Anchor chains

bilbobaggins

bilbobaggins

N/A
Joined
12 Feb 2005
Messages
9,993
Location
Grey Havens Marina - Elves pontoon
Visit site
Recognising the role played by the anchor chain in ensuring a horizontal pull, and that a flat-lying catenary is VIP, I'm surprised there is not more comment - and research - about the effect on anchor stability of the 'weight' of chain used.

I see 8mm and, occasionally, 10mm on the boats I've sailed recently. Rarely more. One on-line marine store recommends 6, 8, 10 and 12mm chain *minimum* as a function of boat size/displacement.

So what's the effect of using rather heavier chain - say 12mm - on anchoring stability?

Thoughts?
 
I initially had 8mm chain and suffered from a lot of swinging when on the hook (in reality, the boat was sailing using the superstructure as sails.) I changed to 10mm chain and this was calmed down so that I was happy to anchor close to other boats, It also provides a far better hold on the bottom in conjunction with the anchor - but it does weigh a lot more! /forums/images/graemlins/crazy.gif
 
I think it is true that a heavier chain will provide more secure anchoring, all other things being equal, because the horizontal pull will be greater relative to the vertical component. However, the problem is handleability. Not just the extra weight, but the flexibilty of smaller chain makes it more likely to self-stow. I use all chain, but prefer HT so that I can use a smaller more flexible chain. I do carry a lot of chain and typically use 7:1 or 80 feet whichever is greater.
No doubt that purely for effectivness, bigger is better!
 
I have a 60lb CQR on the end of 70 metres of 10mm chain. The problem for most boats is the weight of going one size larger, and the bulk of chain in the locker. As it is I have to be careful retrieving the anchor in case the chain piles up and causes the windlass to jam.
 
[ QUOTE ]
Recognising the role played by the anchor chain in ensuring a horizontal pull, and that a flat-lying catenary is VIP

[/ QUOTE ]

Hummm.. but the two first assumptions are wrong...

With STRONG WINDS, when we need most the max holding of the anchor, the difference of the pulling angle between an all chain line and a rope line is minimal..


With STRONG WINDS the catenary given by the chain is close to nothing..

Again all calculations on the excellent web page: Alain FRAYSSE
 
I dispute this - even in storm conditions. The weight of the chain is essential to keep the pull horizontal. It also acts as a damper, so avoiding a snatch load on the anchor.
 
[ QUOTE ]
I dispute this - even in storm conditions. The weight of the chain is essential to keep the pull horizontal. It also acts as a damper, so avoiding a snatch load on the anchor.

[/ QUOTE ]

I'm a little bit fed-up to answer again and again the same topics for poeple who doesn't want to try to understand..

Believe what you want.. and if one day you want to know more on the subject. go the Alain Fraysse's web page..
 
I spend 99% of my night stops at anchor.......I use a "Delta" anchor which I still say is the best anchor on the market but what I would say is if you have the option for a heavier anchor or heavier chain I would always go for the heavier chain. I only use 20mtr of Chain with 14mm warp but the fact that the chain is double the weight that is recommended is a great aid to keep the hook well dug in. I sleepy soundly even on a lee shore ( wind force permitting) never have I dragged, even 3 nights in Soay with wind to 68kts for 3 days!!!

The other main criterea that I use is to anchor in water shallow enough to be able to see the type of bottom and therefore ensure you are clear of any weed.

Paul.
 
I agree with 'starboard' : the heavier the chain the better, but not necessarily over the whole length. On a single anchor, we often use 20m x 8mm and 10mm x 10mm (plus at least 10m nylon to the bow). In terms of the anchor holding I doubt it makes much difference which way round the chains are: but for a comfortable lie, with minimum sheering and minimum pitching, the 10mm nearest the boat is markedly better.
We sail without a windlass or capstan, so that is also the easiest for hauling: the anchor comes up on the lighter chain.
I just hope this wont set Hylas off again!
 
I'm a believer.

45lbs CQR on 90 metres of 12mm chain - though I very seldom use all of that!

It seems to me that the chain does several things:

- it provides a catenary. I don't understand Hylas' point about strong winds, but see below...

- it acts as a damper and cuts out snatch loads on the anchor. This might be what Hylas means if he has in mind shallow water - many people make the mistake of paying out half a mile of chain forgetting that most of it will be lying on the bottom and will come taut suddenly and offer no damping effect

- it cuts down sheering - won't stop it, but she will sheer slower dragging a pile of chain around with her.

And when necessary I will use a weight down the chain - at least 56lbs, if not more.
 
Hi Piota, sounds we are of the same opinion. I have no winch either so total weight a big consideration, the great thing with the "Delta" is that Simpson Lawrence reccomend the ideal anchor weight for boat length is less than you would expect of any other type. This suits me fine and allows me to double up with the dia of 20mtr of chain that I use between anchor and warp. The only problem I ever encounter is with the chain/rope combination I tend to swing more than boats with all chain. This however only a problem in crowded anchorages but as I tend to go to little bolt holes that no other punters use thats fine by me!

Paul.
 
There was an article in Yachting Monthly from one of the blue water writers, Evan Stargazer (?). I remember he had chosen to reduce the length, but had increased the size of the chain he used and added a longer rope cable. This was working for him anchored in some pretty demanding conditions.

For the sake of statistics, I have a 35lb anchor with 30mtrs of 10mm chain and loads of rope, thats on a 35ft boat.
 
Interesting point from the world of big boats - above around 20mm chain it is common to go for stud link chain instead of the common short link in order to get more weight while using the same size windlass.
 
Stud link is altogether better stuff. Years ago, Simpson Lawrence made it in sizes down to 7/16" (say 11.5mm) but nobody does so now.

It is also far less likely to foul up in the locker.
 
Yes, makes sense. For the record, also have 120 metres of nylon warp, though I have no current plans to anchor on the Dogger Bank!
 
First, it's perfectly feasible to anchor safely with warp alone - as long as you have more than 6 x depth veered. But if you're a short keel boat you'll sail around more than when you have some chain out in strong winds, which adds to the snatching as you tack at each end. So you need to reduce the tacking . . . change to a long keel boat, or deploy a second anchor, or add a bridle if you're a cat. Also, you'd need to consider chafe, which is a good argument for using chain at the bottom end rubbing against nasties.

Second, chain - and it's associated catenary - is (by itself) inadequate at providing 'spring', unless you carry a prohibitive weight. If you're tacking around the anchor, or surging in some seaway, the forces as you snatch are very high with chain alone, quite enough to haul the chain taut and remove any effective catenary. A rope spring becomes an essential part of the rode if you want to give your anchor the best chance of holding.

Third, if you're joining chain, join it with a welded link, not just the type with studded rivets - they're only about 30% the strength of the basic chain.

And lastly, if your habit is only to deploy 3 x depth, as appears the case with some vessels, you'll need a grossly overweight anchor and chain to survive any big winds.

Harrrumph. Well, that's off my chest, anyway.
 
[ QUOTE ]

I just hope this wont set Hylas off again!

[/ QUOTE ]

I believe on this forum they are two types of contributors..:

The "traditionalists" who are still using Firsherman anchors, heavy chains and Tandem set anchors.. and by experience I know that NOTHING will convince them to change.. /forums/images/graemlins/grin.gif

"Open minded people” like « Jim Baerselman »who also says:
1° - it's perfectly feasible to anchor safely with warp alone
2° - chain - and it's associated catenary - is (by itself) inadequate at providing 'spring', unless you carry a prohibitive weight.

As it will be impossible to convince the first type that they are wrong and as the second type is already convinced. I have nothing more to do on this thread..

Use heavy chains, attached with “C” links to your Fisherman anchor.. and sleep well on your anchorage.. /forums/images/graemlins/grin.gif
 
You must log in or register to reply here.

Share this page

Top