Ebb, sorry didn't see that you moved the discussion over here until tonight. Like that knot tying animation site, thanks.

As I understand one of the Klemheist knots is for a stirrup and the other is for a climbing harness. One would put their weight onto the stirrup knot and slide the climbing harness knot up the mast. Then transfer ones weight to hanging from the climbing harness knot and pulling up and raising the height of the stirrup knot. Up the mast you go. To get around the spreaders and other obstructions one would need to tie more stirrup and harness knots above the obstacles and transfer to them as one would ascend and descend. Flat nylon webbing I believe grips a smooth aluminum mast better than a round rope but I'd bet they'd both work.

I need to go up and attach a spinnaker halyard swivel block and windex sometime this winter.