Sizing anchor chain...and more chain or more rope

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mike_k

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May be a silly question - but how do I measure the size of my anchor chain.
Not the length - I can do that bit /forums/images/icons/wink.gif - but the specification. If it is say 3/8 or 8mm etc. what is that measurement ? The length of a link, the width, thickness of link or something else ?

Also, it is only 15m long, which doesn't seem enough even for a 23ft boat. 5-1 scope means no more than 3m anchoring depth.
Would I be better off just adding some rope (anchor plait) - say 20m - or more chain ?
Reading other posts about anchor chain, it seems there is quite a loss of strength when joining chain together.
So should I bite the bullet and buy a whole new chain ?
I'm also thinking about emergency situations where more length may be useful.


<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by mike_k on 03/04/2003 14:24 (server time).</FONT></P>
 
size of chain is measured by thickness of the links. 3/8 in = 10mm, 5/16=8mm etc.

15 m is certainly way too short for anything but a lunch stop.

it all depends on your cruising plans. for serious cruising the ideal would be around 50m of chain in one length. if you mostly marina-hop with odd nights at anchor, adding say 40m of 12mm rope to your chain would be fine.

all-chain is best in most cases though i use rope/chain to save weight on my cat and have found it works fine.

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In a small boat of 23 feet I would add some rope to your existing chain which will make a good combination for the situations you are likely to find yourself in. 30m or 40m more of warp will be adequate when added to 15m chain. People will say that for maximum holding power you should have all chain (and they are right), but in a small boat you are sensitive to weight in the bow, and you are probably unlikely to be anchoring in exposed places or high winds. Anchorplait (or similar) is the normal stuff for anchor warp, but for my first 7m boat I had 14mm 3-strand rope, and it did fine. Cheaper too.

<hr width=100% size=1>Adventures of the <A target="_blank" HREF=http://www.xrayted.fsnet.co.uk>Teddy Bear Boat</A>
 
you will have Hylas here pronto with statements like all chain gives maximum holding power...!
don't forget retrieval as a factor on a boat your size - 15m of 8mm will already weigh around 23kg plus your anchor at say 10 kg and you are hauling up a fair old weight - I assume a 7 mtr sloop doesn't have a windlass in this!
I would concur with the addition of a good length of warp spliced to your existing chain / anchor- and even go as far as to suggest it will deliver as good a holding as all chain, used at the appropriate scope, according to the various articles and posts here from the real experts

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For our Hunter Horizon (26) I bought a secondhand GQR and 15m of Chain (for £35 !) to which I've just added 37m of 16mm anchor warp (bought from boat jumble with spliced eyelet for £57).

A key consideration for me was the weight of chain, 50m would be nice but extremely heavy, PLUS check the size of your anchor locker ! Only by careful arrangement was I able to fit all of the above plus anchor in the locker.

Another consideration is do you have a kedge anchor for additional holding and security ? I do, and felt if really necessary I could put this down for added protection.

Cheers

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Age is a question of mind over matter. If you don't mind, it doesn't matter.
 
I agree. The weight of 55 metres of 8mm chain in the bow locker of my Sadler 34 lowers it more than 2 inches. In a small boat this would be far too much, although 6 mm is probably sufficient. Rope warp probably has at least the same holding power as chain, possibly better in some circumstances. Its disadvantage, especially in a small, light boat, is that you will skitter about all over the anchorage. Might find it useful to experiment with an angel and to buy the lead weighted rope warp to help keep it all in the same place.

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Thanks for all the advice everyone. Weight of all chain was on my mind, but I feel re-assured about just adding rope. We aren't planning on heavy weather anchoring - just pottering about the Solent, but I wanted something more than 15m chain !

Last question (I hope!) - if I get line with a spliced eye, should I just ignore it and splice the rope directly to the chain ? From what I've read that would give better strength, or could it be shackled somehow to the existing chain ?

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Good point about the space, but there's loads of room - all the forepeak has in it is the toilet.
And a kedge is on my list for the next boat jumble.

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no need to splice direct to the chain unless you want it to pass over a windlass, just use the biggest shackle that will go through the chain. (and use a cable tie through the shackle and the hole in the pin to prevent it coming undone. yes.. it happened to me, very embarassing.

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personally I would not want to anchor on purely chain, I like the stretch of the warp, which should prevent parting in foul weather. I have anchored a 28 ton diving vessel in some pretty nasty weather on chain + warp and thought nothing of it.

15m of chain and maybe 30-40m of warp should be plenty to keep your anchor down and bedded in, if it comes loose I would be most surprised if an all anchor rode would stay in either.

To those people with all chain, what are you going to do when your windlass packs up, I don't think I would like to hoist it aboard, not having a go here, I am interested, why do you think 'rope' is bad?

<hr width=100% size=1><font color=blue> Julian </font color=blue>

<A target="_blank" HREF=http://www.topcatsail.co.uk>Homepage</A>
 
Why is \"all chain\" better?

I can't answer this from experience, but I am about to invest in 50m chain, and can tell you why! The arguments for are as follows.

- No risk of chafe.
- Less skittish on a windy anchorage.
- When the wind increases, the extra weight ought to maintain a reasonable catenery longer than rope.
- In the area that I will be sailing (West Scotland), I believe that all chain is commonplace. I want my boat to move similarly to others in the anchorage.
- I can alwaysl use a rope snubber or two to provide stretch at the top of the anchor line.

Of course, there are downsides, such as weight on the boat and space required.

You also asked about the weight when retrieving the ground tackle. The first point is that I'll have a well maintained manual windlass, to reduce the liklihood of it going wrong. And secondly, unless anchored in more than 15m of water, the weight being lifted at any time should be no greater than when you are hauling up your last 15m of chain. I don't anticipate ever having all my ground tackle dangling vertically below the bow, at least, not deliberately.

Cheers,

Rich

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I almost never use my windlass, no big problem hauling all chain on board. Sit on the deck and use your legs. I use the windlass to break the anchor out but that's about all.

Rope warp gives the problem I outlined above. I have seen innumerable collisions in anchorages between boats on all chain and those on rope. Chain gives a far more stable location whereas rope-anchored boats move to every breath of wind or swirl of tide.

It is my experience that most dragging has been by boats on rope. This may say more about their technique than the equipment but it remains a fact.

I have anchored for the whole of my sailing career on all chain, during which I have sat out some memorable storms and never dragged. Conversely, I have owned a Fortress on 7 metres of chain and anchorplait for about three years, during which I have dragged twice when either the wind or the tide turned. I never anchor overnight on rope for this reason.

The stretch point is valid. I almost always attach a length of nylon across a bight of the chain to give some shock absorbence and to cut down the noise of the chain dragging across the bottom.

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Interesting answers, thank you, I do not or have not anchored in busy anchorages, maybe if I did I would have to rethink my anchoring technique, either for and aft anchors, or two from the bow set at an angle which should stop the boat skitting around.

The worst case I could join all my chain aboard which will come to about 40m, but that would put all my eggs in one basket so to speak.

Thank you for your answers

<hr width=100% size=1><font color=blue> Julian </font color=blue>

<A target="_blank" HREF=http://www.topcatsail.co.uk>Homepage</A>
 
Nice website! My boat was ashore in Porthmadog when purchased and my previous GK29 Good Knews was berthed in Pwllheli marina when I last had contact with the owner. A lot more picturesque than Holland!

Much of my anchoring (on chain) has been around Anglesey in cruises in company with NWVYC Beaumaris. Owners of rope warps were told in no uncertain terms where to put them and in some places, most notably Abermenai, they are verging on dangerous. I know of one incident in which the owner of a boat that anchored there awoke next morning to find himself a mile out across Caernarfon Bar. He was on rope.

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Re: Why is \"all chain\" better?

<<I don't anticipate ever having all my ground tackle dangling vertically below the bow, at least, not deliberately.>>

We did last year, but only once and it was extreme, I grant you. We were racing down to La Rochelle and had to wait out a tide in 50m of water N of Ushant. We had 50m chain + 130 odd metres of string. Poor old windlass was nicely warmed up by the end - at least it was electric and we didnt have to wind it up by hand. As for the weight - I wouldnt like to guess the anchor alone is 30Kg, the chain? I'd guess something over 100Kg.

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I'm still there.. :0) (You will have Hylas here pronto with statements like all chain gives maximum holding power...)

Yes I was very interested to read first the question and then, all different answers..
Fortunately, I didn't develop any "new exciting product" nor do I sale any product related to the mooring line, then; I'm not obliged to refrain myself for saying what I'm thinking.. But due to the fact that I'm living full time aboard my S/Y Hylas for more than 11 years now, spending quite often nights at anchor.. and also as a designer of two new anchor designs (the last one will be launched soon!.. see: www.oceane-anchor.com) I'm surely more concerned about all anchoring subjects..
As usual, they are pros and cons and I've tried to summarize them.. and after I will tell you my thoughts..
CHAIN only:
Pros:
all-chain is best in most cases (Why?? Can you explain?)
People will say that for maximum holding power you should have all chain (and they are right) (Same question? WHY , please explain??)
I am about to invest in 50m chain, and can tell you why!
- No risk of chafe (OK)
- - Less skittish on a windy anchorage (OK)
- - When the wind increases, the extra weight ought to maintain a reasonable catenery (WRONG)
- I want my boat to move similarly to others in the anchorage. Rope warp gives the problem I outlined above - Chain gives a far more stable location (perfectly true)

Cons:
- there are downsides, such as weight on the boat and space required (OK)

ROPE only:
- ????????????

CHAIN and ROPE:
Pros:
- The stretch point is valid. I almost always attach a length of nylon across a bight of the chain to give some shock absorbance
- I like the stretch of the warp, which should prevent parting in foul weather
- I would concur with the addition of a good length of warp spliced to your existing chain / anchor-! and even go as far as to suggest it will deliver as good a holding as all chain.
- I would add some rope to the existing chain
- 50m of chain in one length.- adding say 40m of 12mm rope to your chain would be fine.
- Would I be better off just adding some rope (anchor plait) - say 20m - or more chain ?
- 30m or 40m more of warp will be adequate when added to 15m chain
- personally I would not want to anchor on purely chain
- Last question (I hope!) - From what I've read that would give better strength,?
- 15m of chain and maybe 30-40m of warp should be plenty to keep your anchor down
- I use rope/chain to save weigh
- why do you think 'rope' is bad?

Cons:
- rope-anchored boats move to every breath of wind or swirl of tide (Right)
- Rope warp gives the problem I outlined above (Right)
- it seems there is quite a loss of strength when joining chain together.
- most dragging has been by boats on rope. (??? Are you sure?? Some figure please??)

Others comments:
- if I get line with a spliced eye, should I just ignore it and splice the rope directly to the chain or could it be shackled somehow to the existing chain?
- I use the windlass to break the anchor (NO.. PLEASE...)

WAAAOOOOO.. very controversial..

Let's study all those different points of view..

Chain:

With the exception of the resistance of the chain sliding on the sea bottom which can be considered as "negligible".. the holding is given by THE ANCHOR.. and not by the mooring line..
The mooring line can in some ways contribute to the holding mostly for two reasons:
- The first one is related to scope.. more the scope more the % of holding you will get from your anchor..
- This is a general rule, but you can consider that at a scope of 4/1 you will achieve about 55% of the total anchor's holding at 8/1 - about 80% at 10/1 around 85% and for more scope.. you will just slightly increase your holding until you reach an infinite line which will give you 100% (pulling horizontally) (and this rule is valid for both chain and rope)
- The second one related to the shock absorbing effect of the mooring line. When the weather is bad and mostly with some waves, the Kinetic energy can reach "Peaks" of several TONS.. and this is during those peaks that either your anchor will drag or you will break the chain.. (no, not unusual..) That's why it is so important to have a possibility of stretching the line to absorb those peaks..
I can hear people in favour of all chain line.. talking about catenary effect of the chain, and about the weight of the chain keeping the chain sitting on the sea bottom.. and THEY ARE RIGHT... at least for light winds..
but who cares about holding during light winds??.. As soon as the wind build up over, let's say, 25 / 30 knots.. the chain is nearly bar tight and there is no longer any catenary effect or horizontal pull.. That's why it is very important to have at least 10 meters of NYLON (elasticity) rope inserted in the line..
But YES.. No risk of chafe.. that's why it is necessary to have at least 15 to 20 m of chain..
- YES Chain gives a far more stable location... but I prefer a good holding..
They are two possibilities to connect chain and rope:
- a spliced eye and then a shackle (one size bigger than the chain) but it will not go through the gipsy of the windlass.
- A direct rope to chain splice (and NOT a rope to rope splice after a "U" turn around the last link of the chain.. ) see on Jimmy Green web page or on www.bluemoment.com <http://www.bluemoment.com> web page. The lost of breaking resistance is low.
And please: DON'T use the windlass to break the anchor.. if your anchor is very deeply buried, come at the vertical of the anchor, tight the line on a (Strong) cleat and take the time to smoke a cigarette or to drink a cool beer.. your anchor will break out very easily.. or, at least, use your engine.. but please, not the windlass..

Fair winds and peaceful anchorages

Alain

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Re: CHAIN OR ROPE?

The main and ONLY advantage of the chain is that it is the only and perfect mean to avoid chafing of the anchoring rode on aggressive sea beds...

Except for this point, chain has all the disadvantages..:
- Stored in the bow chain locker, it adds a heavy weight in the last place you want one.

When deployed, chain is actually working in the opposite way to the way it should work:

- with light wind, it gives a perfect horizontal pull to the anchor and the best holding.

- with moderate wind, its weight and catenary effect give a perfect shock absorbing effect.

- As the wind builds up, the chain will become straighter (and this with as little as 25/30 knots of wind). The pulling angle will increase and as a consequence, the holding of the anchor will decrease.

- When the shock absorbing effect is most necessary, the "bar tight" chain will not allow this to happen.


If there are waves entering the anchorage, the resulting shocks will be then directly transferred to the anchor, which then has more chance to break free.. . and more seriously, the chain is subject to high "peaks" of pulling force and has a consequently higher risk of breaking..

WHAT LENGTH OF CHAIN?

During the last seven and half months, I spent 129 days anchored (out of 228) in 61 different anchorages. The mean water depth was 6.50 metres and the scope 5/1. The total length of the mooring line was about 30 meters, of which 23.5 metres was lying on the bottom (30 - 6.50 m) Therefore, I believe a length of about 25 meters is perfect. If the water height is less, then you will be anchoring with an all chain line .. . if the wind build up, you can pay out more scope but the wind will push the boat and the rope line will not chafe on the bottom.

WHAT LENGTH OF ANCHORING RODE?

Holding is in direct relation to the pulling length of the rode .. . (or more accurately, the pulling angle). Generally speaking, with a scope of 4/1 you will have about 55 % of the maximum holding of the anchor, with a scope of 6/1 about 70 % with a scope of 8/1: 80 % and with 10/1 about 85 % the maximum. - 100 % holding will be achieved with a horizontal rode or a "Infinite/1 scope.

Increasing the scope will be efficient up to 10/1 - With more than 10/1, a large increase in the scope will give only a negligible increase in holding. Therefore, the total length of the rode has to be adapted in relation with the conditions you are expecting to meet, and should be about ten times the maximum depth you expect have to anchor in. (I suggest 100 meters).

WHAT ROPE TO USE WITH THE CHAIN?

Natural fibbers are no longer used .Of the artificial fibbers, the one which has the best elasticity (shock absorbing effect) is polyamide (Nylon, Perlon, Enkalon). As the breaking strength of 10 mm chain is 5 tons, a 16 mm polyamide line will be well suited. (Breaking strain 5.6 tons). Don't oversize the rope. Yes, you will increase the strength, but at the same time you will decrease the elasticity . . . and "elasticity" is the secret.

You have the choice of three strand rope or eight strand rope (also called "square line"). Eight strands rope is better.

CONNECTING ROPE TO CHAIN


Remember: A CHAIN HAS THE RESISTANCE OF ITS WEAKEST LINK...
a) With an "eye" splice over a thimble and then a shackle on the chain.

ALWAYS use a shackle one size bigger than the chain.. and secure the pin with a monel wire. This is a perfectly safe solution but the eye splice will have difficulties to go through the bow roller.. will no pass the windlass gipsy and will never go through the deck pipe...

b) with a rope to chain splice.. There are two ways to do this: the wrong one and the right one.

Wrong: NEVER splice the rope over the rope after a "U" turn into the last chain link . . . you will lose about half of the strength of the rope.

Right: Make a direct rope to chain splice. This is quite easy to do.. when you know how!!! (www.bluemoment.com and Jimmy Green web page)

FINAL OBSERVATIONS:

Last point, I'm currently in the LAS PALMAS (Canaries) harbor covering the A.R.C. event. (Nov 2002). Curiosity prompted me to check the rodes of these boats, which will cross the ocean and spend plenty of time anchored in the Caribbean. I was alarmed to realise than more than half the boats are relying on what is in my opinion a dangerous rode. (Note - I am not talking about inadequate anchors here).

Main points are:

A too small, rusted and not secured shackle

The use of beautiful stainless steel anchor connectors. The most common one has an axe drilled to put a "security " screw on the opposite side.. although this is a wonderful idea to avoid unscrewing of the axe. the hole in the middle of the axe decreases the strength. For a 5 tons chain resistance, this connector has only three tons of resistance ... check yours!!!.

Swivels . . . the theory is perfect, but under load, swivels don't work. More importantly, check their breaking strength, not only with a straight pull but also with a sideways pull..

Connecting links - these have a breaking strength of only few hundred kg . . . NEVER use them on a mooring line.

CONNECTING THE ANCHOR AND CHAIN

A shackle is perfect. As before, always use one size bigger than the chain . . .and secure the pin! The simplest and perfect way is to use a toggle, the same you use for your rigging. Again, use one size bigger than the chain (12 mm for 10 mm chain).


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