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The 3 measurements of anchor chain diameter

Normally the chain diameter of ships should be measured during the Docking Survey. But it is not easy to measure. The below information will help to some extent. Photo and drawing are available if you have interest.

The original diameter

The original diameter is given in the survey report but sometimes the original diameter is unknown because of the report cannot be found on site. We can guess the original diameter measuring the length of the link and divide it by 6. The result will be the original diameter. The length of the link, even in old ships, shows practically no change.

The measured diameter

It is difficult to measure the diameter of all links in the limited docking period, so they pick out 2 or 3 cables on both P and S-side at random and measure the diameter of both end and middle link. The average value is the chain diameter. Measured diameter should be entered in the survey report for the next docking survey.

The wear limit of diameter

The wear limit was 10% according to conventional rules, but after the unification of the IACS standards, this limit has been amended to 12%. When the rule diameter of the chain is 100 mm, a diameter up to 88 mm may be acceptable. If the average value of measured diameter is exceeds 12% the chain cable should be renewed. But the chain cable is a production by order so it is impossible to get the new one immediately. Generally surveyor makes an outstanding recommendation within six months or so.

 

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