Originally Posted by DougSabbag
They are Barlow 32 self tailing / 2 speed.
It seems 3/4" (19mm) is the largest line diameter recommended for the 32. Some say you should not exceed one size smaller than the max on a self-tailer.
Too large a diameter line, particularly one that would stretch and reduce in diameter under load like Sta-Set, would then expand as it exited the self-tailer up against the stripper. Could become too big for the stripper to deal with. Some suggest that the max line should be no larger than one size below the max.
7/8" Sta-Set would also be extraordinarily heavy, particularly when wet. If the load on your sails requires that large of a line, I would consider something with a bit more performance, even perhaps Sta-Set X. The added strength would allow for a smaller line size, less weight on the clew and better performance in the winch.
I'm a bit surprised that your boat would require lines quite that big. I would even think 5/8" would be more than enough in Sta-Set, let alone a higher performance line.