My 6.0NA and a couple of I20's I've seen have some serious difficulty getting the sail to the top - I never considered that it might be the halyard rubbing the sail. I always figured it was the bolt rope bunching up a little but that makes a lot of sense (especially since it only starts getting tough beyond halfway up). Hmmm...yeah one of the slippery high tech chords might do the trick! (like Amsteel Blue or sim). Cool.