At some point you will be caving and be on rigging which utilizes bolts. A wrench is needed as it is not safe or nice to leave a loose bolt for the next person on rope or, if you are rigging or de-rigging the cave a wrench will most likely be required.
Now depending on where and who you are caving with, you will require a certain size wrench. In North America (north of Mexico) the common size bolt used in caving is 3/8” (around 9.5mm), whereas elsewhere around the world 8mm bolts are the most common utilized for caving. They each require a different size wrench to tighten or loosen the bolts.
Some caving hammers, like Petzl’s Tam-Tam, have a wrench (for 8mm bolts) incorporated in their design.
I have begun using the crescent/ratchet wrench (see photos) and have found them to be quiet useful. If the ratchet seizes during a trip, you are still able to use the traditional open crescent. Adjustable crescent wrenches are not as useful or efficient as a fixed size wrench (they also have a tendency to strip the bolts if you are not careful).
Typical wrench sizes for the corresponding bolt sizes:
|Bolts Size||Wrench Size|