Striping
The tops of the mahogany strips
and finishing boards are pre-coated with resin to prevent the
pigment form getting into the pores of the wood. Be careful
when pre-coating, the goal is to NOT pre-coat the inside of
grooves.
Make one final pass with 40-60
grit sandpaper in the grooves to make sure the edges are clean
and straight. Be careful not to round over the edges.
The striping is epoxy mixed
from resin, slow hardener, West System 601 white pigment and
colloidal silica and micro-fibers. Mix the resin, then mix in
the pigment (~1tsp for a 6 pump batch). Then add colloidal
silica plus micro-fibers until it has the consistency of
marshmallow crème. This was the consensus on looks and
texture! The micro-fibers are used 1:2 with the silica. The
micro-fibers were run through a blender to minimize lumps prior
to being added.
Use a flat squeegee to force it
into the gaps. It took six batches to fill all of the grooves.
I also made a final batch that was not as thick and ran it over
the top to get a smoother top finish. Let it harden and start
sanding.
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Touch up of striping gaps. Mask
off sanded wood and then apply more filler.
Remove the tape the next day and sand flush.
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Sanding and trim.
The entire surface was sanded
with 50 grit belt sander, 60 grit air file and then 80 grit
random orbit sander. Sanding took about 8 hours. Removing
the excess epoxy is difficult and you must be very careful not
to add ripples or gouges.
Note: ANY areas that were
originally coated and not sanded completely clean to match the
surrounding wood will very likely not match the surrounding
wood when the final glass / epoxy coat is applied. It will show
a different (darker) color due to the amines in the hardener
hitting the wood twice and darkening the wood's natural
pigments. In addition, the glass wet out may not be as good and
the weave will show through to a greater extent.
The edges were routed and
sanded for an ~ 3/16" radius on the inside. A 1/4"
round over was used on the outside along with plane and sanding
of the outside corner profile. Do not use a sharper radius, as
the glass will not want to conform to a tight curve when wet
out. Sharper edges are also more susceptible to damage during
normal use of the boat.
Pieces of the decking strips
were used to finish off the front deck over the dash opening.
The bottom edge will be final trimmed later. Due to time
pressure I used thick super glue to put on the trim piece.
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Same area of forward cockpit the next day with the
imperfections filled
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Fiberglass application
Of course, the fiberglass is to
get applied on what is the hottest day of the year so far. It
was 92 degrees outside and hotter in the garage (much warmer
than the weather forecast). However, to make an early summer
launch, we had to proceed. Such is spring in Wisconsin.
Mix small batches and work
quickly to squeegee in the resin. If the resin starts to gel,
throw it out as it will not completely hide the weave of the
cloth. We normally use 4 pump batches for fiber-glassing, and
had to cut to 2 pump batches in the heat. The resin quickly
heated up and also made the Jen Poly Foam brushes hot and
soggy. These are the best I could find for this purpose
The hull was taped and draped
below the edge and the final trimming of the deck cloth was
approximately at the bottom of the finishing board trim.
Make all of your fiberglass seams over either a stripe or a
joint in the wood. When cutting the joint, the underlying wood
is scratched and it looks like another joint. The seams over
the stripes are completely invisible. The others do leave a
mark in the wood underneath.
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Saturday and Sunday were over
90 degrees F as we did this.
On Monday, as I write this page
it is back in the 50s.
Cool weather fiber-glassing is MUCH easier!
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Cockpit draped
The cloth was draped over the
inside edges and coated in place.
When sanding after the second
coat, use the random orbit sander to sand off the cloth. This
is much easier the trying to trim with a knife or scissors.
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Second coat
The second coat is applied as
soon as the first starts to set up and looks like this when
done. There are still bubbles, dimples, etc. In addition,
there are a few mummified insects.
Question? Why do the 1-2"
wide moths always end up on their backs with both wings glued
down? Conversely, mosquitoes just get their feet stuck down.
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Forward cockpit finishing board
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Sanding the second coat
Sand to remove the high spots
and sags. do not go for a perfectly even scratch pattern at
this point , as you will cut into the fiberglass.
Vacuum up the dust and damp wash down with vinegar water
and then finally with clear water.
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Forward cockpit edge sanded
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Third and final coats
Apply the third coat to the
sanded surface. Once it starts to set up, apply the fourth
coat.
These coats were rolled on and
then tipped off with a foam brush.
This is the view from the rear
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Ready to sand again
Here is the boat after the fourth coat of resin. The spots
(that look like water spots) are actually in the camera lens
due to the specular highlight from the glossy surface.
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Varnishing
Varnishing is required for UV
protection of the epoxy. Without it, the epoxy WILL degrade in
the sun eventually yellowing, turning cloudy and failing.
To prepare for varnishing the
entire hull must be sanded again. This time use 220 grit and go
for a full uniform scratch pattern. There should be no unsanded
areas. This will level the surface and prep the finish to show
off a perfectly fair surface under beautiful high gloss
varnish. Any ripples, sags, bumps, dimples, pimples, etc.,
become painfully obvious under the varnish.
For the varnish, I used Z-spar
Flagship. This was thinned slightly with T10 thinner to get a
good brushing consistency. With a little practice, you can get
a coat of varnish on the entire boat in 1.5 hours. It takes 1
quart of varnish per coat for the entire hull (excluding
painted portions).
As you will see in later
photos, the epoxy does add a golden color to the finish, and
the white stripes become somewhat cream colored.
I used VC varnish for the dash
and it was absolutely miserable to work with. It would get
bubbles that would not pop and flow out. It also skinned over
in the tightly sealed and nearly full can every night!
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Another shot of the
fiber-glassed hull
Note the bags to protect the
exhaust trumpets. This is still pre-varnish.
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Next:
Engine Hatch
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