Calibrated Anchor Chain

Taz

How do you tell if anchor chain is calibrated or not. Upgrading to a Windlass and I need to know if my existing chain is calibrated, its has the original anchor chain & rode

frenchship

All links have to be the same dimension length wise and width it a must with windlass.
here more Infos 

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.

All windlass gypsys are 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.
Windlass manufacturers change their specification over the years and the details of those changes are not necessarily available without a lot of digging.
Any markings or stamps on the gypsy itself may help in this respect.
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.

The good news is there are a limited amount of calibrations manufactured in Europe.
6mm, 7mm and 8mm are calibrated to DIN766
10mm is more difficult because there are two widely used calibrations: DIN766 and ISO.
Be aware that selecting the wrong calibration, particularly in 10mm, on the vast majority of windlasses will result in ‘jamming’ or ‘jumping’ under load.
There are also other sizes of old, unusual or American imperial chain which don’t fit into these calibrations e.g. ¼” and 9.5mm.
¼” equates to approximately 6.3mm so it is in between the more modern 6mm and 7mm sizes
But there is more good news: the old imperial size 5/16” short link is very often compatible with 8mm DIN766.