TECHNICAL
NOVEMBER 2015 http://www.yachtingmonthly.com 65The cheapest way of producing a
sail is using the standard weave
process, scrimping on quality
yarns but doubling-up around
the clew and tack to compensate.
The weave process is often
economised for speed and not
compacted tightly. Such a sail will
stretch very quickly and may be
less efficient by the end of just
one season.
That doesn’t mean that woven
sails can’t be good, though.A well-woven sail using high-
quality polyester will still stretch
eventually, but it will take far
longer, performing well for many
seasons of sailing.How it’s made
Once a large sheet of sailcloth has
been woven, it might be cooked,
as some polyesters shrink when
heated, which makes for an even
tighter fabric. Melamine is then
added, which adds rigidity to
the material, stopping it from
stretching. The material will be
cut up and re-stitched by the
sailmaker to create the sail.What it’s made of
Polyester. Cloth with strong,
lower denier yarns commands
a higher price. As mentioned
before, some yarns are designed
to shrink when heated, so are
cooked to make a tight weave.Best for
Cruising sailors who are on a tight
budget, or really aren’t interested
in improving the upwind
performance of their boat.Standard polyester
sails are often
referred to as
Dacron – a brand
name of a DuPont.
Regardless, it
has stuck and
sailmakers refer to
polyester weaves
as Dacron for ease
of understanding.
The material is
polyester, but the
tenacity, thickness and quality all
vary between brands.
Compared to cotton, polyester
fibres have a lower denier – the
weight of a 9,000m fibre in
grams. A cotton staple – the
length of a standard fibre – is
short, so each cotton staple is
spun with thousands of others
to create a thread. Polyester
requires less staples in a single
yarn, so they can be thinner
without losing strength.
The line of yarn running the
length the roll of material is
known as the warp, and the
yarn running across it is the fill.The polyester warp yarns are set
up on a large loom – alternating
between upper and lower yarns- and packed together tightly, far
tighter than other woven fabric
for clothes. The upper set of warp
yards are lifted and a fill yarn is
fired from one side of the loom
to the other. The fill yarn is then
compacted against the cloth and
the lower yarns are raised and
the raised yarns lowered and the
process repeats.
Under high pressure the
crimped yarn, which weaves over
one warp yarn and under the
other, will be pulled straight.
Bias is another form of stretch,Woven sails
Dacron and its derivatives
PROS
■ Cheap to buy
■ Durable – can last
for 20 years or more
■ Easy to repairDacron sails can last for many
seasons, but over time the
material stretchesPolyester is the most
common of sail
materials because
it’s cheap and can
last a long timeCONS
■ Prone to stretching
■ The sail shape won’t
last long
■ Vulnerable to tearingPHOTO: GRAHAM SNOOK.COMPHOTO: GRAHAM SNOOK.COMPHOTO: GRAHAM SNOOK.COMbut a far bigger problem in
practice. Pressure in a diagonal
direction to the fill and warp
causes movement in the sail
shape. After just one season of
stretching, pulling and folding,
the sails will not be as efficient,
with significant shape changes
affecting performance.ABOVE: A brand new
Dacron genoa
RIGHT: Dacron is
popular for cross cut
sails as an economical
use of sail clothPHOTO LEFT: GREG GOULDING