Strength and Security

Strength and security are different characteristics in a knot. Relative knot strength -or efficiency- is the breaking strength of a knotted rope, compared with the same rope unknotted, the overhand knot, for example, has a strength of about 45% in other words, it more than halves the breaking strength of any line in which it is allowed to remain, so it should not be used for anything vital. A Steady pull is not the same as putting a shock loading on a knotted rope (e.g., when a climber falls and is brought up short). then the momentum equals the mass multiplied by its speed and direction. To withstand such stresses and strains, the rope should be tied with one or other of the slide-and-grip friction knots, safeguarding knot and line.

Knots that unintentionally slip or capsize rather than breaking the rope (or before they can break it) are insecure ones. knots may be strong and secure, or strong but liable to spill if jerked about. Some are secure but weak. a knot cannot be both weak and insecure since, if it comes apart easily, its strength will never be tested.