Below
are some frequently asked questions about the fabrics chosen by
Bruce Finlay Sails, and responses which may assist you in your
selection process. |
 |
| Q. |
What
difference does the sailcloth make to me? |
| A. |
Bruce
Finlay Sails will design the best shape into your sail but how well
that shape is retained in different wind strengths is down to the
cloth. Obviously good shape retention is important for racing
but increasingly cruising sailors are realising the benefits: less
heeling, better pointing and easier boat handling. Quality
cloth also lasts longer making a little extra for better laminated
or woven fabric a sound investment. |
| Q. |
Laminated
or woven? What's the difference? |
| A. |
Since
sailing began woven sailcloth has been made on a loom with warp
yarns being rocked up and down around fill yarns although the technology
we use today is very leading edge. Most wovens are made of
polyester (also called Dacron) that was introduced by Bainbridge
as a replacement for cotton in the 50's. Wovens are very durable
making them ideal for cruising sails. |
| |
Laminates
are made by bonding together layers of different materials to form
a sandwich. A simple laminate will consist of an open scrim
of fibres with a layer of film bonded to each side. The film
stops air blowing through the laminate while the load is taken by
the scrim. Laminates are far more efficient than wovens as
the fibres have no crimp. |
| Q. |
What
is Crimp? |
| A. |
Crimp
in a yarn after weaving.
When we weave a cloth the yarns have to snake over-and under each
other. This is called crimp. When the cloth is loaded
these yarns straighten resulting in 'initial stretch'.
The scrim in our laminates is 'formed' and not woven. This
process bonds flat ribbons of fibre into a lattice. No weaving,
no crimp, less stretch on the threadline. |
| Q. |
Should
my sail be crosscut or radial? |
| A. |
This
depends on the cloth. In the weaving process warp fibres running
along the cloth are bent round the fill fibres that run across the
cloth. Fill fibres therefore have less crimp so a woven cloth
stretches less across the roll than along the roll. We take
advantage of this by using larger (sometimes 400% larger) fill yarns
than warp yarns. |
| |
So
woven cloth should be used in crosscut sails where most of the load
is across the cloth. Some Sailmakers will offer radial woven sails
using cloth with large warp yarns. This works well for smaller
sails but read on to find out about the ultimate radial cruising
cloth.
In a laminate the scrim is fed into the laminator under tension
so further reducing initial stretch on the warp. Again we
take advantage of this by using more fibre in the warp than the
fill. So laminates should always be used for radial cut sails
where the load travels along the length of the cloth. |
| Q. |
Sounds
good, but not all the load can exactly follow the yarns! |
| A. |
Bruce
Finlay Sails will know how the loads in your sail radiates out from
the corners but with so many variables a fair percentage of the
stress is 'off threadline'. To reduce the effects of this
we try to minimise bias (diagonal) stretch. In a woven we
do this by locking the warp and fill yams together so bias loads
cannot move the weave. This is achieved by making the weave
as tight as possible by compacting and heat shrinking. Hold
your handkerchief up to the window and compare the weave to a 1
100 X magnified piece of our cloth. To further stabilise the
bias we then impregnate our cloth with a resin finish that chemically
bonds the warp and fill together. For dinghies and small keelboats
we also coat our fabrics with resin to make a super hard but very
stable cloth. We call this NYT.
Our latest DIAX laminates use a 45-degree diagonal scrim to resist
bias loads and, just like a road bridge, form a truss that locks
together the warp and fill yarns. In most other laminates
bias load is born by the film which easily becomes over stressed
and then deforms. Using a diagonal fibre helps our laminates
to last longer and lock in sail shape. |
| Q. |
So,
its cross cut woven for cruising and radial laminates for racing,
right? |
| A. |
Wrong!
One of the fastest growing markets for us is cruising laminates.
These are based on our race products so are just as strong, but
have a light woven fabric bonded to both sides to give them the
durability of a woven. We have made over 250,000 meters of
this cloth and firmly believe it is the best cruising cloth available
today. Unfortunately many people still only associate laminates
with high-end race sails with limited durability. For more
information see the Cruising Laminates
page. |
| Q. |
What
about my spinnaker? |
| A. |
Most
spinnakers are made from woven nylon because it has good tear strength.
A few years ago polyester spinnaker fabrics were fashionable
but these are only suitable for specialist applications, so we would
not recommend them. Nylons come in different generic families
ranging from 2.2oz down to 0.4oz but be careful, these numbers do
not directly relate to the cloth weight. See the Spinnaker
Fabrics page for a full explanation. |
| |
Nylons
can also be coated or impregnated and warp or fill orientated, but
the important thing is the relationship between stretch, tear strength
and weight. Heavier nylons do not always have lower stretch
and better tear strength as a high quality light fabric can easily
outperform heavy low quality products. Our new ARX products
have just proved this with lighter fabrics having similar properties
to other's heavier styles. |
