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Old 11-05-2014, 05:24 PM   #41
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Practical Sailor newsletter had a nice article on anchors, going through the composition of the flukes/blades and shanks and such. Several of the anchors had hardened flukes/plows/whatever digs in, but almost all had relatively soft shanks. I don't remember the details in the article, but it gave good reasons for the type of metal in each part of the anchor. The Manson boasted an exceptionally hard grade of steel in their blade as I recall.

They bent quite a few shanks in the testing, some to extremes. Most showed minor deviations from straight, the difference being how deep the anchor dug in before it was rotated for the test.
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Old 11-05-2014, 06:30 PM   #42
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Carl I think "high tensile" means it has carbon added to increase it's strength. And of course the amount of carbon (and other additives) determine the physical characteristics like hardness, strength and many other chacteristics. Usually every steel has a designation number like 4140 ect.

So getting that specification from Rocna tells a great deal. What kind of strength or other chacteristics the anchor has.
Eric, the problem is that the term "high tensile" incorporates a really wide range of physical characteristics so as to be meaningless. Is it high tensile 550 MPa or high tensile 850 MPa, or perhaps high tensile 1500 MPa? There would be a significant difference. All Rocna would have to do is state that they use ASTM A537 or whatever it is and all would be settled. It's not like Rocna is in the back room cooking up a novel grade of steel. They are buying a grade that meets international standards that they chose from a number of possible options and making an anchor shank out of it. That they don't want to disclose what grade they are using isn't a matter of protecting intellectual property, but simply choosing to replace a marketing term - high tensile - for a measurement that actually means something.

"Excuse me sir, but what Octane rating is this gasoline? Oh, it is high performance fuel, trust me. Yes, but what is the Octane rating? Sorry, that is proprietary information."
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Old 11-05-2014, 07:55 PM   #43
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So I would rather have my anchor shank bend than break. Am I correct in thinking mild steel will be more likely to bend and hardened steel less likely to bend but more likely to break when over stressed?
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Old 11-05-2014, 08:29 PM   #44
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So I would rather have my anchor shank bend than break. Am I correct in thinking mild steel will be more likely to bend and hardened steel less likely to bend but more likely to break when over stressed?
Steel will elongate along the outside of a bend and high tensile steel will resist that elongation better than mild steel because its yield strength is higher - that is the significance of the MPa number. All steels will break under load, but the main problem with low tensile steel in thin anchor shanks is that deformation occurs at low loads. Higher carbon steels will spring back without deformation at the same load. They measure the characteristic you are referring to as 'elongation at break', which measures how much the steel will deform before breaking. For mild A36 steel break elongation is 15%. For Bisalloy 80 steel used in the Sarca Excel and Manson shanks, the break elongation figure is 18%.

The physical characteristics of steel are determined by it formulation and its rating, and engineers chose the steel they want based on what the design requires. As in all things, there is a trade off. For example, Knox anchors probably uses the highest MPa rated steel for their shanks at 890, but that particular grade - rqt 901 - has elongation of only 11%. In other words, it is stronger than Bisalloy, but will break more quickly with a given level of deformation. Which is better? I think the lower MPa Bisalloy since it will spring back over a greater range of deformation, but perhaps not.

So yes, mild steel is more likely to bend than higher tensile steel, but it is also more likely to break and will do so at much lower loads. You get what you pay for, I guess.

And of course, the lower the strength of the steel the cheaper it is, which may explain why Rocna is reluctant to answer the simple question of what grade steel they are using.
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Old 11-05-2014, 08:30 PM   #45
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So I would rather have my anchor shank bend than break. Am I correct in thinking mild steel will be more likely to bend and hardened steel less likely to bend but more likely to break when over stressed?
Yes. But mild steel covers a lot of territory unless parameters placed. Strength and hardness are two different arenas when referring to metals. Much like bones for those in the medical profession.
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Old 11-05-2014, 08:44 PM   #46
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Yes. But mild steel covers a lot of territory unless parameters placed. Strength and hardness are two different arenas when referring to metals. Much like bones for those in the medical profession.
With respect Tom, hardness is related to Yield but elongation at break is a different characteristic. There are new "advanced high strength steels" that are very hard with yields of 1500 MPa but that have ductility (elongation) of much weaker steels. Metallurgy is pretty complex and you can only speak in generalities unless you know the actual grade used. Which is why asking Rocna what they make their shanks of is essential if you want to have the slightest clue what its performance will be relative to other products of known grade and dimension.
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Old 11-05-2014, 09:07 PM   #47
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With respect Tom, hardness is related to Yield but elongation at break is a different characteristic. There are new "advanced high strength steels" that are very hard with yields of 1500 MPa but that have ductility (elongation) of much weaker steels. Metallurgy is pretty complex and you can only speak in generalities unless you know the actual grade used. Which is why asking Rocna what they make their shanks of is essential if you want to have the slightest clue what its performance will be relative to other products of known grade and dimension.
You are correct. Metallurgical complexities have been drilled into me since I obtained that Degree. But absent facts on design and build parameters pretty hard for me to opine. Any indication that Rocnas made by CMP are substandard?

Perfectfully logical that Rocna cannot reveal all as there are likely CAs in place.
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Old 11-05-2014, 09:48 PM   #48
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You are correct. Metallurgical complexities have been drilled into me since I obtained that Degree. But absent facts on design and build parameters pretty hard for me to opine. Any indication that Rocnas made by CMP are substandard?

Perfectfully logical that Rocna cannot reveal all as there are likely CAs in place.
No, there is no data to support a contention that the shank is substandard. However, there is no reason I can think of not to disclose what the shank is made of, anymore than there would be a basis for an auto maker not to disclose what their body panels were made of.

And CAs on the steel used? With whom? And suppose there were. Would it be likely they would not want to disclose that they were using a robust, and expensive high tensile steel in the shank or that they were using a borderline product that can be referred to as high tensile without defining what specifically that means? Seems to me the latter is more likely as a reason not to disclose this basic information. Which is not to say that whatever they are using isn't satisfactory, just that for a company selling a product formerly made by people who lied about that precise issue, it comes across as inexplicable unless they aren't proud of what steel they are using.
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Old 11-06-2014, 12:48 AM   #49
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If anyone cares to summarise Carl's posts on this thread - he hits the nail on the head.

If CMP find themselves carrying some negative baggage, the fault is theirs. They could have dispelled the negativity expressed on this, and other threads, by simply being transparent. Its not our fault that people question their integrity.

Rocna set the benchmark for the definition of HT steel in anchor shanks - they trumpeted from the roof tops their use of Bisplate 80 (aka ASTM 514A) if CMP are not comfortable - you harvest from your own plantings.

I doubt they are using ASTM 514A, as if they were they would say so, see below. Bisplate 80, the quality they used originally is made in Jinan Steel, 150,000t per year (joint venture with Bisalloy in Oz) and it is freely available (but maybe at a price).

Today Manson's Supreme and Boss, Anchor Right's Excel and Super Sarca, the Knox and Mantus are all made from ASTM 514A, or better, in the shank (maybe fluke). Use of this steel, or better, is not unusual.

To suggest the tensile strength is confidential is, plain rubbish. Cut a section from the shank of the Vulcan take it to a metallurgical lab and within hours you will have tensile strength, chemical analysis, hardness, yield point - all for a couple of hundred US$. If you know enough about the characteristics of HT steels in the market (really needs to have steel maker in your pocket), you will know who made it and to what spec. Just the sort of investigation for Practical Sailor - except they have better things to invest their little money, unless something untoward happens.

HT steels are various:

The tensile strength, measured in MPa, is just one characteristic but these steels can be optimised for hardness, strength and 'armour plating' or a combination. Each steel maker has his own thermal processing schedule (quench and tempering) and this schedule is dictated by raw steel chemistry. and what they want to make Even the quenching varies, some use water, some oil - there might be others.

But 2 steel companies can make the to the same specification, say ASTM 514A, using different raw steel chemistry and different thermal processing. I'm guessing that makers of HT steel focus at whatever their market demands, here in Oz we are big on mining, so abrasion resistance is a significant characteristic, maybe in China with high construction levels high strength is the focus and America, big in defense (along with China) might have a strong presence in armour plating.

One phurphy, now is that a word you Americans know?, is that HT steels are brittle, some can be because other characteristics are achieved. But most HT steels are very 'tough'. HT steels have very high yield points, near (within 20% of) failure point whereas mild steel, say 300 MPa have a yield only 60% of failure. Most steel mild or HT has the same modules of elasticity (load it, it stretches, release the load, it returns to its original length). So a HT might stretch twice as much as mild steel (which seems advantageous) and might also deform (though rapidly) unto failure. If you want to check this check Pewag or Gunnebo HT chains - staggering elasticity to yield and then huge deformation to failure - the spec for American HT steel for chain is min total elongation to failure 20% but for G70 or less a miserly 15% - so much for HT steels being brittle (G30 or G43 is more brittle than G80!)

But to return to CMP, declaring the tensile strength simply reassures the questioning public that the shank is made from strong steel. It does not give any secrets away - you can check the tensile strength with the 'ball bearing test' anyway.

The interesting feature is - how do they make it. Pressing tractor seats seams pretty simple technology and welding a pocket underneath (to eventually hold lead if it does not all work out?) looks simple. And the wedge also has a real usage.

But the shank on the basis it is alloyed highER tensile steel, like the Delta, could be cast or milled. Milling seems pricey but Chinese industrial accounting is different to 'ours' and anything is possible. But casting leaves the spectre of huge Classification Society costs - which might be why they are only making small models. Milling of real HT steels is quite common, most super Maxi racing yachts have a fin milled from ASTM 514A - so its not exceptional.


Will the anchor work - I'm sure it will, too much egg and too many faces otherwise. I think it will cannibalise Rocna sales at the smaller end of the market, it will never replace a Fortress in soft mud, it might destroy Spade sales and it might encourage Ultra to produce a galvanised version of their stainless model. Does it move technology forward - hardly as even CMP make no claims to fantastic performance - its just another model chasing a very small niche, market.

Somehow I do not think they will be sending me one to test!
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Old 11-06-2014, 08:16 AM   #50
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Have you tried contacting CMP in a professional non aggressive fashion to obtain relevant information? If the marine guys at CMP were to read this thread I'm not sure if they'd laugh, cry or ask Rocna WTF?
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Old 11-06-2014, 09:57 AM   #51
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Djangbi

Have you tried contacting CMP in a professional non aggressive fashion to obtain relevant information? If the marine guys at CMP were to read this thread I'm not sure if they'd laugh, cry or ask Rocna WTF?
Tom, I believe Hop Car did exactly that. As a dealer no less and it was he that got the non response others have questioned. Simple matter to clear up really. When someone asks what international standard the steel in your product meets, give them an answer. Easy. Now, if the standard is for a low yield steel, that by itself is meaningless. Rex from Sarca can explain why the use of lower yield steel in the Super Sarca is up the task assigned. Why can't CMP?
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Old 11-06-2014, 09:46 PM   #52
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Is it correct that all Rocnas are made in China?
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Old 11-06-2014, 10:01 PM   #53
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These were made in China. I don't trust steel made in China
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Old 11-06-2014, 10:24 PM   #54
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Is it correct that all Rocnas are made in China?
I believe the answer is yes. According to Canadian Metals, when they acquired the rights to make the Rocna anchor, they moved production from the fabrication plant in China that had been making them to their own, wholely-owned fabrication plant in China.

The first plant is the one to which Holdfast subcontracted Rocna fabrication when they acquired the rights to make the anchor.

Again according to Canadian Metals, moving production to their own plant gives them total oversight into the production of the anchor so that the materials specifications, fabrication processes and quality control would be correct and consistent. As I understand it, this plant makes a lot of Canadian Metals' products; the anchor fabrication is just one more item on the list.

Originally, of course, the anchors were made in New Zealand by Rocna themselves. At the time we bought ours, we were prepared to pay the exhorbitant shipping cost from NZ to Seattle. Rocna said they'd be happy to do this, but they suggested that we buy our anchor from Suncoast Marine in Vancouver, BC, which at that time had just begun fabricating the Rocna for North American customers. In fact, Rocna told me that some of Suncoast's fabrication processes were superior to their own in New Zealand.

So that's what we did. Some years later, Holdfast entered the picture, and Rocna fabrication was halted in both New Zealand and Vancouver, and production was moved to China. I believe Suncoast remained a distributor of the anchor, but I don't know what their status is today.

A Chinese-made Rocna can be identified by the raised lettering on the underside of the turned-up lip at the wide end of the fluke. The earlier anchors made in New Zealand and Vancouver (like ours) don't have this.
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Old 11-06-2014, 11:35 PM   #55
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Hi Marin,
That's interesting. Not the stuff you know about Rocna but the fact that you know that much about your boat anchors history. I don't know anything like that about any of my anchors as my interest is in anchor design almost exclusively. If I thought you knew it I'd ask you about XYZ or Manson history but I'm quite sure you hardly know anything about that. And I don't care to look it up either and don't know if I could.
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Old 11-07-2014, 12:12 AM   #56
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Eric--- The only reason I know something of Rocna's history is because I initially talked to Rocna directly in New Zealand about their anchor when we were trying to figure out what would work best as a replacement for our previous anchor. They told me about the development of the anchor and how it works and then we talked about the best size for our boat.

When we decided to buy a Rocna, I had several conversations with the fellow who owned Suncoast in Vancouver (unfortunately I've forgotten his name although I think it's Chris). At that time, Suncoast only made Rocna anchors to order. They did not make them on spec.

So we decided to order one, Suncoast made it, and when they told us it was ready we drove up to Vancouver and picked it up from the company that did their shipping. It was an interesting visual when we walked in to collect our anchor. Suncoast had just completed two anchors--- our Rocna 20 (44 pounds) and a 200 pound monster. They were sitting side by side on the shop floor, and when I first saw ours I had serious doubts about it being big enough.

Our anchor came with an instruction pamphlet and a manufacturer's call sheet that lists the metal the components are made of, the dates they were made and the anchor assembled, and the name of the QC person.

I don't know much of anything about Holdfast other than they acquired the rights to manufacture the Rocna and subsequently moved its fabrication to China, at which point fabrication in New Zealand and Vancouver ceased. I assume Holdfast moved the production to China in an attempt to reduce the price of the anchor, which at the time was much higher than the cost of most other anchors. Our Rocna 20 was just shy of $1,000, for example.

The Canadian Metals info regarding moving Rocna fabrication to their own plant in China came from press releases on their website.

I don't know much about any of the other brands. I recall reading that Manson initially tried to interest Peter Smith in some sort of partnership and when Peter refused, Manson stomped off and did his own thing, altering Peter's design enough to avoid any patent disputes (or maybe he didn't avoid any patent disputes, I don't know).

And I know that the Bruce anchor is based on his designs of very large anchors to hold North Sea oil rigs in place, but everyone knows that.

The XYZ, Fortress, CQR, Spade, etc I know nothing about in terms of their history or development.
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