Rope Construction

Introduction

The construction of rope impacts its shape and how it performs under load.  The combination of a rope’s material(s) and construction determines it’s overall performance.

Twisted

This fairly new nylon three strand twist rope will provide years of strength.

Twisted ropes are commonly available and the most affordable.  They are formed by twisting three strands of fibers, and then letting them twist together to form a rope.  Twisted ropes are commonly formed from nylon and polypropylene.  The main advantage of twisted ropes is that it is easily spliced and inexpensive.  The disadvantages of twisted rope are that it is not as strong as other types of the same diameter, the strands can separate under certain kinds of abrasion, the rope can cause twisting when under load (e.g. lifting heavy loads) and the rope is not as perfectly round like braided ropes.

Single braid

This single braid rope is in use as temporary lashing to keep an oar safely stowed in a speed boat.

Single braid ropes are also quite readily available and affordable.  They are formed by braiding together 8 – 10 thin fibers into a tubular or hollow braid.  This type of rope is readily available in polypropylene and nylon.  This type of rope is slightly stronger than a twisted rope of the same diameter, but is more expensive.  A braid is preferable in many applications because it does not unravel as readily as a twisted rope.  One other important characteristic of a single braid rope is that it generally is not perfectly round.  Due to the hollowness of the braid it often has a flat or oval shape.

 Double braid

This double braid is over a decade old but performs extremely well and shows few signs of wear.

A double braid consists of two single braids – one inside the other.  This type of rope is mucstronger than a single braid and does not lie flat.  It is available in a variety of materials including polypropylene, nylon, and polyester.  In some cases, a double braid rope will have two braids of different materials – the inside material is chosen for it’s strength, and the exterior material chosen for its abrasion resistance.

Kernmantle

Kernmantle rope (as seen in the header image) is a specialized type of rope which has a braided shell and a core consisting of many twisted fibers.  This type of rope is used in applications like rock climbing, where high strength, high abrasion resistance, and a specific amount of stretch is needed.  The shell is usually made from a highly abrasion resistant polyester, and the core is made from strong and shock absorbing nylon.  In static (non-stretchy) ropes a polyester core may be used, and/or a tighter weave on the shell.