, flows easily), being clear, and having a working time (pot life) of 20
minutes to an hour.  Now-a-days there are a large number of epoxies
available.  Again visit your yachting or boating shop for this.  West System
(Gougeon Brothers Inc.) or System Three resins are excellent choices.

A word of caution ... do not confuse polyester resin with epoxy resin ...
they are not the same thing.  Polyester resin is greatly inferior
strength-wise and will not bond well with the original epoxy or wood.  One
of the greatest lessons of the past several decades of using polyester
resin on wood is that the polyester will lose its bond with the wood over
time.  This is because polyester resin shrinks about 12% when it cures,
giving off solvents and leaving behind tiny "pin holes".  These minute holes
do not allow liquid water to pass, but
do allow water vapor to pass, which
is absorbed by the underlying wood, causing alternate expansion and
contraction, which in turn breaks the resin/wood bond.

Now, keep in mind that the epoxy itself, contrary to what many think, is not
what gives strength to your repair, although it
is a pretty tough substance.  
But it is the fiberglass that provides the real strength.


4.  But what if the wood strips of your hull have been damaged ... the hull
has perhaps been holed by impact on a rock or has undergone severe
abrasion ??  Well ... this can be repaired as well ... we just have to go one
step further.

Keep in mind that all the steps and information in the previous paragraphs
apply ... but at this step we must remove a section of the damaged
wood-strip hull and "graft-in" a repair section.  If you examine the hull, you
can see that the wood strips run parallel, and are fitted tightly against each
other.  Our repair should duplicate the strip pattern, with the strips
end-beveled (scarfed, or tapered) to fit the patch area.  A good procedure
is to cut a rectangular hole around the damaged area, with the two sides
parallel to the existing strips cut at existing edges.  The ends of the
rectangular cut should then be beveled in a uniform fashion.  New strips
can then be cut to the length of the rectangular cut plus the length of the
two beveled ends, with the new strip ends also beveled to match the taper
on the cut.  The new strip pieces can then be epoxy glued in place, each
strip edge glued to its parallel neighbor and glued at the beveled ends.

An alternative pattern is to stagger the lengths of the individual strips ... a
little more difficult to do.

You also have the option of simply making butt joints instead of beveled,
scarf joints.  In my opinion butt joints are to be avoided, and the beveled
joints are greatly superior.  Unless a special design is fitted into the hull
strips, your Sanghalei canoe or kayak has no butt joints.  The edges are
cut concave and convex for an interlocking fit and no lengthwise butt joints
are ever made ... we buy our lumber in up to 20 foot lengths to insure that
we preserve this feature.

The selection of wood to use for your repair is up to you ... you can try to
match the existing wood, or you can attempt a unique "patch" look.  Our
shop can put together wood strips to help with this ... we cannot mail such
things as epoxy resin and varnish, but we can easily mail a customer a
small quantity of wood strips and even fiberglass cloth.


5.  As a final consideration, it is not difficult to completely strip off all the
existing varnish, fiberglass, and epoxy, interior as well as exterior, making
repairs in the damaged wood strips, and rebuilding from there.  We have
several rental canoes on the Khao Laem lake in Sangkhlaburi, and we have
done this a few times.  It is a good idea to do the exterior first, then the
interior as a second operation ... otherwise the hull will want to fall apart or
become distorted.  It is also a good idea to leave a narrow strip (1 to 2
inches wide) of existing fiberglass/resin next to the keel and gunwales so
that the keel and gunwale do not need to be removed.


6.  You are also free to make alterations to your canoe or kayak.  For the
canoes, you may want to fit a small fore and aft deck, or install a mast
post and sail fittings, or change the center thwart to a carrying yoke.  Or, if
your canoe is to be frequently pulled up on a rocky shore, you may want to
fit a stainless steel strip to the keel.  Or, another choice, you may even
want to fit a pair of "bilge keels", again with stainless steel strips ... these
could be approx. 1/2 inch thick by 3/4 inch wide strips, about 5 feet long,
positioned lengthwise where the hull touches the ground when coming to
rest on a shore.


A final note . . .

I will be updating this page over time, and I will include a few illustrations
and photos as soon as possible.

I also invite any buyer or potential purchaser to contact me for additional
information.

Brent Bateman      brentbateman@hotmail.com
With that said, however, normal abrasion and weathering, including
exposure to sunlight when your craft is out on the water, will rarely require
more maintenance effort than periodic light sanding and applying additional
coats of varnish.  The time between re-coating will vary, depending on use
and conditions ... it may be that once every season is enough ... or it may
need to be done as often as every two months.