Dyneema has been tested by several companies that provide it to the 4x4 market, and find it’s knotted strength to be 80% of it’s original. Those are the figures posted at any rate. One of those companies, Viking Offroad is very, very particular about posting proper load limits for the equipment they sell, and does it’s own testing to assure that. They are also one of the few that lists products by the minimum breaking strength acheived, and that’s the only way it should be done IMO. With no set standards for the 4x4 market on equipment like there is for overhead hoisting, it’s a very gray area on ratings.
Indeed, using a pulley halves the line speed and doubles the amount of force applied to the moving object. That’s a basic mechanical advantage of 2:1, and while that can be handy for a seriously stuck situation, I use the pulley more frequently to keep the winch operating properly on the first wrap. Re-rigging is frequently required if the length of pull exceeds the room on the spool. Dyneema tends to melt if cleeved between wraps under high tension. It’s expensive, so taking care of the line is an economical decision as well as a safety issue.
The next time I shorten a line with the sheepshank and pins, I’ll try to remember to mark the knots with a piece of tape or something. I honestly can’t tell you if it creeps or not - I’m never close enough to watch it under tension, and never will be from a safety stand point. I’ve got a GoPro, I guess I could do a test pull with that capturing the line and see what actually happens.
Perhaps I should add a second half hitch to the sheepshank to lock it as well.
Mark