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To meet Transport Canada regulations, we'll be adding 8 cubic feet of flotation
foam to the boat. The intent is to install the bulk of the foam up high under
the deck. This will require building an in-situ mold which will conform to the
curvature of the deck beams. A foam thickness of 3 inches will yield 5 cubic
feet of flotation material in the forward deck. An additionnal 3 or 4 cubic feet will be cast under
the deck between the carlings and sheer clamps, intermediate deck at frame # 4 and
across the transom deck. The custom molded blocks will be fastened to the deck
battens so that they can be easily removed for competition use or storage. If
this sounds like a lot of extra work, you're right !
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A template for the top frame lamination was traced onto a piece of 1/2" Black Joe building board.
(31-JAN-2007)
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A jigsaw was used to cut the stock 1/4" oversize. The piece was then
fastened to the 3/8" thick template with 3/4" screws and trimmed on the router table.
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Closeup of the top-bearing trim bit.
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The screws were removed from the stock.
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A duplicate piece was produced.
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The two pieces were installed on each side of the frame and taped to hold them in position.
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Once the foam has been poured and has cured, the inner piece will be extracted first. This will
allow easy removal of the outer piece when the foam core is unmolded.
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Here's a shot of the two 1/4" plywood panels which will be installed on the bottom of
the frames. They were coated with contact cement and covered with aluminum
foil. A plastic autobody filler squeegee was used to apply the foil and remove
air pockets and wrinkles. We'll be laminating one layer of 6 ounce fiberglass
cloth on this surface before pouring the foam. In the winter, the shop is home to
many snowmobiles in for maintenance or repair. This is my 2003 Rev 600 HO waiting
for its regular maintenance. Due to the lack of snow this year, we've only
been out once this year (2 day trip, 450 km). I guess we'll keep working on the boat
until the trail conditions improve !
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The frames were wrapped with plastic before installing the bottom
mold pieces. Support for the plywood was provided by clamping
scrap lengths of spruce 1" X 3" to the underside of the ply.
(03-FEB-2007)
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Wood shims were jammed between the plywood and strapping to minimize
gaps between the center part of the mold and frames.
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Two 1/2" Black Joe side spacers were installed along the sheer and
covered with plastic film. Duct tape was used to seal all the seams.
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6 oz. fiberglass cloth was dry-fitted to the mold.
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The cloth was wet out with catalysed polyester resin. A second
coat of resin was applied after the initial coat had cured. In the
background, resting on the transom, you can see the piece we molded
for the bow section. A single 8 liter pour foam kit wasn't enough to
do the job. We're 1 quart short . . . We'll have to
order more foam on Monday !
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The second kit we ordered last week was picked up this afternoon. Four
small batches (10 ounces Part A, 10 ouces Part B) were mixed and poured into the
molds to complete the job. An old crosscut handsaw was used to trim the
expanded foam flush with the frame tops.
(10-FEB-2007)
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Once the foam was fully cured, the spacer blocks were removed from the sides of the mold.
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This view shows the one inch gap between the sheer and foam.
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The surface quality of the molded fiberglass lining on the bottom of each billet
was quite good. Very little filling will be required prior to finishing.
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Total of 5 cubic feet will support up to 300 pounds.
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We laminated a layer of 7-1/2 ounce fiberglass cloth to the topside of each billet.
In an effort to cut costs, we switched to polyester resin. Overall, we
might have saved a few dollars over the more expensive epoxy resin, but we didn't
save any time. It didn't stick too well to the foam so the fiberglass
cloth kept lifting and creating air bubbles.. Once cured, we applied 2 coats of
resin, sanded the billets and applied several rounds of polyester autobody
filler. We sprayed two medium wet coats of Feather-Fill polyester primer-surfacer.
(14-MAR-2007)
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The billet in the foreground was blocked with 100 grit alumide paper.
A round of polyester finishing putty was applied to the low or blemished spots.
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The flotation billets can't be installed under the deck battens unless they're
cut into two pieces.
(24-DEC-2007)
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A long shank 1/4" drill bit was used to drill through the billet.
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The two piece billets are held in place by 6" lengths of 1/4"-20 stainless
steel threaded rod.
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Here's the finished product.
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Here's the under-deck view. Mounting the foam up high will ensure
that the hull doesn't 'turtle' over when swamped. We could have
increased the thickness somewhat, but we wanted to minimize the amount
of weight (and weight moments) in the bow section. Total weight
is approximately 12 pounds. To offset this weight and balance
the hull, more billets will be cast along the gunwales, intermediate
deck beam and transom.
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For a sleek contemporary look, we've chosen a stainless steel pop-up
bow light. When not in use, it's flush with the deck . . .
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. . . and pops up when needed.
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The bow light is housed in a plastic receptacle which can be equipped with
a hose barb and drain hose. This unit was purchased from Marine Toys in
Delta, British Columbia.
See our
Links Page for supplier information.
(a new window will be opened)
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To ensure adequate ventilation and prevent rot issues, we installed
1-1/2" diameter 3/4" marine grade plywood spacers between the deck
battens and foam bilets
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The deck battens where counterbored to accept stainless steel barrel nuts.
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Once installed, the recess will be filled with epoxy and ground flush.
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Work on the billets will continue. We'll post more pictures as work progresses.
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