Nix Wax Soft Shell Proof. There is also a rope-specific version, Nikwax Rope Proof, but is somewhat less available and not very different. Used by ice climbers and winter mountaineers, it reduces water absorption and thus prevents line freezing (life-threatening, since a frozen rope is useless), reduces friction through carabiners, and helps the rope slide more easily over rough surfaces. It reduces the loose in strength every rope experiences when wet. Climbing ropes often come with a "dry" treatment to prevent freezing, and this product is meant to maintain that treatment. For sailors purposes, it replaces the internal lubricants, washes out the lime and discourages re-deposition, makes the line run through blocks more smoothly, and reduces water up-take resulting in lighter sheets. Not quite like new, but much better. The effect lasts for 1-2 seasons, depending on use.
When washing a rope....
- Never wash a double braid less than 1-year old. Damage can result - the inner braid can actually come through the outer braid. This is not a danger after 1-year.
- Tie the rope in a loose daisy chain. Wash according to treatment instruction.
- Air dry while still daisy-chained; it will dry more quickly than in a pile or coiled.
Brand spanking new dockline (New England Ropes) after 10 minutes in a machine on the gentle cycle, inside a pillow case! The herniations repeat every 1-2 feet. After a full cycle, as much as 4 inches of core was exposed. Ouch.
I've treated ice climbing ropes many times and balky mainsheets few times. The rope will feel slightly slippery for just a little while, like a new line, but this passes quickly with use. I assure you, rock climbers do not tolerate slippery ropes.