8mm or 10mm Anchor Chain & How Long?

[Burge]

Hi,

I am preparing my boat (Farr 44) for offshore cruising and need to replace the very rusty anchor chain which is currently 8mm. I have been told that for a boat of this length and a net weight around 13-14 Ton I should be considering 10mm chain. If I go to 10mm chain then I might be struggling for space in the anchor locker if I maintain the 100m length that the boat originally came with.

So my question is do I upgrade too 10mm or stick with 8mm and if I go to 10mm do I really need 100m or would 80m be adequate. I would tend to take the more cautious option.

Appreciate advice.

Thanks Anthony

[JPA Cate]

On our boat that displaces approximately 12 tons with full tanks, we use 10 mm chain; we have approx. 85 m.

It will partly depend on how deep you may want to anchor. For instance, some of the anchorages in French Polynesia exceed 21 m.

[noelex 77]

100m of 8mm weighs 145kg. The same length in 10mm is 230kg.

People worry about the weight of their anchor, but this one step change in link size is a 85kg (190 lb) difference. As you note, there is also a significant increase in bulk. If it does not have sufficient drop from the anchor winch, it will jam. You also need to check your anchor winch can cope with the extra weight and also that a gypsy is available for 10mm chain.

80m of chain is generally fine for most crusing locations, but more is occasionally helpful. Where are you planning on going? 80m of 10mm is 39Kg (86 lb) more than your existing 100m of 8mm.

However, I agree that 8mm G3 or G4 is not adequate for your boat. An option is 8mm G7. This is as strong as conventional 10mm chain. As well as retaining your existing length of chain you should be able to use the existing gypsy.

[Burge]

Thanks for your helpful replys.

Good idea sticking with the 8mm but going to a G7, I have found a maggi chain G70 High Tensile which is reasonably priced and should do the job. I have minimal chain drop and even with 8mm I have to hand flake the chain otherwise it jams so 10mm would be even worse - probably why it had 8mm fitted.

That's solved I will go with 8mm G70 HT maggi chain.

Thanks

Regards Anthony

[Weyalan]

I have been pondering a similar issue myself. We are only 40' and probably around 8 to 8.5 ton loaded, so lighter / smaller than you, but even so, standard 8 mm (5/16") chain, while fine for mooching around our local relatively sheltered waters, didn't really have the "sleep at night factor" for more extended cruising.

However (a) I didn't want to replace the anchor winch gypsy and (b) didn't want the extra weight of 10 mm (3/8") chain.

So we have just purchased some new 8 mm Maggi Aqua7 (G70) chain...

The tricky thing is finding shackles, etc. strong enough to do justice to the chain... aand also bear in mins that if you are using any rope rode on the end, size that with the strength of the chain in mind (1400kg Working load, 7 ton break load, from memory)

[noelex 77]

Originally Posted by Weyalan

The tricky thing is finding shackles, etc. strong enough to do justice to the chain... aand also bear in mins that if you are using any rope rode on the end, size that with the strength of the chain in mind (1400kg Working load, 7 ton break load, from memory)

It can be a problem. The easiest solution is get the manufacturer to weld some larger links on the end. Maggi will do this for a nominal fee.

There're are a number of G8 shackles which are generally just OK even without a larger link (although I have not looked at exactly what will fit and compared the SWL for 8mm chain). The Crosby G-209A are the most popular solution:
The Crosby Group 2014 General Catalog

But there are similar products from green pin. Wichard also produce sone high tensile SS shackles and some titanium models, but the galvanised G8 shackles are usually the best option.