Abstract
PBO delivers low stretch, high strength, but degrades rapidly in outdoor light. Carbon also has low stretch and high strength but not quite as high as PBO. Carbon does not degrade in UV but is more brittle in flexing than PBO. Both of these fibers are in the early stages of development as sail materials. Both show great promise for the future if development continues. For a number of reasons, some racing classes and organizations have restricted the use of one or both of these fibers in sails. While restricting both may be appropriate in some classes, picking one in favor of the other seems inappropriate and surely will stifle development that could lead to better sail materials in the near future.