Dennis D Photos.pm7 - Dennis Desprois R

Building Gambit
by Dennis Desprois
When John Davis, the editor for Model
Yachting, suggested that I do a feature
article documenting the building of my
new Gambit US One Meter, my initial
reaction was “yea sure, just what’s
needed, another over written piece
detailing how to build a boat with the
obligatory picture of a hull in the mold
with juxtaposed clothes pins lined up like
Nutcracker solders ringing the top of the
mold.” (Editors note: I really do like
those shots... with lots of clothes pins.)
John knows that I am a has-been big
league sports photographer so he
cleverly appealed to my visual
orientation by saying that since my boats
The completed Gambits. The Standard version has a raised foredeck and skiff aftdeck. The skiff version has a full skiff deck.
The Gambit hull is made with three
molds. The hull and foredeck are laid up
in female molds, while the aft deck is laid
up on a reverse mold. Before a part can
be laid up, the molds have to be cleaned,
and polished with several layers of wax
applied. Here, the mold is being waxed.
Trimmed carbon fiber cloth, ready to fit
into the hull mold lies in the foreground
on the table.
The carbon fiber cloth is fitted into the
mold with a minimum amount of excess
material (the stuff is a bit pricey) and
then wetted out with epoxy resin.
Because a laminated structure makes for
a stronger part, a layer of 2 oz fiberglass
cloth is laid over the carbon fiber and
wetted with epoxy to gain the proper
stiffness.
Wetting-out the aft deck. Because epoxy
resin generally sets more slowly than
polyester resin, I prefer to use epoxy resin
to wet the carbon fiber cloth. He gains a
longer working life than if he used
polyester resin. Therefore it isn’t a race
to get the part wetted out before the resin
goes off.
The inside of the Orco hatch is cut out
and its outside trimmed. The shape of
the hatch is then cut in the aft deck and
the hatch fitted under the deck before
being bonded in place with epoxy.
With the Orco hatch installed in the aft
deck and a slot cut for the mast tubes,
both the aft deck and foredeck are ready
to be bonded to the hull with epoxy
are so unique in their construction, the
piece could be primarily a photography
project. I didn’t want to admit that, after
thirty years of shooting Major League
Baseball and the NFL, making a picture
of anything that isn’t moving can easily
turn into a rather challenging endeavor
for me. However, since there were a
couple months until Spring Training here
in Arizona, it was a chance to dust off
the cameras and use up some of the
outdated film taking up space in a
refrigerator. I agreed to photograph and
document my next build.
As luck would have it, I had just started
building a Gambit US One Meter with a
raised foredeck and skiff aft deck. This
After the excess cloth has been trimmed
from the mold, a balsa brace (strake) is
glued to the top of the hull to hold its
shape and act as a base for the decks
when they are installed. The vertical
bulkhead, keel box, and mast tubes have
also been installed.
After the foredeck has been installed and
trimmed around the hull, the edge over
the vertical bulkhead is sanded.
Protective tape prevents damage to the
carbon fiber finish. A carbon fiber
reinforcement plate has been added to
the top of the keelbox for strength where
the keel attachment bolt will be.
The completed foredeck after it has been
trimmed and the seam has been sanded.
Before it is attached to the hull, the
carbon fiber jib rack and a support for
the fairlead are resined in place under
the deck.
For the hull with the internal winch,
mounts are made for the rudder servo,
so it can be easily bolted to the underside
of the aft deck just behind the hatch.
Before resining the aft deck to the hull,
tape is applied to the hull to shield it from
resin overflow and to protect it while
trimming and sanding the seam. A clamp
is used to hold the mast tube in the middle
of the deck and to the plate on the keel
box. The deck is also held in place by
tape. The lines on the table are a sail
pattern.
Once the aft deck is resined onto the hull,
the overlap is trimmed, using a Dremel
tool with a cutoff wheel, and then sanded.
During any sanding, the value of the
protective tape is obvious
The carbon fiber chain plates are made
of several layers of cloth and molded
under pressure. A slot is cut into the deck
near the hull and the chain plate is then
resined to the inside of the hull.
The Gambit hull with mounts for the
internal electronics. The Futaba S-5801
holder box is installed with a battery
holder.
The hull with the Orco hatch. The aft
deck is ready to be resined to the hull. A
balsa brace is tacked inside the transom
to prevent hull distortion when the deck
is taped on. It is removed when the
transom is resined on.
one was fitted with Swede Johnson’s
Orco hatch and I had an order for another
Gambit US One Meter that would be a
bit different in it’s construction. This
Gambit was going to a skipper in
Geneva, Switzerland who wanted to
have the only US One Meter sailing in
the Alps (I liked that). Since his local
pond happened to be Lake Geneva with
potential big winds and constant chop,
he wanted all of the electronics to be
tucked away inside the hull. My boats
are continually evolving so the idea of
figuring out how I’m going to get from
point A to point B with the modification
was something I was looking forward to.
Since I have never liked making a radio
board, I ended up machining a four-part
aluminum mold for a carbon fiber piece
to go inside the hull. It fit the shape of
Here is a hull with a completed Orco hatch. Before it is detailed, I like to put all of
the components together to see what everything looks like.
With the keel fin in place, a guide hole is
drilled in the deck of the finished hull to
mark the spot where the threaded bolt in
the keel trunk will be located.
The aft deck of a Gambit with an Orco
hatch. The rudder post is installed before
the transom is resined in place. A carbon
fiber plate is added around the rudder
post for strength. The Pekabe block is
for the sheet return.
The foredeck with the carbon fiber jib
rack. The Pekabe block is for the sheet
tension line. The hole in the bow is the
internal drain. The drain-hole plug is a
rod that extends above the deck to act as
a water splitter. It helps keep the bow
from plowing under (submarining) in
heavy weather.
The Gambit hull with an internal winch
box. The Futaba S-5801 winch and
batteries are in place. Unlike the model
with the modular Orco hatch (where all
of the sheeting is above decks), in this
configuration, the winch is inside the
boat, and the sheet runs from the winch,
under the aft deck to an exit at the stern.
An elastic tension line and sheets are
positioned above deck. The jib sheet and
tension line then pass through the
bulkhead and exit on the foredeck aft of
the jib sheet fairlead.
A completed hull with an Orco hatch. The seams have been sanded smooth. The
hull and deck have been completely polished, and the trademark gold trim has been
added.
Some of the ancillary, molded, carbon
fiber parts and their molds: the mast tube
minus the mandral, the Orco hatch cover
with its two-part mold, the S-5801 winch
holder with its four-part mold, and the
keel box with its two-part mold.
Parts out of the molds. Keel box, mast
tube, Orco hatch cover, and both halves
of the S-5801 winch holder.
The Orco hatch and hatch cover in their
molds. The hatch cover is laid up first,
trimmed, and put back into the mold.
Then the hatch is laid up inside the cover
for a perfect fit.
Completed Orco hatch with the winch,
rudder servo, receiver, and batteries
attached to the underside. An On/Off
switch with a waterproof cover and a
sheet-exit bridge complete the hatch.
Completed aft deck of a Gambit with an Orco hatch. The sheets, tension line, and
all of the components are above deck for easy access. The rudder arm is milled
aluminum (since modified) and the rudder shaft is a carbon rod with an adjustable
clevis on either end. A knurled nut holds the fin and a carbon fiber tab washer holds
the front of the hatch. The antenna wire goes up the shroud.
the Futaba S-5801 drum winch perfectly.
This “winch box” holds the winch
securely but allows it to be simply lifted
out if necessary. As a side task, I was
also making a mold for a completely new
and rather radical full-skiff deck
configuration for both the Gambit 36/600
and US One Meter. So in fact, I was
simultaneously working on three
variations of the same theme.
Because the first two boats, one with
the Orco hatch and one with the winch
inside the hull, were at different stages
of construction, keeping in sequence, I
took the liberty of co-mingling the
photographs of the two different boats
so don’t get confused when you are
looking at the pictures. The full-skiff
deck version was completed shortly after
the first two, so in a short period of time,
I had three versions of the same boat
sailing. For guys who design boats, that
is about as good as it gets. The jury is
still out as to which deck version is the
fastest, but since the deck isn’t going to
have all that much influence on how fast
a boat goes, I suspect it will be a wash.
Most importantly, my concerns about
water pooling on the deck of the radical
full-skiff deck, proved to be unfounded
(a relief since it looks really cool!). And
the report on the version sailing on Lake
Geneva is that it is easily the second
fastest boat on the lake, the fastest being
Alinghi.
What sets my boats apart from the
others is that they are made completely
of carbon fiber and except for a few parts;
literally everything is made in my shop.
Laying up carbon fiber does take time
so how long it takes to make a boat is
dependent on how many of the ancillary
The two halves of the molded, hollow,
carbon fiber booms are trimmed before
they are sanded and resined together.
After the fin is out of its mold, the trunk
is roughed out and placed in an
alignment mold. Resin is added to form
a trunk that is matched to fit the keel box.
Completed fin with the treaded rod that
extends through the deck where it is
secured in place with a knurled nut.
he Gambit US One Meter sailing on Lake
Geneva, Switzerland.
Sand casting the lead bulb is a multi-step process. First, screened sand goes over a
half mold of the bulb in a frame. The sand is packed tightly, and the process is
repeated for the other half. A spout for pouring lead into the pattern is positioned,
and the patterns are removed. The two frame halves are carefully put together and
the lead poured. Once it has cooled the bulb has to be trimmed, and a slot cut for
the fin. The last step is to smooth the bulb.
mold in two pieces and have to be resined
together to make the complete part.
I don’t mean for that to sound at all
cavalier because anyone who has built
or even assembled a boat knows that
putting together or installing a part
sounds simple but in reality means
trimming, sanding, looking for a tool,
gluing or resining, fumbling for a 2-56
bolt, dropping the church key under the
fridge and answering the telephone with
Bulb ready to be attached to the fin.
just mixed resin waiting for immediate
application.
I find the most complicated and timeconsuming part is building the fin. Mine
takes four separate and somewhat
complicated lay-ups with each taking a
day to cure before trimming and
preparing for the next mold. The end
result is a light, very stiff fin, so it is well
worth the time.
When talking about sails, I often quote
Bob DeBow, the dean of R/C boat
The Gambit US One Meter, with the
designers and builders, when he declares,
raised foredeck, sailing in light air.
“sails are a sailboat’s motor and you
parts I have pre-made... like the mast don’t want to put a Pinto motor in a
tube, keel box, bulb and so on. My Corvette!” Some skippers like to make
approach is that things take as long as their own sails. which is something I
they take and the best you can do is be encourage. However, there is an
efficient in the building sequence. If you undeniable learning curve to sail making
count every nut, bolt and bowsie, there and anyone making their own sails
are about a hundred and forty parts in hopefully realizes that there is a very big
the Gambits (fifteen to eighteen of which difference between assembling sails and
are multiple part carbon fiber). Most of making sails. My Walrus sails are made
the carbon fiber parts come out of the with a 1.4 polyester film that shapes well
The Gambit US One Meter with full skiff
deck.
and with no sewn seams they have a
remarkably smooth surface. Making my
own sails allows me to experiment with
different rig aspects and ratios. After
trying a couple different rigs, I can pretty
much compliment the boat with the sails
that I think are going to make it go the
fastest in each condition.
Since this is specifically an article
about building the Gambit US One
Meter, I resisted getting into design
theories or even commenting on my
ideas of what makes one boat go faster
than another. For those skippers who
have an active imagination, the allure of
the development classes is that any idea
you may have can be transposed to his
or her boat. As Swede Johnson says,
“Either it works or it doesn’t.” The joy
is that you get to try. Now that’s fun!
To see the other boats, etc. that I
manufacture, visit my website at:
www.rc-yachts.com.