How to Establish The Correct Anchor Chain Calibration
The simplest way to check that you are buying the correct calibration is to measure your existing chain, providing that it fits correctly.
How to Measure Anchor Chain
We measure ten links because, in practice, it is difficult to measure one link accurately enough.
The links should be laid out flat and pulled tight.
Measure from the outside edge to outside edge.
Measure a section that is in as reasonable a condition as possible, i.e. not worn or corroded.
| Titan Grade 43 | Lofrans Grade 40 | MF Grade 40 | MF DAMS Grade 70 | |
|---|---|---|---|---|
| 6mm DIN766 | 195 mm | 193mm | ||
| 7mm DIN766 | 228mm | |||
| 8mm DIN766 | 253 mm | 253 mm | 253mm | 253mm |
| 10mm DIN766 | 297 mm | 298 mm | 295mm | 295mm |
| 10mm ISO4565 | 316 mm | 318 mm | 317mm | 317mm |
| 12mm ISO4565 | 375 mm | |||
| 13mm DIN766 | 375mm | |||
| 14mm DIN766 | 430mm |
Jimmy Green measurements have been taken from our actual stock here in Beer.
There is room for tolerance because the measurement is over ten links.
If your existing chain is old and worn, the measurement over ten links may be slightly longer than our new stock by a small percentage.
The diameter of the links on your existing chain may have expanded due to corrosion or rust, making the measurement a little shorter than a new chain.
If your chain falls between the measurement for 8mm DIN766 and 10mm DIN766, it may be 5/16″ US Specification.
This is an 8.7mm chain with a 26.1mm pitch:
Calibrated Anchor Chain, USA Dimensions, and Load Limits
The length for 10 links of 5/16″ US will therefore be approximately 275mm-280mm (26.1 x 10 Plus 2 x 8.7 = 278.4)
The normal measurement range for each calibration is listed in the chart below:
| Calibration | Size/Diameter | Pitch | 10 links |
|---|---|---|---|
| 6mm DIN766 | 6mm | 18.5mm | 190-195mm |
| 7mm DIN766 | 7mm | 22mm | 228mm |
| 8mm DIN766 | 8mm | 24mm | 250-253mm |
| 10mm DIN766 | 10mm | 28mm | 295-298mm |
| 10mm ISO4565 | 10mm | 30mm | 313-318mm |
| 12mm ISO4565 | 12mm | 36mm | 375mm |
| 13mm DIN766 | 13mm | 36mm | 375mm |
| 14mm DIN766 | 14mm | 41/42mm | 430mm |
| 5/16″ USA | 8.7mm | 26.1mm | 275mm |
Size/Diameter refers to the diameter of the bar from which each link is made, so don’t measure the welded part.
Pitch refers to the inside length of each link.
The ten links should be measured from outside edge to outside edge, and the results can differ slightly according to the manufacturer.
N.B. Both DIN766 and ISO4565 allow a small tolerance in the link dimensions.
It can be challenging to differentiate between 12mm and 13mm unless they are lying side by side because the ten links measurement is the same.
You can either use callipers to check the gauge (not on the welded part), or you can measure the outside width – 12mm: link width = approximately 43mm, 13mm: link width = approximately 46.5mm
Gypsys are generally manufactured to cope with some variation.
It isn’t possible to give that variation a specific figure, but 2% should generally be OK.
The classic problem that crops up the most frequently is the ‘wrong’ 10mm chain for the gypsy.
The difference between DIN766 and ISO4565 is approximately 2mm on each link, making the chain ‘jump’ under load.
Some modern gypsys are cleverly designed to cope with more significant variations in pitch.
If you are starting from scratch, i.e. you have a windlass gypsy but no chain that fits, bearing in mind that it doesn’t matter how old and rusty it is as long as it works on your gypsy, then it is more complex, but we can still help.
Examine the gypsy to see if there is a definitive manufacturer stamp or marking – you may need to remove it from the windlass for a proper check.
We can research the windlass and gypsy for you to narrow down the options and send you a short sample to lay in the pockets of the gypsy.
You can purchase 10 Links of Sample Anchor Chain to establish your calibration.
You are looking for each link to fit snugly into a pocket.
If you detect that the links will become out of kilter with the pockets on the gypsy, then the chain is probably not the correct calibration, and it will ‘jump’ under load.
If the sample is inconclusive, we can send you a longer (returnable) length, which you can rig up with some rope for a practical trial under load.
We make every possible effort to send out the correct calibration because a bit of time spent before despatch is much better than trying to sort out the mess afterwards if it doesn’t fit.
Chain is heavy, expensive, and tiresome to move around unnecessarily.
Carriers also make a surcharge for collection, so returning heavy parcels becomes even more expensive than the original carriage cost.
Customers should be aware that once a piece of chain (or rope, for that matter) has been cut to length for you, the ‘distance rules for selling’ do not apply, so it is best not to leave anything to chance.
Essentially, this means that if you have made a mistake with your order, you are not entitled to a refund.
Under our returns policy, you may be offered a credit or partial credit against your return of the goods.
If you are exchanging or, better still, upgrading in the process, it will certainly help your case regarding the credit allowed.
Our returns policy is fully explained on our Returns page.
We have retained the dimensions for individual links of AQUA4 calibrated chain: AQUA4 DIMENSIONS.
AQUA4 was the brand name for the Grade 40 calibrated anchor chain manufactured by Maggi Catena, who are sadly no longer in production.
For more general information on Calibrated Chain: Calibrated Anchor Chain Information
This article on how to choose your anchor chain may also prove helpful.
The Jimmy Green team are very keen to help you order correctly, so if you are still uncertain after reading this article, please get in touch with us by telephone or e-mail if you need more help establishing the calibration you need.
