The Perfect Pram?
  
After building a foam-core fiberglass dinghy, I realized that
there are probably lighter and easier methods of building. Since
I had moved across the country to Jersey City, NJ, and had a small
workshop but not enough space to complete the trimaran, I decided to
build another small boat. This would be a 9-foot nesting sailing
dinghy, the Two-Paw
9,
designed by B&B Yacht Designs. This is a clever pram-style dinghy
that you cut in half when it's complete. The bow half rests inside the
stern half so it takes up less than 5 feet of space on deck. Judging
from the numbers, it also met the goals of lighter and easier to build:
only 60 pounds total, and 70 hours building time before it hit the
water. Some caveats, though to explain why it's so light and was built
so quickly: 1) I used some slightly lighter plywod than the designer
specified, and covered the entire exterior with S-glass, 2) it sailed
for the first time with only one splashed-on coat of paint, 3) some
parts (boom, daggerboard, and rudder) that can take a while to build
were borrowed from the Foamee, and 4) a few small details (such as
knees) still weren't
finished at launch.
I later spent about 40 hours improving the paint, tuning
the sailing rig, converting the rudder to kick up, and adding
floatation to the stern section. While I used the boat as a
tender in Ohio and for the first part of our Bahamas trip, in Miami,
eventually I broke down and bought an inflatable because the solid
dinghy was just merciless on topsides paint. I tried several
variations on fenders and rubrails but nothing worked well, and those
hard corners were big trouble. If you have access to old fire
hose you could use this dinghy as a tender but if not, watch out.
The other advantage to the inflatable is that I can simply drag it over
the aft beam on the trimaran and lash it to the net for passages,
whereas dragging the keel of the hard dinghy would have scraped up the
beam badly.
Here's a link to the cost of
materials, and weight breakdown.
Summary building log:
| Day |
Hours |
|
| 1 |
3 |
Set up shop. Loft one bottom half. Glue extension piece
to bottom (2 pcs 8oz tape, 1 side only). |
| 2 |
2 |
Loft one side. Rough-cut side. Sand first bottom half -
sloppy. Glue 2nd bottom half. |
| 3 |
2 |
Cut 2nd side, and side bow extensions. Glue
both side extensions, using peel ply. Loft bow and stern transoms. |
| 4 |
2 |
Loft and rough-cut center bulkheads and
doublers. Glue doublers to bulkheads. Use excess resin to coat
bulkheads. Trim and sand both bottoms. |
| 5 |
4 |
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. Problem: sides are very concave near bow. Loft
and cut seat bulkhead and stitch in. New problem: port side shifted
during gluing so it starts to bend at the seam. |
| 6 |
4 |
Disassemble. Fix port side: gouge out epoxy with Dremel
and refill gap. Cut out and install 1/2" 1/4-round stiffener for bow
seat bulkhead, leaving 3" gap for mast brace. Drill 1/4" holes in
nesting bulkhead and bolt together, leaving gap for cut. Sand both
edges of bottom for better fit and bevel center edge. Sand edges of
transom stiffeners. Re-stitch panels, using nesting b/h. Much better
fit than last time. Screw nesting b/h to sides with drywall screws.
Measure to verify front half is smaller than back half. Nesting b/h are
too flexible and need a temporary stiffener. |
| 7 |
2 |
Bow seat b/h notch. Nesting b/h stiffener. Screw sides
to transom stiffeners. Tape keel and stitch to bottom for stiffness.
Tighten stitches and measure diagonals. |
| 8 |
4 |
Glue seams (high density: silica). Remove stitches.
Fillet (low density: 50/50 silica & microspheres) aft keel and
chines. Tape aft keel. |
| 9 |
3 |
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" + 2x3" + 3" on nesting bulkhead at
sides. 3" on transoms. |
| 10 |
4 |
Fillet bow. Tape complete interior. |
| 11 |
3 |
Round stbd outside seams. Fillet keel, port chine, and
transoms.
Glass port bottom. Glass overlaps keel by 6", chine by 2", transoms by
2-4".
Bottom covered in peel ply at overlaps, release film in center.
Overlaps are smooth, release film is smooth but crazed. |
| 12 |
4 |
Clean up port bottom. Round and fillet stbd. Glass stbd
bottom, both sides, and both transoms. Cover entire boat with peel ply
and release film. |
| 13 |
2 |
Sand outside. Glue outside gunwales. |
| 14 |
5 |
Cut and install inwales. Install forward
seat cleats. Glue mast collar parts together. |
| 15 |
1 |
Coat interior with epoxy. |
| 16 |
3 |
Scrub interior with Ajax-- still sticky. Attach mast
collar to b/h and bow transom. Reinforce collar. Cut out fwd. seat. Cut
out daggerboard trunk and glue spacers to half. |
| 17 |
3 |
Fit forward seat, fill with styrofoam, and screw down.
Cut slot in keel for skeg. Glue on keel, then reglue after it pops off.
Glass skeg. Glass inside of d/b trunk. Coat dry spots on bottom. Glue
d/b trunk halves together. |
| 18 |
5 |
Sand bottom. Trim, fit, and install d/b trunk. Fillet
d/b trunk seams. Glass in trunk. Fill inwale/outwale cracks. Scrape and
sand aft interior. Drill and install bolt in mast. |
| 19 |
2 |
Coat d/b trunk and fwd seat. Glue trunk braces. Glue
skeg. Fillet keel and keel ends. Fair 1/2 bottom with microballoons. |
| 20 |
3 |
Sand gunwales, grout groove. Coat d/b trunk. Saw in
half. Sand nesting b/h inside. Fair nesting b/h. |
| 21 |
4 |
Complete bottom fairing. Glass nesting b/h. (Move shop). |
| 22 |
8 |
Bolt together. Fair sides. Trim excess glass from
nesting b/h & sand. Sand gunwales. Sand daggerboard trunk. Drill
mast hole and glue on plug. Sand nesting b/h edge and fill. Complete
mast parts. Screw down seat top. Paint interior and parts. Cut rowing
thwart, glue d/b insert and toggle. |
| 23 |
3 |
Sand bottom and sides. Sand keel. Paint outside. Touch
up parts paint. Cut gudgeon backing block. |
| 24 |
2 |
Varnish trim. Install hardware: oarlocks, painter,
traveler ends, gudgeons. |
| 25 |
|
Go sailing! |
| Total: |
70 |
|
The following pages give more information about building, or
you can skip the gory details and go straight to the launch.
|