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Intermittent Load: Many knots can loosen with prolonged intermittent strain. For example, a bowline just "floated undone" when Grog was swimming around scrubbing the boat's waterline; a perfectly good scrubbing brush sank before he realized it was no longer attached.
Additional Half Hitches: Mooring lines also present intermittent strains and it is wise to use additional half hitches or seizings to provide greater security. A seizing is a wrap of small line holding the bitter end against another adjacent part of the knot. Although a seizing may be very secure, it is a nuisance because it cannot be easily "untied". By contrast, it is quick and convenient to add extra half hitches, and they are commonly found on the: Round Turn & Two Half Hitches, Rolling Hitch, Anchor (Fisherman's) Bend, the Clove Hitch and, of course, the Reef (Square) Knot.
Stopper Knot: Climbers are particularly wary of the bowline especially when carried around at the end of a coil of rope. One technique they recommend is to use a stopper knot to secure the bitter end round the adjacent part of the bowline's loop.
Under Load: Four knots are valuable specifically because they can be tied and untied under load: the Round Turn and Two Half Hitches; the Cleat Hitch; the Rolling Hitch; and the Munter Mule combination. Learn these well. By contrast, the bowline is impossible to tie or untie under load.
Rope, and the sports associated with rope, can be dangerous. Wrongly handled, gripped, or tied, rope can kill, maim, or burn. You could be the victim! So, handle rope with care, inspect and test any knot you tie, and respect any rope subject to a heavy load, e.g., a rope controlling a large sail, a mooring rope when you are docking or berthing, and especially your own climbing rope. Never try to control a heavily loaded rope or fishing line with your bare hands. Control rope by taking two or more turns round a winch, cleat, or post, and use appropriate equipment for fishing line. It is unfortunate, but true, that the danger associated with heavily loaded rope or fishing line is commonly learned by experience, which is often very painful and could be lethal.
They do! A great deal is written about which knots weaken a rope most. An angle, a kink, or a knot, stresses the fibers unevenly and weakens the rope. If this concerns you, you are using rope that's too thin. Although some knots in some ropes are claimed to only weaken a rope to about 80% of its rated strength, other knots weaken a rope to about 50%. It is therefore simpler, and certainly safer, to assume that even brand new rope will perform at no more than 50% of its rated breaking strength. And, if the rope is old, worn, or damaged by sunlight or chemicals - expect considerably less. For some useful test results visit Dave Richards' Knot Break Strength vs Rope Break Strength on the National Speleological Society Website.
Disclaimer: Activities involving ropes are potentially hazardous. Lives may be at risk - possibly your own. Considerable attention and effort have been made to ensure that these descriptions are accurate. However, many critical factors cannot be controlled, including: the choice of materials; the age, size, and condition of ropes; and the accuracy with which these descriptions have been followed. For this reason no responsibility is accepted for incidents arising from the use of this material.
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Animated Knots Privacy Policy Updated: Jun 24th 2009 |
