Impact Force of a Falling Climber

We all know the scene: A giant boulder out in the wilderness, the night theatrically lit to focus only on this rock, a story being written. Several metres of empty space separate a boulderer from the Ultimate Dyno, and the latest greatest grade hangs in the balance.

The legs swing far to the rear, with only a single hand preventing our hero from sailing backwards into the bushes and rocks behind him. Below, his friends arrange the crashpads and raise their hands towards the sky in the direction of his butt.

The Underrated Forces Involved in Climbing Falls

What the pictures do not show can be seen in the videos that follow. If the climber falls, the spotters will quickly shift their position and drop their hands lower. Some people might call this poor spotting, but these people have likely never tried to catch a climber mid-fall.

After considering the forces involved in such a fall, it is quickly clear that there is no possibility of stopping or catching the climber. By doing so a spotter puts themselves seriously at risk of injury. In other words, have you ever attempted to catch a moving car?

When climbing on ropes, a fall in the first few metres is comparable to bouldering wherein the climber can still land on the belayer or on the ground. However, as soon as the climber is caught by the rope, the forces involved are completely altered and depend on the fall factor and impact force in relation to the relative friction in the system.

The tasks of a spotter when bouldering

To consider catching such forces is completely unrealistic. An experienced boulder will be aware that the goal of spotting is not to catch the falling climber, but rather to guide them onto the mat and to prevent them from landing in awkward positions such as headfirst. This is correct, but is also quite risky once the climber is above a certain height. Yes, you can try to redirect a falling body with the force of 540kg (a 90kg climber falling from 6m), however you must pay very careful attention to not injure your fingers and hands during this process.

In this case, one could easily question why the spotters are even present. Surely experienced climbers should know to step back a little and prevent themselves from getting hurt? The answer is simple - there’s more to spotting than simply guiding the climber in a fall.

Boulderers hold their hands up not to catch the climber directly, but to reduce reaction time and increase awareness. A spotter with their hands in the air and their eyes on the climber is going to react a lot faster than one with their hands in their pockets and their eyes on the birds in the distance. Even when the boulderer is well outside of a suitable height from which they could easily be guided to the mat, a spotter still has a few very important tasks.

Aligning the Crashpads

Very important: the spotter is responsible for ensuring that the crashpads below are always arranged correctly to protect the climber in the event of a fall. Many boulders do not climb vertically upwards and so require some careful arrangement in order to prevent a fall directly onto the ground. Outdoors there tends to be only 1-2 crashpads per person and it is relatively unlikely that there are enough to cover the fall zone. In this scenario, it is up to the spotter to adjust the existing pads regularly to make sure that the climber remains safe.

Stabilising a Fall

The second important task of a spotter is to stabilise the falling climber. Anyone who has watched gymnasts perform has seen exactly how difficult it is for them to stop still after landing straight. After landing it is easy to spin or fall awkwardly and depending on the terrain this can result in serious injury.

The job of the spotter is to prevent over-rotation or awkward falls. Like a human fence, the spotter is perfectly placed to prevent the boulder falling away from the crashpad after the initial impact.