Originally Posted by xort
A thin messenger line will suffice...but thin line can jump the sheave and wedge next to it, jamming. Either make darn sure you keep it tight or use a thicker messenger.
Its a good idea to stitch lines together with some whipping when pulling one line thru with another. Tape-only works until it doesn't!
Agree that a thin messenger can jump a sheave, but keeping the messenger-halyard pair under tension will likely prevent that. In 16 years I've never had the 1/8" messengers jump a sheave.
I do agree that taping the messenger to the halyard is a recipe for disaster. I've used the tape method for running wires in a cableway, as it provides for a "fair" transition, but it is a risky technique and doesn't work well with sharp bends.