Releasable knot to attach blocking device in slackline setup

Question

Main specification

I need a knot to attach the self blocking non-releasable part of the pulley used to my slackline setup with a small piece of cord. Therefore the knot should be secure for high loads and against accidental releasing. On the other hand it needs to be releasable safely (without fingers getting crushed) while the slackline is still under tension. The release does not have to be controlled however, it is allowed to release fully immediately.

Use Case

I try to find a suitable minimal slackline setup and the method explained here has too much friction for my use case. So I went for a slightly less minimal variant where I use a cord (static 6mm) to setup a pulley. So I needed a one-directional blocking knot/device for this cord instead of the flat webbing. All methods I know from climbing are not releasable under tension (except Grigri which does not block with the 6mm at all and is not really minimal).

Alternative

If you happen to know a knot that blocks in one direction, is releasable under tension and is "minimal" (i.e. using two general purpose climbing carabiners would be fine, using a dedicated device not), that would also solve my problem.

Illustration

As always when I try to explain something, it gets messy and hard to understand. I hope the following schematic drawing can shed some light. Please excuse my poor writing and drawing skills.

Answer 1

This is a community wiki to add appropriate knots that will work since there will be several.

• Munter Mule

• Tensionless Hitch - Assuming you have a long tail after tensioning your line this "no knot" method may work for you.

• Radium Release Hitch - This incorporates a munter but also builds in a 3:1 load-lifting system, so unlike a munter it's suitable for "rescue loads".

• The Mariner's Hitch is releasable under load, but may slip a bit when weighted. This might not be what you want if maintaining tension is desired.

• The Super Munter tie-off - Builds on the munter to provide increased friction for heavier loads. (Scroll further down the linked page for information.) Alternatively, a mule knot with a Super Munter may work.