What is the issue?The stainless steel standing rigging that extends from the mast-head to the larboard and starboard sides of the vessel, stem to stern, supporting the mast is perfect... until it breaks. A well-maintained, well-built rig used under normal conditions is highly robust but it needs some care. Unfortunately, it does degrade and independent and sometimes trivial components could fail and cause the whole rig to come down.
Why address this?Rigging issues 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. If a degraded shroud should fail unexpectedly, or something so horribly trivial and unlucky as a clevis pin works loose, the rig will in an instant be outside of its support design and will most likely collapse. Such a dismasting could result in injury or, if not acted upon decisively , the loss of the vessel and further jeopardy to the lives of the crew.
How to address this?If you are sailing deep ocean or to remote locations, it makes sense to thoroughly check the rig before departure and carry ample spares to be able to cater for wear and tear.
A well-maintained, well-built rig is not going to give many problems under normal conditions. But 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 fissures 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.
Image: Krystof Dvorsky
Fortunately, rigs typically provide ample pre-failure warnings before they fail. There are always signs of imminent failure and they’re not difficult to spot which is why it is essential to regularly send a rigger up the mast to thoroughly check the rigging. The inspection may need to be a little more than a visual check to detect crevice corrosion. In all cases the following checklist will provide a helpful guide to the key areas that should be observed:
- ☐ Check that the rig is properly tensioned. If the shrouds are slack each time the boat tacks there is a build-up of pressure against the mast and the points where it is connected to the deck which will cause unnecessary fatigue. On the other hand, over compression can lead to buckling.
- ☐ Check for broken strands in shrouds. 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. If you find some broken strands, replace that shroud and its opposite.
- ☐ Check all swage terminals for cracks or in the mast around terminal fittings.
- ☐ Check clevis pins for flats, bends etc. Sadly something as horribly trivial such as a clevis pin working loose could take the whole rig down.
- ☐ Check that all the fastenings are in good condition and seated correctly and secure. Remove paint if necessary for inspecting cracks.
- ☐ Check the chainplates for crevice corrosion, which attacks hidden parts of the structure not exposed to air.
- ☐ Check the condition of all the rivets and any signs of deterioration.
- ☐ Check all welds for deterioration.
- ☐ Check eyes for elongation and cracks.
- ☐ Check free turning sheaves, exit boxes, sheaves cages etc. for cracks and snags.
- ☐ Ensure adequate toggles in rigging terminations.
- ☐ Check rigging screws, in particular for thread damage.
- ☐ Check all areas for signs of chafe.
- ☐ Check alignment of standing rigging.
- ☐ Check spreader sockets and spigots.
- ☐ Check for signs of cracks and denting.
- ☐ Check spreaders for cracks, bends, dents etc.
- ☐ Check for chafe especially forward and trailing edges.
- ☐ Check end fittings are secure.
- ☐ Check shroud tangs for elongation, cracks, corrosion, secure etc.
- ☐ Check all shackles. Make sure they are properly seized with split pins as vibration can cause shackles to come undone over time.
- ☐ Check halyards.
- ☐ Check that the sail sliders are all secure. If one fails, the rest could follow.
- ☐ Check articulation for rigging screws and that the rigging screw is the correct way up.
- ☐ Check for corrosion in all areas but in particular around deck and heel areas.
- ☐ Check mast step is secure and corrosion free
- ☐ Check all areas for sharp edges.
- ☐ Lubricate all moving parts.
- ☐ Check standing rigging attached securely to ends of spreaders.
A practice that is bad for the shroud bases is using them for securing mooring lines. The loading can deform rigging toggles and weaken bottle-screws, creating an uneven load that increases the chances of fatigue and failure. Arrange for a handy cleat to be fitted to avoid this and if this cannot be done use the genoa cars, winches or padeyes instead.
Long distance cruising boats need to rely as little as possible on specialist equipment for repairs. For instance, if broken strands are found, the rigging wire is degraded and requires replacement. So a good set of spares that are easy to assemble is essential:
- ☐ At least one spare length of the heaviest / longest rigging stay aboard.
- ☐ Two pairs of swageless terminations, or compression terminals, end fittings to fit this cable.
- ☐ Clevis pins
- ☐ Split pins
- ☐ Shackles
- ☐ Nuts and bolts
- ☐ A selection of screws - machine screws and self-tap
- ☐ Snap-shackles
- ☐ Blocks
- ☐ Toggles
- ☐ Spacers
- ☐ Rigging screws
- ☐ Thimbles
- ☐ Sails slides
- ☐ Mast and boom sleeving kit
- ☐ Wire and rope
- ☐ U-clamp bolt
- ☐ Seizing wire
- ☐ Bulldog grips of various sizes
Photo: Courtesy of Blue Wave
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.
Drawing: Tony Gibson
Finally, a pop rivet gun used to apply pop rivets to a workpiece is a very useful general purpose tool to have aboard a yacht. It will allow you to do many mast repairs without calling on a rigger and, more importantly, on a remote island away from civilization. Any rivets that look degraded during a mast inspection can be drilled out, and the old rivet can be replaced by a new 'model' rivet immediately. If it all goes wrong and you ever have to set up a jury rig from the remains of a broken mast, a pop riveter would be a highly useful tool to have.
All experienced skippers will do everything they can to avoid a mishap but at the same time will be fully prepared and know what to do in an emergency. When it comes to dismasting , it is definitely worth considering the possible causes to try to prevent it ever happening and then to look at what to do if disaster strikes.
With thanks to:Michael Harpur, Yacht Obsession.
Badly fraying wire rope
Photo: eOceanic thanks CC0
Rig inspection before departing the dock
How to Install Sta-Lok fittings
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