Here's two shots. The double sheave is the aft side of the mast. Single sheave is the forward part.
02-14-2012 12:41 PM
There's an inner groove in the sheave that is supposed to accommodate the wire. It's u-shaped and about 1/4 inch across. The outer grove is for the rope. I would guess that, as the halyard transitioned from rope to wire, it got caught on the edge from the large groove to the inset smaller groove. When we took our sheaves out, they were all cut-up at this transition point. Also, it looked as if the wire had jumped its groove a few times and chewed up the outer groove. Either way, lots of sharp edges.
Another possibility: the clearance between the sheave and the box that holds it is very small. If you have a bulky bit of tape, it could have jammed as it exited the sheave box.
As far as obstructions inside the mast: You have wires for your gear into the masthead. You have 3 cross bars where the shrouds connect to the mast. It's possible that something got caught on a cross guard.
FWIW, we took our sheaves to a machine shop, had them route out the inset groove and went to all-rope halyards for about $90. Plus, that allowed them the put in a new oiled brass bearing; this made for worlds better action and easier pulling.
Our boat: 1981 C&C 32
01-09-2012 06:09 PM
C&C 32 main halyard sheave
I have a 1980 C&C 32 and i tried to replace the wire main halyard this weekend. I wipped the new 5/16 line to the old 5/32 wire and taped it up and pulled to the top. The new line made it over the sheave and then in behind, but then stopped and would not go any further. Upon pulling it back down i noticed that the tape over the wire was all chewed up but the tape around the rope was fine. So my question is, is there something behind the sheave like a hole or some sort of metal gap that only 5/32 wire can pass through. Any pics of the 32 mast head or advice would be helpful. Thanks