Main halyard friction with prebent mast

We use a 3mm spectra rope as halyard for the main, and have no problems with raising the main with lots of pre-bend in the mast.

How thick is your halyard ?
I have seen some people use 5 mm halyards, without any significant trouble tough.

If you have drilled holes in the groove, for the attachment of the spi-block. Are the knots in there rubbing against the sail ?

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.

I had amsteel in there before, and it worked better. The problem is that amsteel does not have a protective cover, and chafes away rather quickly. I am using the standard New England ropes 4mm stuff and it becomes umoveable when it rubs the boltrope after the sail is raised above the spreader.

I also am running 3mm spectra on my Marstrom mast without a problem.... give 3mm a go and see how it is.

I have seen problems raising sails on prebent masts, The worst lines are the ones with hard outer braids. However, most of the time when the sail locks up the problem is something on the leading edge of the bolt rope. Either a hard point or it's worn out and allows the halyard to get caught between the bolt rope and the mast.

I settled on Yale Lite or Sampson ultralite in 4 or 5mm as the best compromise for cost/performance/life for halyards. The slippery polypro outer cover really helps raising the sail.