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Calibrated Anchor Chain

Every sailing or motor yacht that ventures from their home berth will be sure to need an anchoring system that they can rely on in adverse weather at some point.

Calibrated anchor chain forms an integral part of that system. An anchor rode can vary between:

  • All chain for serious cruising on yachts fitted with a windlass - a short warp at the bitter end and/or a snubbing line will help absorb any shock loading
  • A combination of rope spliced to chain offers the best of both components - the proportions can be selected according to individual requirements
  • A long length of warp with a short piece of chain for the anchor end - for kedge warps, doubling up as drogue or towing lines

It stands to reason that the strength and the durability of the chain will be extremely important for yachts that rely heavily on their anchoring system on an extended cruise, and especially those equipped with all chain and combination rodes with a substantial proportion of chain.

Calibration is extremely important to the successful and reliable operation of your windlass - there is more information below, and also in these two articles:

How to identify the correct calibration for your gypsy    General information on Calibration and why it is important 

Jimmy Green Marine offer a choice of 3 different top quality manufacturers for Hot Dip Galvanised Calibrated Grade 40 Anchor Chain, an option for hot dip galvanised high strength Grade 70 hot dip galvanised chain and a choice of Grade 3, Grade 6 and Grade 6+ stainless steel anchor chain

Jimmy Green offer Hot Dip Galvanised Grade 40 Calibrated Anchor Chain available from three world respected manufacturers:

Lofrans ChainLofrans Grade 40 Calibrated Anchor Chain

Sourced exclusively from Lofrans, renowned worldwide for their range of top quality windlasses. Lofrans manufacturing is based in Monza, Italy. Lofrans have been producing top quality windlasses for over 50 years and now they have the chain to match. Lofrans Grade 40 chain is clearly stamped LFR at regular intervals as testimony to their belief in the quality of their chain.

Titan ChainTitan Grade 40 Calibrated Anchor Chain

Titan™ Marine is a brand of Canada Metal (Pacific) specialising in World Class Marine Anchor Chain. Titan Grade 40 Calibrated, hot dipped galvanised Anchor Chain is engineered and proof-tested by CMP to specifications exceeding industry standards. Titan specification and break loads are testimony to the quality of the steel and the manufacturing process. All Titan Grade 40 Chain is clearly embossed at regular intervals with G43, CMP and DIN766 or ISO4565 as appropriate as a clear testament to their confidence in the chain and galvanising quality.

MF CatenificioMF Solid Zinc

MF Grade 40 and MF DAMS Grade 70 Hot Dip Galvanised Calibrated Anchor Chain with Enhanced Solid Zinc Hot Dip Galvanising

Sourced exclusively and directly from MF Catenificio Frigerio, a modern chain manufacturing plant in Italy. MF Catenificio manufacture, hot dip galvanise and proof test their MF40/MF70 chain in their cutting edge, research, test and production facility. The state of the art MF factory is located in Olginate, near Lecco, Lake Como, Italy. The proof load testing process ensures that each individual weld has been completed successfully. MF Calibrated Anchor Chain from 6mm-14mm features enhanced Solid Zinc Galvanising treatment with greater micron depth and longer lasting corrosion resistance.

MF CatenificioMF Solid ZincDAMS MF Grade 70

MF DAMS Grade 70 Hot Dip Galvanised Calibrated Anchor Chain with Enhanced Solid Zinc Hot Dip Galvanising

Sourced exclusively and directly from MF Catenificio Frigerio, a modern chain manufacturing plant in Italy. MF Catenificio manufacture, hot dip galvanise and proof test their MF40/MF70 chain in their cutting edge, research, test and production facility. The state of the art MF factory is located in Olginate, near Lecco, Lake Como, Italy. The proof load testing process ensures that each individual weld has been completed successfully. MF DAMS Grade 70 Calibrated Anchor Chain is available from 8mm-12mm featuring enhanced Solid Zinc Galvanising treatment with greater micron depth and longer lasting corrosion resistance

Galvanising and Provenance

Hot Dip Galvanising is the process of safeguarding the chain from corrosive elements by immersion in molten zinc at a temperature of around 450 °C (842 °F). The zinc chemically reacts with the steel to form a metallurgically bonded protective coating which is infused into the steel i.e. it is not just a surface finish that can flake off. The process of galvanising anchor chain presents some problems due to the number of moveable parts (chain links) and the weight involved. All our chain deliveries are manually checked for any sign of defective galvanising. Galvanising treatment is measured in microns and is typically 80-100 microns on good quality anchor chain.

Galvanising - the treatment explained

Provenance is extremely important for your peace of mind when it comes to your anchor chain because although a careful scrutiny of the galvanising will reveal any rust stains or defects, it is well nigh impossible to check the steel specification without a metallurgist report. Hallmarking will at least confirm the manufacturer and certification will state the grade of steel and the rated break load.

Jimmy Green offer Stainless Steel Calibrated Anchor Chain from two world renowned manufacturers

William Hackett stainless steel calibrated anchor chain, manufactured on automatic chain making machines from A316L to Grade 3

Jimmy Green G3 stainless steel chain specification

Cromox G6 AISI 316L and G6 PLUS AISI 318LN calibrated stainless steel anchor chain, manufactured in the Ketten Walder factory based near Munich in Germany.

Cromox G6 stainless steel chain

Ketten Walder have been producing the highest quality marine grade 60 chains for 60 years. The attention to detail, stringent testing and checking processes ensure that every chain meets the highest standard.

Available in two specifications: G6 AISI 316L and G6 PLUS AISI 318LN Bright polished finish is standard. G6 Plus comes with a manufacturer 2 year corrosion free warranty as standard. The guarantee can be extended to 3 years with an extra electro-polish process which smooths out micro imperfections and removes ferritic ions to prevent corrosion and staining.

Quality Control and Accountability

Every length of chain is quality checked and labelled with the manufacturer, the date received and a corresponding batch number when it arrives at Jimmy Green Marine

The batch number is then recorded at the point of sale.

Every chain order is therefore traceable and accountable to the manufacturer Test Certificate.

Chain Certificates

A copy of the Manufacturer Test Certificate corresponding precisely to the manufactured length from which your chain has been cut is available with your order on request.

Chain is heavy to manhandle and costly to deliver:

Our Delivery charge is based on the total weight and the delivery destination Zip Code.

Lengths of chain under 50kg will generally be packed in a polypropylene sack (sometimes doubled for security)

Lengths of Chain over 50kg will generally be packed on a pallet.

The Freight cost is calculated in the basket and assumes a UK Mainland delivery address until you are signed in with your registered delivery zip code

You are welcome to collect from our Chandlery Store to save this cost.

Calibrated Anchor Chain - General information

Calibrated chain is absolutely essential if you have a windlass fitted on your yacht or if you are considering a windlass in the near future.

Calibrated means that each link is manufactured to the same dimensions within a given tolerance.

Windlass gypsys are generally designed and manufactured so that they are compatible with a given size and calibration of chain.

When the dimensions are close but not correct then it is difficult to detect without a practical trial. The problem then normally occurs after a short length has been through the gypsy under load. The difference in size between the chain link and the pocket on the gypsy eventually leads to a jam or a jump.

There is a lot of information available on the internet regarding the calibration of windlasses. This information may come from the manufacturer or even from a fellow yachtsman. This is a very good guide and could well be accurate. However there are some ‘caveats’ which need to be taken into account e.g. Windlasses are normally offered with a choice of different chain sizes and calibrations Any markings or stamps on the gypsy itself may help in this respect. Windlass manufacturers change their specifications over the years and the details of those changes are not necessarily available without a lot of research. If you are not 100% sure of the provenance of your yacht, windlass or gypsy then it is possible that the gypsy has been replaced at some time. The replacement could be a different calibration.

There are only two main calibrations for chain manufactured in Europe: DIN766 and ISO4565

The good news is that the dimensions for 6mm, 7mm, 8mm and 12mm are identical.

10mm is more difficult because the dimensions are different for DIN766 and ISO4565

Both 10mm calibrations are very commonly used in Europe.

Be aware that selecting the wrong calibration, particularly in 10mm, on the vast majority of windlasses will result in ‘jamming’ or ‘jumping’ under load.

Please note that US Calibrations are entirely different to European DIN766 or ISO.

US Chain Descriptions can be confusing because American chandlers tend to cite Working Load Limits rather than Break Loads and they don't normally refer to the grade of the chain as we do in Europe. Be careful with Working Loads because the Break Load will depend entirely on what safety factor the manufacturer is using. The Break Load is self explanatory as is the Grade (30, 40 or 70) The term HT is quite commonly used in the USA but confusingly can refer to two entirely different things. HT meaning High Test which refers to Grade 40 or Grade 43 or HT meaning High Tensile which refers to a higher grade, commonly Grade 70

For information on how Jimmy Green Marine can help you select the right chain for your windlass, please go to Calibrated Anchor Chain - Determining the correct calibration

Calibrated Anchor Chain - Information on Load Capacity (strength) and Brittleness (shock absorption)

Calibrated Anchor Chain for yachting and boating is generally manufactured in Grade 30, Grade 40 (also sometimes known as/available as Grade 43 High Test) and Grade 70

Grade 30 is adequate for mooring and anchoring but Grade 40 is 25%+ stronger and a minimum requirement for any serious minded cruising skipper. The weight does not increase with the grade which affords weight saving opportunities for the long lengths required for long distance cruising.

Typical Break Load comparisons e.g. 8mm: Grade 30 = 3200kg ~~~ Grade 40 = 4100kg up to 4400kg according to the manufacturer ~~~ Grade 70 = 70kN   = approx. 7100kg 10mm: Grade 30 = 5000kg ~~~ Grade 40 = 6400kg up to 7200kg according to the manufacturer ~~~ Grade 70 = 110KN = approx. 11200kg

There are 3 Different Methods of recording Manufacturer Load Limits

  1. Working Load Limit - Manufacturers publish a working load limit which is their break load divided by a safety factor. The safety factor sometimes varies between chain manufacturers but is generally 4:1 i.e. WLL is a quarter of their tested break load. Safety factors can be very different according to the industry e.g. Tested Galvanised Shackles of proven provenance will normally be 6:1. The Working Load Limit is an indication of what the manufacturers regard as normal use. The WLL is declared on the Manufacturer Test Certificate
  2. Proof Load - Lofrans and Titan Chain is all proof loaded during the manufacturing process. This is a very important check that each link has been successfully welded as it passes through the machine. The Proof Load is generally twice the Working Load Limit whichequates to half the Tested Break Load. The Proof Load is declared on the Manufacturer Test Certificate.
  3. Break Load - Manufacturers publish a Break Load for their chain. This is the actual tested load which distorts the chain link beyond it's capacity to sustain further load. DIN766 and ISO require a certain level of Break Load for each size, calibration and grade of chain. Manufacturers test their chain to ensure that it exceeds the minimum standard. Manufacturers may then elect to declare their Break Load Limit according to the appropriate standard or additionally declare the Actual Break Load. Manufacturers may do this as a claim to be stronger than the competition but the DIN766 and ISO standard load limits are quite sufficient. The Break Load is declared on the Manufacturer Test Certificate.

Grade 70 chain is produced from Grade 40 steel by means of a specially designed heat treatment process which results in a break load inexcess of the Grade 70 standard. A specially amended and carefully supervised process for the intitial hot dip galvanising treatment is also required to ensure that the subsequent strength loss is minimalised and the finished product satisfies the appropriate standard. There is no evidence to suggest that re-galvanising has any detrimental effect on the strength of anchor chain, not even Grade 70 if it is carried out professionally because the heating effect is not cumulative.

Brittleness and Shock Loading

It is not a myth that Grade 30 chain is very slightly more ductile than Grade 40 and Grade 70 chain. This means that it may distort very slightly more just before breaking. However, the relative difference in brittleness should not be a concern. Once you have subjected your anchor chain to anything like the break load limit, the brittleness effect on the capacity of the chain to survive the extreme forces involved will be minimal. This applies to any of the different grades: 30, 40 , 43, 70. The higher the grade of chain, the tougher it is. Tougher means more resilient to higher loading and more resistant to damage from e.g. impact or abrasion. By far the most important aspect of deploying an anchor chain in severe conditions is to avoid shock loading at all costs. Evidently, the higher the grade that you select for your anchor chain, the less likely you are to overload it.

Higher Grade = Higher Break Load = Less chance of Overloading

Shock Absorption for your anchor chain

Jimmy Green insight into Anchor Chain Snubbing

The best methods of protecting your chain from having to cope with a snatch load:

  1. Have as long a main (bower) anchor chain as possible ready to deploy so that even in the worst conditions, there is still enough to cope without the chain straightening at the climax of the surge caused by the combination of wind and waves or even dire cases, surf. It's the jolt (jerk, snatch, shock) that may cause the chain to fail. N.B. the shock load will also be detrimental to any deck fitting that attaches the chain to the deck.
  2. Extend your anchor rode with a stretchy Anchorplait Nylon rope to to absorb the shock if the chain does straighten. Anchorplait can be spliced directly to the chain to ensure a secure and in most cases gypsy friendly connection.
  3. Deploy an Anchor Chain Snubber - Snubbing helps to smoothe out any movement and also protects the chain from jerking if it should straighten.
Read More
3 Links of Anchor Chain
10 links of Sample Anchor Chain

cromox G6 Stainless Steel Anchor Chain AISI 316
10mm DIN766 or ISO MF Grade 40 Hot Dip, Solid Zinc Galvanised Calibrated Anchor Chain

6mm DIN766 William Hackett Grade 40 Calibrated Anchor Chain
6mm DIN766 Lofrans Grade 40 Calibrated Anchor Chain
View +
8mm DIN766 Lofrans Grade 40 Calibrated Anchor Chain
10mm Lofrans Grade 40 Calibrated Anchor Chain
12mm ISO Lofrans Grade 40 Calibrated Anchor Chain
8mm DIN766 Titan Grade 40 Calibrated Anchor Chain
10mm Titan Grade 40 Calibrated Anchor Chain