SailCloth
Good Day Gentlemen,I hope you don't mind my interjection, as I have hosted a guest forum on this site in the past.As was stated previously, Not all sailcloth is created equal, and not all fabrics suit all applications. That being said, let me address Pauls initial inquiry.340 Square weave is produced by Dimension/Polyant Sailcloth. It is an 8oz Dacron, as the name implies, a square weave. This fabric incorporates a Rip Stop pattern of slightly heavier yarns than the rest of the fabric. It is a very good Balanced weave cloth, and is used in applications that call for a very stabile balanced weave fabric. Because of the weave, it is also one of the more costly Dacrons available. However, for a cruising Main, it would not be my recommendation. I would recommend a more Fill oriented fabric in a crosscut design. The Fill direction is in the width of the fabric, Warp is run the length of the fabric. So using a fabric that has more yarns in the Fill, which in a crosscut main will be up the leech, will create a stronger more shape retentive sail than the same weight balanced fabric.As to Allens comment, if you are racing, then Kevlar is a great choice for the reasons you point out. However, Kevlar is not as durable as Dacron, nor as tolerant of UV exposure. Kevlar is not what I would normally recommend for a Cruiser. There are however, alternatives to both Dacron and Kevlar for the more performance oriented Cruiser/Racer.Good Sailing,Tim Stodola