I am not an experienced rigger and have only owned yachts for about 12 years so do not pretend to be an expert. I do however have a university degree in engineering and my hobbies over the last 40 years have included building and racing cars.
Stainless Steel cables on suspension bridges such as the golden gate bridge in San Fransisco are not replaced at such short periods and I can see no reason that standing rigging should be replaced automatically at 10 years. I cant see why the rigging should not last 25 years or longer subject to thorough and regular inspections and a knowledge of the rigs loading history.
I have owned my current boat for about 8 years and in that time have replaced a turnbuckle on starboard shroud about 5 years ago, and the forestay using norseman fittings about 2 years ago.
The reason I replaced the forestay was because of concern of the substantial lateral loads imposed by the furler. I disassembled the furler to service it and check the forestay, and although the forestay looked perfect I decided to replace it whilst I had it lying on the dock. The fact that it had norseman fittings installed made it easy and cheap(er) .
Perhaps the recommended 10 years is a constraint of swaged fittings which in my opinion are inferior to the "norseman" type, or perhaps a result of the fact that we are constantly manipulated (ie screwed) by lawyers, insurance companies, and corporate "suits" whose opinions override good engineering and scientific advice.

On my little H28 main mast I'm using 6 mm rigging wire and 7 mm on the fore stay a Ill be fitting Pro furl C320 furler. I think the max wire thickness is 7mm for the fore stay
Some use 5 mm some 6mm and some 6.5 mm all round there H 28
Hoping( will be) to buy Korean rigging wire rather than the Chinese wire
As far as swag and swag less Ill be using the later swagless.
Unfortunately my Norsman fittings are now redundant as there no longer manufactured
My original main mast spreader wire diameter was 8 mm 5/16 I think Ive found some cones for 1/19
I feel 8 mm is a bit of an over kill

I'm inexperienced and unqualified so you might want to ignore everything I say (I have bachelors and masters engineering degrees but they are not
in this area).

Yara said..
I think there are two main modes of failure- fatigue and crevice corrosion.

Unfortunately though as soon as you have:

* any pitting, crevice corrosion, or rusting due to iron contamination.

* some tension, as little as 10 percent of the yield strength of the wire (it is normal to tune the rig to 10% to 12% of the maximum strength on
the lowers, 12 to 15% on the intermediaries, and 15 to 20% on the uppers - "The Riggers Apprentice", Brion Toss)

* the presence of chlorine compounds. "The chloride levels necessary are very small, well below the levels normally found in sea water"
- "The Boatowner's Guide to Corrosion" by Everett Collier, p.209 (sea salt is a chlorine compound: sodium chloride)

Then austenitic stainless steel (including 316, 316L, 304 and 304L) are prone to chloride stress corrosion cracking (CLSCC). CLSCC is temperature
dependent. It is observed to occur at temperatures between 25C and 40C in austenitic stainless steel, it is more rapid above 60C.

"The rate of crack propagation is strongly dependent on temperature but is relatively unaffected by stress intensity. Rates of CLSCC propagation can
vary from 0.6mm per year at near ambient temperatures to >30mm per year at temperatures approximately 100C." - from the literature review in
"Chloride stress corrosion cracking in austenitic stainless steel", R Parrott, H Pitts, 2011. Note this paper is about CLSCC in the chemical
processing industry, so I guess you can argue that I am quoting research out of context if you like. After all, Everett says "Stress-corrosion
cracking in as a rigging concern is a bit controversial." I am inclined to think the root of the controversy is companies wanting to sell
us stuff made out of old alloys that are susceptible to it though. Anyway, Everett concludes "Given the cumulative concentrations of salt
crystals referred to above and the temperatures that can occur on metal surfaces under a blazing summer sun, especially in the tropics,
this writer comes down on the side of those who feel that stress-corrosion cracking is a possible, even likely, explanation for some
otherwise unexplained rig failures".

Since CLSCC is temperature dependent, the rigging life will depend on the climate the sailboat is in.

Practical Sailor recommend 10 to 12 years replacement for the rigging on a typical cruising sailboat - PS Advisor: Replacing Wire Rigging,
Jan 2010 issue.

The US Coast Guard in Hawaii after a review of a rigging failure of a swageless terminal on a charter catamaran in Hawaii (a fatal accident)
require replacement at 6 years for wires, 12 years for the fittings, and 18 years for the chainplates.

Crevice corrosion and then stress corrosion cracking can occur in the threads of the bolts that are holding the chainplates, or behind the
chainplates where they are attached to the knees or bulkhead, or commonly in the section of the chainplates that are hidden by the deck they pass through.
Or in a swage or swageless fitting. Swageless fittings can be opened periodically to check if the caulk that was applied during their fitting is keeping
out the salt water to avoid the crevice corrosion.

The biggest single cause of dismastings is chainplate failure ("Hidden Causes of Rig Failure" - Brion Toss, Practical Sailor May 2015 Issue).
You can avoid the stress corrosion cracking problem with chainplates and chainplate bolts by using a metal that is resistant to CLSCC in the chainplates,
bolts and washers, such as "6 Mo" (6 percent molybdenum) alloys - 254 SMO, 20Mo-6 or AL-6XN. Or titanium.

It seems hard to avoid though in the rest of the rigging, as all the commonly available rigging components and wire are made in 316 stainless steel.

If we were rich we could import Aminox 255 stainless steel wire from Smiths High Performance in the UK or super duplex stainless steel wire
from S3i Group also in the UK. That would only remove the problem in the wire though. I think Aminox 255 or super duplex wire would last a lifetime,
but the insurance companies could probably not be persuaded on that though. I am thinking it might be better to spend time and money on the
chainplates, bolts and washers, swageless terminals, and the mast before going to such expense on the wire.

if you can afford to drop the rig and replace it then don't insure it.

They are pretty clear on their rules around it. I wouldn't fight them and as such replaced my rigging last year even though a rigger said it could go a few more years.

My bet would be that the insurance company would take the rigger to court to prove his opinion or try to take the cost of the new rig from his professional liability insurance. So any opinions on rig durability should come in writing from a person with all the applicable insurances, not just public liability.

Lots of good technical info here but not a lot of answers on when one needs to replace standing rigging. Everywhere from 6 years to 30 years.
Does anybody have personal experience of a rig failure where they knew the history of the rig and the type of failure that occurred? I don't include loss in a roll over as that has little to do with rig age. Personally, I don't know anybody who has had their rig go over the side except in a roll over.

Yara said..

MorningBird said..
Lots of good technical info here but not a lot of answers on when one needs to replace standing rigging. Everywhere from 6 years to 30 years.
Does anybody have personal experience of a rig failure where they knew the history of the rig and the type of failure that occurred? I don't include loss in a roll over as that has little to do with rig age. Personally, I don't know anybody who has had their rig go over the side except in a roll over.

You hit the nail on the head. Time is really only a very blunt instrument to judge the condition of a rig. All the theory in the world cannot cope with the huge range of variables of different boats, usages, and material qualities.

Nowadays there is another variable of concern. The quality of materials on the market, especially when it comes to metallurgy, can be very suspect. The average Joe or rigger cannot tell by looking. All you can do is to buy from reputable brands, and hope that they have not succumbed to cost pressures and sourced from dubious suppliers.

It seems that if you want insurance, you just have to submit to their requirements. Otherwise look very hard at the rig, sail very conservatively, and dont carry passengers who could sue you.

BTW many small boat owners have reported failure due to crevice corrosion of chain plates, particularly the U bolt type. Luckily most that I have heard of still manage to hold up the mast while the owner hurriedly drops the sails. In my personal experience, the U bolts were corroded half way through, but had not yet failed. There was also a case a few years ago in WA where the rig dropped due to a backstay failure, and the crevice corrosion could be clearly seen just inside the fitting.

Agree. Some good ideas and discussion I feel.

I am not concerned about the insurance of the rig as I don't expect to lose it outside losing the boat, in which case the rig is covered, at least by Paentanius.

Risk is assessed through the probability of the event occurring and the consequences if it does.

In making a risk assessment probability of the event occurring always has to come first. If you start with consequences, the worst consequence of going sailing is everybody onboard dying. A catastrophic outcome so nobody could go sailing. We know the probability of the worst case is very very low so we assess the risk as low.

The consequences of a rig failure are easily determined through others experiences and can include fatalities. Let's not start there, let's start at determining the probability side of the risk assessment.

I know of only one S&S34 that lost its rig, a MacAlpine built boat in light airs off Norah Head that had a shroud chainplate fail due to corrosion of a weld below deck level. Poor design and construction. Swarbrick shroud chainplates are one piece.

The only two S&S34 rollovers I know of (Solandra in the 98 Hobart and another boat going to NZ) didn't damage their rig and kept sailing.

There are many S&S34s sailing all over the world, many I would hazard a guess, with very old rigs.

Are there higher risks to worry about than replacing standing rigging because an insurance company says they won't cover it if you don't. They may not cover the rig even if you do replace it.

Anything which passes through the deck is a candidate for crevice corrosion. Even a solid piece of steel. Look carefully at the sealing, and for tell-tale signs of rust marks.