Dismasting - Why Does it Happen - How to Prevent it

[roverhi]

PooBeetle, you're paranoid.

[Sailmonkey]

Poobeetle,

Do you have a boat? Is it made of unobtainium? Do you sleep at night?

[sparau]

Originally Posted by PooBeetle

The lack of fixity between the two stiff layers of glass on either side of the foam results in movement which starts to stress and break the glass in micro scale. Even attached good glass on foam loses around 10% of its' stiffness in the first year.

i dont know boat construction but wouldn't it be fairly easy to place posts through the foam for the outer epoxy to key to?

[PooBeetle]

Dismasting - why does it happen, how to prevent it
Part 7– Fittings

316 Stress Corrosion Cracking is invisible. It is a chlorine or salt catalysed microscopic path inside the metal. If there is visible rust, then it is crevice corrosion, and you are lucky because you can see it. With SCC the part looks perfect, and then suddenly splits completely in two without warning.


Dismasted by SCC of a 316 toggle. The surveyor said the boat was exceptionally well found, and the rigging had just been inspected.


Note how all the metal outside of the crack is utterly unaffected.

316 Split pins and Split Rings
If these fail, you're stuffed. And they fail routinely, due to all the above mentioned 316 metallurgy factors. If a big solid metal beefy part like a chainplate can just snap in half without warning, how fast then do you think the SCC will happen in a tiny 1mm diameter split pin?

Guys have lost their masts due to a single tiny little 316 split pin becoming brittle and then breaking in half, and so then the main pin works out.

Imagine loosing your entire rig for the want of a 20 cent part. And it has happened.




316 Bolts
Using 316 Chainplate bolts? Madness. Bedded 316 breaks, rusts away, evaporates, turns into mush. You simply can't find a worse or more stupid alloy to use. It will look AOK on the outside and be broken completely in half inside. Madness to use 316. Surely your brain can see that something is wrong here.



Swages
The mechanical press cold worked the outside of the swage, so the 316 swage is now brittle and ready to crack. There will be salt water up inside and the now cold worked and brittle wire rope will never dry out. Any microscopic cracks produced by swaging will be permanently wet on the inside of the fitting. The density change boundary, where the wire rope meets the swage will be where most of the energy from the thrumming and the stress waves will be absorbed and transduced into thermo/electro/chemical/mechanical changes.

The result is that any small crack has buckets of energy available to grow. So both the wire rope strands and the swages fail all the time at the union.

[PooBeetle]

Turnbuckles
Note how shiny the turnbuckle looks. The fitting looks perfect.You generally can't tell that micro-crevices and microscopic stress corrosion has rotted all the way through the entire part.


Attachment 45636



Remember the Seawind catamarans Vendor guy? - “316 is the best possible quality”


here is a photo of his best possible quality. Wonder if any friends and family were killed? If family were killed, I wonder if they could send the company out of business if they sued? Perhaps Seawind should read up on Australian Law (Rigging safety requirements). Was the PREN above 40? for the alloy used?


New Seawind Catamaran turnbuckle.
Attachment 45637


This is from a new Seawind catamaran, and note how good the turnbuckle looks. The fitting looks perfect. So we know that the alloy used was a cheap, stupid, old PREN below 40 alloy.


Toggles
SCC. 6 months old this toggle. Free replacement parts from the manufacturer; and exactly the same thing happens again. Is it possible to learn from other peoples mistakes? Are we learning yet? The fitting is NEW. And looks perfect. It is 316 that is the problem.





Metal Fatigue. You bend 316 in the vice and it goes hard. it has work hardened. Gone extra hard, but extra brittle.

[PooBeetle]

Chainplates
you are all insane – all of you. To use 316 for a chainplate when any 6% moly will NEVER fail on you, and never have to be checked, EVER.

Dismasted, Kiribati



There are one thousand MODERN alloys that will never fail on you. Not ever. Not even look like they will fail.



316 Crevice Corrosion happens in an anaerobic environment and it is unavoidable with bedded stainless hardware. If your 316 is fabricated correctly, then hand polished to remove micro-crevices, and after that electropolished and/or citric treated, and then you still have to get them dye tested, or X rayed, and surveyed often, and even AFTER all this endless dribble, they will STILL look perfect and fail without warning and kill, injure, or dismast you in the middle of nowhere. SCC is the heart of the entire matter.



endless dribble, and ZERO safety, all from trying to use the cheapest crap that is not up to the job in the first place. There is no worse alloy for SCC.

use titanium, or a 6% moly, or a Super Duplex alloy.

it actually costs LESS than buying 316 chain plates new from a shop if you are able to drill a hole. (as flat bar + drilling holes equals chain plate)

and yet so many people have lost their mast. Broken chain plates are all over the sailing forums like a rash. They break clean in half with no warning.



here's the 100% BEEF patty capitalists supplied you with. Can anybody see there's a problem with 316?


vendors say 316 is the BEST quality. I Can't wait to wrap my lips around this 100% all beef patty (in the middle of the pacific, a thousand miles from shore, in a storm). The bit that's visible looks fantastic though.





SCC = a new, good looking solid metal part splits completely in two without warning.


PREN >40 = safe forever. Actually legally allowed to be called salt water resistant.


If you use 316 for a chainplate you're insane.

[PooBeetle]

Dismasting - why does it happen, how to prevent it

Part 8 – Rig Design

Why is your rig designed the way it is?
Sex.
Sex sells. Ugly doesn't. If cat makers didn't produce a desirable product, they'd loose business. Who wants to buy an acknowledged slow mobile that comes last, behind all other cat manufacturers, when the HOT chicks all like guys who drive Porches and Ferraris. Given the choice, you will always buy the Desirable, lusted after version. Nobody wants to sail slowly, like cruisers, in heavy, long life expectancy, tough boats. When they hit the dance floor, they want flared trousers, a wide collared shirt unbuttoned and open to the waist with a gold bar on a necklace and bling. So there is competition between manufacturers. They don't want to loose business, go broke, and flip burgers for the rest of their lives. They want to stay in business and sell boats instead.

So we visit every single one of their web sites, and they all say exactly the same dribble. We are so safe it's bizarre, and yet our boats are also FAST.

Any time they mention performance on their web site, it's speed, and not longevity (true safety) they are talking about; they all say their boat is fast.

As fast or faster than everybody else. All of them say exactly this.

So exactly how do you set about being a WINNER! ? Every body here already knows how to be a winner.

You have to increase the power to weight ratio. And since you can't change from polyester/foam due to cheapness and astounding speed of manufacturing, then you have to increase the sail area.

More i tell you, MORE! I tell you, MMMMOOORRRREEEE!!!!! sail.

If you don't keep up with the Jones'es they will stay in business, and you will go out of business. So more sail than is prudent is the new capitalism market forces derived normal.

Cheap sloppy lumps of polyester poo driven hard, a thousand miles from land and with the worst, cheapest, most treacherous type of steel available (316) rigging fittings under heavy loads in chlorine.

Boats with a higher power to weight ratio will fail more often than those with lower power to weight ratios. (Kg displacement per meter of sail)

You can either buy a car off a little old lady ( a slow volvo station wagon with low miles on the clock) or a twin turbocharged nitrous injected V8 off Peter Petrolhead.

There is a difference in the life expectancy. Google images “dismasted” – endless thousands of people get dismasted, but most are racers.

[micah719]

Back when sail was amusement for idle rich and royalty and the rest went to sea for work, the materials were natural. The sails blew out more often than the rigging, a kind of safety valve. Now we have polymers stronger than steel and wonder what's wrong when the weak links happen to be essential components. Because it's the way it's done....habit, convenience, convention, status, and for some, profit. Nice pics PB

[Factor]

Originally Posted by PooBeetle

TurnbucklesRemember the Seawind catamarans Vendor guy? -

If you are referring to me I dont recall saying that?

“316 is the best possible quality” here is a photo of his best possible quality. Wonder if any friends and family were killed? If family were killed, I wonder if they could send the company out of business if they sued? Perhaps Seawind should read up on Australian Law (Rigging safety requirements). Was the PREN above 40? for the alloy used?

The facts on this matter are probably best obtained from the owner of the boat, here is a link to his blog. Ronstan Fitting Breaks. Short story is that Ronstan had a failure in a batch of fittings, this was one, no one was hurt, it was all fixed in a day. Of course it would have been better had it not happened.

But Poo Beetle already knows that - he got the photo off the owners blog site so he knows no one was hurt, he knows it was fixed and he knows it was a ronstan issue. Builders can do little more than use quality suppliers.

Poo can preach the evils of stainless as much as he likes, matter for him, but abjectly false and disingenuous statements like this don't serve him well.

New Seawind Ronstan Catamaran turnbuckle.

(fixed)

[Factor]

Originally Posted by PooBeetle

.......snip........Can you now see the difference between using leeches for a headache versus using an aspirin? And then wondering why the leeches dismasted you and killed people.

Just a quick aside folks. Unless you can find your own leeches for your headache, please don't buy them, because medicinal leeches (Hirudo medicinalis) are covered by the Convention of International Trade in Endangered Species.

The medicinal leech is classified as Near Threatened (NT) on the IUCN Red List (1). Listed under Appendix III of the Bern Convention, Appendix II of the Convention on International Trade in Endangered Species (CITES), Annex V of the Habitats Directive, and protected in the UK under Schedule 5 of the Wildlife and Countryside Act, as amended.

Sometimes I wonder how I know these things.

[micah719]

Leeches, Roaches....I haven't a clew. Back on topic....must look at cases of dismastings of unstayed rigs.

For the Cal Yawl project, reasons of budget and availability are tempting me to bamboo-epoxy laminate masts and booms. Especially the midnode external fibres from the top culms of Tonkin cane, with a glass wrap to counter the weakness in shear. Probably the world's biggest flyrods, though the layup would be hollow tubes-in-a-tube for low weight and stiffness. Doing that, I'd better look again at the mast partners and parrels; better sacrificial components with spares, rather than ripping the partners off the decks....

And for the 316SS wire question.......isn't galvanised wire safer than stainless? Are the loads below the fatigue limit?

[Jim Cate]

Originally Posted by micah719

And for the 316SS wire question.......isn't galvanised wire safer than stainless? Are the loads below the fatigue limit?

G'DAy Micah,

I'm not sure w hat Poo's agenda is, but his rants seem to ignore the tens of thousands of boats rigged with 316 (or the even worse 302/304 more commonly used) whose masts have inexplicably remained upright.

So, galvo wire safer than s/s??? Well, I guess that it all depends on what failure modes you worry about, where you source your wire and what sort of terminals you select.

From previous discussions here on CF, it is becoming difficult to obtain high quality galvo wire... especially with respect to the quality of the galvanizing. If there are any spots in the wire which are not perfectly galvanized, rapid failure is a possibility here as well.

If one has the ability to hand splice galvo wire (a la Larry Pardey) very reliable terminations are possible. Otherwise, folks tend to use Nicopress or other swaged ferrules to form eyes in the wire, or some form of mechanical terminal, and these have similar failure modes to terminations in s/s.

Back in the "good old days" (ie 1985) one could buy 1x19 wire made from Nitronic 50 alloy, something that even Poo would like I think. Sadly the plant that made it was sold to China and the whole thing exported, and AFAIK the wire is no longer available. It was really good stuff... cost about half again what 316 did then, but was pretty much good forever if not overstressed.
Now I'm not sure where Mr Poo thinks one can source his magic high Molybdenum alloy wire, doesn't seem to be from any of the regular suppliers. But as I (and others) have pointed out, the incidence of wire failure is pretty low, especially when you realize how many boats with really old s/s wire are out there sailing.

As far as unstayed rigs, there are a few Freedoms, Wylies, Nonesuches and so on whose mast data may be available via their owners groups or perhaps the builders. It is certainly t rue that the unstayed rigs have far fewer potential failure points than conventional rigs, but the stresses on the partners and step as well as the mast itself are large, complicated and critical. Some careful and qualified design work should go into such a rig IMO, not unsubstantiated guesses by an amateur NA.

Cheers,

Jim

[Stumble]

Micah,

Bamboo is wholy unsuited for use on boats. For all it's advantages in other areas it just doesn't have reasonable characteristics for marine use. The biggest problem is that it rots very fast in the marine environment. If you are trying to build a cheap mast, at least look at a hollow wooden mast. It will be a much better option.

As Jim pointed out, unstayed masts are very hard to design well, and take specialized skills and knowledge. Way beyond what an amature builder/designer will have. It might be possible to design a free standing wooden mast, but I can't imagine anyone but a very knowlagable designer pulling it off.

[ewsponberg]

Originally Posted by Stumble

Micah,

Bamboo is wholy unsuited for use on boats. For all it's advantages in other areas it just doesn't have reasonable characteristics for marine use. The biggest problem is that it rots very fast in the marine environment. If you are trying to build a cheap mast, at least look at a hollow wooden mast. It will be a much better option.

As Jim pointed out, unstayed masts are very hard to design well, and take specialized skills and knowledge. Way beyond what an amature builder/designer will have. It might be possible to design a free standing wooden mast, but I can't imagine anyone but a very knowlagable designer pulling it off.

As a matter of fact, there is quite a good book called "Practical Junk Rig" by HG (Blondie) Hasler and JK McLeod, first published in 1988 by International Marine, now available from Tiller Publishing. This book tells you how to design and build hollow wood free-standing masts. The authors admit to not being naval architects, but their method is straightforward, practical, and produces reasonable masts. You don't have to set junk sails on them--any sorts of sails will do.

Blondie Hasler, you may recall, sailed a junk rigged boat called Jester in the very first Transatlantic Race in 1960, a race that he had conceived. That boat went on to sail many other Transatlantic Races under the ownership of Michael Richey.

I've reviewed the engineering of the wood mast method in the book, and it produces reasonable masts for smaller boats, say under 40'. They are heavy, but they are cheap and relatively easy to build. It's a good book if you are seriously interested in building your own mast.

I agree that bamboo is totally not suitable for a free-standing mast, particularly one covered with fiberglass. It would not have nearly the strength and stiffness required without adding A LOT of weight.

I personally don't have any statistics for broken free-standing masts, and having been in this particular business, involved in their design and engineering for over 30 years, I would probably know about it. I can only recall a few instances in which some aluminum Nonsuch masts failed due to fatigue in the aluminum, I think, but I don't have any specifics, and that was a long time ago. There have been no recent happenings of aluminum, wood, or carbon fiber mast breakages, even amongst boats that were built in the 1970s and 80s (approaching 40 years old now), at least that I have heard of. Such dismastings are extremely rare, much rarer than for stayed rigs. The only breakage stories that come across my desk, and these are very rare too, are the ones where the boats hit bridges, had collisions, or the mast got hit by a truck or fork lift, which I think I mentioned earlier.

Eric

[micah719]

I wouldn't dismiss bamboo so quickly.

It is a grass and has some major drawbacks compared to wood and the usual downside that all organics have. However, it also has some excellent properties that are hard to beat, and its disadvantages can be overcome.

The structural fibres are composed of cellulose arranged with much better tension properties than wood fibre. The concentration of these power fibres is highest in the outer layer of the culm, and toward the top. It matures in three years. It is cheap and readily available, though not at well as it could be.

The nodes prevent buckling and splitting in the culm in its natural form, but present problems for using it structurally. One way around this is to use the internodal fibres only. Flyrod builders have done this and found it is less work to splice these splints than to heat flatten or cut the nodes flat. Bamboo has to be heat treated anyway, and doing it one time only is much simpler and safer. Spliced together and then laminated, one can have a material that has the excellent tension properties and superior compression strength of bamboo, and better overall homogeneity compared to lumber. Since the laminated mast is internally subdivided by the glued joints, any water damage is better compartmentalised compared to wood, as are any checks. If one uses a waterproof glue and is careful to work accurately and consistently, there is no reason why one can't have a straight, stiff, flexible, light, tough and very strong hollow mast.

The more I hear of aluminium the less I like it. Carbon would be nice but it's expensive and when it breaks it is sudden and complete. Steel is too heavy for the little boat but still viable for the big one.

Birdsmouth hollow timber or laminated bamboo are the two best options for me and I see the bamboo as being the better structurally. Nobody is doing it much yet, I suspect mainly for labour reasons rather than the other properties of the material. Engineered bamboo is becoming popular on land, it is only a matter of time before it does so on the water.

The unstayed mast seems to be the way to go. That it isn't more popular than the stayed has a lot of reasons, and I wonder how much of that is influenced more by status-quo and the better repeat-business for the rigging industry.

I've already started on the laminated bamboo and will ramp up the speed and do some proper testing and see if the reality matches the researched theory. There are two aspects I'm especially aiming at; stiffer mast and more flexible spar, for the dipping/standing lug yawl rig. That should be a worthy test-bed. Now if only there were more water and better winds here....anyone care to ship me some?