Glossary of terms

GLOSSARY OF TERMS

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Rope making terms can be confusing and often obscure, so here is a glossary of some of the more frequently used words and phrases used in this website or other Marlow or rope-making literature.
Average Break Load: (ABL) The average load at which a rope will break 

Bedding in: Permanent elongation that occurs when a rope is first used.  Caused by the fibres settling into the most efficient load path. 

Braid: Rope construction formed from interlaced fibres spiralling on opposite directions. 

Break load:  the force at which the rope will break, see Average Break Load, Minimum Break Load, spliced break load. 

Coefficient of Utilisation: the coefficient by which a rope or system is de-rated to obtain the WLL.  Sometimes referred to as a ‘safety factor’ or ‘design factor’. 

Continuous Filament: Synthetic fibres that are extruded and supplied as a continuous unbroken filament. 

Creep: Permeant elongation that occurs over extended time, normally associated with HMPE fibres. D:d Ratio – ratio of the sheave diameter (D) and the rope diameter (d) 

Design Factor: See ‘coefficient of utilisation’. 

Doublebraid: Rope construction consisting of 2 braids one on top of the other. 

Elastic elongation: elongation that occurs immediately when a load is applied and recovers as soon as the load is removed. 

Elongation: The amount by which a rope stretches (strain).  Normally quoted as a % length change at a given condition such as ‘elongation at break’. 

Fatigue: Any process that reduces the strength of a rope over the time it is in service. 

Grommet: Loop of rope made by splicing the ends together.  Often used as a lifting sling. 

Heat Set: A stress relaxation process that involves heating a rope after braiding or twisting. 

Kernmantle: Rope construction consisting of a core (Kern) and a cover (Mantle).  Normally used in reference to climbing and static ropes. 

Minimum Break Load: (MBL) a statistically derived figure that represents a minimum strength that the rope should exceed.  Normally either 2 or 3 standard deviations below the ABL. Modulus – See stiffness. 

Pre stretched: A stretching and heating process that relaxes residual stress and improves performance. 

Safe Working Load: (SWL) maximum load that can be applied to a system in a given configuration.  May never be more than the WLL but could be less if weaker components or configuration are used. Safety Factor – See coefficient of utilisation. 

Seize: Similar to whipping, often used to bind 2 ropes together with smaller cordage, or to form an eye. Splice – a method of terminating a rope. 

Spliced Break Load: The break load (either minimum or average) including a spliced termination.  Typically Dyneema and other high strength ropes will be testing in this way. 

Staple Fibre: sometimes called ‘spun staple’ short length fibres that are spun (twisted) together to create a longer yarn.  Can be either synthetic or natural. 

Stiffness: measure of the elongation as a function of load. Strand – twisted construction where the fibres are spiral in the same direction. 

Stretch: See Elongation. 

Viscoelastic elongation: a time dependent and recoverable elongation.  Normally associated with HMPE fibres. 

Whip: Binding around a rope made with smaller cordage.  Used to tidy a rope end and prevent fraying or to secure a splice. 

Woking Load Limit: (WLL) Maximum load that can be applied to a rope in a given application, for lifting in the EU this is typically 1/7th of the terminated MBL.