- Why does it happen, how to prevent it
Part 11 - Conclusions – The Answer to Post Number One
After all that background, now comes the answer to the original questions. Remember, i still haven’t finished answering the very first post yet.
"I understand basically that dismasting is - under rough, windy conditions the mast either breaks or falls over due to some kind of stress failure in the rigging."
yes. you are right. Invariably from 316 Stress Corrosion Cracking
316 is the CHEAPEST crappiest metal you could possibly put on your rigging. as it will look GREAT, (which is why it is used) but it will be riddled with an invisible cancer all the way through.
Rather than stretching, it will brittle snap clean in half just when it is needed most. ie under a sudden sharp stress.
There is no other alloy more primitive, more stupid, and more treacherous. ie it looks perfectly good, solid, sound, SHINY and sexy, but will fail suddenly from an invisible crack, and only then when it has broken clean in half can you see the rust and rot
that was present.
Embedded 316 Bolts and chainplates need oxygen. If the 0.0000013mm protective chrome oxide (a ceramic) coating gets the tiniest scratch, or a microscopic speck of normal steel from using normal tools damages this surface coating, then the entire part can rot
away to nothing.
This is a 316 chainplate deprived of oxygen.
Bolts do exactly the same thing. Sheer madness to use a 316 bolt. They simply disappear, evaporate.
If your bolt has butyl to keep out the water, then you have also kept out the oxygen.
Even if the outside air, oxygen can't get into microscopic cracks, then the 316 bolts will just snap clean in half.
"What I don't fully get is why this happens on modern, production-type boats - particularly a fiberglass catamaran
with a good quality mast and rigging."
Answered by the Crapitalism Paradigm. (Part 5). They all of them call their products the highest quality, when they should all of them actually be in jail for killing, injuring, and maiming unsuspecting people by using the cheapest, lowest quality, and most treacherous alloy they can. 316 was not designed to take stress in salt, it was designed to look nice. Quality and safety never exist until a government
steps in and puts a floor of minimum safety standards to limit capitalist stupidity.
ASME II says 172 MPa for statics (17.2 Kg/mm), VIII says 108 N/mm2 (10.8 Kg/mm2) for pressure. 316 rated, stamped and legal rigging fittings in australia
out of salt water on dry land are rated at one quarter of the proof, and proofed at 90% of the design yield of 316, so 5 Kg per mm2 is legal, but any talk of any safety factors even at this incredibly low level of stress in salt water is just silly, due to the stochastic failure mode of 316 in salt water at 35000 ppm chlorine.
There is NO design data for 316 for dynamic loads in any level of chlorine because that is just so stupid. Yet rigging companies use 170 Kg/mm2
or similar. Astounding stupidity. A prime example of an unregulated industry begging for a government to introduce legislation to put a floor in to limit stupidity.
MacDonalds will sell you a burger with 100% beef in it, but that is lips, eyeballs, and testicles. and this is exactly the same as Yacht building capitalists. They simply must compete with other companies doing this or they go out of business.
the stainless they use LOOKS FANTASTIC! and shiny, but is invisibly ROTTEN to the core
. Do you see how it perfectly mirrors the capitalist paradigm that spawned it?
It is called steel, but it is absolutely not (Steel is tough, steel is iron plus 2% carbon, very tough stuff). It is an IRON alloy that has no carbon in it and so it is very soft, but the chemistry is so primitive and stupid that then it gets very hard and fragile if you give it just one bend, and then it is so brittle that a whole solid metal chainplate just suddenly snaps completely in half. Astoundingly primitive and stupid chemistry.
with simple maths we examined a professional riggers attempt at rigging a new boat that failed twice in 6 months. (he was in the tropics though, and this speeds up SCC vastly)
the poor rigger was probably in good faith using non-engineering data that resulted in the mast stays (probably – as we don't know exactly what riggers know about the 316 alloy and so how much tension they would put on 316) being over the yield strength of the 316 in the rigging, even before leaving port.
"Is it sailor error?"
to do it properly you'd have to dis-assemble the entire mast rigging and do X rays or a dye penetration test every 3 months. 6 months is TOO LONG.
On land out of salt any rated 316 fitting has to be proof tested, all components stamped with the working load limit, and issued with ‘Proof Certificates’. If you tried proof testing your 316 fittings that had lived in salt water in the tropics, depending on the stress they had seen, the temperatures, and the chlorine, I suggest they would fail proof testing within 6 months. If you live in a cold climate with heaps of rain washing
the fittings all the time, then they may last forever. 316 stochastic failure mode says you can never be sure when it's going to fail on you. You should read up on the chlorine ppm, temperature, and stress, and how if they all combine they can kill 316 very quickly.
so the answer is NO. it is not due to poor maintenance
or negligence. SCC is invisible.
"Construction flaws? "
if balsa then bell shaped curve individual fiberglass
strand stress fractures equals gradually loosing stiffness; or, if a foam core
and Polyester then it may be possible as they can delaminate on their first hard sail, and if delamination
does occur, then the hulls become sloppier and sloppier, and loose their stiffness over time, so the stress on the rigging, the chain plate
loading and mast base movement gets worse and worse, until something pops. And more stress gives a much
shorter life. 316 in chlorine stochastic failure mode suggests double the stress gives incredibly shorter life.
you can't expect a little crap 316 rig fitting to take the weight of an entire boat hull
for one million cycles. there should be no load input from the hulls flexing, hogging, or sagging when sailing in heavy waves. the hull
should be stiffer than delaminated foam and polyester sandwich which was designed for cubed stiffness suddenly becoming a linear stiffness relationship allows.
so it is possible for light sandwiches to put more hull loads into the rigging than stiff, heavy hulls.
"Or an unpreventable eventuality that is going to hit sooner or later to anyone sailing blue waters?"
no. it won't hit everybody. some people are TOTALLY and utterly immune from this 316 SCC disease.
Custom made Super Duplex fittings and rope. There is NO 316 anywhere on my rig. Zero. And also the go fast guys who use uhmwpe ropes and composite chain plates. Real cheap, but you have to replace the ropes every so often due to sunlight degradation.
Some guys are starting to use 6% moly alloy chain plates, also in the NEVER FAIL category, others are starting to use 2205 (cheap crap - designed from the outset to be CHEAPER than 304), and other guys are just now starting to use Super Duplex stainless for chainplates.
"IOW, is this a totally preventable mishap, or an endemic risk of sailing open seas? "
yes it is TOTALLY preventable, but you will never do it unless you;
1 - AVOID any professional rigging person; as they will ONLY sell you what they have on hand to sell you, the awful, twisted, sick and perverted fruit of capitalism.
ie it LOOKS BRILLIANT!!! sexy and shiny, and you will fall in love because it looks so beautiful,
but in reality it will actually kill you and your family.
i refer you again to American Coast Guard Alert 07 09, mandatory rigging inspections due to deaths in 29 dismastings over the last 6 years due to 316 Stress Corrosion Cracking
i refer you again to $9.95. They actually, and in reality, will burn you and your family alive for $9.95.
The fruit of capitalism? you are going to SEA, with your family and you wanted 100% beefy fittings, and so that's exactly what they'll give you.
A 100% all beef patty (eyeballs, testicles, and lips. rubbish in other words, but it'll look fantastic) that everybody else is eating without complaining. Yumbo!
2 - AVOID talking to the soul-less vampire muppets that seem to infest this forum. The idiots who drag the tone of the discussion down. The guys who don't contribute or refute with data and instead insult others. The guys who can't use Google
themselves and expect you to google it for them.
The guys that say that there is NO PROBLEM. it was YOUR fault for speaking up.
The vendors who say they KNOW EVERYTHING and there really is NO PROBLEM.
Don't listen to them. if you do, you will just accept your plate full of testicles, lips and eyeballs and start to call it a 100% all beef patty.
The real story is that they have ZERO passion, and so are never willing to do any reading or work.
Other guys raise the tone of any thread, increase the meat in the sandwich, deliver chunky goodness. I skip over the evil muppets of the dark side of the force, and only read the guys who help others.
3 - AVOID reading ANY rigging companies web site. The reason is they do not love you, they want to stay off un-employment, and as a result, they will slowly twist, pervert, and dilute the truth until you start to believe them. This is called marketing
the ONLY thing on their web site is marketing. and YOU WILL be infected, and once their information is in your head
, it will take 1000 hours of hard work to get it out, and arrive at a sensible opinion.
4 - RESEARCH
yourself. it is the ONLY way. Do not let yourself be pushed around by know nothing muppets because they will push you around if they can. On this forum right here.
ie We are PROFESSIONALS, therefore we KNOW ABSOLUTELY what the truth is. absolute dribble. they are capitalists. They know how to quash rebellion, how to keep you in line, how to move their lips so as to get more money
from you. They are NOT interested, and so they have no understanding of the whys and wherefores of why such a perverted reality exists, because they are NOT interested.
IF they were interested then they would have ALREADY done the reading needed to arrive at these conclusions. They would be the guys that knew all this stuff and they would be the ones telling all this to you.
yes, I admit they do know other stuff, and it is great if they actually contribute rather than trying to stifle other people. i ignore people i don't think are straight, as if they were truly interested, then they would have already Googled and be contributing instead of hassling or insulting others; and for those people that are actually interested in the topic and who contribute their time and experience and what they've got, then i do the same.
- do the maths for your rigging yourself. That way you will know exactly where you stand.
- redundant rig design; add a solent stay, add baby stays, nested diamonds instead of a single or twin diamonds. see how easy it is? Cheap too.
- redundant rig design - you can design a rig so that if a single toggle fails, you loose the entire mast, or you can design the rig to be redundant. ie if a single stay fails, then the remaining super duplex stay has more than enough tensile strength to hold the mast up, and with no problems. Use one Super Duplex chainplate per stay
; don't do what the cheap arse capitalists do and have two stays on a single 316 chainplate. Absolute insanity. Astounding Stupidity. Asking for trouble. Just begging for trouble. ie 316 Stochastic failure mode vast
- use titanium toggles - 316 toggles or 316 chainplates will most likely be the cause of a dismasting
- guys have lost
their rigs due to split pins failing (SCC cracking in half and disappearing) so either inspect your pins religiously, or try and learn from seeing all the other people here that have lost
their rigging, and so buy a packet of titanium split pins, or higher alloy split pins. Cost you $5 for an entire bag full. So get your act together. Spend an hour on google. Or order them off one of the guys here on this forum.
- avoid 316 SCC by avoiding 316. use titanium toggles, pins where ever you can. You can order better alloy bolts and pins from heaps of places online. Use anything with 6% moly, or the Super Duplex stainlesses.
- AL6XN or 254SMO chainplates - cheap as. NEVER have to inspect them EVER. Many many
guys have lost their mast due to 316 chainplates suddenly breaking in half. Broken chainplates and all the real tears stories that go with them are all over the web like a rash. Super Duplex Stainlesses are of course better
, and what you should use if you want true, real, and indisputable safety factors that will last forever, and not vanish after 1 year in the tropics as 316 safety factors do, but these will cost you an extra 2 cents. Or maybe SHOCK! HORROR! Having to get up off your fat arse and drill a hole yourself in some flat bar.
- order Super Duplex wire rope - there are many companies out there that build these ropes - Ferralium 255SD50 has a big edge due to being the most modern chemistry available, the copper increasing malleability, self healing microscopic cracks via electrolytic deposition, and side stepping cold work hardening due to thrumming at frequency while under heavy load. Never fail. Absolutely never fail.
- If you listen to capitalist verbiage, you will go as soft in the head
as their hulls are after the first hard sail. Their smooth honey marketing will seep into the cracks in your brain, much the same as water flowing into the cracks and crazes of their cheap polyester.
So go and talk to a boat builder
instead. Commission a custom build with hulls that will still be stiff after the first hard sail.
- 316 cold working can kill a part in months ( promotes metal fatigue and SCC by a HUGE factor ) but with other modern alloys you can't even make manufacturing fabrication mistakes
- 316 wire rope - just stunningly ridiculous. the concept
of 316 used under STRESS in salt is so stupid it hurts. Metal fatigue wise, stress hardening wise, SCC wise, yield data wise, swaged fittings wise, rig tuning wise. the whole concept is so stupid it hurts. Download a scientific study on 316 SCC and read it. It won't kill you.
- swaged fittings - hide the fractured 316 strands, and promote metal fatigue due to both a change in density when pressure/shock wave frequencies hit the boundary layer of the structures density change, and swaged fittings promote cold work hardening. Swaging WILL promote fractures close to this boundary. (heaps of pictures of this phenomena on the web) so use swageless only.
- pushing too hard – the faster you sail, the stresses rise exponentially, but the life expectancy of the 316 fittings falls even faster
. with a true math rig in any MODERN alloy of course this would not matter, but with 316 rigging it matters a great deal.
- temperature plays a huge role. ie a 316 fitting is stressed for 10 years on a yacht in a cold country, so there's nothing but tiny microfractures that never grew, or they are only growing very slowly. But then one day the yacht gets sailed somewhere warm and tropical. The salt water fills all these tiny cracks that have never given any trouble and suddenly Stress Corrosion Cracking
explodes, and grows a hundred times faster due to the temperature. 6 months till dismasting would be about right.
- you want a modern cars performance, and would hate to have to accept the performance of a horse and buggy. It would drive you mad. You would hate to be forced to accept the performance of a record
player versus an MP3 player. The modern product beats the **** out of the old version. 316 is no different. You have a modern, sexy, no expense spared racing
yacht? And you're still using 316 rigging parts? If you use a modern alloy you will get exactly the same performance increase. ie an astounding difference. Super Duplex Stainless Steel
. Say it . . .
- Google images
“dismasted “– thousands of people dismasted. most are racers. They spend a million on the sexy yacht and nothing on upgrading from crap 316 to Super Duplex wire and fittings. It is so easy to avoid being dismasted.
3 cents molybdenum the difference between being dismasted and loosing a race
and winning. If they really were serious they'd spend the tiny bit extra like me.
- some modern cats are being made very very lightly, as less material used equals a cheaper boat, but it also means less inertia (stiffness), so they therefore transmit more of the whole boat flexing loads into the rigging. Have your hulls strong enough to take any wave loads without buckling, hogging, sagging, or flexing, and without transferring ANY hull displacement
loads into the mast rigging.
- if you absolutely must be a racer
and so foam or balsa are your only options, then DEFINITELY use the SUPER DUPLEX wire ropes, as they can take FAR more punishment than the mere 0.2% yield data indicates. Orders of magnitude more punishment than the simple yield figures indicate over 316. (ie chlorine, temperature, crevice corrosion, stress corrosion cracking, fatigue especially etc etc etc). You will then never loose your rigging.
- if you absolutely MUST use balsa, understand that even if a hard stressed balsa sandwich doesn't bell curve sloppy glass, then the balsa is absolutely going to rot away, again leading to an (alleged) cubed sandwich stiffness dropping to single thin laminates either side of some rotted powdery wood stiffness. Make sure you treat every single piece of it with boron before you fiberglass. (use nothing else, only boron (as chemicals will break down or decompose or degrade over 20 years)). Make sure you read all the thousands of posts on the boat building forums
of guys having to strip out rotten balsa. If there is one thing balsa does, it's rot.
- Light cats are MUCH better than heavy is the perfunctory mantra. And it's dribble. They are competing to stay in business and sex appeal equals selling product. Half the weight of materials equals half the cost, therefore a much cheaper boat. That is the product they have to make to stay in business, so their spin doctored verbiage then turns the negative into a positive. Marketing works. Therefore the normal mantra today is that everybody knows cat hulls should be half the weight they should be. Everybody knows this. But Ponder the inertia and life expectancy of light hulls versus wood sandwich, solid glass or steel hulls. You can side step some of the vibrations heading into the rigging by using different, better alloys that can easily take the cycles. Or you can buy a dye penetration kit and check your rigging often and replace all the different bits that keep failing and breaking all the time. Me? I'd be ordering those titanium toggles real quick. And i'd install Super Duplex chainplates straight away.
(This is off topic, but I couldn't help myself. Perspective is everything. “Cats are more weight sensitive than yachts”. You hear that so often, and it is True, but why? Only because your 10 ton cat doesn't have 5 tons of lead in it's bum in the first place (to be on par with a yacht). So any less lead than this, must be a pure bonus. All gravy anyway; “Cats must be light to sail fast”. Again true. But for every 400 Kg extra load, my cat sits 1cm lower in the water. Ridiculous buoyancy. Ridiculously huge extra load carrying capacity. And how much of a difference will 1cm extra displacement
make to sailing FAST? So these statements are all perfectly true, and yet utterly silly. Formula One race
car owners talking to Caravan owners really. So yes, everything the light hull, go fast boys say is true, but they also have carbon fiber toilets and the handles sawn off their toothbrushes. Not a home, a toy.)
- Sex sells – ie going FAST! sells. And everybody knows that cats must be as LIGHT as possible to go fast. (as forced by the demands of capitalism post ipso facto rationalisation) And so there are astoundingly light balsa and foam things out there that look just fantastic. smooth, sleek, and sexual. Great for racing
. But a lightly built racer
is vastly different from a heavy cruiser in terms of life expectancy, the beating they can take from waves, and what hull loads will transfer into the rigging. If you already have a Polyester, foam or balsa boat (admittedly GREAT affordable fun toys) you really should give serious thought to replacing whatever you can with higher alloys. Cost you very little if you do the work yourself. Going on a big cruise
to the tropics? Replace whatever parts you can with a PREN above 40 alloy. Titanium or Super Duplexes mainly.
- Safety Factors and Capitalism.
Safety factors my arse. A safety factor of 6 is what they are talking about. just remember that. and what does a safety factor of 6 TRULY mean? Zero. Absolute zero safety. Which is exactly why we are having this conversation. If you want to get real, get a safety factor on your alloy first.
And then do your maths, keep your safety factors inside the yield, and ignore capitalists utterly (because there is no law forcing them to real safety standards as on land, they mouth off complete dribble instead). This is the only way to get what normal everyday people would call approaching real and true safety factors. Remember though, there really won't be any safety at all, as susceptibility to Intergranular Corrosion "eliminates any
safe stress level".
Capitalists will blind you by science, by maths, by claiming their own years of experience, they will sooth your fears, they will pour honey in your ear, they will tell you black is white. They'll do anything, except do it properly, up to beyond reproach quality, as demanded by law on land.
They will sell you nothing but what they have on hand and on the shelf.
They will do anything except spend the $9.95 extra the job actually needs.
- Remember; a safety factor of 6 means that the wire is already deformed, rubbish fit to be thrown out, and would be thrown out by any professional engineering firm on land, as they would go to jail if they tried this sort of deceptive maths on land based rigging.
- If any of your crew is injured by falling rigging, then sue your rigging company. Make them explain how the safe load allowable on land is 5 Kg/mm2, and yet they sold the rig to you while alleging and alluding that they actually had a safety factor of 6, when in reality they were using 170 Kg/mm2 and claiming safety factors on that, and that is still excluding the fact that the actual alloy they used has absolute zero safety when used in warm salt water, as it fails randomly.
If for normal, dry land, rated and stamped 316 lifting and rigging safety factors as required by law are to be inside the proof strength, then by using Breaking Loads, how many percent are yacht rigging firms really out when they say they have a safety factor of 6?
They sure sound like dodgy criminals to me. Any jury of normal people would be convinced they were con artists being deceitful. This is because they are
knowingly misleading you as to the true safety that actually exist.
"is this a totally preventable mishap?"
316 is the CHEAPEST crappiest metal you could possibly put on your rigging. and the reason it is used is because it was great 100 years ago when people had nothing else. So it slowly took off and became a tradition. De Rigueur. The yacht standard. And if you never stress it, it looks good.
it is merely a legacy tradition from the time when they used to cure all disease with leeches.
316 is exactly the same as leeches. and of exactly the same quality, calibre, and stupidity. Surely one single photograph here on this thread is proof enough that something is very very wrong.
In some countries it is illegal to use in building structures exposed to salt. If you used it you could be sent to jail, sued etc
Why mast rigging fitting companies have escaped any law or legislation so far is beyond my understanding, particularly as deaths have been caused by their negligence. Of course they know more about metallurgy than you or me. They know all this stuff. Yet sell it anyway.
the stupidity of using instant fatigue (one bend) 316 under stress in a tropical salt environment
cannot be over stated.
hmmmmmmmmmmmmmmmmmmmmmmmmmmm . . . . . .
316 is ace
should be diligent
you know nothing, 316 is the best
you know nothing, and vendors are ACE!
you know nothing, and vendors are ACE!
dye test at 5 years
316 is good
all these replies were FUN, and i did enjoy reading all of the answers here.
I had a personal interest in this subject because I was recently designing my own rig to never fail, and so passion had motivated me to hit this subject hard many months ago. After reading all the answers, i felt that nobody else was really interested, or had put in 100's of hours of study, and so arrived at my own conclusions. I felt that some people knew less than they should, that some were actually saying that black was white, and some were actually just speaking out of their arse.
So i tried to answer as best as i could,
to the best of my ability,
and to the full extent of my own understanding.
hope you enjoyed it,