What are shock cords? Here is everything you need to know

Shock cords are exceptionally versatile pieces of equipment, used in a wide range of industries for a variety of applications, from securing cargo to absorbing shock in mechanical systems. Here at Ibex Marina Ropes, our own history with fibre rope manufacturing stretches all the way back to 1843 – so you can rely on us to know all the technical details and applications of these uniquely useful assets.

So, if you need a quick introduction to the world of shock cords and their potential uses, here we have rounded up some of the most essential information you will need to know.

What is a shock cord?

Sometimes known as a bungee cord, a shock cord is a specialised type of rope that consists of an elasticated rubber core, covered by a braided sheath. While the sheath itself does not stretch, its spiral construction allows it to squeeze the elastic core when pulled, enhancing its elasticity. The shock cord is designed to absorb force and return to its original shape after removing the force.

Shock cords come in a variety of materials, including rubber and synthetic elastomers, each of which offers different stretch limits. The core is usually made from natural rubber, and it is this that provides the elasticity. The sheath on the other hand is often made from single or double covers of polyester, polypropylene, cotton, Dyneema or nylon, and offers protection and durability. This combination of strength and flexibility makes shock cords ideal for applications such as securing items, absorbing shocks, and providing tension.

All that goes some way to explain why they are so widely used in so many sectors and markets, from aerospace and marine to fire and rescue, or sports and leisure.

A brief history of shock cords

Shock cords were first developed in the early 20th century for aviation, where they were used as shock absorbers on aircraft landing gear. During World War II, both US and UK military forces adopted shock cords to decelerate planes on aircraft carriers. Their ability to absorb shock and rapidly slow down aircraft made them essential for landing on short carrier decks. (And indeed, decelerating aircraft remains one of their major aerospace applications today.)

Post-war, shock cords saw widespread adoption in civilian applications, including securing cargo and in outdoor gear like tents tarps, baggage and clothing. By the mid-20th century, shock cords had become a vital tool in both industrial and consumer products – just as they still are today.

What are shock cords used for? Some common applications

As you may well have concluded already, one of the most common uses for shock cords involves securing objects without the need for tying knots, and they are also useful for absorbing shock in various applications. Their flexibility and stretching ability makes them perfect for situations where both tension and impact resistance are required.

Here are a few of the most typical uses.

• Securing objects. Shock cords are often used to hold items in place, particularly when a knot-free solution is needed. From securing luggage to a car roof rack to fastening equipment during transport, the elasticity of the cord ensures a tight grip without the need for complicated ties.

• Bungee cords. Some inexpensive types of shock cords (known as “bungee cords”) are marketed as general-purpose utility items. Typically featuring metal or plastic hooks at either end, these can come as individual straps or in sets, often bundled with a metal or plastic ring to allow for versatile tie points. (This makes them particularly useful for securing larger loads.)

• Cargo nets. For larger or irregularly shaped loads, bungee cords with hooks on the edges can be used to create “cargo nets”. These nets are ideal for securing items like luggage or cargo on the backs of trucks, car roofs, and similar spaces. They are particularly useful for providing peace of mind, so you can be sure that objects are held securely even during rough handling.

• Military applications. Shock cords have also been widely used in military settings, particularly in securing equipment and weapons. (Indeed, this is a major sector we serve here at Ibex Marina Ropes) Their stretchability makes them ideal for holding items in place within vehicles, on aircraft, and even in field operations. They are also routinely used in parachute systems and other tactical gear due to their reliability in absorbing shock and providing secure, flexible support.

A quick introduction to our shock cords at Ibex Marina

At Ibex Marina Ropes, we offer a range of shock cord products designed to meet various needs, from general utility to more demanding technical applications. Our primary product range consists of heavy & light duty to international standards, Dyneema-covered and commodity shock cords. Each type is carefully manufactured to ensure reliability, and they can be distinguished from each other through several subtle but crucial differences, which reflect their intended use and performance capabilities.

Commodity / commercial shock cord

Our commodity shock cords are designed for general-purpose use. These are typically more affordable and are ideal for lighter-duty applications. Some of their most distinguishing features include:

• No recognised standard for construction or physical properties. These cords are not bound by specific regulatory standards.
• Relatively inexpensive and disposable. Ideal for short-term or less demanding tasks.
• Mainly used for restraining lightweight items. Perfect for holding down smaller loads where minimal tension and impact resistance are needed.
• Highly durable. Our commodity shock cords contain the highest quality natural rubber thread for enhanced performance over time compared to lower-cost alternatives.
• Limited dynamic capability. Not designed to withstand high-stress or repetitive stretching.
• Single cover. Offers basic protection for the elastic core, without the added durability of a double cover.

Dyneema shock cord

Our Dyneema shock cords are designed for the most demanding applications. They are ideal for situations that require exceptional strength-to-weight ratio, durability, and resistance to extreme conditions.

Here are the key features that set our Dyneema shock cords apart:

• Incorporates Dyneema fibres for superior performance. Known as one of the world’s strongest and lightest materials, Dyneema significantly enhances shock cord capability.
• Extremely high tensile strength with low stretch. Notable for exceptional load-bearing capacity while maintaining control, making Dyneema shock cord ideal for high-performance tasks.
• Outstanding resistance to UV, chemicals, and abrasion. This durability makes it perfect for outdoor, marine, and industrial environments.
• Low coefficient of friction. Ideal for applications requiring smooth movement or reduced wear when in contact with other surfaces.
• Lightweight with unique buoyancy. This makes it easier to handle and it will not sink – so it is especially useful in water-based applications.
• Minimal maintenance and long service life. Offers excellent value over time, reducing the need for frequent replacements in critical applications.
• Suitable for technical and safety-critical uses. Commonly chosen for aerospace, defence, and advanced outdoor gear, all of which require flawless reliability under pressure.

Technical shock cord / heavy-duty shock cord

Our heavy and light-duty shock cords, also known as technical shock cords, are made to meet international standards for strength and durability. These are used in more demanding environments, where reliability and longevity are critical. Here is a quick overview.

• Recognised robust standards for construction and physical properties. Built to meet specific performance criteria for demanding applications.
• Their shelf life is clearly specified for critical applications. These cords are designed to be used in environments where their longevity and reliability are vital.
• Shock absorbing and heavier load restraints. Ideal for applications requiring high levels of tension and impact resistance.
• Dynamic/high cyclic load capability. Suitable for tasks that involve repeated stretching or heavy loads.
• Higher added value opportunities. Offers better performance and reliability, often used in more complex or technical applications.
• Mainly double covered (diameter dependent 3F71). Provides enhanced durability and protection for the core.

This is everything you need to know in a nutshell. However, it is a relatively quick guide, so if you have any more detailed questions, or you need some in-depth assistance or advice on the best shock cord for your intended application, you can always get in touch with our team here at Ibex Marina on 01706 360 363. Our expert team is always happy to help!