Use these only when you really need them, not as a matter of course, because they have a bad habit of causing trouble, especially if rigged through a ring. If the ring is lying on top of the quay, lead the end of the warp up through it, then release this end when you’re ready and pull in the other one. Do the same if it’s hanging on the quay wall, so that the warp lifts the ring away from the quay as it is pulled. It’s a small thing, but it might make the difference between jamming and running clear.