Fall Arrester

What you see here is our bosun wearing a so-called Fall-arrester.
In earlier days a life line against falling from heights was nothing more than a rope around your waist. If you were so unlucky to fall down, you didn't got hurt by falling itself, but by cutted in two by a rope when it came tight.
To prevent shockloads like that, there is a smart device on the back of our bosun in combination with a short of bungee cord attached to it. If you fall down with this device it is actually like bungee jumping, your fall energy will be absorbed till bearable level.