BACKGROUND
ON DACRON
Specific styles of woven polyester are commonly named by weight, such
as "6.1 oz. dacron" or "8.3 oz. dacron". It should be understood that
these designations are names and not necessarily actual weights. There
is a considerable variation, both up and down, between the actual weight
and the named weight assigned to a particular fabric by the manufacturer.
This variation is inherent in the manufacturing process, and is not an
attempt at deception. Nevertheless, with these fabrics, the actual weight
is a reasonably reliable guide as to both its strength and its cost.
The unit of weight in the United States is ounces per "sailmaker's yard,"
which is 36" by 28.5". The British use ounces per square yard, and Continental
Europe uses grams per square meter. Thus 1 oz. American equals 1.26 oz.
British and 42.8 grams per square meter.
Woven polyester can vary from a balanced weave where the yarns have equal
strength in both warp and fill directions to an unbalanced weave whose
strength is concentrated in either the warp or fill direction. An unbalanced
weave that has more strength in the fill direction is called "Fill-Oriented."
Cross-cut sails use fill-oriented dacrons because the panels are perpendicular
to the leech of the sail. Since the leech of the sail carries the greatest
load, the stronger fill threads line up to carry the leech loads. |