Fabric decks, spray shields, and cockpit tents are comfortable, space saving, and lightweight. They can significantly increase your living space, make a
rough passage a bit safer and dryer, or
turn sleeping aboard on a cold, wet night
into a pleasant experience.
Fabric structures should be as low as
possible to keep windage to a minimum.
Well designed fabric foredecks and small
shelters may sometimes be left in place
when under way. If you want to, you can
sew plastic windows, vent flaps, and
mosquito netting into the fabric.
A wide variety of fabric types, weights,
and colors is available. Quality is related
to price — you get what you pay for. Some
fabrics stretch, fade, or wear more than
others, and even shock cords may not be
able to take up the slack of cheap fabric or
wet, untreated canvas. We've found heavy-weight fabric advantageous in
building these structures. And when in
doubt as to the best fabric weight for a
specific application, we call our supplier
and ask his opinion.
No matter how it's designed or which
fabric is used, a structure that flaps, sags,
or leaks is as bad as none at all. A good
support system is the key to success.
Every boat offers different options for securing and supporting fabric structures.
Battens, ridgepoles, upright poles, and
shock cords can provide tension and
support. Fabric also needs slope to effectively shed moisture. Even a heavy dew
will fill pockets in a flat and loose-fitting
piece of fabric. And a bit of flex is necessary because a stiff and unyielding fabric
structure will strain lines, bend supports,
and stretch fabric.
Narrow boats with small spray shields
don't usually pose difficult design problems, but wide hulls often require a more
complex structure to provide proper
Options for framing and support of a
fabric structure are limited only by the
imagination. A ridgepole is the simplest
support and does a creditable job (Fig. 1).
Ridgepoles usually run fore and aft down
the centerline, although they can also be
positioned on one side of a hull for a
"lean-to" shelter. A boom is the classic
ridgepole, but we've also used a 10-foot
sculling oar supported by a forward tripod and a notch in the transom.
Halyards attached to sewn-in D-rings
provide prime, adjustable overhead support (Fig. 2). However, they offer such
strong leverage that you must be careful
not to tear the whole affair off the hull and
hoist it to the masthead. When using halyards, you may have to snub the line to
the mast to quiet flapping in a breeze.
Telescoping supports may also be situated inside the structure, braced up from
thwarts or the sole (Fig. 3). I made three
good aluminum supports from an old tripod. I adjust them by tightening two
knurled knobs on each leg. These supports can be placed in a grommet or reinforced patch in the fabric.
Battens & Beams
Support battens may be rigged under
or above the fabric or sewn in between
layers (Fig. 4). One method for supporting fabric is an external batten much like a
mountain tent (Fig. 5). All you need is a
pocket at either end for the batten and
small loops or ties along the rest of the
batten length. If these ties are small diameter shock cord, they can be adjusted
to keep the fabric at exactly the correct
tension to shed water and wind. This
structure only requires tie-downs at corners and along the edges to be self
You may find fiberglass, plastic, or
aluminum battens that work well and do
not require any finishing, but wood battens are the best looking. They finish
nicely and bend to a uniform curve.
Hardwoods like ash or mahogany or
straight-grained softwoods like spruce
and fir make fine battens. All wood battens should be well sealed to keep their
strength, since soaked wood will lose
much of its stiffness and may snap in response to a gust of wind or a sudden load.
Three coats of epoxy, followed by varnish
if exposed to sunlight, are best for sealing.
Wood battens made for supporting a
fabric structure usually need to be wider
than thick to prevent twisting and make
rigging easier. A successful size for us has
been 1/4 inch by 1-1/2-inches, but each application seems to require some experimentation as to best size and shape. Start
big and keep shaving the batten with a
block plane until it bends easily to the
shape you want. Keep in mind that laminated and epoxy-sealed battens will be
stiffer than plain, unfinished battens, but
they will also retain uniform strength
under all weather conditions.
You may wish to drill small holes in the
ends of the battens to provide a tie off
point. Straight battens maybe slipped out
of the batten pockets and rolled in the
fabric, allowing a large assembly to be
stored easily in a small place, in many
fabric structures, the battens are different
lengths, and having each batten labeled
makes it easier to rig. If fhe batten pockels
start to wear, consider wrapping the batten ends in duct tape.
Fabric decks can be supported with
beams that fit into sockets or notches in
the gunwale or deck structure (Fig. 6);
Sometimes these beams can be permanent and the fabric covering removed or
left in place according to the weather. By
laminating, you can make the beams to
almost any shape for a small boat.