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
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
The striping is epoxy mixed from resin, slow hardener, 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
Touch up of striping gaps. Mask off sanded wood and then apply more
Remove the tape the next day and sand flush.
|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.
area of forward cockpit the next day with the imperfections filled
We were on a tight schedule to launch for the summer. So here it is early May in Wisconsin and of course the fiberglass is to get applied on what is the hottest day
of the year so far. The morning started out warm and by the time the first coat was complete, it was 92 degrees outside and hotter in the garage. The first 90 degree days of the year always feel unbearably hot after the cold of the winter. There was no way to even use a fan, as it would blow the fiberglass around as well as bring in dirt and insects to land in the sticky resin. The problems included not just the resing curing far too quickly, but controlling my sweat. As I would lean over the boat, drops of sweat would fall on the wood and the not yet wet out glass. The drops on the wood would dry, but now the texture was changed and the wood would absorb the resin unevenly. So this lead to last minute scraping of those areas. The gloves quickly filled with sweat and if I lifted my fingers up, the sweat would pour out or drip on my work. So the most practical method was to strip down to my shorts then coat my chest, arms and hands in "Gloves in a Bottle" and wipe the sweat off frequently. For each coat of resin, I scrubbed off and then reapplied more "Gloves in a Bottle". I am sure a safety engineer would frown on this, but it was the best I could do.
To do the fiberglassing, you must 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 foam brushes hot and soggy.
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
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 other seams do leave a mark in the wood underneath. I have heard other suggest to slide in a piece of metal or plastic under the gelled fiberglass before cutting but I have not been able to make that trick work.
Saturday and Sunday were over 90 degrees as we did this.
On Monday, as I write this page it is back in the 50s.
Cool weather fiber-glassing is MUCH easier!
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. Another alternative is to use a double cut file at about a 45 degree angle to the edge. They are both much easier the trying to trim with a knife
or scissors and provide a very neat edge.
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
This was it for the day.
Forward cockpit finishing board
|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.
Forward cockpit edge sanded
|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
|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
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 initially 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
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. Later when refinishing the second time, I switched to Imron%20Clear which is dramatically better.
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!
Another shot of the fiber-glassed hull
Note the bags to protect the exhaust trumpets. This is still
|Next: Engine Hatch