Dyneema truckers hitch shroud

[Essington]

The deal with a whoopie sling is that the tail is fed back through the standing part to create the adjustable eye. What this does is guarantees that the sling stays locked while it is under tension.

What you are using here is what I call a Textile brake. where the standing part is fed through the tail Or even a completely separate line. The difference from a whoopie is that the brake can be adjusted while the main line is under tension. This might be convenient in some situations ...

1) It doesn't create a stress riser (weak spot) where the brake enters / exits the loaded line.
2) Sometimes it is handy to adjust something along a loaded line.

However the nature of a brake like this is that ... well ... it can be adjusted while things are under load due to the tail of the chinese finger trap being free (unloaded). Even with bungee to tension the tail to prevent unwanted movement, an errant sheet or simply rubbing against it while walking past could adjust your length (in the case of a shroud, that could have catastrophic results).

So, I'd be really hesitant to use such a construction on a mission critical load.

A regular style whoopie sling could probably work fine for a trap adjuster on a cat (albeit more fiddly than a normal jam cleat), but a textile brake like this would dump you in the water the first time the tail of one of your lines went over the top of the trap wire.