Rocna: is the problem now confined to the past ? nm

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I think your information may be confused. The flukes have always been made from a relatively low strength steel, either edge welded plate in new Zealand or cast in China. I suspect the reason they have changed back is simply due to economics, or maybe the new plant does not have casting capability. There is no need for higher strength materials in the flukes.

end quote

Presumably this means they are now cheaper?

My understanding is that, in China, with the right volume (whatever that means) it is much cheaper to cast than, cut, bend and weld. So I suspect your second option is correct.

As an aside - and maybe Vyv can validate (from a metallurgical background) - it is my understanding that the whole sorry affair was as a result of 'differential' galvanising. They had a cast fluke, a mild steel rollbar and a HT shank and when galvanised it looked awful - each component (on one anchor) looked a different shade of metallic grey. Even multiple galvanising did not solve the problem. Moving to a lower strength steel allowed them to galvanise the anchor with a, more, even shade of metallic grey. The rest is, of course, history. A better answer would have been to simply spray the whole thing with a metallic paint (but they never asked me - cannot understand why:)

Jonathan
 
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We are looking at adding more chain to our setup here and as I mistrust the polished stainless steel bruce copy we inherited ( not yet used by us in anger) I was thinking of swapping for a 45lb Delta which we had years of good experiences with back your side of the puddle. Our local chandlers sell Rocnas ( I know not where made), and Mansons and I believe you once said you had a Manson supreme?? how do you find the Manson? aside from it's grip on the bottom does it sit nicely on the bow and stow without taking chunks of gel coat from the bow on raising? The Manson 45lb is about $100 more than a 45lb Delta but heck it's only monopoly money and the daft gits are devaluing that by the hour anyway, the chain is our expensive part of the equation, running at $5 or $6 per foot for 3/8ths chain which is what I guess we need although our existing stuff is possibly 10mm it being an imported French built boat and all. Current local wisdom is that 100ft of chain is ample for the Bahamas where 10ft is a normal water depth anchorage and 20ft is considered a deep water anchorage, we currently only have 50ft of chain with an unknown length of warp attached ( until I get it out to measure it) we do have about 5ft of polished stainless on the existing anchor so as not to dirty the foredeck to the windlass with rust a Full 'marina Queen' poser setup you see!

On the assumption you are considering joining the old and new, not something I'd go for, but if its 10mm chain then 3/8th chain will not fit the gypsy. The link dimensions are different, and BBB, G30 and G43 dimensions are different to each other. American chain is marked for its quality and also who made it - though deciphering might not be easy, but a chandler might help.

Take the gypsy apart - it should have the chain size in the casting. If its a metric chain I suspect you have major issue getting any more - it might be cheaper to buy a new gypsy (most windlass makers stock both Imperial and Metric gypsies) and use American chain. If its metric Maggi are trying to enter the market and were at the Miami Boat Show - they might be worth contacting.

Jonathan
 

vyv_cox

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[QUOTEJ
My understanding is that, in China, with the right volume (whatever that means) it is much cheaper to cast than, cut, bend and weld. So I suspect your second option is correct.

As an aside - and maybe Vyv can validate (from a metallurgical background) - it is my understanding that the whole sorry affair was as a result of 'differential' galvanising. They had a cast fluke, a mild steel rollbar and a HT shank and when galvanised it looked awful - each component (on one anchor) looked a different shade of metallic grey. Even multiple galvanising did not solve the problem. Moving to a lower strength steel allowed them to galvanise the anchor with a, more, even shade of metallic grey. The rest is, of course, history. A better answer would have been to simply spray the whole thing with a metallic paint (but they never asked me - cannot understand why:)

Jonathan[/QUOTE]

I suspect the 'right volume' is a hell of a lot more than 1000(?) small shanks per year!

I really cannot answer about the galvanising. Since the zinc forms a series of intermetallic compounds with iron with ever increasing zinc content to the surface, I would not have thought the substrate composition would affect the final appearance. But it sounds like you have more knowledge than I do on the subject.
 

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There are several aspects of hot dip galvanizing that often are not appreciated. They are immersion of hollow fabrications (not an issue here) and the effects of steel chemistry on thickness, finish and colour.
Galvanizing isn't just a coating its an alloying process where the zinc alloys with iron in the steel to form multiple layers of iron-zinc alloy, and usually ends up with a layer of "pure" zinc on top, due to being immersed.
The typical alloy mixtures are about 90/10 (Zn/Fe), 95/5, and 98/2, but a bit variable.
The rate of alloying is affected by the steel chemistry, and the temperature.
For production reasons the temperature is mostly 450C +/- about 4. (much higher and a steel kettle to contain the zinc isn't suitable as the kettle dissolves in its contents, much lower and its too close to freezing point 419C)
The main constituents of steel that infleunce the alloying rate are Si and P. Most grades aof thse types of steel minimise P, but Si is used to deoxidise steel, and sometimes to help harden it.
The % Si that has an impact varies, with nil Si having slow reactivity, and about 0.10%Si being the most reactive, but reactivity tailing off as Si rises above 0.2%.
This reactivity changes the nature of the coating from dense crystaline layers to porous coarse crystals in the most reactive. And one effect of that is colour and appearance.
Reactive steels (about 0.1%Si) often result in dull grey porous looking galvanizing whereas lower Si, or higher, produces more shiny smoother surface. Further the dull, crystalline galvanizing is more brittle, harder and is actually porous.
Harder can be better, with more abrasion resistance (harder than mild steel), but being brittle can suffer impact damage more easily.

Jonathon (above) mentions "multiple galvanizing". I'm not sure what is meant by that? Its usually not practical to galvanize over galvanizing. Zinc doesn't alloy with zinc, nor does it react. It usually makes a mess in terms of aesthetics. Thats why re-galvanizing is preceeded by stripping the remaining old off first.
Galvanizing doesn't normally suffer from lack of adhesion. If the steel wasn't chemically clean, no reaction = no coating. If it was clean, alloy forms and the coating is there.

An issue with galvanizing some high strength steels can arise in the chemical cleaning. This is usually by immersion in hydrochloric acid (about 10% for about an hour). Hydrogen embrittlement of the steel can occur, with H2 migrating along the grain boundaries in the steel. It can be overcome if the galvanizer knows about this and knows the grade of steel. Most often the customer doesn't tell the galvanizer the steel grade, so they operate in ignorance of that fact. (Though this summer, CE marking of construction related steel fabrications in Europe will cause better information between those fabricators and galvanizers, but anchors are not a construction product and so not affected).

So where galvanizing comes out a different colour, its most often due to different chemistry of steel.

Most galvanizing is shiny to start with, but soon dulls down as the surface oxidises and also forms carbonates on its surface. the differences in colour (grey - silver) become less with time, and exposure and use. But when you buy, its fresh and that the time when aesthetics might matter most - at time of purchase.
 
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Hi Geoff,

Thanks for that. Rocna tried multiple galvansings, they regalvanised an existing galvanised anchor, I have a small model it looks as if it was dipped in zinc treacle. Your final comment was apt - it was the appearance at point of sale they seemed to worry about.

However that was an aside - this is not an issue now and I think the new generation of Rocnas and the previous ones, with the cast fluke, have shown they are sufficiently robust or in the case of the new ones seem robust. But there are a number of new gen anchors about, plenty to choose from. It is also healthy that new ones are being introduced. I suspect, as has been mentioned, choice is determined as much by availability as anything else (many eventually forgive and forget, or just forget) equally whether it fits on the bow roller and how much it costs are part of the equation - at the end of the day, for many, these 3 factors, availability, price and fitting far outweigh the subtleties of performance.

Jonathan
 
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An issue with galvanizing some high strength steels can arise in the chemical cleaning. This is usually by immersion in hydrochloric acid (about 10% for about an hour). Hydrogen embrittlement of the steel can occur, with H2 migrating along the grain boundaries in the steel. It can be overcome if the galvanizer knows about this and knows the grade of steel. Most often the customer doesn't tell the galvanizer the steel grade, so they operate in ignorance of that fact. (Though this summer, CE marking of construction related steel fabrications in Europe will cause better information between those fabricators and galvanizers, but anchors are not a construction product and so not affected).


Apologies to the OP for prolonging thread drift:)

Geoff,

Does, or will, this cover galvanising of construction bolts? From something you said a long time ago you mentioned that you were well aware of cases of HE and these commonly occured in items with a high surface area and construction bolts are particularly prone. Galvanised construction bolts, or the specification is HT bolts, are being used to secure some, or at least one, design of anchor. Most cases of HE in bolts seems to lie with imported bolts, cases in both Australia and America. I note you would sand blast HT items, is this normal practice in Europe? Are there no moves to demand that such items are only sand blasted rather than acid washed. And - given your deeper knowledge of the problem what might you say to an anchor whose shank is secured by galvanised HT bolts.

Jonathan
 

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My question at the moment would be why have they gone back to fabricating the blades out of mild steel ( in another factory in China) instead of using the much touted "stronger higher spec" cast blades? Surely a stronger cast blade is the way to go, that's what they told us as justification for using China instead of the NZ factory.

To close the point relating to our change, we eventually went with a 45lb Delta and 150ft of HT 3/8 USA chain since this was what the short length we inherited with a warp attached was identified as by West Marine, this fits the windlass gypsy well and I think the original 50ftwith warp was probably installed on the boat by the importing dealer. as yet we have still to test the system in anger, but I think we can plan to use all chain rode and with plenty of scope deployed in the skinny waters round here and in the Bahamas which coupled with the oversize (for our 36 foot boat) Delta we should be rock solid. My only slight concern is dinging the bow on retrieval, although we have a triangular bow fender rigged tight up under the rollerto help hold the anchor in postion and aid it in getting there sans too many dings in the grp. I'm also thinking of using some polished stainless steel door kickplate pads to make some protection plates to glue on the affected parts, one kickplate will cut in half to make a pad for each side of the bow. There is a proprietary system for fitting a thin S/S plate that bends around the bow but it is pricey and especially so with carriage to the USA added on. We are also in the process of adding an up/down toggle control at the helm position to control the windlass and allow singlehanded dropping and recover should we wish, otherwise our windlass (oddly) has foot switches mounted on the top of the windlass, usable by hand but a little strange to my years of having either a hand control or foot switches in the foredeck.
 
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Hi Robin,

The 150' of new chain, is that going to be the new rode and the old rode is to be retired, become a spare (for a second anchor) or are you going to join the 2 together?

Jonathan
 

Robin

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Hi Robin,

The 150' of new chain, is that going to be the new rode and the old rode is to be retired, become a spare (for a second anchor) or are you going to join the 2 together?

Jonathan

the new rode is a single length of 150ft of galvanised 3/8 HT chain, We are keeping the original 30lb polished stainless claw anchor with it's short length of s/s chain and rope rode as a spare anchor, but the extra 50ft of galvanised 3/8 chain originally on it is being retired until the next opportunity to sell it arises. I did not want any joins, hence we purchased a 150ft length of new chain, which is plenty for our current cruising ground so that we will always deploy all chain only but we could always add warp to that if needs be.
 
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