Block
In canyoneering, blocks are applied to rope so that the rope can only pass through an anchor ring in one direction. This makes the use of single rope technique possible.
Contents
Construction[edit]
A block can be constructed from anything available that will create an obstruction attached to the rope that is too small to pass through the anchoring ring. Among the most common materials used are the rope itself (knot block), a carabiner ('biner block), and a figure 8 (figure 8 block).
<needed: diagram showing block>
Usage[edit]
After the rope length is set, a block is applied to the bag side of the rope allowing canyoneers to rappel on a single strand on the opposite side of the anchor. The last person at risk either removes the block and rappels double-stranded, or he leaves the block attached and rappels normally on the same single strand. Leaving the block attached does not prevent rope retrieval because the block is not attached to the anchor, but it does increase the risk of sticking the rope during the retrieval pull.
Dangers[edit]
The most common mistake when using blocks is rappelling on the wrong side.
This technique is extremely dangerous if the block can fit through the anchor ring; it must not be possible to fit the block through the anchor ring in any orientation. In particular, using a carabiner block on a carabiner anchor ring has been responsible for more than one serious accident and at least one fatality.
