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Trade secrets! (shhhh!) How we do it:

The Making Of A Seamless Fiberglass Hull
A Step by Step Guide

Preparing the mold

We'll start off with prepping the mold. Starting with mold wax, 100% carnuba. This stuff
is hard to put on, and even harder to remove. This mold already has had 15 parts pulled
from it and is very seasoned with about 25 coats of wax.

Once the wax is polished off, about 3 medium/heavy layers of PVA (plastic vinyl alcohol)
are sprayed on with a detail cup gun at a pressure of about 80 psi which creates a very
fine mist. PVA creates a barrier between the part to be created and the mold making it
easier to release. Think of it like applying grease to a cake pan so it comes out easy.
After about 4-5 parts are pulled from the mold, there really is no use for PVA since the
mold is then "seasoned" and only an application of release wax is required.

Gelcoat Application

Gelcoat layer. The final outer layer of the hull is actually the 1'st thing done when building
a hull. Gelcoat basically is resin with a color pigment that is sprayed directly inside the
mold before layers of fiberglass are placed; creating the final "paint" coat once the part
is pulled.

The small dropper contains the hardener or activator used to harden the gelcoat.
Typically 20 drops per ounce are mixed together and thinned slightly at less than 10% in
order to be sprayed with my detail cup gun. 2 heavy coats are applied in the mold. You
can also use a spray gun specifically made for the application of gelcoat, called a "cup"
gun (bottom middle). No reducing of the gelcoat is required since the gel literally pours
out of a hole on the cup. Now we'll wait a couple hours as the gelcoat kicks and hardens.

Trimming the mold edges

The DCS is a seamless design so before the gelcoat completely hardens, I need to trim
the edges that won't be used while still pliable. Makes it easier to pull form the mold as
well when the time comes. The green that you see is the PVA that was sprayed on the
sides to make this task easier. Not that it's even slightly difficult, as long as you do it
early before it hardens completely. At this time, the gelcoat is more like flexible plastic,
and trims very easily. Another hour and it will be too brittle to trim.

Cutting the fiberglass mat

Have quite a few picts to post, but to make sence I'm breaking it up into sections.

Before you begin mixing your resins up, make sure you are ready for everything. You
are given basically 20 minutes +/- of working time once you start mixing your catalyst
with the resin. Having the fiberglass sized and pre-cut makes all the difference. Here
I'm tearing the edges of the 1 oz mat leaving a frayed edge that will blend in to the other
layers when I overlap the seam inside the lower hull. If the edges are not torn and just
cut sharp, you loose strength and see an unsightly seam inside your hull. I normally
overlap by 6" up from the bottom of the hull on each side so making sure you don't cut
yourself short is important. Nothing like working the glass down and realizing your not
able to run it all the way up the side.   Ask me how I know.

Filling sharp details with made up bog mixture

Fiberglass mat can only bend so much and be worked so much before you start to affect
the gelcoat (softens a little, possibly causing wrinkling or tripe). I mix some resin with
micro fiber and cabosil until it's the consistency of applesauce. Using a tool I then work
the catalyzed mixture into the strakes and corners, anywhere else I think may be
difficult to work into with the wet glass. This creates “filler” and allows the fiberglass to
roll right over the corners and over the strakes without any air pockets or bubbles.

Notice in other pictures you may see a fan I keep in the window. This exhausts the resin
fumes and powdered fiberglass as I'm mixing to the outside and not in my immediate
work area.

Spread the resin

Here is where the fun begins. Start out by mixing resin and catalyst to this time 10 drops
per ounce. Here I use 9 oz disposable cups that has exactly 8 oz of resin. Count out 80
drops for this cup, mix for about a minute. I then use a disposable brush and spread out
the poured resin directly over the gelcoat, smoothing out my applesauce glass mixture
making sure no air pockets sneak by. Using about 6 oz of resin, I create a thin layer that
the mat can stick to once I lay it down.

Placing the fiberglass mat

Once your have a even coat of resin covering the mold, time to pick up your mat and lay
inside. Using your hands at first, position the mat so that you overlap the middle by 6"
for this hull. Notice the torn edges are INSIDE the hull? Using a trim roller and roller pan
of resin, apply a generous amount of resin directly to the mat enough to soak and
remove air bubbles. I start with the middle usually and work my way to the sides and up
rolling in all directions once it's down, this helps break up the microscopic little strands
creating a much stronger bond than just wetting out. You will use lots of resin with this
step, I think almost 16 oz was used for the mat lay up.

The third picture shows only 1/2 of the mat installed. The last 3 pictures shows that I
overlapped my prevous layer creating 2 solid layers for structural strength of mat.
Notice how quickly the roller wets out the fiberglass with just one pass. I'm using a 1/4
inch nap roller for this job.

Placing cloth

As soon as the mat layer is wet and rolled out, I apply a 2'nd and final layer of 6 oz cloth
directly over my still wet mat. This part is done in one piece from the middle outward.
Typically the roller is fairly dry however the wet mat underneath the cloth is usually
enough to wet out the fabric.   Usually a few extra ounces of resin are needed to fully
wet out the cloth.

Second picture I have my two layers completely wetted out, rolled and checked for air
pockets. Little bubbles can usually be manpulated out with a little more resin.

Trimming the edges

Keep in mind than this is a totally seamless hull design. Once the upper deck is mated
to the lower, you will not see the seam at the attachment point. No overlapping shoebox,
or lip will be on this design.

Once the resins have kicked off and have began to get hard, but still sort of soft, I trim
with a carpet knife using my mold as the guide. This is referred to as "green trimming"
Keeping the knife perfectly flat and taking my time makes for a perfect fit once it comes
time to join the two halves in the mold.   I can apply pressure to the sides of the hull from
the inside making sure no separation of the gelcoat occurs while I'm trimming the
fiberglass.

Transom install

Using the same applesauce mixture of resin and microfiber, I butter both mating sides
of the transom. Clamps are placed for a solid squeeze. Once cured, the rails will be
positioned inside. Notice the hull is still in the mold. Will not be removed untill after the
rails have been glassed in place and hardened. This ensures the lower hull stays
perfectly straight and aligned through the entire process.

The transom sticks out of the hull about an inch so when they are joined, the upper deck
has something solid to grab onto. It's purpose is to give the external hardware
something solid to attach to and distribute the load.

Transom wood

Wood used for the engine rails like stated a few posts above is 1/4 birch ply, with zero to
no flaws or "biscuit" fills. This would be considered aircraft grade, basically same
quality as Midwest products. I purchase this material in full 4x8 sheets and rip them
down to 2" strips as shown. Once I'm ready, I cross cut to a length of 26".

The rails are then placed inside the hull for test fitting. Few trimmings later and they fit
in there like a glove. Once fit perfectly, I sand the rails with 220 grit and then 320. This is
really unnecessary, but remember this isn't your average production boat so every little
"extra" I add makes the quality better.

Look at the difference in the appearance of the rough cut production-type quality rails to
the ones I use in these boats. A little sanding makes a huge difference, especially when
I glass them in and fuel proof.

Engine rail installation

Once my test-fitting is complete and rails sanded, it's time to tack glue them into place
for fiberglassing. Using wood blocks cut to exactly 5 1/16", I loosely clamp the
assembly into place. The little over 5" comes in handy when installing the engine
mounts. Since I glass both sides of the rails, the little extra makes the fit a little easier
as the fiberglass tape compensates for the slightly extra thickness.

The rails are shifted around until I'm pleased with the centering and fit inside the hull.

I use a small amount of 5 minute epoxy to temporarily hold the rails in place so nothing
moves while the fillets and fiberglass tape are installed.

Glassing the rails

After the epoxy has cured, clamps come off and rails stay put.

Again it's good to pre cut the pieces of cloth and have everything you need within easy
reach. Notice the pre-cut pieces in the background? Remember, once you start stirring
the catalyst in there, the clock starts ticking. With the applesauce resin mixture I work
the goop into the corners and everywhere I want to apply fiberglass tape filling in any
voids between the rails and hull.

I've found it much neater and easier to simply lay the fiberglass tape directly into
position, overlapping each corner a little while dry. When I finish sticking it into place
close to where I want it, I use an inexpensive disposable paint brush with pure resin and
basically paint directly over the tape. The tape quickly wets out and I'm able to tool the
tape around for minor adjustments if needed. Just enough resin is used to saturate the
tape and make the bubbles to away.

Keeping things clean

Here's where the perfectionist or anal-type person comes out with me.   Before I'm
finished, I use a rag and acetone to clean up any drips inside the hull. If my name is on
these boats, they have to be perfect. Leaving smears or drips there would be lazy. It
takes all of 2 minutes to wipe the inner hull clean and ready to accept the upper deck in
the next step. Just as an added bonus, for an extra small fee I sometimes will add a
layer of urethane clearcoat directly over the final glasswork. Doing this will make your
hull interior nice and smooth, making for a very easy clean up

Forgot to mention, did you notice all this work was done before the hull has been pulled
from the mold? With these rails in place, theres no chance of a misalignment or
twisting when solidly held in place with it's own mold. Makes a great heavy stand as well!

Separating the hull from the mold

The moment of truth! I always get a little excited on my favorite part of building a glass
hull.....the removal!

Remember I fully prepped this mold with wax and release agent (PVA) before I started
the glasswork. Here's why all that is necessary.

Using a plastic spreader I work a corner in between the mold sides and the hull. Then at
an angle I work my way around the lip of the mold all the way around separating the
sides.

Removing the hull

With all those layers of wax I've applied making other hulls, the part basically started to
pop out on it's own. Grabbing the engine rails I just started lifting the part out at the
transom, and then at the bow.

It's obvious to me right away this is a good pull. Came out very easy.

See all that green stoff? PVA!!!

If I had some problem with removing, I would have stuck wooden or plastic wedges all
around the edge and try to pop out that way. If still giving problems, than running water
into the mold instantly dissolves the PVA making it into basically slime that should easily
separate the part. Not the case here, probably the easiest pull yet!

PVA

Now that the hull is removed, what about the PVA? Easy enough, just like peeling a
sticker, grab an edge and start pulling! Sort of feels like plastic wrap you would use to
cover a food dish. This is an extremely excessive amount of PVA shown on this hull only
for illustration purposes. Typically only 2-3 mist coats would be used, shown here is the
result of over 5 heavy spray applications.

Notice the little divot in the second picture? I guess my PVA sprayer dripped a drop or
two and hardened like that. No problem though, quick sand, paint prep and these hulls
get painted anyway.

Last shot shows the part next to the mold, front and back.

How strong is a seamless joint?

Not quite sure how else to describe the way this is done except to draw up a cross
section of basically how it's held together seamlessly. I'll be taking pictures but it may
be difficult to from inside the hull.   Pictures worth a thousand words.

Trimming the upper deck

The upper deck was already built prior to the lower so I won't cover how it's
accomplished again. Easy way to trim the edges is to tape along the area you want to
stay. Using my drill press with a sanding drum has been an easy way to trim the glass
away. Yes I do wear a respirator and also use a fan to suck away all fiberglass dust
created. Finish up with my palm sander for a perfectly trimmed edge.

You may have noticed a slight imperfection in the gelcoat. I know for sure I was thin in
spraying that area and this is what could happen. No worries, simply will be filled with
lightweight body filler, sanded smooth and painted anyway.

Upper and lower deck alignment

Before anything else, the surface area that will be fiberglass taped will be scuffed with
50 or 80 grit sandpaper so the resins get a better "bite". Next step in the seamless joint
is to place strips of tape about 3"-4" apart along the seam edge while out of the mold.
Place back into the mold making sure the tape doesn’t double over into itself.

Before I secure the upper deck to the lower, another batch of micro fiber mixture is
made and used as the bonding agent for the transom locking it into place. I butter both
sides of the mating area to ensure a good hold. Place the upper deck on top and wrap
the tape making sure the seam is tight and placed where you want it.

Finally to seal the seam completely and give the resins a backer to dry up to, I use
electrical tape stretched around a few times. This holds things together nicely and
when removed the hull will be like one piece.

Joint preparation

In preparation for assembly, again everything out and ready. I've taped a brush to an
arrow shaft so I can glass down deep inside the hull.

When glassing like this, it's best to let gravity work for you. I prop the hull and secure it
to a floor lamp with an adjustable arm. A low wattage fluorescent bulb is attached
because regular bulbs are way too hot!

This is really the part that I do not enjoy doing. Difficult to work with limited spaces and
sometimes blind, and the resin fumes.....

Glassing the seam

Time to get messy! There really is no easy clean way to do this part, just have to get in
there.   Here I have a batch of resin mixed and getting ready to pre-saturate the
fiberglass tape. Having it pre-wetted out makes it easier to stick once positioned.

Basically dipping into the cup and squeezing out like a sponge works great. From that
point it's dropped into the hull and positioned whatever way I can. Usually with the help
of the arrow shaft paint brush. Once in there, it's manuvered around into position and
worked into the hull corner right over the gorilla snot of resin previously applied.

Completed seam

After the resins have cured, you can remove the tape. Notice how tight the seams are.
Any gaps that may have existed have been filled with resin from the work done inside
the hull while assembling.

Sanding the seam smooth

Some preliminary sanding of the edges to give the hull a slightly softer look. Using my
palm sander and 8o grit I round the edges slightly. As you do this you will remove all the
gelcoat from that corner exposing raw resin and/or fiberglass. That's ok because one
of the reasons I add all that resin mixture inside the seam is to thicken up the corner so I
can round off these edges without risk of weakening the joint.

Primed and ready for paint!

After initially smoothing out the jointed seam with 100 grit and a palm sander,
subsequent sandings of 180 and 220 were then done.

A light dusting of automotive primer will show areas that needsome attention easier.
Looking closely, can you see the little divots in the corners? If these were left
unaddressed, than it would definitely show through the paint job.

Next some spot putty will be used to fill these little voids. Putty, primer, sand...putty,
primer, sand...putty, primer, sand should definitely make this absolutely perfect without
any flaws or divots showing. No hurrying this part! If anybody has ever painted cars,
bikes, or whatever, a good painter knows that a good paint job is the result of 90% good
preparation, 10% spray skills....

A few examples of completed hulls

Once paint prep is complete, it's off to the booth!   Personally I prefer automotive quality
basecoat/clearcoat systems.   A couple really nice brands that are budget minded are
the Nason line from DuPont and Cross Fire systems. All my hulls leave my shop
completely painted in the color of YOUR choice

Take a look at the photo gallery for other interesting designs that have
left my shop.