Re: totally destroyed chain link


Porter McRoberts
 

Interesting link to that research Nick. 

A pearl which I never knew:  Force (in kg force) =  (1/500) x (LOA in metres squared) x (wind speed in knots squared).  

Happy thanksgiving to those who celebrate!

Porter 
A54-152 IBIS
Fort Lauderdale 


On Nov 24, 2022, at 1:14 PM, Nick Newington via groups.io <ngtnewington@...> wrote:


Hi  Martin,
This guy in the UK has done some great research on chain and connectors http://coxeng.co.uk/anchoring/chain/ the great thing is he is a yachtie and an engineer with a workshop and the gear to test equipment to breaking point.
I urge you to check his web site. Stainless chain does not score well on actual test, although strangely stainless shackles perform very well.

I personally think you need to change all of that old chain. If you want extra strength specify galvanised G70 10mm from Chaineries Limousine in France. Amel sources their chain there but supply grade 40 to Amel 54’s rather that the 70. Or go for top quality s/s but it is now so expensive, I can not see the point.

Nick

Amelia AML 54-019
Leros GR

On 24 Nov 2022, at 16:20, Bruno COTTE <cotte.bruno@...> wrote:

Unbelievable really strange looks like the corrosion destroyed everything inside and left it as an empty tube !!!! I have no explanation. However a good recommandation is not to use stainless steel chains more than 20 years old …. 
And for your information the windlass is limit with a 13 mm chain and a galvanised 13 mm is almost the same résistance than a stainless steel 10mm… except some unique and highly expensive products 

Envoyé de mon iPhone

Le 24 nov. 2022 à 17:03, Martin Birkhoff <mbirkhoff@...> a écrit :


Hi all,

I think this will be of general interest. Currently we have encountered an interesting problem. Attached are three photos. Two show a damaged chain link, one photo the direct adjacent chain link for reference. The rust on the chain links is mainly due to the rusting tubes. 
 
I have contacted several duplex chain manufacturers and am curious to see if there are any helpful or explanatory responses. 

 
History of the chain:
- The chain is a 10mm duplex chain that we purchased in May 2000. 
- In April 2004 we had the chain lengthened by 25m. 
- The chain was stored in the anchor locker of an aluminum boat (Reinke S11) from May 2000 until around May 2016. The anchor locker was lined with rubber mats covering a three-dimensional polyester mesh and had reliable drainage.
- Since May 2016, the chain has been in a GRP anchor locker (Amel 54) with a comparatively small volume. The drainage was unreliable in the first two years and it cannot be excluded that the affected chain link has been in retained (salt) water for a longer period of time. 
- Another possible problem seems to be that the chain tubes between windlasses and chain lockers are galvanised steel. Both tubes secrete rust to a considerable extent. 
- From July 2004 to October 2009, the Reinke Super 11 was on a round-the-world voyage. From 03/2005 to 09/2005 and from February 2008 to March 2009, the boat was in tropical waters. From January 2006 to July 2006, the boat was in partly very warm freshwater areas in South America (Rios Parana and Paraguay). Outside of these periods, moderate to cold waters were sailed. 
- For the last year we have been in the Mediterranean, although we have done little anchoring.

Notes:
- Unfortunately, I cannot say at today whether the chain link is from the original 50m supplied, or from the added section.
- The damaged chain link was about 10 m from the on-board end of the chain. It is not the link that was used to connect the two sections of the chain. 
- The entire chain has hardly been used since the change to the Amel 54, as we prefer to anchor with the stronger 13mm chain since then.
- After intensive visual inspection, all other chain links appear to be in perfect condition along the entire length of the chain.
- We never noticed any damage during previous visual inspections. This may not mean much as a questionable link is certainly easy to overlook if you are not specifically looking for it.

Fair winds

Martin
SY Mago del Sur - 54#40
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