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Old 05-10-2019, 23:00   #1
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Cruising Anchor Chain Length

Is there any consensus about what is the ideal anchor chain length to carry on a cruising yacht. We intend to cruise the Med then over to the Caribbean and possibly further, so there isnít any specific cruising area. I intend to have only chain as I will be anchoring out as much as possible. Ideally the more the better, but cost, weight and itís distribution also have some bearing. Thought there might be some long-term cruisers that may have an opinion based on experience.
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Old 05-10-2019, 23:40   #2
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Re: Cruising Anchor Chain Length

You should have 80m, better 100.
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Old 06-10-2019, 00:31   #3
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Re: Cruising Anchor Chain Length

For the med I have 30m chain which is sufficient for up to 10m depth, using the 3 to 1 ratio as guideline. And then another 50m of rope adding another 10m of anchoring depth on the conservative side, perhaps my max depth is therefore 25m, also depending on the conditions.

Isn't it so that the main purpose of the chain is to ensure horizontal pull on the anchor? So once 30m chain is lying on the seabed you should be able to continue with rope. To have more chain thereafter on my 44ft boat would start to become a significant weight issue in the bow whereas the rope is nice and light, relatively speaking.

Nevertheless to respond to the question, indeed 80 to a 100m would suffice in most conditions and would be very comfortable. But it's very heavy too. So rope is a good compromise for me. I do have it hanging next to and above the chain in the locker though, to ensure it is not permanently soaked getting abused in a thankless state underneath the chain.
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Old 06-10-2019, 04:13   #4
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Re: Cruising Anchor Chain Length

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Originally Posted by CAVOK View Post
Is there any consensus about what is the ideal anchor chain length to carry on a cruising yacht. We intend to cruise the Med then over to the Caribbean and possibly further, so there isnít any specific cruising area. I intend to have only chain as I will be anchoring out as much as possible. Ideally the more the better, but cost, weight and itís distribution also have some bearing. Thought there might be some long-term cruisers that may have an opinion based on experience.
It's the possibly further that makes it hard to suggest a length. The Carib has decent anchoreges, most not that deep and you don't anchor in coral. If you end up in the S Pacific then you have a number of deep anchorages (25m) along with the requirement to anchor among coral bommies. This means you need all chain rode. 90-100m with a quality, new gen anchor.
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Old 06-10-2019, 06:29   #5
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Re: Cruising Anchor Chain Length

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Isn't it so that the main purpose of the chain is to ensure horizontal pull on the anchor? So once 30m chain is lying on the seabed you should be able to continue with rope.
The advantage of chain providing a more horizontal pull is only apparant at low windspeeds. The main purpose for using chain instead of rope rode is to provide abrasion resistance. In some seabeds this is essential or at least highly desirable. In other substrates rope rode may be arguably an acceptable calculated risk, especially if the rope is kept well above the seabed, but there is always the risk of debris (unfortunately often man made rubbish) or isolated uncharted rocks so this is a decision that needs to be assessed by each skipper.

30m of chain will lift off the seabed and form essentially a straight line at around 20-25 knots of wind, so the advantage relative to rope is lost. More chain helps this, but even with all chain rode the catenary has effectively disappeared in anything much above a moderate windspeed (say 30-35 knots) so the value of chain weight in improving the rode angle tends to be lost before the anchor is close to reaching its maximum holding power.

There are some secondary advantages of all chain. By keeping the rode angle low in the early stages of setting, the anchorís ability to penetrate more difficult seabeds is enhanced . Its also helps holding in very poor substrates and reduces the speed that the anchor has to rotate with a significant change in the direction of pull. However, considering the considerable extra weight, the advantages are small.
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Old 06-10-2019, 06:36   #6
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Re: Cruising Anchor Chain Length

noelex 77, this is very interesting to read. Have there been tests carried out on that topic?
From my point of view situations where you need holding in very poor substrates are as common as situations with strong wind. So, a long chain is quite helpful in many cases.
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Old 06-10-2019, 06:38   #7
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Re: Cruising Anchor Chain Length

We have 61m of chain plus 100m of 8-plait rope. I wish we had 100m or more of chain. The chain is 3/8". If I were doing this again I would buy 100m of 5/16 G4.

We are in French Polynesia where the anchorages tend to be very deep by comparison to British Columbia where we started out from and the Sea of Cortez where we spent 9 years cruising.

More is better.
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Old 06-10-2019, 06:44   #8
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Re: Cruising Anchor Chain Length

I have 35m of chain, as our relatively small cat is more weight sensitive, and 100m of rope.
We have cruised from the UK down and then across the Med in the last 3 years spending this year in Greece. The deepest we have anchored is 15m in Greece. I am quite happy that in the 8knts of breeze we had i doubt the rope touched the bottom. In 12m it will not touch the bottom
Have we just been lucky or is this others experience of anchoring depths on european Atlantic coast / Med??
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Old 06-10-2019, 07:18   #9
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Re: Cruising Anchor Chain Length

"Consensus" and "anchoring " in the first sentence. Funny.
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Old 06-10-2019, 07:27   #10
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Re: Cruising Anchor Chain Length

CAVOK

I would stick to min 100m chain with and one size up new anchor with no swivel. A friend who started in Buoeno Aires to Malaysia via Panama use one size down chain with high tensile.

In some area where there are corals/rocks, the 5:1 is nice but often during slack tide, the boat can drift and wrap around bommies/coral heads and that would cut the rope.

Most of time, I let out all the chain as the chain in the locker is no good.

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Old 06-10-2019, 08:25   #11
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Re: Cruising Anchor Chain Length

My thinking is it might be better to get 100 m of 8 mm (5/16) chain rather than say 60 m of 10 mm (3/8) chain. Provided the 8mm chain is high strength/quality it will still be strong enough for a relatively large yacht. I would be interested in people's thoughts on that.
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Old 06-10-2019, 08:26   #12
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Re: Cruising Anchor Chain Length

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noelex 77, this is very interesting to read. Have there been tests carried out on that topic?
From my point of view situations where you need holding in very poor substrates are as common as situations with strong wind. So, a long chain is quite helpful in many cases.

It is based on the underwater observation that even with all chain the catenary will effectively disappear at around 30-35 knots.

Therefore if the substrate is adequate to provide enough ultimate holding ability with your chosen anchor, the advantage of all chain rode in terms of holding ability is small. However, if the substrate is poor and the chosen anchor cannot obtain enough grip to hold the boat at this type of windspeed, at lower windspeeds the anchor of the boat with all chain rode will be more horizontal and therefore have higher holding ability, if all other things are equal.

Here is a photo of a boat with a Rocna and an all chain rode in about 25 knots of wind (higher in the gusts). You can see the chain is essentially straight in the gusts with no beneficial catenary:




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Old 06-10-2019, 08:37   #13
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Re: Cruising Anchor Chain Length

I believe that a long and stretchy snubber helps a chain ride ride out those gusty winds.
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Old 06-10-2019, 08:38   #14
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Re: Cruising Anchor Chain Length

All good advice. Keep in mind also that you can get away with less scope using a modern design anchor such as Rocna especially if it’s a bit oversized. As long as expected wind is light, 3:1 is quite possible. 4:1 is surprisingly solid. If we need a tight hold, 5:1 up to 7:1 is nearing the anchor maximum potential. We did 15:1 in Newport during Mathew.
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Old 06-10-2019, 08:41   #15
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Cruising Anchor Chain Length

Donít forget shock loading either, chain has very little stretch or give, three stand nylon has a lot of stretch or give, this will spread a shock load out over time as the rope stretches and significantly reduce the peak load.
Yes I know we all use snubbers, but even 50í of snubber which is much longer than Iíve seen used, wonít stretch like 100í or more of rope rode will.

Length wise to carry figure ten times the depth you will ever anchor at. 7 to 1 may be optimal, but having s little extra is always nice.

3 to 1 is crazy except for a lunch hook in a tight anchorage type of thing, although in a perfect substrate with a large enough anchor it will work fine, but how do you know your set perfectly and the anchor hasnít found hard bottom just under the sand?
I carry all chain as primary, but also have two pieces of 300í of nylon rode too, so long as you can carry it, you canít have too much rode.
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