An ice screw is a threaded tubular screw used as a running belay or anchor by climbers on steep ice surface such as steep waterfall ice or alpine ice during ice climbing or crevasse rescue, to hold the climber in the event of a fall, and at belays as anchor points. Ice screws are made by several manufacturers. The various products available offer essentially similar functionality but typically offer subtle differences in design. For example, some ice screws come with one or more of the following: an in-built or separate ratchet mechanism to speed up placement, conical centre-hole to aid removal of ice cores, different lengths, different numbers of cutting teeth, different cutting angles, different surface finishes, different size hangers/clip holes. Price and durability are usually design considerations too, as a usable rack of ice screws will be a significant financial investment for many climbers. Titanium ice screws, often made in the former Soviet Union using Cold War-era missile technology, were generally too brittle and so the majority of ice screws are made of chromoly steel .
The strongest and most reliable type of ice screws currently available are the modern tubular ice screws which range in lengths from 10 to 23 cm. The approximate strength rating on a modern tubular ice screw is around 7 kN, although it has been found that short ice screws in "good" real-world ice hold about 7-8kN, no matter what the fall factor or configuration is, according to research by Beverly and Attaway. The UIAA drop test uses a particularly taxing configuration for ice screws. That is, when multi-pitch lead climbing and the leader has only placed one screw (typically merely clipping one of the anchor screws) before climbing up a couple of meters and falling (i.e. fall factor 2). The dynamic ropes used in climbing can mitigate failure of an ice screw by keeping the impact forces low, especially if using a new rope that has not had any previous falls. It is rare that an ice screw fails in fall factors of 1 or less, if placed in good ice (which is why it is so important to place a screw or other running belay soon after starting a pitch).
An older type of screw that is rarely used today is a pound-in ice screw. Instead of screwing these into the ice one would pound them in with a mountaineering hammer or a hammer from the ice tool, and then screw them out to remove them. The pound-ins have been largely replaced by modern tubular ice screws that are stronger and easier to use.
The subtle nuances of ice screw placement should be mastered before using them for climbing. Learn from a professional how to best protect yourself using ice screws.
The latest ice screws incorporate replaceable tips, thereby increasing the useful life of the screw and enhancing placements.
Read more about Ice Screw: Placement, Other Uses, Manufacturers
Famous quotes containing the words ice and/or screw:
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—Anonymous Antebellum Confederate Women. Previously quoted by Mary Boykin Chesnut in Mary Chesnut’s Civil War, edited by C. Vann Woodward (1981)
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—Anthony Trollope (1815–1882)