A stemple is a wooden crossbar set into a wall or shaft and used as a step. Stemples can be seen in mines, mountaineering, and similar settings. They are an important part of access, and it is possible to install them very quickly, facilitating rapid progress in building what amounts to an access ladder. This can be useful in settings where the wait for more established access would be too long, and personnel are eager to get started.
Installation of a stemple requires cutting notches into the rock to support the wooden bar. These notches must be deep and large enough to bear the weight comfortably. It is important to select the right location, avoiding weak spots in the rock that might crack or crumble with use, as this could create a safety hazard. To cut the notches, it may be necessary to use a harness and rope to dangle down the face of the wall and use hand tools. Personnel above can lower the bar to allow the worker to put it into place.
Stemples create fast access, but they can also be hazardous. One concern arises in damp and wet conditions, where stemples can become slick with moisture. They may also attract algae and fungus, even when treated wood is used as the construction material. People climbing or descending the ladder may slip and could fall, potentially incurring serious injuries. Regular scrubbing is necessary to keep the stemples as safe as possible, and caution is critical when using them for access.
There is also a risk of rot over time. In a mine, shade over the ladder can facilitate the growth of fungi, while in mountaineering applications, the stemples may be in shadow for a substantial part of the day, allowing fungi to grow on some areas of the access ladder. The fungi will gradually eat into the wood, softening it and making it appealing for insects. This damage over time can compromise the integrity of the stemple and create hazards. Even if the wood appears dry and rough enough to provide traction, a stemple may crumble underfoot and cause injuries.
Once personnel establish stemple access, it may be necessary to install a safer and more permanent access route. There are a number of other options available, including installing lifts and elevators in settings like mines. It is also possible to plant permanent anchor points in the rock near the stemples, allowing for the use of a safety harness to prevent injuries from falls.