Is 10mm chain really 10mm?

Roberto

Roberto

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My 10mm anchor chain is badly rusted, I hammered the rust to bare metal in a number of sections and measured the minimum thicknesses here and there, especially in the area of contact between two adjacent links: some links were down to 8-8.5mm, most 9-9.5mm, the worst links were oval say one axis 8mm and the other axis maybe 9ish
Surprisingly a significant number was slightly over 10mm, up to 10.5mm (of course *not* at the weld, where links are thicker). They were also rusted and needed hammering, though the rust thickness was very thin.

As this is a very used chain, what could have been the original thickness?

btw the caliper is correct (or maybe I have three calipers all wrong by exactly the same amount)
 
It can vary a bit. The steel wire used to make it should be 10mm but it will be stretched a little in the forming process which will thin it a bit, after which the galvanising adds a little. If your "10mm" chain was actually American 3/8ths chain, the latter is actually not 3/8ths inch wire at all, but made from 13/32 inch wire and thus starts out at 10.31875mm give or take whatever the wire drawing tolerance is! My old supposedly 10mm anchor chain was actually American 3/8ths, and the few links that had all their galvanising measured almost 11mm.
 
As Norman says the wire is nominally 10mm, or whatever. It would not normally be imperial as imperial link sizes are very different to metric, being much bigger. It could conceivably be imperial wire made to a metric size - if very old and originated in the UK. I would be surprised if the wire size was less than 10mm, but not surprised if it was a bit more. In terms of fitting your gypsy the wire size is not critical but the wire does determine strength (and for the last few years G30 and G40 chain as been well overstrength). For your gypsy the link size is the critical issue (not the wire). Again as Norman mention it is difficult to measure wire diameter on new chain as the wire is covered in galvanising - which might be 100 micron thick when new.

The rule of thumb is that if you have lost 10% of wire size then the chain would be retired - and it looks as if you have been living on borrowed wire (that is not there!).

You need to determine what your chain is, metric or imperial, unless you want to buy a new gypsy - and gypsies are very expensive. The gypsy should be stamped or embossed with its size and whether it is ISO or DIN.

There are many sources of chain - depends on where you are located and the supply to the local handlers but good chain ha been coming out of China, CMP/Titan (of Rocna fame) have good chain (all from China), Lofrans are selling a G40 (I assume from China). Maggi chain was alway strong enough but had a terrible reputation for galvanising (and at the last count were under administrators). If you need imperial chain then the best bet is CMP or Peerless (the latter are stocking in Germany - I have no idea how they distribute).

Most people in Europe (and Australia) are using G30 and it is proven more than adequate. No-one complains their chain failed, through inadequate strength. There is a move, in America (and to a lessor extent Europe) to G40/G43 - it is difficult determine the driver. Maggi and Lofran (as far as I know) only sell G40, no G30. In America BBB, G30, G43 and G70 are all different link sizes and a gyspy might not accept both 3/8th" BBB and G70. In Europe all link is the same size, but check for DIN and ISO in 10mm.

Chain life is determined by usage (obviously) and the rate determining characteristic is galvanising thickness. Shiny gal does not mean good, it just means fresh. If you have a linen glass you can look at gal thickness on a fresh and neatly cut link (but it is unlikely you will have access to a nice clean cut link :( ).

Its a lottery.

Once you wear through the gal then the wire type determine life and G30 is the softest and will wear most quickly - G70 will wear more slowly (for the same size of chain) - but you would really to regalvanise before you start to eat into the underlying steel. The gal itself is much harder than the steel (the same sort of hardness as G70) - except for that layer of shiny zinc on the outside.

Good luck
 
There are some funny sizes - I've seen some 7mm and even some smaller than 6mm (I think 4mm) but I'm not sure that today's windlass necessarily have gypsies to suit.

Most windlass makers now seem to offer 6mm, 8mm, 10mm and 12mm (and then bigger), most again offer 1/4", 5/16th", 3/8th" and 1/2" for BBB, G30, G43 and G70 and some do offer intermediate metric sizes 7mm and there is some overlap with the myriad of imperial sizings (some gypsies seem more forgiving than others). I'd try before I buy - its simply too expensive to get it wrong.

It seems American yachts, for the American market, are being increasingly sold with G43 gypsies as the default option. G43 'looks' good as it is sold to a 3:1 safety factor whereas metric G30, G40 are sold to a 4:1 safety factor. As far as I can ascertain its a simple arithmetic fudge and there is no data, of which I am aware, in the public domain that G43 is any safer in the anchor rode than G30 or G40.

Most windlass makers have spreadsheets of windlass vs gypsy for size of chain usually hidden in their website (or they will forward upon request).
 
vyv_cox said:
Only if you are American :)
Click to expand...

In Australia we have to accept either measurement.

Temp Chain.JPG

I am always confused regarding UK measurements: I'll have to do some more research. I think you guys had to convert to metric when you joined the European Union but apart from that I become confused.........:confused:

Even 50 years later, many Britons still refuse to move entirely to metric. Distances are still measured in miles, yards and inches, weight in pounds and stones, even pints and gallons are still used. The US isn't pressured by the same trading problems as the UK, license however.May 19, 2017 (zmescience. com)

OMG!! It's not surprising I am confused....................:rolleyes:
 
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Australian chain is made to a different metric standard and should not be confused with European metric chain. Our, Australian, chain is defined as Grade L (same steel as G30) and we have others, for example Grade P, (which is a G50, I think) and our link sizes are different.

Grade L chain will not fit a 'standard' European metric gypsy. But does fit an, some, imperial gypsy. Our Muir gypsy for 8mm G30 (Grade L) was embossed 5/16th".

It gets even more bizarre - Muir and Maxwell are both antipodean (or antipodean to the mother country) and both are major windlass supplier. Both need cater for the totally unnecessary alternative metric standard established by Oz. If you enquire of our local chandlers they will also supply, from stock, imperial size, courtesy of Titan/CMP who are selling off the back of G43 being 'better', because of that arithmetic fudge of safety factors. I know of one owner who bought imperial Titan G43 because 'it is so much stronger' (read it has a arithmetically high WLL) than G40 and fantastic v G30/Grade L - the power of marketing!

Our new chain, 6mm G80, and another rode recently made 10mm G100 is supplied to EN 818 - 2 (which might be identical to the DIN standard) and Maxwell make gypsies to suit.

No wonder people are confused.

Jonathan
 
Chain dimensions and calibration
Chain dimensions, and therefore the gypsies that will accept them, vary considerably according to whether they are made to imperial or metric standards and even between manufacturers. European made chain is to DIN 766 and/or ISO4565 and most European gypsies will accept it. There is a strange anomaly that has caught out many owners. The dimensions of the two standards are identical for all chain sizes except 10 mm, in which the link length is 2 mm different. The gypsy should be marked in some way to identify to which standard it conforms.

Suppliers normally proof test chain to between 40% and 50% of the rated Minimum Break Load (MBL), whereas the quoted Safe Working Load (SWL) is 25% of the MBL.
Note that many other standards exist for short link non- marine chain whose dimensions are different. Chain to these standards will not fit any gypsies.
American chain is made mainly to ISO G30 and G43 standards with longer links that may not fit European gypsies. Note that the dimensions of these two grades are not the same. G43 (Grade 40) is more widely used for anchor rodes in USA

http://www.amelowners.net/YahooFiles/Anchor Chain, Galvanized dimensions and calibration.pdf
 
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coopec said:
Chain dimensions and calibration
Chain dimensions, and therefore the gypsies that will accept them, vary considerably according to whether they are made to imperial or metric standards and even between manufacturers. European made chain is to DIN 766 and/or ISO4565 and most European gypsies will accept it. There is a strange anomaly that has caught out many owners. The dimensions of the two standards are identical for all chain sizes except 10 mm, in which the link length is 2 mm different. The gypsy should be marked in some way to identify to which standard it conforms.

Suppliers normally proof test chain to between 40% and 50% of the rated Minimum Break Load (MBL), whereas the quoted Safe Working Load (SWL) is 25% of the MBL.
Note that many other standards exist for short link non- marine chain whose dimensions are different. Chain to these standards will not fit any gypsies.
American chain is made mainly to ISO G30 and G43 standards with longer links that may not fit European gypsies. Note that the dimensions of these two grades are not the same. G43 (Grade 40) is more widely used for anchor rodes in USA

http://www.amelowners.net/YahooFiles/Anchor Chain, Galvanized dimensions and calibration.pdf
Click to expand...

All American chain is batch tested to Ultimate Tensile Stress (it is tested to break). I think all American chain is continuously Proof Tested to 2 time or 1.5 time WLL, Working Load Limit (it should not extended, permanently). WLL can be 25% or 33% of MBS.

Minimum Break Strength MBS is simply an arithmetic calculation based on wire diameter and the MBS, determined by minimum tensile strength of the wire from which the chain is made.

G43 is sometime, wrongly, called G40 by individuals for Imperial chain, but not by manufacturers.

Edit

Full detail on the differences between ISO and DIN standards have been on Vyv's website for some years. He also has test results on a range of chains he sampled.

Test results on American (Imperial), Maggi, (Metric), CMP Titan (Metric), and Australian Grade L chain are available if you search on Practical Sailor website. There are a number of articles

Close Edit

Further edit

I've just seen your post No 13 (our posts crossed) - I had not realised it was simply 'lifted' but was well aware you had made an issue of it - hence my comment.

Close

Distasteful and sloppy - it not as if you are unknown here.

Jonathan
 
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coopec said:
Chain dimensions and calibration
Chain dimensions, and therefore the gypsies that will accept them, vary considerably according to whether they are made to imperial or metric standards and even between manufacturers. European made chain is to DIN 766 and/or ISO4565 and most European gypsies will accept it. There is a strange anomaly that has caught out many owners. The dimensions of the two standards are identical for all chain sizes except 10 mm, in which the link length is 2 mm different. The gypsy should be marked in some way to identify to which standard it conforms.

Suppliers normally proof test chain to between 40% and 50% of the rated Minimum Break Load (MBL), whereas the quoted Safe Working Load (SWL) is 25% of the MBL.
Note that many other standards exist for short link non- marine chain whose dimensions are different. Chain to these standards will not fit any gypsies.
American chain is made mainly to ISO G30 and G43 standards with longer links that may not fit European gypsies. Note that the dimensions of these two grades are not the same. G43 (Grade 40) is more widely used for anchor rodes in USA

http://www.amelowners.net/YahooFiles/Anchor Chain, Galvanized dimensions and calibration.pdf
Click to expand...

Incredible. Those are my words, downloaded from my website apparently without acknowledgement.
 
Neeves said:
Our new chain, 6mm G80, and another rode recently made 10mm G100 is supplied to EN 818 - 2 (which might be identical to the DIN standard) and Maxwell make gypsies to suit.

No wonder people are confused.

Jonathan
Click to expand...

Jonathan, I am assuming that G100 chain is not for your boat! If so, pics please of some rough old Southern Ocean anchorages ;)
 
Further edit
I've just seen your post No 13 (our posts crossed) - I had not realised it was simply 'lifted' but was well aware you had made an issue of it - hence my comment.
Close
Distasteful and sloppy - it not as if you are unknown here.

Jonathan

What is that all about?
 
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Well spotted :)

The G100, 100m x 8mm, is for a FreeFlow 50 (catamaran) in build in Thailand. The designer of the Freeflow happened to be one of the builder of our Lightwave. The original idea was that most of the length of 100m went into the primary rode and some 15m/20m was for a second, mixed, rode. The owner opted for a steel Excel primary and a slightly smaller aluminium Excel secondary.

Unusually the build is based round hybrid with Oceanvolt and electric propulsion and is focussed at higher latitudes

Its a development of my chain, same technology - Armorgalv coated (or Thermal Diffusion Galvanising), same coating thickness. Uses the same Idea of Omega links, Boomerang and, the latest development, a matching chain hook. Coincidentally we both opted for Maxwell windlass.

I'll be writing an update soon on our experience (all good) after almost 3 years, with much detail on abrasion resistance and including in the article detail of the 100m, above. The bigger change ha been in use of longer snubbers. A further development is on making a 6mm chain with the strength of 10mm.

But I'm guilty of unhealthy thread drift - apologies :)

Jonathan
 
coopec said:
Further edit
I've just seen your post No 13 (our posts crossed) - I had not realised it was simply 'lifted' but was well aware you had made an issue of it - hence my comment.
Close
Distasteful and sloppy - it not as if you are unknown here.

Jonathan

What is that all about?
Click to expand...

You appeared to quote without acknowledging the author.

Jonathan
 
Neeves said:
You appeared to quote without acknowledging the author.

Jonathan
Click to expand...

I acknowledged the source of my quote by giving the URL. Sorry you didn't see that.

I've taught Intellectual, Patent, and Copyright Law so don't you dare lecture me on what my obligations are.

Clive
 
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