How to select a new anchor chain.

[Cliffhanger]

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 system.

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?

[hlev00]

(North American take on your question) Look around more for chain suppliers in your area. In the US, Peerless / Acco is a good source and you can easily get lengths of 120 meters. I expect more if you had a big enough truck.

Are you, or do you plan to use a windlass? If so G30 is not normally compatible with the windlass gypsy. For that you want at least BBB. Some people go to G4 / G40 / G43 for higher strength to weight ratio. I'm not sure if G7, the next step up, is compatible with windlasses. You also need to consider how much your windlass can haul up if all chain is out hanging straight down. Granted that should never happen, but ...

What do you need / want for holding, and how much weight do you want to allocate to ground tackle. My 42' sailboat came with 30' of 3/8" BBB and 150' of nylon rode and a 45# CQR. I changed that out to 250' of 5/16 G4 and 100' of nylon rode with a 55# Spade anchor. For me it was more important to get the larger anchor. There are plenty well reasoned analyses on catenary arguing I should have 3/8" but I've been fine with 5/16". I had to change the gypsy on my windlass to accommodate the smaller chain size.

I've never heard of stainless chain and if you search CF with the google search you will probably find some discussions as to why.

Maybe this will help.
https://www.anchoring.com/blogs/anch...ut-chain-types

harry

[Cliffhanger]

Originally Posted by hlev00

(North American take on your question) Are you, or do you plan to use a windlass? If so G30 is not normally compatible with the windlass gypsy. For that you want at least BBB. Some people go to G4 / G40 / G43 for higher strength to weight ratio. I'm not sure if G7, the next step up, is compatible with windlasses. You also need to consider how much your windlass can haul up if all chain is out hanging straight down. Granted that should never happen, but ...

I am starting to realise that part of the confusion is a difference in standards. None of the suppliers quote these ratings and I think the standard size of windlass gypsy (wildcat) is different in Aust. so the chains are not compatible.

As for the length of chain, we almost always anchor in less than 10m of water, often in 2m. 35m of chain plus 50m nylon works fine. Our windlass is comfortably oversized (Muir Cheetah)

[NevilleCat]

Did you try Southern Seas Marine for Lofrans chain?

[dlj]

I have no idea of what you have in Australia for regulations. Here in the USA I use ABYC standards (American Boat and Yacht Council standards). Here I'd use ABYC H-40 ANCHORING, MOORING, AND STRONG POINTS. That standard lists the strength you need for your anchoring system depending upon your boat size. Boat size is based off both length and width - but these are for monohulls. I'm not really sure how to handle a catamaran - what you have listed as your boat. For an 11m monohull you'd be looking at a design load you should be working with as 3600 pounds (16kN). So for your 10mm chain you'd need high tensile strength - BBB would be notably below your required strength level, at least according to H-40...

The most corrosion resistant chain will be hot dipped galvanized - has to be specifically hot dipped, not just heavy galvanized. There is a galvanizing technique now commonly performed called mechanically galvanized. It is often stated to be "equivalent" to hot dipped, or it may say "heavy" galvanized, something along those lines. However, it is not the same in the marine environment as hot dipped galvanized. When performing hot dipped galvanizing, there is a metallurgical reaction that takes place causing multiple layers of zinc and zinc/iron combinations that does not occur during mechanical galvanizing. Those layers provide both additional corrosion resistance as well as notably higher abrasion resistance.

dj

[Bruce K]

MarineDirect in Sydney sell Grade L in Full or Half drums (110m or 55m), when I bought it it was Titan brand, a Canadian Company, but made in China. Did very well in a comparative test I read some time ago. I'm happy with mine, Gal seems good. Freight to anywhere seems to be $50, or you can do as I did and pick it up in MonaVale.

[chrisr]

you mention

"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 system."

but think this is a common misconception that you should reconsider. imho chain weight should be as light as you can go, for the strength required. put the extra weight in the anchor where it will do some good.

while ago we switched 90m of 10mm chain for 8mm G40 grade. same SWL but saved 50kg. this was lofrans chain fm southern seas (https://www.southernseasmarine.com.a...hain-g40-grade)
$14.24 pm x 35m = under $500 = bargain

other advice ;

- go all chain rode instead of chain + rope
- don't use stainless steel chain unless you are 110% sure of the origin and the SWL...and even then think twice. it work hardens
- regalvanizing chain is relatively cheap and easy (esp if passing thru bundaberg)
- get single length. if you absolutely have to join, be very very careful about your joining piece material and SWL

cheers,

[dlj]

Originally Posted by chrisr

you mention
- don't use stainless steel chain unless you are 110% sure of the origin and the SWL...and even then think twice. it work hardens
- regalvanizing chain is relatively cheap and easy (esp if passing thru bundaberg)

Two additional points to the above.

Stainless chain is nowhere near as strong as high strength hot dipped galvanized. So to get the same strength, you have to go to bigger sizes. It suffers from stress corrosion cracking in addition to work hardening. I am not aware of a stainless steel alloy used in chain making that is actually rated for underwater usage. Hot dipped galvanized is rated for underwater usage.

Regalvanizing chain is relatively cheap as mentioned, but you need to be aware of what kind of chain you have. If you have high strength chain and you regalvanize, it will no longer have the same strength. You won't know what strength it is.

dj

[skipmac]

First thing thing, confirm which size and type of chain will work in the gypsy of your windlass or be prepared to purchase a new gypsy if the chain you choose doesn't fit. The critical spec for chain to fit a gypsy is the length of the link which determines the number of links per foot (or meter).

Not sure about metric or DIN chains but in the US you can buy the same chain size, based on the diameter of the metal in the links, for example 3/8" chain or in metric 9mm chain BUT the length of the links is different. 3/8" BBB has shorter links that 3/8" G4 (also called G43 and HT) and so they take different gypsies. However 3/8" BBB has the the same length link as 5/16" G4 so both work in the same gypsy.

Next I agree completely that the weight is better in the anchor than in the chain. Also prefer an HT or 5/16"G4. The G4 was not only stronger and lighter but also cheaper. Seemed like a no brainer until I found a deal on almost new, used 3/8" BBB for 25% the cost of new.