Anchor chain: How rusty is too rusty

[Macka1706]

That would have gone over the side years ago if mine. THE anchor and it's fastenings are your life guard.
Try holding through a Cyclone sometime. Once the galv, starts to look tired and pit. Get it regalved.
I used on my 32ft steel 8.5ton Pugh. 35lb Plough (plus another one in bilges) Swivel 10mm chain x 40ft. with Another swivel,110mtrs of 8mm Galv Industrial chain behind. You ever tried to haul up, by hand or Gypsey a multi twisted chain with a weight on the end of it?.
Second anchor beside it is 85lb Admiralty roped to bow rail ready to deploy as "feel safe" pick I use if my greased, bomb dropper don't give me indication of consistency on strange bottoms. I've gone through too many big blows on my boats over the decades. and watched too many drag picks past me thank you.
I TRUST my anchors. AND the gear behind them, 2 at bow. with another 40lb Sand pick on 40ft of chain and 100mtrs 1 in Nylon in box at Transom as a brake.
I get all my chain/rope, from chain and rope suppliers. It's ALL graded. and tested. Think about High Tensile galved, as soon as it's HOT dipped in the Galv. The H/T (which is a HEAT treatment) is no more, just soft steel again.
I'm an ex Crane/Dragline/Excavator operator all my working life. Lived Chains.Cables and ropes/slings every working day.
Plus 65+ yrs on fishing boats and Sailing. You NEVER see more than SURFACE rusting on any working boat or machine do you.
Hammerlocks we used to join chains they sized/rated to .
ALL shackles . DO NOT use zip ties on pin eyes. Galv or stainless wire only. twisted through eye and round shank. Plus. I always use "neverseize" on all threads under and above the water. Otherwise at least every 6 months. Pull the shackle pins. grease and reset. and dump when galv gone.

Picks and their boat holding bits are working. Life saving bits. Don't even think about it. Just dump it mate.
Another tip. You drifting/being blown onto anything hard. rocks/beaches etc and no propulsion.
Drop your pick on ALL the chain. Hopefully it'll catch/dig in to something till blow over and you still afloat.
It did me once years ago (late '50's) in a timber yacht off N/E England coast (Hartlepool on leave from Army.

 

[Neeves]

Think about High Tensile galved, as soon as it's HOT dipped in the Galv. The H/T (which is a HEAT treatment) is no more, just soft steel again.

Just adding a minor correction

Absolute rubbish

Gunnebo, now owned by Crosby, make a G80 galvanised chain for fish farming.

Peerless make a G70 galvanised chain (from a G43 feedstock).

Maggi make a G70 galvanised chain, now made by a different Italian chain maker whose name I forget.

Crosby, Peerless, Campbell and others. make galvanised G80- shackles

I took a 6mm G80 chain, had it galvanised, had it tested by an independent test facility - it has the strength of the chain, 8mm G30, it replaced.

The US Navy and Marines use galvanised high tensile chains for tie downs and anchor chains because being HT they can use smaller chain but of the same strength as larger 'soft steel' chain.

Like the tie downs for the military vehicles on this hovercraft.


All galvanised and not soft steel.

You can then takes these products when they have worn the gal off (as long as you do not leave it too long) and regalvanise and retain the exact same strength.

You need to start with a HT steel - and yes - you will lose strength but with care and sensible choices you will not end up with 'soft steel'. If you were a chain maker, as opposed to me, you would know the optimum Quench and Temper schedule of the alloy steel and be able to optimise the galvanising process for strength.

I worked with a galvaniser for about 6 months to get as close to optimising my rode as possible and have made a number of rodes since (and galvanised hammer locks, shackles, omega links and chain hooks (and had them independently tested).

Technology moves on

Jonathan

 

[doug748]

I do not know where you get your data from, but it is wildly wrong. Your 1600lbs is just not believable. Basic Grade 40 chain is well over 3 times that. jimmygreen.com/content/217-calibrated-chain-break-load-and-weight-guide You will not break 6mm chain with a boat attached to even the best holding anchor of the size that even the most conservative person might use. It is well over twice the maximum holding of the best 15kg anchor. There is simply no justification for going up to 8mm on "strength". In fact as has been mentioned already in this thread, the weak point in the link between the boat and the anchor is not the chain but the connections, typically the shackle attaching the anchor to the chain.

As far as anchor setting and holding is concerned the only role of the rode (whether it is chain or rope) is applying the load to the anchor. Its weight and size is irrelevant provided it is strong enough. Most of the tests of anchor holding power use rope to exert the pull. You never see any suggestion that chain will improve the holding power of your anchor. To put some figures on this, a typical smallish yacht like the OPs, mine and yours may be able to exert between 250-300kgs of pull in reverse, which is roughly equivalent to the pull in 25-30knots of wind. Ultimate holding power on a good anchor for this size boat is around 1000kgs (and remember the chain can withstand over twice that).

I do not understand your comment about vertical pull that you imply occurs with rope but not chain. This simply does not happen. By definition when a boat is applying load to an anchor the angle is the same whether the rode is chain or rope and the effect on the anchor will ,be the same. The only benefit of chain in the way it reacts with the anchor is that it forms a catenary which dampens the effect of movement of the boat on the anchor. However this disappears at around 25knots of wind and the chain becomes straight, just as it does with a similar load being applied to set the anchor by using the engine in reverse. There is a small difference in catenary between a heavier 8mm and a 6mm chain, but doubt you would notice it in practice.

I think you would be considered very unobservant if you did not notice a 2mm loss in thickness of your chain. I doubt there is any noticeable loss in strength of the OPs chain, which being 8mm is well over 4 times the maximum load his boat could ever put on it. Note that he anchors in shallow water in the Solent, and I guess in relatively benign conditions. I doubt the load from that type of anchoring approaches even 10% of the breaking load of his chain.

Personally I prefer all chain rodes for 2 reasons. First and important even if you are considering rope, is abrasion resistance for the short length that rests on the seabed in most anchoring situations (ie below 25knots of wind ) and particularly so in tidal or changeable wind situations when the chain moves around on the seabed. Secondly with a well set up windlass and anchor locker, retrieval is seamless and much easier to control.

My Bavaria came with a 10kg Delta and 50m 8mm chain. It really only needed 6mm for the reasons given above, but not worth changing and of course no more difficult to handle. My GH (which has much the same displacement, but less windage) has 6mm chain and now a 10kg Epsilon and a Lofrans Kobra windlass. For connections I have Kong swivel plus 3 links of 8mm which overcomes the shackle limitations. This decision was made after researching all the available tests and reliable data. In reality I shall never anchor in situations that would stress this set up - indeed I might just as easily kept the old 35lb CQR copy which previous owners over the last 45 years or so seem to have been happy with.

I note the OP does not have a windlass, so there really is no argument for keeping 8mm chain if he does decide to change it. Why have something that is way over sized and offers no benefits that weighs more, costs more and is a PITA to handle?

Sorry you don't understand the matter.

* 8mm chain has a more useful catenary than 6mm, it's heavier
* If you neglect a chain you can afford to do it longer and more safely with larger diameter chain
* Shock loads could well break a chain reduced by corrosion
* 8mm will give you a greater range of windlass, should you decide to fit one
* The weight of chain and it's associated catenary helps keep the pull on the anchor horizontal as you set it.

Further to point one the weight of chain on the seabed and it's catenary, is what keeps a boat where it is in light conditions - this is a good thing.

(The figure in line 8 should read 1200kg not 1600llbs. It is taken from information provided by Jimmy Green. Note these are breaking loads not SWL)


No matter how many reams of waffle you write, these matters are factual, wont go away and likely known by the vast majority of people reading this thread.

I have never seen or heard of any credible recommendations that suggests 6mm chain for a 5 ton 31 ft boat.

.

 

[Tranona]

I too are sorry you seem have some difficulty in following logical argument and relating it to what happens in the real world. Catenary does NOT help setting the anchor. Having chain on the bottom does not either. What sets the anchor is a load placed on it and that only happens when the rode is straight so that either the weight of the boat or the use of the engine in reverse is applied to the anchor. Catenary is limited to relatively light winds and I clearly said it was useful - but it does not make the anchor set or hold better. Your statement that the chain on the bottom keeps the pull horizontal is just wrong as shown many times by videos of anchors setting - posted and illustrated here many times.

Can you explain how shock loads can break a chain when the holding power of the anchor is less than the breaking load of the chain (whether it be 1200kg or 2240kg)? Given that in real life the anchor may well not achieve its maximum holding power surely the anchor would drag before the chain breaks?

Would the knowledgeable yachtsmen really let his chain rust to the extent that its breaking load was compromised? Or even worse choose chain on the basis that it will last longer because it can be allowed to rust to that extent? Of course weakened chain will break more easily but can you give some concrete examples of this actually happening?

All The Lofrans and Lewmar windlasses suitable for the size of boat in question here are available with 6mm gypsies.

I suspect your definition of "factual" is rather different from mine as you seem just to rely on "everybody knows" rather than any actual evidence.

I am afraid you win in the waffle stakes. The mixture of statements that are simply untrue and claiming they are "factual" and "likely known by the vast majority of people reading this thread" just does not stand up to scrutiny.

 

[Neeves]

I have never seen or heard of any credible recommendations that suggests 6mm chain for a 5 ton 31 ft boat.

.

Our 38' cat is 7t and has the windage of a Bav 45. We sail to Tasmania, you may have heard of the 'Roaring Forties' ? and have been using 6mm chain for over a decade.

This is a picture of 50m of 8mm chain, the top 2 drums and 75m of 6mm chain the lower two drums. Now I don't know 31' yachts that well - but I am sure the chain/anchor lockers are small and I know which size of chain would best fit a small locker (the difference in weight would be reflected in sailing performance - but that is a bit subjective.... and a different discussion.

The 'technology' behind catenary can be replaced with elasticity, or a snubber. I know which is cheaper and lighter, especially if you have a 31' yacht.

I think every credible windlass maker makes a windlass focused at 8mm chain but has a 6mm or 10mm gypsy that will fit (and vice versa). When we down sized from 8mm to 6mm in consultation with Maxwell we opted for a windlass nominally designed for a yacht for which 8mm would nominated (because the tension, or loads), would be for our size of cat) but chose a 6mm gypsy and 1,000 watt motor.


I'm disappointed that having made 12,000 posts, so an active member, you have not read any of my posts on anchoring - most people are overly critical of my single minded postings - you are quite unusual?

I have not repeated Tranona's evidence - but agree with his posts.

He has a much better handle on the English language than I - but then I've been in Australia for 25 years now - and standards slip and I, apparently, have become verbose . - to the point of tedium.

Jonathan

 

[AndrewB]

Apart from the loss of thickness the rusty chain makes a real mess of the deck. Mine is going the way of yours. Will replace it in a month or so when I get to Martinique.

That's right! The chain may be good awhile yet, but a shame you didn't get it regalvanised a year or two ago. Looks too far gone for that now. It's a fraction the cost of new chain (if you avoid yacht chandlers prices), and the chain will last almost forever.

 

[geem]

That's right! The chain may be good awhile yet, but a shame you didn't get it regalvanised a year or two ago. Looks too far gone for that now. It's a fraction the cost of new chain (if you avoid yacht chandlers prices), and the chain will last almost forever.

If you are in the Caribbean regalvanising isn't an option.

 

[Kelpie]

If you are in the Caribbean regalvanising isn't an option.

That's a shame but understandable. Would the US be our closest option?

 

[doug748]

I too are sorry you seem have some difficulty in following logical argument and relating it to what happens in the real world. Catenary does NOT help setting the anchor. Having chain on the bottom does not either. What sets the anchor is a load placed on it and that only happens when the rode is straight so that either the weight of the boat or the use of the engine in reverse is applied to the anchor. Catenary is limited to relatively light winds and I clearly said it was useful - but it does not make the anchor set or hold better. Your statement that the chain on the bottom keeps the pull horizontal is just wrong as shown many times by videos of anchors setting - posted and illustrated here many times.

Can you explain how shock loads can break a chain when the holding power of the anchor is less than the breaking load of the chain (whether it be 1200kg or 2240kg)? Given that in real life the anchor may well not achieve its maximum holding power surely the anchor would drag before the chain breaks?

Would the knowledgeable yachtsmen really let his chain rust to the extent that its breaking load was compromised? Or even worse choose chain on the basis that it will last longer because it can be allowed to rust to that extent? Of course weakened chain will break more easily but can you give some concrete examples of this actually happening?

All The Lofrans and Lewmar windlasses suitable for the size of boat in question here are available with 6mm gypsies.

I suspect your definition of "factual" is rather different from mine as you seem just to rely on "everybody knows" rather than any actual evidence.

I am afraid you win in the waffle stakes. The mixture of statements that are simply untrue and claiming they are "factual" and "likely known by the vast majority of people reading this thread" just does not stand up to scrutiny.

It's easy you just have to take each proposition in turn:



* 8mm chain has a more useful catenary than 6mm, it's heavier

True? If not tell me why.

* If you neglect a chain you can afford to do it longer and more safely with larger diameter chain.

True? If not tell me why.

* Shock loads could well break a chain reduced by corrosion

True? If not tell me why. Tip, Google broken anchor chain


Two things you have questioned:

* 8mm will give you a greater range of windlass, should you decide to fit one.

Look at the Force 4 site and see what is actually stocked in the better ranges, not the stuff designed for small power boats. If the OP decides to fit a used windlass he will find it not an easy proposition to find a strong unit with a 6mm gypsy. Manual or electric

* The weight of chain and it's associated catenary helps keep the pull on the anchor horizontal as you set it.
Seriously? You doubt this. Here is a picture to help:

"The benefit of this catenary action is that it decreases the initial angle between the seafloor or ocean bed and the anchor rode. "


.

 

[geem]

That's a shame but understandable. Would the US be our closest option?

No, Martinique is best. Way cheaper

 

[doug748]

If you are in the Caribbean regalvanising isn't an option.

I think it's a diminishing option in the UK as well. I had it done about 12 years ago in Birmingham, since then the price has trebled, even if you get get someone to do it and get the stuff to and from the site. I gave up and reluctantly and bought new

There is one place in Scotland who may take it on I believe, one contact sometimes posts on here. I think they also do the surface treatment for, and are involved with, Knox anchors.

.

 

[Kelpie]

No, Martinique is best. Way cheaper

Sorry I was meaning regalvanising

 

[geem]

Sorry I was meaning regalvanising

By the time you have sent it to be galvanised and waited in a marina, the cost is really not worth it. Also, I have no desire to go back to the USA.
It's as cheap to buy new in the French islands

 

[Tranona]

It's easy you just have to take each proposition in turn:



* 8mm chain has a more useful catenary than 6mm, it's heavier

True? If not tell me why.

* If you neglect a chain you can afford to do it longer and more safely with larger diameter chain.

True? If not tell me why.

* Shock loads could well break a chain reduced by corrosion

True? If not tell me why. Tip, Google broken anchor chain


Two things you have questioned:

* 8mm will give you a greater range of windlass, should you decide to fit one.

Look at the Force 4 site and see what is actually stocked in the better ranges, not the stuff designed for small power boats. If the OP decides to fit a used windlass he will find it not an easy proposition to find a strong unit with a 6mm gypsy. Manual or electric

* The weight of chain and it's associated catenary helps keep the pull on the anchor horizontal as you set it.
Seriously? You doubt this. Here is a picture to help:

"The benefit of this catenary action is that it decreases the initial angle between the seafloor or ocean bed and the anchor rode. "


.

Yes, 8mm chain is heavier and has more catenary. That is not the real question - which is how much and what evidence is there that this is of significant benefit. I have never seen any research that quantifies this , nor crucially what the difference is between different sizes of chain, Another "everyone knows" kind of belief. It has no impact on the set or ultimate holding power of the anchor, and while it has value in light conditions because it can reduce swinging circles and dampen movement of the boat, its effect has been demonstrated to disappear when wind strengths reach the range of 25-30 knots. As pointed out many times the use of nylon snubbers can replicate much of the effect of catenary over a much wider range of conditions and are used by many serious experienced "anchorers" including several members here.

Just because something has superior properties it does not mean they are of value in specific circumstances. Sensible (and questioning) people look at those properties and determine whether they have any value in a specific set of circumstances. Others seem to rely on belief that they do without providing any evidence.

What kind of person would let a chain get to the state where it has lost well over half its strength? Just stating that chain loses strength as it corrodes is obvious - but does it actually happen? Do people really make a chain purchase decision based on how long it will stay strong enough after the galvanising has gone and it has rusted away? The OP says his chain is at least 10 years old (and I suspect it is original to the boat) and only the last 1m has corroded. Quite sensibly considering replacement which may well last 20 years with his pattern of usage before there is any significant corrosion. Even frequent long term anchorers like geem who anchors in far more demanding conditions than most of us reckons 4-5 years before considering replacement (or regalvanising if possible)

So, quite why you consider longer life after loss of galvanising as a desirable property of heavier chain than is necessary is beyond me

I have as instructed googled broken anchor chain and see nothing that is in the least bit relevant to this thread, or even to anchoring of small yachts in general. Even the threads from popular US forums fail to come up with any concrete verifiable instances of standard chain breaking in the way you claim. Several secondhand stories mostly involving large poorly maintained boats with chain to match, plus many comments along the lines "never heard of such a thing". I really am struggling to get a feel of where your beliefs come from.

6mm gypsies are available for Lewmar Pro1000, Lofrans Royal manual (which Force 4 do stock), X1 vertical, Kobra (which I have) and Cayman, all of which are "serious" enough to be recommended and used on boats up to 9' longer and over twice the displacement of the OP's boat. Force 4 are not the only supplier but do stock the 6mm version of the V700 would would be fine for the OPs boat and pattern of anchoring. Usable windlasses of any type are rare in the secondhand market and as always you can only buy what is on offer at any given time.

I am not sure what your pretty picture is designed to show - other than you can draw pretty pictures and post them on here. You are claiming that it shows how the pull is horizontal because of the chain on the seabed. Your picture is static and shows nothing of the sort. If you watch any video of anchors setting when pulled by a boat above the height of the anchor (as your picture shows) as soon as the load is applied the chain lifts off the seabed and forms a straight line to the source of the load. Until that happens the anchor is not moving. By definition the pull is not horizontal but has a vertical component that increases with the depth of the water.

It is not a question of doubting - your claim is just not supportable with any evidence either theoretical or empirical.

 

[NormanS]

I'm intrigued why some on here use chain at all. We have people advocating lighter and lighter chain, - perfectly understandable for those with light displacement boats. We have people stating that chain goes "straight" at quite modest wind strengths.
If this is the case, why don't these same people use wire of suitable SWL? Wire would be easy to manage on a "magazine" winch, where the wire would wind into the winch drum. Wire would be lighter than chain capable of handling the same load.
Show your confidence, anchor with wire.

 

[doug748]

"Yes, 8mm chain is heavier and has more catenary."

Thank you, at last.....

"your claim is just not supportable with any evidence either theoretical or empirical."

Oh dear, I thought we were getting somewhere.


"I am not sure what your pretty picture is designed to show - other than you can draw pretty pictures and post them on here."

It's not my picture nor my explanation. The copyright belongs to Marine Insight:

Marine Insight is a global leader in providing maritime news and training maritime professionals with an expert panel of writers, news reporters, and consultants. The content from Marine Insight is used by global online media, institutes, and Organisations as a reference tool for Maritime and Shipping Industry.​

" I have never seen any research that quantifies this , nor crucially what the difference is between different sizes of chain, Another "everyone knows" kind of belief."

Nor have I. All I have said is that the advantages are there, will be measurable and the prudent yachtsman might want to note the fact. I have never used the term "everybody knows" or even hinted at it. All I have said is that these things are established science.

"I have as instructed googled broken anchor chain and see nothing that is in the least bit relevant to this thread"

Several examples on this thread: Breaking an Anchor Chain - Cruisers & Sailing Forums
Plus some closer to home.

"That is not the real question........"

Aye well, we can all change the question.
I think it's good policy to concentrate on what is said, not what you thought was said, or wish was said, or might be imagined through the veil of your own imagination.

.

 

[geem]

I'm intrigued why some on here use chain at all. We have people advocating lighter and lighter chain, - perfectly understandable for those with light displacement boats. We have people stating that chain goes "straight" at quite modest wind strengths.
If this is the case, why don't these same people use wire of suitable SWL? Wire would be easy to manage on a "magazine" winch, where the wire would wind into the winch drum. Wire would be lighter than chain capable of handling the same load.
Show your confidence, anchor with wire.

You first

 

[geem]

Yes, 8mm chain is heavier and has more catenary. That is not the real question - which is how much and what evidence is there that this is of significant benefit. I have never seen any research that quantifies this , nor crucially what the difference is between different sizes of chain, Another "everyone knows" kind of belief. It has no impact on the set or ultimate holding power of the anchor, and while it has value in light conditions because it can reduce swinging circles and dampen movement of the boat, its effect has been demonstrated to disappear when wind strengths reach the range of 25-30 knots. As pointed out many times the use of nylon snubbers can replicate much of the effect of catenary over a much wider range of conditions and are used by many serious experienced "anchorers" including several members here.

Just because something has superior properties it does not mean they are of value in specific circumstances. Sensible (and questioning) people look at those properties and determine whether they have any value in a specific set of circumstances. Others seem to rely on belief that they do without providing any evidence.

What kind of person would let a chain get to the state where it has lost well over half its strength? Just stating that chain loses strength as it corrodes is obvious - but does it actually happen? Do people really make a chain purchase decision based on how long it will stay strong enough after the galvanising has gone and it has rusted away? The OP says his chain is at least 10 years old (and I suspect it is original to the boat) and only the last 1m has corroded. Quite sensibly considering replacement which may well last 20 years with his pattern of usage before there is any significant corrosion. Even frequent long term anchorers like geem who anchors in far more demanding conditions than most of us reckons 4-5 years before considering replacement (or regalvanising if possible)

So, quite why you consider longer life after loss of galvanising as a desirable property of heavier chain than is necessary is beyond me

I have as instructed googled broken anchor chain and see nothing that is in the least bit relevant to this thread, or even to anchoring of small yachts in general. Even the threads from popular US forums fail to come up with any concrete verifiable instances of standard chain breaking in the way you claim. Several secondhand stories mostly involving large poorly maintained boats with chain to match, plus many comments along the lines "never heard of such a thing". I really am struggling to get a feel of where your beliefs come from.

6mm gypsies are available for Lewmar Pro1000, Lofrans Royal manual (which Force 4 do stock), X1 vertical, Kobra (which I have) and Cayman, all of which are "serious" enough to be recommended and used on boats up to 9' longer and over twice the displacement of the OP's boat. Force 4 are not the only supplier but do stock the 6mm version of the V700 would would be fine for the OPs boat and pattern of anchoring. Usable windlasses of any type are rare in the secondhand market and as always you can only buy what is on offer at any given time.

I am not sure what your pretty picture is designed to show - other than you can draw pretty pictures and post them on here. You are claiming that it shows how the pull is horizontal because of the chain on the seabed. Your picture is static and shows nothing of the sort. If you watch any video of anchors setting when pulled by a boat above the height of the anchor (as your picture shows) as soon as the load is applied the chain lifts off the seabed and forms a straight line to the source of the load. Until that happens the anchor is not moving. By definition the pull is not horizontal but has a vertical component that increases with the depth of the water.

It is not a question of doubting - your claim is just not supportable with any evidence either theoretical or empirical.

Our chain is 4 years old. Corroded from a lot or time deployed at anchor in hot water (circa 25 to 30degC) most of the time. We have end to ended the 60m length so we are on then good end where the galvanising is still reasonable. The middle section is the worst. When we deploy more than 30m of chain the bit in the middle is seeing twice the exposure to hot salty water as the ends, over its lifetime. It will be replaced in the next month or so.

 

[NormanS]

You first

Not me. I'm not a believer.

 

[NormanS]

Our chain is 4 years old. Corroded from a lot or time deployed at anchor in hot water (circa 25 to 30degC) most of the time. We have end to ended the 60m length so we are on then good end where the galvanising is still reasonable. The middle section is the worst. When we deploy more than 30m of chain the bit in the middle is seeing twice the exposure to hot salty water as the ends, over its lifetime. It will be replaced in the next month or so.

Does the water temperature make a difference? Our water probably averages about 10°C. So should our chain last longer or shorter?