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post #3 of Old 02-22-2013
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Re: Mainsail Design Question...

Radial sails are used with laminate cloths. The panels are oriented so that the fibres in the laminate are aligned with the load path. That allows them to use cloth that has most of it's strength in one direction. The result is a much lighter sail.

Woven cloths like Dacron have more uniform strength in both the warp and fill directions, therefore they do not need to be aligned with the load paths on the sail. Instead they just make panels the width of the roll of cloth. (The width is the "fill" part of the weave and has a higher thread count than the length, or "warp" of the roll so it is a bit stronger in that direction) Because dacron is stretchy, it requires more fibres to resist the stretch, making the cloth much heavier than laminates. Cross cut is far easier and therefore cheaper to build.

The crosscut dacron sail will be cheaper and more durable than a radial laminate sail, but it will also be much heavier. Dacron is also easier to repair with basic tools and materials.

Laminates sails are much lighter and hold their shape better but are more expensive and won't last as long. If you don't race you probably don't need laminate. Unless of course you have lots of money and love the look of plastic sails!

I don't know why any sailmaker would make a radial sail out of Dacron, it seems to be pointless to me. I suppose they could align the fill with more precise load paths to gain a bit of strength and stretch resistance but I would guess it would be an incremental benefit for a much greater cost.

1979 Santana 30 Tall Rig

Last edited by SchockT; 02-22-2013 at 11:24 PM.
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