New core stops rope snap-back

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Malcolm Latarche
Malcolm Latarche
ShipInsight

A new development in rope technology by Wilhelmsen Ships Service could end mooring rope accidents and fatalities.
Despite the industry’s best intentions, such as designating hazardous snap-back zones on mooring decks, or the drawing up of detailed line management and mooring plans, mooring remains an incredibly high-risk task. Serious, often fatal, accidents continue to happen with depressing regularity, with seemingly no end in sight. 
Proving impossible to accurately calculate or predict just how fibre ropes will behave when they fail and snap, Wilhelmsen Ships Service have instead developed a unique solution which dramatically reduces a rope’s recoil, or snap-back potential.
The Snap Back Arrestor (SBA) is an energy absorbing core which sits within the company’s Timm Master 12-strand plaited, mixed polymer rope. With the appearance of a rope, held within the heart of a 12-strand mooring line, if the outer, load-bearing construction breaks, the SBA absorbs the snap-back forces, transforming them from a potentially deadly snap, to a much safer, slump. 
In development for close to seven years, the Timm Snap Back Arrestor, is being claimed as a genuine market first. The result of a laborious process of trial and error, 25 different variants of the system were put through their paces in more than 120 different tests. Finally identifying a viable alternative in early 2016, DNV GL verified Wilhelmsen’s SBA solution in May 2016. Since then the Timm Master 12 SBA has been exhaustively tested, passing both TCLL testing and OCIMF MEG4 tests, in both dry and wet conditions. 
Recently type-approved by DNV GL, the Timm Master 12 SBA is produced according to ISO 9554:2010 and ISO 10556:2009 and tested according to ISO 2307:2010. It has also been tested according to the latest 4th Edition of the OCIMF Mooring Equipment Guidelines. The Snap Back Arrestor technology used in the Timm Master 12 will be rolled out across Timm’s entire 12-strand range.
Veronika Aspelund, Business Manager, Ropes, Wilhelmsen Ships Service said, “The Snap Back Arrestor is a massive step forward in maritime rope safety, significantly mitigating the considerable risks personnel are exposed to during mooring. Using the same material composition as our best-selling premium Timm Master 8 rope, Timm Master 12 SBA is buoyant, light, reliable, features anti-twist colours and offers one of the best strength-to-weigh ratios on the market. These are all of course great selling points, but the safety element hidden within its core is truly unique and could quite literally be a life-saver”.


From time to time, we learn of accidents that are sometimes fatal (but most always horrific) wherein mooring line "snapback" figures prominently. These events are a product of the various synthetic blends of rope that are being used in the tying up of most commercial ships these days. 

These synthetics all have extraordinary stretching abilities, but they also each have an ultimate load at which they break (part). The energy that gets stored up before the actual break is enormous. And when the break occurs that (often deadly) force is propelled within the "snapback zones" at either end of the rope.


Over the last few years, there have been mooring line "fuses" that have come onto the market which serve to absorb a synthetic line's stored up energy. These fuses permit the line to drop harmlessly (without snapback) once the breaking load is experienced. 

The article below provides a new twist to the fuse concept.
The only questions that remain, are 1). which avenue ocean carriers will choose to pursue in eliminating mooring rope snapback hazards (and the tort liabilities that accompany them) and 2). How quickly they are willing to act.

Ron Signorino


to Longshore Safety




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