Sumara of Weymouth

The Standing Rigging

Reading time: 12 minutes

November 2021

There is the age-old debate for when is the correct time to replace a yacht’s standing rigging. All my rigging has been changed at least once over the thirty-one years that I have owned Sumara. With my planned expedition trip to Scoresby Sund in 2022, I decided to take the plunge and replace all the standing rigging and the halyards. My old policy was to replace a couple of shrouds each year, but I have rather lost track of the paperwork and it seemed more straightforward to just renew everything in one go.

As I was going to replace all the rigging, it could have given me the opportunity to choose synthetic shrouds. I quickly ruled this out because strangely Dyneema actually stretches when it gets cold. Even with a wooden mast, which remains pretty much static lengthwise under varying temperature, I didn’t want to reset all my rigging screws when the temperature drops. I would stick with stainless rigging.

Terry Newman built Sumara and designed the sail plan and the rig. Rigs on Vertues are very varied with masts being deck-stepped and keel-stepped, plus options of gaff rig, masthead sloop rig or, as is the case with Sumara, cutter rigged. Terry had chosen to use 6 mm 1 x 19 stainless steel wire throughout but with the twin backstays being 4 mm 1 x19. As I have owned the boat for 32 years, I have no reason to doubt his choice. If I were starting from scratch, then I would be entering a whole world of differing opinions with very few hard facts to justify the choice. How do you calculate the forces to take into account of boat weight, tenderness, sail area, accidental gybes, slamming etc.? Lloyds were unable to lay down any specification despite being pretty specific on yacht scantlings and suchlike. It’s the same in the lifting industry, cranes are heavily specified on land but once they are mounted on a ship then the Captain takes over. No one is willing to calculate the forces involved on the slew ring when the whole caboodle tilts over to lift the load!

As for tension, then the same thing applies. Crank up the rigging screws too far on a keel stepped mast and you may open up a garboard. Leave them too loose, and the mast might shake itself to bits. The only rule I apply is to try to get the mast even port to starboard with a slight rake aft, and to ensure the leeside rigging is not slack when sailing close hauled in the moderate breeze. I suspect I could probably just feel the tension in the shrouds and get it about right, but I do use a Loos Gauge to tweak things.

I have chosen to use KOS stainless wire rope (316 grade) for all the 1 x 19 shrouds. KOS wire has a good reputation and, when viewed alongside other brands, it is noticeably smoother. The shrouds are all 6 mm diameter except for the twin backstays which are 4 mm. The breaking strength (BS) of the 6 mm wire is given as 2,878 kg. The 4 mm wire has a BS of 1,285 kg. Although the combined strength of both backstays falls short of the BS of the forestay by 308 kg, it is not a problem because the included angle between the twin backstays and the mast is far greater than that of the forestay, so less strain is exerted on the backstays.

The initial constructional stretch in the wire varies between .025% up to .1 % as the strands bed in. To allow for this, I usually remove .05% from the overall length of the wire rope assembly. Realistically the rigging screws can easily absorb this small amount of constructional stretch. Once the wire has bedded in there is some elastic stretch which can be calculated using Hooke’s Law but life is too short to worry about this minimal amount.

Most of the roll swage fittings are selected from Sta-Lok’s range with the exception of four shrouds which required an eye big enough to take a 12 mm hex bolt. I chose Blue Wave swages for those shrouds. The rigging screws are all Sta-Lok chromed bronze type B24 with strap toggles to the chain plates. I like strap toggles to ensure full articulation. I have ordered lock nuts for the rigging screws to allow for easy early season adjustments to be made before the split pins are finally inserted. I renew the split pins every year. The ISO 12324 regulation states:

“Each leg of the split pin shall be capable of withstanding being bent
back upon itself once, with no visible indication of fracture occurring at
the point of bend.”

The implication being that repeated bending would fall outside the regulation.

The length of the split pin should be double the length of the hole.

I have posted the complete parts list and lengths in the download section of this website together with the old rig tensions as of September 2021 measured with a Loos gauge before the mast was unstepped. It was set up evenly at the start of the season so obviously a mid-season rig tension check would have been helpful. However, at no point was there any slackness in the lee shrouds which is a very good sign as slackness causes extra stress. I’ll re-check all the rigging tensions after sailing a few hundred miles and again mid-season in future.

As I have some qualifications from the Lifting Equipment Engineers Association and have carried out thousands of wire terminations and inspections, I will be swaging all the fittings myself using a WireTeknik A200 hand roll swaging machine mounted on a PlanKform in my garage. The machine will swage up to 8 mm diameter wires. I’ve borrowed this machine from my old company to complete this job.

Roll swaging is a relatively simple process requiring a bit of arm strength for the manual hydraulic pump. The crucial thing is that the correct swage is selected for the wire and the correct rollers are used on the machine. All the calculations have already been carried out by the boffins so there is no need to proof load, but it is essential the swage diameters are measured after rolling to check they are within the tolerances given. It is also important the wire is inserted fully into the swage prior to swaging and marked with a Sharpie at the exit point. It can then be held against the swage on the outside and the swage marked where the rolling needs to commence. It will also quickly show you if some foreign object has got into the swage. The Blue Wave swages are clearly marked with a line where the roll compression needs to start. It would be nice if Sta-Lok could do the same.

My old rigging had a copper sleeve compressed onto the wire over the lower spreader and a cable grip under. This time I will be using stainless steel split collars to locate the spreaders.  

A Note on Certification

Occasionally people ask whether their rigging wires need to be “Certified”. All wire assemblies that are used for lifting in the UK and Europe need to be “Certified” and should carry a CE mark plus individual identifying mark and the WLL. They must be supplied with the appropriate paper certification and instructions. However, all lifting wire rope assemblies are made from steel with a strength of either 1,770 N/mm2 or 1,960 N/mm2. Sadly stainless steel is not strong enough to comply with the lifting specification (BS EN 13414-1:2003+A2:2008). Most stainless steel flexible wire rope is only 1,570 N/mm2 so it is not possible to get “Certified” rigging wire in stainless steel. I believe most marine insurance companies are satisfied to see an invoice from a reputable company to show that your rigging has been replaced.

The Halyards

The main, Yankee and stay halyards have now all been remade using 10 mm Liros Herkules in a classic beige colour. Herkules is a high tenacity polyester rope with a good breaking strength of 2,549 kgf and a robust hardwearing construction. For cruising halyards, I reckon it to be the ideal rope. The working stretch of this rope is low at less than 5%. However, it doesn’t hold knots very well, so I personally wouldn’t consider it for sheets, although Liros recommend it for this use. I always secure my sheets to the sails with a bowline, I suppose if you use a soft shackle, or suchlike, then Herkules would be a suitable rope for making sheets. For Sumara’s sheets I prefer to use the softer Liros Seastar which has a matt finish but a lower breaking strength of 1,937 kgf and a bit more stretch.

I have spliced a thimble eye into the ends of all the halyards using the excellent Blue Wave thimbles which seem tougher than most. The splices were following “Splicing Modern Ropes” technique rather than the Liros instructions. The Liros technique leaves the outer cover outside the splice and it is then hidden under a whipping. The “Splicing Modern Ropes” technique tucks the outer cover down inside the rope and only requires a whipping on loosely laid ropes.

I like to avoid captive snap shackles in halyards in case I want to use the halyard for mast climbing. I feel more secure clipping into the thimble eye with a climbing karabiner rather than relying on a marine snap shackle.

End of Season 2022 Note

I have just replaced the hard eye termination on the main halyard because, when combined with the slightly oversized Brookes and Adams snap shackle, it became too bulky and started to wear against the top of the track. I should have checked once the sail was fully hoisted by using binoculars or a telephoto lens, or even climbing up, but I didn’t! Luckily the rope was long enough for me to resplice with a soft eye which I hope will resolve the problem.

I finished the tail end of the halyards with a Flemish eye so they can be reeved with a mousing line if necessary.

Halyard Lengths

a) Staysail Halyard 14,680 mm with Blue Wave Stainless Thimble with 4″ Brooks and Adams fork swivel snap

b) Mainsail Halyard 19,960 mm (After cutting off thimble eye) Soft Eye currently with 4″ Brooks and Adams fork swivel snap but may change to Captive Pin “D” shackle

C) Yankee Halyard 20,050 mm with Blue Wave stainless thimble and 4″ Brooks and Adams fork swivel snap

Mooring Ropes

Sumara is 26 ft long and weighs 5 tonnes. For my mooring lines I use a 16 mm diameter three strand spun polyester rope in a classic colour. It happens to be a Liros product with a breaking strength of 2,200 kg and a working stretch in excess of 15%. Personally, I don’t like Nylon ropes for mooring. Although Nylon is stronger (although it loses some strength when it gets wet) I find that it is just too stretchy. In gale force winds with Nylon warps, the boat would be able to surge along the pontoon potentially colliding with other boats or walkways. I have never found my polyester warps to cause any snatching and I don’t use any fancy gizmos. I also believe Nylon tends to go stiff after a few years.

If I was Channel cruising I would probably have chosen 14 mm diameter warps, but for Northern areas I find a bit of extra diameter is reassuring. Don’t over do it though, as ropes can be heavy especially if you need to throw them ashore. The Liros Classic rope is very soft to handle and easy to coil. I like to put an eye in one end of each rope. The internal length of the spliced eyes is 450 mm and the springs have black polyester tubing slid around the eye. This helps to instantly recognise the springs from the shorter bow and stern lines.

Length wise, my springs are 15 m long and the bow and stern lines are 9 m. I would normally have used the formula of one and a half boat lengths for the springs and one boat length for the bow and stern lines. I increased the springs’ length because I may transit the Caledonian canal in a couple of years and 15 m is their recommended length. I tagged on an extra metre to the other lines to help when moored against tidal harbour walls. I also carry a shorter mooring line normally only used if I am moored in a finger berth and can use an extra short line to pull the bow off the finger pontoon. If I am rafted out, the mooring lines will often reach as shorelines and I have lots of suitable sheet lines that can be pressed into action.

I also carry 60 m of 16 mm polyester Octoplait in a special bag. It is used as a shoreline in certain anchorages or to haul the yacht off a wall in stormy harbours. A floating line would really be better as a shoreline but I don’t have room for both types. I also often use this line for kedging off if I accidentally hit a shallow patch. The rope flakes down into its bag and behaves impeccably. Splicing it is a bit tricky but I have loaded a video of my technique below.

The Classic Colour!

Most of the ropes below were described as “Classic” in colour. Maybe we need an ISO standard!