Rigging lessons

The trouble with lessons about mast rigging is that they come with a jolt, both to the boat and the skipper’s self esteem. For nine years I examined the wire terminals on our 37-foot yawl Mollymawk both aloft and at deck level, regularly and conscientiously. Until one day it turned out I had been looking in all the wrong places.

Underway north from South Bight, Andros Island, Bahamas, we sailed through smooth water. The bulk of New Providence Island kept the seas down until we arrived off its north coast and the swell began heaving the boat over cresting waves. We tacked and barely trimmed the jib hard when a loud “peeeng” rang through the boat! The port lower aft shroud (on the windward side) swung free and swiped the mainmast. I collided with Nancy in a rush to the tiller to go about to the starboard tack. We left the jib sheeted, though, and the sail pressed against the windward shrouds stopping the forward motion – we hove to.

At the mast I found that the eye at the lower shroud end had sheared where the threaded eye piece entered the body of the terminal. Now what? We could not do repairs right there. The reefs off West End, New Providence, were breaking ominously near, and we could not run off wind since the rolling motion would whip the mast from side to side. Our 1960s-built mast, however, had a heavy wall thickness for its length. It was stepped through the deck and was still well stayed in the lower section with the remaining double lowers, inner stay and runners. Could it take some more abuse? We tacked again, and the mast stood ramrod straight even when we hit steep waves. Just 11 miles to windward lay Nassau and shelter to do the repairs.

Once we made Nassau, I inspected the rig and found badly corroded terminals at the lower ends of two more shrouds and hairline cracks in others. In all the cases the corrosion attacked the threads of the eye pieces while the terminal bodies that held the wire looked healthy. The standard swaged wire terminals normally reveal internal corrosion by hairline cracking along the body, and that is where I had been inspecting our terminals – it was the wrong place to look. I had just learned that the swageless terminals that utilize threaded ends usually begin crevice corroding at the threads, the ready-made crevices. Much of our rigging needed replacement, and the nearest place with rigging supplies was 150 miles away. I had to make sure the mast stood long enough to get there.Jury rig

First, using nicopress sleeves and a small crimping tool, I made a temporary lower shroud out of 9/32-inch (7mm) 7 x 19 wire that we carried for emergencies. This flexible wire is almost as strong as the 1/4-inch (6mm) broken shroud made of 1 x 19 wire – 6,200 lbs versus 7,000 lbs. Next, I had to do something about the other two corroded terminals. I took the easy way, making doubler pieces that would take over the load if the terminals broke. The doublers were three-foot-long (one-meter) pieces of 9/32-inch (7mm) 7 x 19 wire with eyes nicopressed over heavy thimbles at one end. I used wire grips (also known as bulldog grips) to attach each doubler to the shroud so that its eye ended level with the eye of the shroud terminal connected to the rigging crew. One doubler’s eye was then lashed tightly through a closed, dock-line fairlead bolted through the bulwark. Conveniently the fairlead lined up well with the run of the shroud. The eye of the other doubler was lashed through a shackle run through a hole in the bulwark at the hull/deck joint. Some years earlier I drilled holes in the bulwarks next to the chainplates to create a spare attachment point should a chainplate break. The chainplates on our Invicta I yawl are bolted through and encapsulated in fiberglass gussets under the deck before appearing above deck. I suspected that, hidden like this, they could corrode and break unexpectedly.

Now, if, despite my extra lashings on the suspect shrouds, one of them went bust, I would tack the boat to take the load off the weakened rigging, undo the lashing and switch the rigging screw to the eye of the doubler. After tightening the rigging screw, the doubler and the shroud would work as one.

My set-up was never put to test as we made the trip back to Florida without further rigging mishaps. Rigging replacement

In Ft. Lauderdale I sought advice from Peter Messinger, the head rigger at Norseman Marine, who had probably seen more rig failures due to corrosion in tropical waters than any other man. He recommended going with Norseman fittings. He advised filling my new fittings with Teflon grease, which made the final assembly a snap and promised easy dismantling in future. Both the terminals and the new Dyform shrouds were made of 316S31 stainless alloy, which would minimize corrosion due to dissimilar metals in close contact.

We were leaving for extended voyaging, so I also installed a new headstay wire, keeping the old one as a spare since its end fittings looked good. I could not bring myself to replace the backstay, one cap shroud, and the inner stay, all of whose terminals looked intact. Now that I knew how to look for impending trouble, I just made sure I added the right materials to my kit to make repairs while voyaging. When a wire terminal goes, it has to be cut off, and the remaining shroud or stay will be a few inches too short. If you have a boat large enough to carry big coils of wire, you can make a whole new stay or a shroud. Otherwise, you have to use a short piece of matching 1 x 19 wire with new fittings to make up the difference in length. These repairs are possible at sea since, most of the time, corrosion accelerated by airborne salty spray attacks the terminals on the lower ends. I already had enough spare rigging wire, so I stocked up on Norseman fittings and, sure enough, a year later I had to repair one cap shroud.Emergency rigging kit

Apart from spare fork-and-eye terminals by Norseman or Sta-lock, every boat should carry some 1 x 19 wire and a generous length of 7 x 19 wire, which handles aboard much more easily than the stiff 1 x 19. Seven x 19 is weaker, so one should use a diameter one size up from the 1 x 19 wire it replaces. Heavy-duty stainless thimbles or, preferably, solid rigging thimbles will protect eye splices. To form neat-looking eyes I use nicopress sleeves and portable hand crimping tools which can be adjusted to fit four wire sizes.

Wire grips, by the way, make much stronger splices than nicopress sleeves. Tests made by Phil Dean and Florida Wire and Rigging proved the grips will hold past the nominal breaking load of the wire if properly installed. The saddle of the grip must bear on the long, standing part of the wire and the nuts must be cranked to the prescribed torque, 15 ft/lbs for 1/4 inch (6mm) wire and 30 ft/lbs for 9/32 inch (7mm) for example. Wire up to 7/16 inch (11mm) diameter requires a minimum of two clips spaced not further than six diameters of the wire apart. After the assembly has worked for a while, it should be retorqued. A torque spanner should join the rigging kit – it will serve equally well for tightening engine head bolts after head gasket replacements.

Include a couple of vice grips in the kit; they help hold lengths of wire during assembly in awkward places. Wire cutters capable of chopping through the largest wire aboard are a must. However, gear minimalists will find that a hacksaw with an ample supply of fine-toothed blades will cut pre-formed stainless wire quite evenly. Just tape the wire on both sides of the cut and clamp the long end in a vice with protected jaws. A small aluminum vice makes a useful addition to the rigging kit

After going over the rigging with a pair of calipers, write down the sizes of clevis pins, toggles, and cotter pins and then buy spares as well as some shackles and link plates to match. Throw in some spare turnbuckles, especially if the ones on the rigging have stainless steel studs. Crevice corrosion, a cancer of stainless steel alloys, starts in the threads. n

Tom Zydler and his wife Nancy live aboard their yawl Mollymawk and are currently based in Ft. Lauderdale.

By Ocean Navigator