Time to replace the rusty old anchor
chain but it is not as simple as it first seems. I need 35m of 10mm chain. All the info online doesn't match the designations of the local suppliers.
Prices locally vary from $450 to $1200 (AUD) and some only supply in 22m lengths. It seems there is an "L Grade" or G30 that is used for anchor
chains. Plus there are high and low carbon steels used. Which is best? High carbon is stronger so a lighter chain can be used. But then the weight of the chain is an important part of the anchoring
So, what do I know? Well, the breaking strain of the low carbon chains is around 5000kg with a working load of 1200+ kg. A category 5 cyclone could theoretically put a wind
load on the boat
of up to 2500kg. (140kt winds with 10sqm windage) But what anchor is going to stay put in those conditions? Even if the anchor held, I doubt the deck hardware
would survive. I would be happy if the boat
remained anchored in 70kts which is within the safe working load. So, bottom line, none of the chains is in danger
of snapping, worst conceivable conditions and the chain might stretch a bit.
So, I figure the chain should last as long as it remains rust-free and that is entirely due to the quality of the zinc galvanising. I expect (but don't know for sure) that the $1200 chain will have better galvanising but does that mean it will last 3 times as long? How can I tell? Of course, stainless steel
should be much more corrosion
resistant and does not cost much more than the more expensive Galv options....
Also, some of the chain is only available in 22m (50kg) lengths so I would have to join lengths. A continuous length seems a better option if possible.
I would like to hear what you think. Is there something I haven't considered? Do the more expensive chains last 3 times as long as the cheaper ones? How do I tell the difference?