How to choose ropes ?

(4)
Add a comment

ROPES

From any point of view, this is the most important piece of gear. It is the most sophisticated (technically speaking) and the most complex (given the large number of models). The rope is the key element of the entire safety chain.
 
 

Rope construction

Climbing ropes are made from polyamide (commonly called nylon) and are comprised of:
- A sheath. This protects the core from abrasion. The sheaths of dynamic ropes are always coloured while semi-static ropes are generally white.
- A core. This gives the rope its mechanical strength. It is coloured and enclosed by the sheath. It is made of numerous short twisted fibres.
 
There are two types of rope:
 
 
 

Semi-static ropes

Semi-static ropes are usually used for abseiling and as fixed ropes climbed with ascenders. They do not stretch much and their dynamic power is limited. In other words, they are not made to absorb a fall and are not used in either rock climbing or mountaineering for leading. These ropes are ideal for caving, canyoning and rope access work, where the rope is always taut (abseiling, ascending a fixed rope).
 

Dynamic ropes

Dynamic ropes are designed to withstand dynamic loading (a fall). They are used whenever there is a risk of falling (rock climbing, mountaineering, ice climbing, etc). The role of a dynamic rope is to optimise the reduction in the amount of energy transferred to a climber during a fall via the belaying system. To achieve this, the rope stretches to absorb the maximum amount of energy possible.
 
There are 3 types of dynamic ropes:
 

Single rope

Single ropes are used as single length. They are best suited to sport climbing or for routes without belays where the descent is not by abseil.
The diameter of single ropes generally ranges from 9 to 11mm.
It is important to choose the right length of rope depending on the height of the wall or crag to be climbed. The minimum rope length required is twice the height of the wall or crag. The most commonly used ropes are 25/35m (indoors) and 60/70/80m (outdoors).
 
 
 
 
 
 

Half rope

A half rope consists in a pair of ropes tied to the leader. However, two seconds may each tie into just one of the ropes each. In order to limit rope drag, the leader can clip one rope only into each runner. Half ropes are only used for mountaineering and multi-pitch rock routes, where an abseil descent is necessary. Equally, where there are less than perfect gear placements (ice climbing for example) using two ropes reduces the shock loading on individual protection points. In addition, clipping the two ropes separately offers better protection against stonefall or falling on an arête.
The diameter of a half rope varies from 8 to 9mm.
To make it easier to tell each rope apart when abseiling and belaying one or two seconds, ropes of different colours are generally used.
It is important to choose the right length of rope depending on the length of the route and abseils, and 50 to 60m ropes are generally used.
 

 

 

 

 

Twin rope

Twin ropes are always used together: each climber ties into both ropes and these are always clipped together, as if it were a single length of rope. The advantage of this over a single rope is that it allows for abseils as long as the rope. It is lighter than a half rope but does not allow for clipping of each rope separately.
Twin rope diameters range from 7 to 9mm.

 

 

 

 

As with half ropes, two different coloured ropes are generally used. Again as with half ropes, it is important to choose the right length of rope for the length of the route and abseils.
A walker’s rope is not strictly another type of rope. It allows hikers to be roped up while moving across glaciers or difficult terrain. A minimum requirement is a single twin rope. It is important to choose the right length of rope depending on the number of people to be tied in (glacier walking) or the length of the difficult terrain to cross (hiking).
 

Maintenance, storage and lifespan

 
A rope should be stored in the shade, away from moisture or any heat sources. To wash a rope, immerse in clean cold water (less than 30°C), use a mild detergent and end by brushing with a synthetic brush. Dry in the shade away from direct sources of heat (preferably hung up in circulating air). The lifespan of a rope depends on how it is used and how frequently it is used. A rope can be damaged beyond repair as early as its first use. They generally have a lifespan of between three and five years. Where there is intensive use this can be very much shorter, and as little as a few months!
 
There are some ropes that meet the rating standards for all three kinds of rope, e.g. Simond 9mm Falaise.
CAUTION: When used as a single rope, the Falaise should only be used by experienced climbers with the correct device. Its thinness means it requires expert belaying technique, and the use of belay gloves is recommended.
USE: As a single rope, by very experienced climbers only.
As a double/twin rope, by all-round rock climbers/mountaineers.

 

Features of dynamic ropes

Detailed information can be found in the rope’s technical notice of use. It is important to read these user notices to help you choose the most suitable rope and compare the different models.
 
Technical information on the packaging of the Simond 9.8mm rope.
 

Impact force

 
 
This is the force felt by the climber when a fall is held by the rope. This force is also transferred to the belayer and last point of protection.
The lower the impact force the greater capacity of a rope to absorb the energy of a fall. Impact force is expressed in kilo Newtons (kN). 1kN is the approximate equivalent of 100kg (or 101.94kg, to be precise).
 
Impact forces required by international standards:
- Single rope: impact force of less than 12kN for a first factor 1.77 fall with an 80kg falling mass.
- Half rope: impact force of less than 8kN for a first factor 1.77 fall with a 55kg falling mass.
- Twin rope: impact force of less than 12kN for a first factor 1.77 fall with an 80kg falling mass on two ropes together.
 

Sheath slippage

 
The sheath of a rope is independent from its core and can slip if the rope is not manufactured correctly.
This can create an occasional bulge (‘sock effect’), which accelerates wear and tear and may cause the rope to jam in the belaying system.
 

Diameter and weight

 
Larger diameter ropes generally last longer (better abrasion resistance) and are safer to use for belaying (better braking in the device). However, they are heavier and less easy to handle. Smaller diameter ropes are lighter and more fluid, and better for routes where lightweight and easy to handle ropes are more important, and for use by more experienced climbers.
The relationship between a rope’s weight and its dynamic characteristics is one way of evaluating its overall performance.
 

Number of bobbins

 
Bobbins are groups of fibres woven together to make the sheath. For a given diameter, a higher bobbin count improves the dynamic characteristics of a rope, whereas a lower bobbin count provides better abrasion resistance.
 

Number of falls

 
To comply with minimum safety standards, a rope must withstand a minimum of five factor 1.77 falls with a given mass, which varies according to the type of rope:
- Single rope: 80kg
- Half rope: 55kg
- Twin rope: 80kg on 2 ropes
 

Dynamic stretch

This is the amount of rope stretch measured during the first fall assessed for the number of falls test. It must not exceed 40%.
As the number of falls increases, the dynamic capacity of the rope diminishes and the impact force increases. The fibres of the core gradually lose their elastic capacity. During a fall these fibres lengthen and become heated. After a ‘rest’ of around 30 minutes, they return to their original state. This capacity will gradually fade with the rising number of falls. During assessments in the lab, the time allowed between two tests is 5 minutes. This means the rope is tested under extreme conditions.
 

Static stretch

Measured with an 80kg mass (without a fall), it cannot exceed 10% for a single rope, 12% for a half rope, and 10% for a twin rope tested on two ropes used together.

 

  • 1
  • 2
  • 3
  • 4
  • 5
Score
Post a comment
TOP OF PAGE