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Preparing for a rigging degradation when sailing to out-of-the way locations



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What is the issue?
The stainless steel stranded rigging that extends from the mast-head to the larboard and starboard sides of the vessel, supporting the mast is perfect... until it breaks. The material is unfortunately subject to stress cracking which is caused by hardening.

Stranded rigging hardening is caused by cyclical loading when the boat is underway. Even the vibrations from the wind blowing through the rigging alongside or at anchor adds to the problem until eventually, the metal fatigues. Saltwater makes this worse by working its way into tiny failures to start crevice corrosion which is vastly accelerated when the rig is subject to the loading. As a result, a reasonable expectation for stainless rigging on a seagoing vessel is that it will start to degrade at about 10 to 15 years.

Fortunately, the rigging typically provides ample pre-failure warnings by way of broken strands before they fail. As shrouds are made of multiple cable strands they individually break down before they fail as a whole, particularly so where they connect to the swage or terminal, and likewise the terminal itself typically shows cracks before it gives. These external broken strands in the wire are easy to detect but internal ones are a little harder to find. They do create a distortion in a cable which will be detected when you run your hand up it, you'll feel a little ripple on the cable.

Once broken strands are found, the rigging wire is degraded and requires replacement. This can be addressed effectively in almost any location with a busy marine supply industry. However this is far from the case when en-route deep ocean, or sailing in out-of-the-way locations where it could be difficult to have new rigging made up or it is prohibitively expensive to ship in.

Why address this?
If a degraded shroud should fail, the rig will be outside of its support design and will most likely collapse.

How to address this?
If you are sailing deep ocean or to remote locations, it makes sense to carry at least one spare length of the heaviest / longest rigging stay aboard plus a pair of swageless terminations or compression terminals as they are also called.

Blue Wave swageless eye terminal
Photo: Courtesy of Blue Wave
With these fittings and cable, you can easily jury-rig a replacement section of standing rigging. Just cut the cable to size, see cutting through stainless steel rope and rigging wire, and attach the swageless terminations at each end.

Unlike swaged terminals, which require expensive dedicated machinery to create, swageless or compression fittings can be assembled with simple hand tools. The terminals are reliable and at least as strongly rated as the breaking load of the cable itself. Because they are so easy to assemble, the terminals are ideal to use in temporary jury-rigging situations. Swageless terminations are available from Norseman, Sta-Lok terminals, Quick Attach, Petersen and Blue Wave amongst many.

If you do not have a replacement rigging stay or swageless terminations, all is not lost. You can support a failing shroud that is failing at the swage connection in the short term by splinting a supporting section onto the area. All that is required is a section of rigging wire and some bulldog grips to fix it on.

Rigging Splint
Drawing: Tony Gibson


With thanks to:
Michael Harpur, Yacht Obsession.


Badly fraying wire rope
Photo: eOceanic thanks CC0




How to Install Sta-Lok fittings


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