By Hal Kelly

T HIS STABLE little sailboat, with a

bottom like a power cat, is fast, light,
easy to build and unsinkable. The con-
cave bottom gives her firm footing, a lot
of load carrying ability and little ten-
dency to heel in an average breeze. The
superior flotation makes her float high
enough so that, with her centerboard up,
she can handle very shallow water
while skimming along.
Though 14' long and with a beam of
6', she weighs only about 200 pounds.
This, and her safe non-sinking ability,
are a result of planking with 1/2" Rigicell,
•mi
a new foam-type material made by
Shelton, Conn., branch of B. F. Goodrich HOMEMADE lamp of heating element in re-
Sponge Products. The stuff can be cut flector is sufficient to set curve of bottom.

March, 81
Unsinkable Uniboat

DECK is removed after fitting, propped up HULL is removed from jig and battens to
for taping of seams and glassing underside. support decking are installed and fastened.

BACK in shop, deck is refitted and fast- DEPRESSIONS from nailing Rigicell are
ened. Top surface is then fiberglassed. filled and finish coat of tinted resin applied.

and trim-fitted with a razor blade, and gether and cut as a unit with a saber
is held in place with toothpicks during saw. The transom remains solid, but the
construction. A final covering of fiber- ribs have lightening holes cut in them as
glass and resin inside and out gives it a shown in the plan. These, too, can be cut
strong hard surface. as one unit. Rib #2 is smaller but simi-
Construct the frame jig on which to lar in shape. The bow piece is solid.
build the craft from two 15' 2x4's on a Ribs, bow piece and transom are now
level surface with 2x4 cross members positioned on the jig, clamped in place
positioned and fastened at each station. in the case of # 3 , # 4 , #5 and transom
Ribs # 3 , #4, and #5 will have a 12° until the 12° slant is checked, and then
slant. Cut this same angle in the cross temporarily nailed or screwed to the
beams at the corresponding stations. cross members.
Ribs are cut from a 4'x8' sheet of 1/4" Battens are cut from three pieces of
exterior grade plywood. The transom 1"xl2" cedar 14' long. All battens are
plus ribs # 3 , # 4 , and #5 are the same 3/4" square except the center battens for
size and can be temporarily fastened to- [Continued on page 102]
82 Mechanix Illustrated
Unsinkable Uniboat handled by this material. Heat it before
forming. A round heater element
[Continued jrom page 82] screwed into a light socket with a photo
the bottom and the deck. These are reflector can supply sufficient heat.
3/4"x2". Where the battens fit into the The sides are easily planked with 4'x6'
slots in the ribs, glue and nail small sheets cut in half lengthwise. These are
blocks 3/4" square and 1-1/2" long angle-butted and cemented with epoxy
to the ribs. After the blocks have been resin just as with the bottom. I experi-
faired off even with the edges of the mented with small fin keels similar to
slots, the battens can be fitted. Secure leeboards at the bottom of each side.
them to the ribs and blocks with Weld- Though not really necessary, I found I
wood Plastic Resin glue and 1-1/4" #12 could sail without using the centerboard
boat nails. unless I was beating to windward.
Planking with Rigicell starts at the After the edges of the bottom and side
transom. Where the sheets butt, the planking have been carefully trimmed,
edges can be cut at a 45° angle with fine- polyester resin is applied to the bottom
tooth cross cut blade on a table saw, or and allowed to harden. Next, a length
even with a razor blade. These butt of 8 oz. fiberglass 38" wide is stretched
joints overlap 1/2"and are held in place down the center of the bottom. It will
with round toothpicks every three overlap each side about 6". Transom and
inches. Epoxy resin can be used to ce- bow are also covered by it and it is
ment the joints. trimmed to fit. Remove the cloth, apply
Two 4' wide sheets of Rigicell about a coat of resin to the bottom with a
5' long are positioned across the hull for brush, and then reposition the cloth in
initial fitting. Once secured they can the wet resin. More resin is now squee-
later be trimmed with a razor blade. geed through the cloth and all air
Apply epoxy resin to ribs and battens bubbles are worked out. Lengths of
before fastening the planking sheets. fiberglass cloth from a sheet cut in half
Nail them in place with 7/8" roofing nails. are applied to each side in the same way.
The large heads will not pull through. They will overlap the bottom fabric
The forward part of the bottom can slightly.
be covered with two full length sheets Now the hull is removed from the jig,
6' long by 3' wide. The bow section has after the fiberglass has cured and hard-
a slight compound curve which is easily ened, and positioned right side up on a
level floor. Use shoring blocks beneath
the bottom if you have added the keel
fins so that they do not touch the floor.
The inside of the boat is now fiberglassed
as well, a somewhat messy job, since
small pieces of fiberglass are pasted be-
tween the ribs and battens. Exact fit is
not necessary, and the fabric should be
allowed to extend up the ribs to inte-
grate the planking with the ribs and
battens and further strengthen the craft.
A brush and squeegee can be used to
push the fabric scraps into position. If
washed with a strong detergent soap
before the resin hardens, the brush and
squeege can be salvaged for further use.
Mast supports are next fastened in
place, rudder and centerboard are cut
from 1/2" exterior plywood, and the cen-
terboard well is finished off at the deck.
Since the centerboard will bear consid-
COMPLETED hull minus decking shows in- erable strain, it is well to fiberglass this
terior structural members, curve of bottom. board as well as the centerboard trunk.
102 Mechanix Illustrated
March, 103
104 Mechanix Illustrated
 glassed, or the boat may be painted after
Unsinkable Uniboat completion. I used Flexion, from Flex-
ion Polymer Coatings, Ft. Pierce, Fla.
This white paint requires universal pig-
ment for colors but adheres well and
requires no undercoating.
Deck hardware is next installed as
shown in the plans. All fittings, as well
as the self-locking kick-up rudder hard-
ware, are available through Wilcox-
Crittenden outlets. Tiller handle.and the
cockpit trim are cut from a 14' length of
1-1/8x3" cedar, the cockpit trim installed
and the tiller rounded.
Spars consist of a wood mast and alu-
minum sail frame. Use 1-5/8" round oak
for the mast. Fir is not strong enough.
The aluminum 1" tubing is 14' long for
the gaff and 13' for the boom.
The sail as shown, and available from
Hard Sails, Islip, New York, is the right
size for beginners and will provide a
good turn of speed. Expert sailors can
CENTERBOARD well must be carefully increase this sail area by 50 percent be-
made, all surfaces luted to prevent leaks. cause of the innate stability of the craft.
Trailering the craft is easy. Add lift-
ing handles bow and stern if the boat
To form the decking, 4'x6' planking will be carried cartop. An outboard
sheets are laid across the hull. Since the plank or bracket is also easy to install
craft is six feet wide, the sections fit on the transom, and worthwhile. When
without waste. Joints are butted as be- the wind drops, a light 3-1/2 hp aircooled
fore, with toothpicks holding the angled Chrysler outboard has been found to
overlap together until the epoxy hard- push her along at a respectable 8 miles
ens. Sections must be cut out, of course, an hour. •
for the cockpit, centerboard well and
mast. A 3" wide glass cloth tape is ap-
plied with epoxy resin over all seams.
When the epoxy has hardened, lift the
decking carefully and place it on a flat
surface, propped up so that it can hold
its slightly curved shape. Apply resin
and fiberglass cloth to the underside of
the deck.
Once the deck undercoating has hard-
ened, apply epoxy resin to all battens
and ribs and replace the deck in posi-
tion. Then nail it securely to all framing
and battens. Glass cloth and polyester
resin are applied over the complete
decking. When it has hardened into
place, the glass is carefully trimmed
around the cockpit and edges. These
edges are then bound with 3" glass cloth
tape and epoxied completely around the
edge of the deck and the cockpit.
Color can be mixed in with the resin
when the hull and decking are fiber-
Mechanix Illustrated