How do shock cords absorb energy in offshore crane and lifting operations?

Offshore crane and lifting operations typically require components that can withstand heavy loads, unpredictable forces, and constant exposure to demanding conditions. That is exactly where shock cords often play an essential role, absorbing sudden loads and vibrations while maximising safety for both equipment and staff. One of the most pivotal ways they do this is by providing a buffer against sudden forces that could otherwise strain or damage the lifting system. 

With well over a century of history to our name here at Ibex Ropes Marina, we have extensive experience with shock cords and similar solutions in the marine sector, including subsea and offshore. So this week, our experts are taking a closer look at how shock cords are used to absorb energy in offshore lifting operations. 

How shock cords function as energy absorbers in offshore lifting

It makes sense to start with the basics. Shock cords are designed with elasticity that allows them to stretch under tension. When a sudden load or force is applied, the cord elongates and disperses that energy across its length. This prevents the force from transferring directly to the lifting equipment or load. Essentially, the cord takes the strain that would otherwise be felt by the crane hook, rope, or the load itself. Crucially, by extending and then gradually returning to its original shape, the cord reduces the peak force that gets transmitted.

This energy absorption is particularly valuable in offshore lifting, where sea movement and unpredictable weather are notorious for affecting stability, Every swell or jerk from a crane movement can send sudden shocks through the system, but shock cords moderate these impacts. As an active part of the lifting system, they can ensure that forces are managed more steadily, helping keep any lifting operation controlled and efficient even in shifting conditions. 

The role of shock cords in protecting equipment and extending service life

Almost all lifting equipment is effectively an investment, and the more protection it receives, the longer it will stay at maximum effectiveness. Shock cords reduce the stress that heavy loads place on cables, hooks, and other crane components. If this buffer is absent, the equipment faces far greater wear every time a sudden force hits. Absorbing and dispersing the energy helps to limit abrasion, fatigue, and eventual failure in other parts of the system. This prolongs the service life of essential lifting gear and reduces downtime caused by maintenance or replacement.

And of course, bearing in mind the costs associated with offshore operations, extending the life of lifting equipment is a without question a perennial priority. Every time a shock cord smooths the impact of a load, that avoids a sharp jolt to the machinery that could otherwise contribute to cracks, frays, or deformation. That ultimately means more operational stability, fewer interruptions, and reduced costs, all because of the protective role played by shock cords.

3 safety improvements delivered by shock cords in crane operations

Reducing the swinging of loads. Offshore lifting is vulnerable to unpredictable motion caused by sea conditions and wind, which can often make loads shift suddenly. Shock cords can to help stabilise it by absorbing part of the force that would otherwise cause the load to move, making it safer for crew to work around. By controlling that swinging, they can effectively reduce the risk of collisions with nearby structures, and cut down on the likelihood of associated accidents.

Lowering the chance of equipment failure. Crane hooks, ropes, and connections are subjected to enormous forces, especially when sudden shocks are introduced. Shock cords moderate these stresses through stretching and dispersing energy, which keeps the strain from concentrating at a single point. This helps you protect the integrity of any lifting equipment and lowers the risk of sudden failure, which is one of the most dangerous outcomes in offshore lifting.

Reducing the risk of recoil injuries. When a load shifts or releases quickly, cables and other components can whip back with extreme force. Shock cords take in part of this energy and release it gradually, so the system does not respond violently to a sudden change. That results in greater protection for staff, as it means that crews are far less exposed to dangerous recoil that could cause severe injury. 

4 factors to consider when using shock cords offshore

When you are choosing your own shock cords for offshore lifting, you will need to take into account several important factors. These include:

• Load rating
• Material resistance
• Length and stretch capacity
• Maintenance requirements

So, let’s look in a bit more detail at each one in turn. 

Load rating

The load rating determines how much force the cord can safely handle while still performing its role in energy absorption. You will need to ensure that the cord rating matches the maximum weight you expect to lift, and ideally with a margin of safety for unexpected surges. A shock cord with the proper load rating protects itself and also ensures that connected components remain within safe stress levels. Taking load rating into account also helps you plan lifting operations more effectively, because you will know that your equipment is operating within its limits. This is one of the main things that makes the choice of load rating one of the most decisive aspects of safe offshore lifting.

Material resistance

Offshore environments are notoriously some of the harshest for lifting gear. There is the corrosion from saltwater, constant sun exposure that degrades many synthetic materials, and the abrasion from the constant motion of sea-based work. That means you will need cords made from materials specifically designed to resist these challenges, with coatings or treatments that preserve elasticity while preventing breakdown. Choosing cords with proven resistance to offshore conditions also means you can expect consistent performance, as well as limiting unexpected downtime, and ensuring that your lifting equipment is always supported by reliable components.

Length and stretch capacity

The length and the degree of stretch are key to how effectively a shock cord can absorb energy. You will need to consider both the maximum extension and how that extension affects load control. A cord that extends beyond the controlled range of movement can make the load more difficult to handle, while one that barely stretches will not take in enough energy to protect your equipment. It is therefore wise to calculate the required elongation in relation to your expected loads and crane movements in advance, as it can enable you to achieve a balance that maximises both energy absorption and precise handling. 

Maintenance requirements

Even the most durable of shock cords are not immune to wear and tear, and ultimately they will degrade with repeated use in offshore environments. However, the key is how quickly. You will need to implement routine inspections to check for fraying, loss of elasticity, and other early warning signs of failure. A maintenance schedule ensures you replace cords before they become unsafe, and it also provides you with data on how long they typically last in your operating conditions. This enables you to accurately predict future needs, manage budgets, and consistently maintain safe lifting practices. 

These are all the essential points covered – and if you ever need any help or more specific advice on shock cords and their applications for vibration damping, that is exactly where we can help here at Ibex Marina Ropes. We have unrivalled experience with shock cords, and serve a wide range of sectors across the UK and beyond, including not just subsea and offshore, but also aerospace, military and defence, and sport and leisure – just to name a few.