If a person is having a dacron sail built,is there an advantage to having it built as a tri or bi or crosscut sail. It seems I read that a crosscut pattern was as good as it gets using dacron. Is this true?
Dacron Sails
- Thread starter Ron10127
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Not so.....
A cross-cut has more 'adjustability' inbuilt .... meaning the shape of the sail will better change with the application of more or less outhaul and HALYARD/cunningham tension. A cross cut is more vulnerable to seam damage .... and when the UV ultimatily weakens the polyester stitching... the seams can easily break and the panels will separate (beginning at the broken stitching usually on the leech). A radial cut is stronger, less 'shapable' and doesnt suffer the vulnerability of seam stress as most of the 'edges' are essentially all cloth instead of sewn/stitched panels (on the 'edges'). PLUS .... for roller furled sails one can apply heavier weight cloth at the leech and lighter weight (easier to roll) at the luff which will enhance roller-reefing performance .... as when reefed in the higher wind ranges only the heavier weight cloth is exposed (the lighter weight cloth on the luff rolled-up on the furling foil). A radial cut is labor intensive and therefore more costly .... but is more stable and longer lasting than a cross cut. BTW ... when ordering new sail that have 'boltropes' at the luff ask the sailmake to add extra length of boltrope to make it easier to 'ease' the boltrope later on when the sail ages. If you dont have the extra boltrope added when building the sail it becomes expensive to change the boltrope for new. With extra boltrope all the sailmaker has to do is cut a few handstitches, slide the boltrope a few inches and resew .... and that will restore 90% of the shape to an 'old' dacron sail.
A cross-cut has more 'adjustability' inbuilt .... meaning the shape of the sail will better change with the application of more or less outhaul and HALYARD/cunningham tension. A cross cut is more vulnerable to seam damage .... and when the UV ultimatily weakens the polyester stitching... the seams can easily break and the panels will separate (beginning at the broken stitching usually on the leech). A radial cut is stronger, less 'shapable' and doesnt suffer the vulnerability of seam stress as most of the 'edges' are essentially all cloth instead of sewn/stitched panels (on the 'edges'). PLUS .... for roller furled sails one can apply heavier weight cloth at the leech and lighter weight (easier to roll) at the luff which will enhance roller-reefing performance .... as when reefed in the higher wind ranges only the heavier weight cloth is exposed (the lighter weight cloth on the luff rolled-up on the furling foil). A radial cut is labor intensive and therefore more costly .... but is more stable and longer lasting than a cross cut. BTW ... when ordering new sail that have 'boltropes' at the luff ask the sailmake to add extra length of boltrope to make it easier to 'ease' the boltrope later on when the sail ages. If you dont have the extra boltrope added when building the sail it becomes expensive to change the boltrope for new. With extra boltrope all the sailmaker has to do is cut a few handstitches, slide the boltrope a few inches and resew .... and that will restore 90% of the shape to an 'old' dacron sail.
Dacron™ is Polyester
Dacron™ is DuPont’s trade name for its type 52 high modulus polyester fiber made specifically for sailcloth. Crosscut, or panel cuts are mainly used in Dacron™ sail construction because it is a woven cloth and has much better stretch properties along the fill fibers than it does along the warp fiber axis. Panel cuts are not inherently weaker than radials - they are merely taking advantage of the cloth’s properties. If anything, radial cuts are weaker due to higher number of seams. Because the fill yarns dimension is defined on how wide the weaving machine is, it may be difficult to align it along the load line of a radial sail. Besides, there would be a large amount of waste material in the cutting process which would be passed along to the consumer. I personally wouldn't recommend using Dacron™ in a radial construction. But, there is away to get around all of this and still have a properly constructed radial sail made with Dacron™. Not all Dacron™ is made the same. You can buy higher modulus Dacron (which can run about three times the cost of average cloth.) You need to be purchasing fabric with a high Denier per inch count, higher modulus, good elongation spec and a wrap to weave ratio that approximates the sails aspect ratio. I ran the numbers when purchasing sails a couple of years ago and found out that to get 363 square foot genoa, using a very high modulus Dacron™ in a radial cut, it was going to run me about the same price as Kevlar™. And due to the high denier count (smaller thread diameter is inherently weaker), had about the same life span as the aramid. As all sail makers get their Dacron™ from DuPont, and make all their money from sewing, you need to be careful in making sure they are not using cloth with an inferior spec just so they can run up the bill on you.
Dacron™ is DuPont’s trade name for its type 52 high modulus polyester fiber made specifically for sailcloth. Crosscut, or panel cuts are mainly used in Dacron™ sail construction because it is a woven cloth and has much better stretch properties along the fill fibers than it does along the warp fiber axis. Panel cuts are not inherently weaker than radials - they are merely taking advantage of the cloth’s properties. If anything, radial cuts are weaker due to higher number of seams. Because the fill yarns dimension is defined on how wide the weaving machine is, it may be difficult to align it along the load line of a radial sail. Besides, there would be a large amount of waste material in the cutting process which would be passed along to the consumer. I personally wouldn't recommend using Dacron™ in a radial construction. But, there is away to get around all of this and still have a properly constructed radial sail made with Dacron™. Not all Dacron™ is made the same. You can buy higher modulus Dacron (which can run about three times the cost of average cloth.) You need to be purchasing fabric with a high Denier per inch count, higher modulus, good elongation spec and a wrap to weave ratio that approximates the sails aspect ratio. I ran the numbers when purchasing sails a couple of years ago and found out that to get 363 square foot genoa, using a very high modulus Dacron™ in a radial cut, it was going to run me about the same price as Kevlar™. And due to the high denier count (smaller thread diameter is inherently weaker), had about the same life span as the aramid. As all sail makers get their Dacron™ from DuPont, and make all their money from sewing, you need to be careful in making sure they are not using cloth with an inferior spec just so they can run up the bill on you.
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