Building the Two-Paw 9
Day 1
Set up shop. Loft one bottom half. Glue extension piece to
bottom (2 pcs 8oz tape, 1 side only).
Shop
My shop is in a 20x25 foot room in a mini-storage warehouse. However,
when I started building, the room wasn't ready, so I had to work in a
10x20 foot room. All of my building materials had been shipped from the
West Coast and took up most of the space in the room. Since I wasn't
going to have space to set up my table saw, I was going to have to
improvise.
Scantlings
I've learned the hard way not to mess with the designer's scantlings.
So I thought long and hard before deciding to go with a slightly
lighter plywood. Most boats of this size require 1/4" (6mm) plywood for
the bottom, perhaps slightly lighter for sides, bulkheads, and
transoms. I decided to use 5mm marine okoume for the bottom, and 4mm
for the rest. The main reason was that I wanted to cover the outside of
the hull with 5-ounce S-glass set in epoxy, but I didn't want to add a
lot of weight while doing so. S-glass is much stronger and tougher than
normal boatbuilding fiberglass (E-glass), and gives a much more durable
covering than simply "painting" the hull with epoxy, which allows water
to penetrate after the very first scratch. Finally, I find
that fiberglassing an entire outside panel is no more or less messy and
time consuming than glass taping the seams, and results in a smoother
finish.
Lofting
I found lofting the hull panels from small-scale patterns much
more
enjoyable than trying to wrestle full-size patterns into position and
keeping them there while you trace the whole panel. With full-size
patterns,
you're going to want to retrace the line with a lofting batten (in my
case, a 3/4"x3/4" piece of oak) anyway,
because the pattern inevitably shifts slightly.
Size and Scarfing
I consider 9 feet the absolute minimum size for carrying 3 people while
rowing, but that's just personal preference. I sure wouldn't want to
have 3 people in my 2-Paw
in anything but perfectly flat water. Plus I already had a rig
for a 9-foot sailboat, and wouldn't put 50 square feet of sail on
anything smaller. The big advantage of building an 8-foot boat is that
panels can be cut from single sheets of plywood. Since the Two-Paw 9 is
a bit longer than a sheet of plywood, you have to attach an extension
to the bottom and side panels. I've tried butt-blocks and fiberglass
tape but not scarfing, yet. For this boat I used two layers of
fiberglass tape to attach the extension pieces, but only on the inside,
since I didn't want tape bumps and seams to fair on the outside.
Day 2
Loft one side. Rough-cut side. Sand first bottom half - sloppy. Glue
2nd bottom half.
One detail that's not mentioned in the plans: when you're
cutting out the side panels, leave plenty of "overrun" at the gunwale,
and just trim it down after you've attached the gunwale. I didn't, and
ended up filling the gap between my inwale and outwale (more on that
later) with putty filler (epoxy, silica, and microballoons), which
doesn't look nearly as good as wood would have.
It's also important to mark the position of the center
bulkhead now, so you're not guessing later.
The first bottom half to which I glued the extension didn't
look too good. I had forgotten most of my fiberglassing technique, so
there was a messy pool of cured resin on and around the glass tape,
which required lots and lots of sanding.
Day 3
Cut 2nd side, and side bow extensions. Glue both side extensions, using
peel ply. Loft bow and stern transoms.
I'm slowly re-learning how to use fiberglass and epoxy. For
the side extensions, I used peel ply, which not only soaks up excess
resin, but it also leaves an extremely smooth surface on the tape. I
didn't have to sand these parts at all.
Day 4
Loft and rough-cut center bulkheads and doublers. Glue doublers to
bulkheads. Use excess resin to coat bulkheads. Trim and sand both
bottoms.
When you're doing small taping jobs like the panel extensions
(each piece of tape is only 8-10" long), mix plenty of resin and
squeegee the excess over as much of the panel as you can. You're going
to cover the whole panel in resin eventually so you might as well start
now and not waste any.
Day 5
Trim and sand sides. Peel ply makes much better surface. Glue
stiffeners onto transoms. Drill bulkhead compression holes and fill
with epoxy mix. Overfill as epoxy shrinks. Stitch bottom to sides and
transoms: looks like a boat, after only 5 days of work! I mostly used
baling wire, supplemented by nylon tie-wraps in lower-stress areas. I
needed at most one tie every 8-10 inches. Problem: sides are very
concave near bow. The designer says this "may" happen, which is
designer-speak for: "This will happen to you." Loft and cut seat
bulkhead and stitch in, which solves concavity, but causes a new
problem: port side extension shifted during gluing, and there's only
tape on the inside, so the panel starts to bend at the seam.
  
Day 6
Disassemble. Fix port side: gouge out epoxy with Dremel and
refill gap. Cut out and install stiffener for bow seat bulkhead. Drill
1/4" holes in nesting bulkhead and bolt together, leaving gap for cut
using cardboard spacers. Sand both edges of bottom for better fit and
bevel center edge. Sand edges of transom stiffeners. Re-stitch panels,
using nesting bulkhead: much better fit than last time. Screw nesting
bulkhead to sides with drywall screws. Measure to verify front half is
smaller than back half. Nesting bulkheads are too flexible and need a
temporary stiffener because the sides want to squash them in and bend
them.
Day 7
Notch the bow seat bulkhead for the mast brace. Screw sides to
transom stiffeners with drywall screws. New problem: since I'm not
using 1/4" plywood for the bottom, it tends to sag depending on where I
put the sawhorses. So I put a piece of clear plastic tape along the
part I'm eventually going to use for the keel and stitch it to the
bottom for stiffness. I could probably omit the tape and permanently
glue the keel on at this point, but if it doesn't go on perfectly it
will cause big problems. The tape allows me to pull it off when I
remove the stitches. Tighten stitches and measure diagonals, to square
everything up.
    
Day 8
I glue the seams with a high density (silica) glue. I'm careful not to
use too much, since this stuff is tough to sand, and to avoid hitting
the stitches. After it's cured completely, I remove the stitches, then
fill in the gaps with a low density (50/50 mix of silica &
microspheres) fillet on the aft section of the keel and chines.
Finally, I glass-tape the aft keel before the fillet cures completely.
I don't like the recommended technique of gluing the entire
seam at once (including stitches), then pulling the stitches before the
glue cures completely. It's too risky that you'll start pulling
stitches too early, and your seams will come apart, or too late, in
which case you'll have to wrestle the stitches out and risk splitting
the seams anyway. Gluing a little at a time requires sanding after
cure, but it's much safer. Plus I can use a small quantity of
high-density filler to keep the parts together, and a larger volume of
low-density filler to keep the weight down.
Day 9
Fillet all seams except bow, forward of seat bulkhead. Tape aft chines
and transom. 3" + 4" on chines and keel. 3" + 4" on nesting bulkhead at
bottom. 4" + 2 x 3" + 3" on nesting bulkhead at sides. 3" on transoms.
One thing I couldn't find in the plans was the schedule for
taping seams. It's got to be in there but I must keep missing it! The
only directions I can find concern taping the nesting bulkheads to the
sides, which requires a lot of tape. So I improvised the rest and used
2 layers on long seams (lengthwise) and a single layer on short seams
(breadthwise).
Day 10
Fillet bow (forward of seat bulkhead). Tape complete interior.
Squeegee excess resin onto bottom and side panels.
   
Day 11
Flip boat over, and round starboard chine seam. Fillet keel,
port chine, and transoms. Glass port bottom. Glass overlaps keel by 6",
chine by 2", transoms by 2-4". I covered the bottom fiberglass with
peel ply at the overlaps (keel and chines), and release film in the
center of the panel. Peel ply gives a slightly textured surface that's
suitable for further glassing without sanding, and release film is
supposed to give a mirror-like surface. The peel ply works great but
the release film is smooth but crazed. More like a cracked mirror, but
adequate.
   
Day 12
Clean up port bottom (scrape and sand). Round and fillet starboard
chine. Glass starboard bottom, both sides, and both transoms. Entire
boat (except port bottom) is covered with peel ply and release film.
Pet peeve: most builders and designers, when describing
fiberglassing, recommend a second coat of epoxy to "fill the weave" of
the fiberglass. Don't do it! "Straight" epoxy is dense and
heavy, and is going to add a lot of weight. By the time the first layer
has cured, the fiberglass fabric either is or isn't completely
saturated with epoxy. Adding more epoxy on top isn't going to improve
strength one bit, but it's going to add weight. To fill the weave, use
peel ply! Even if you use cheap nylon bunting from the fabric store,
instead of the real stuff, your surface will be far smoother. Any and
all fairing should be done with lightweight mixes of epoxy and
microballons, spheres, or glass bubbles, never with unthickened
epoxy. As a side benefit, peel ply surfaces have no amine blush, since
they don't cure in air, which eliminates scraping and scrubbing before
sanding or coating. The only time it's appropriate to re-coat with
unthickened epoxy is if you are going to clearcoat (varnish) the
surface.
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