Mike, That would be - 1) improperly stored - as in 'spooled' line. 2) improperly used - as in a twisted manner. 3) damaged cordage - core pulled from cover. 4) inferior quality control. cheap stuff. I think there may be a couple of other reasons - but check with the supplier for a full explanation. GO In a message dated 5/10/2009 6:02:26 P.M. US Mountain Standard Time, carterconsultants@comcast.net writes: All, I'd like to take advantage of this discussion of halyards and sheets to pose a related question: last week I got my 15 into the water for the first time and, over the course of two days, sustained two ruptures of my mainsheet. I thought I might be able to whip one back into submission, but the larger of the two completely blew out the outer braid to form what now looks like a big, ugly knot. The sheet is original equipment and had never been stressed until last week. What do you think? Was it operator error, some bad braid, or ?? BTW, I am in love with this boat. She was stable, nimble and just plain good fun in light to moderate winds. Thanks to all for the lively and informative discussions. I don't post much (or haven't until now), but the collective wisdom of the group has been invaluable to me. Mike La Pequenita, #654 _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats Remember, there is no privacy on the Internet! **************The Average US Credit Score is 692. See Yours in Just 2 Easy Steps! (http://pr.atwola.com/promoclk/100126575x1222376999x1201454299/aol?redir=http... ay51009AvgfooterNO62)