Releasable anchor
Contents
Introduction
A releasable anchor (different from a releasable rigging) is a system where rigging and/or anchor material can be dropped to the bottom of the rappel without pulling down at least the rappel length worth of rope or retrieval cord. The page describes that meaning. Most, but not all, retrievable systems are also releasable.
Uses
In addition to generally (but not always) having all the advantages of retrievable systems, releasable systems can reduce rope grooves and sometimes make retrieval easier. Releasable systems are also the only systems which are capable of allowing rope retrieval when both the rappel and pull sides have knots in them.
Dangers
By definition, releasable systems have some mechanism that drops material to the bottom of the rappel in response to a relatively small amount of force under certain circumstances. If this mechanism is accidentally triggered while someone is on rappel, he will fall to the ground likely resulting in serious injury. Most releasable systems have some kind of safety mechanism that attempts to prevent release while someone is on rappel; this often takes the form of making release very difficult while there is weight on the rappel rope in the rigging. However, this is not completely safe because the rappel rope can be accidentally unloaded when the rappeller reaches a shelf or has a large bounce. Therefore, releasable systems are inherently more dangerous than non-releasable systems.
Greater tension on the pull side is what leads to increasing danger with a releasable system. Longer drops require a larger amount of rope to hang from the releasable system, which biases the system closer to releasing prematurely. In the same way, a pull rope/cord in flowing water also increases tension and danger of premature release.
Fully-releasable systems
- CEM knot
- FiddleStick/Smooth Operator
- The Buckle in ghost mode
Partially-releasable systems
- The Buckle in extension mode
- Pin block
Releasable anchors
Use in flowing water
The use of a releasable system in flowing water can be dangerous because absorption of water by the pull line and the force of the flowing water on the pull line can put extra tension on the release mechanism, causing it to be more likely to release prematurely. A few things may be done to mitigate (but not eliminate) this danger:
- Choose a relatively hydrophobic pull line such as polyester or AmSteel
- Redirect the pull line outside the water flow (this may be done on an earlier rappel when the releasable system is locked against releasing)
- Load the releasable system with one or more rappels while locked against releasing to tighten the system against release for LAPAR (though this may not be possible or helpful for some specific releasable systems)
