Now I'm not talking about that man who sits behind his computer in the dark corner of your office, peering over the top of his computer as you walk past...no, there is another creep in the workplace. Let me explain.
Simply put, creep is the continued extension of a material when subjected to constant, long-term static loading. For a rope, creep is the length or rate at which the fibres in the rope stretch irreversibly over time. However, it should not be confused with constructional elongation as creep relates to the fibre in the rope, not to rope construction. Put simply, if you have a rope that is holding a heavy static load such as a mooring line, over time the rope will become stretched (called creep), and once the fibres are stretched, they don't recover.
Creep is dangerous because it happens over months or years and is hard to notice visibly, but it will likely result in the rope breaking. There are three stages a rope goes through before it breaks.
In the first stage under load, the fibres in the rope are elastic and recover when stretched. This stage only lasts for days.
In the second stage, the load stretches the fibres but they don’t recover. This can start after a few months and take hundreds of years.
Finally, creep rupture occurs in stage 3 when the fibres are stretched beyond their ability to hold the load.
How the right fibres prevent creep.
Temperature, loading level, time, and the type of fibre used all affect the creep lifetime of a rope. The first two are important, as high temperatures and high loads are accelerating factors. It's important that you select the right type of rope needed for your boat.
There is a boatload to learn if you just research the term 'Creep' online. Just swim past that 'creepy' stuff, but regarding ropes and lines, there is a huge amount of science including molecular chains and studies of rope fibres and how the different fibres act under long load periods. One rope that has been designed to help minimise the amount of creep is Dyneema fibre. This is not only super strong but has approximately four times longer creep lifetime than your other generic lines.
Data-driven prevention
No one ever wants a line to break, the results can be catastrophic. Yet in the harsh marine environment, ropes do get chaffed, creep happens, lines get sun damage and all of a sudden you can be up the creek without a paddle. Stay ahead of such breakages by implementing regular servicing and thorough inspections of all the lines and ropes, onboard and on the wharf. Creep is difficult to see, yet by looking for the signs of wear and tear, you can prevent the worse. SeaLogs has an excellent Recurring Task section designed to keep you one step ahead and track and record when servicing is due.
Keen to learn more, check out this helpful video here.