Anchor Swivels

Timely post Noelex.

If you want to turn your anchor at the bow roller - why not use a bent link or boomerang.

Swivels do not turn the anchor when the chain is on the seabed, nor when the chain is under tension - so why use one?

Swivels tend to be larger, more surface area, than the chain - and will reduce anchor performance. You scoff? think it unnecessary? - then why do anchors have a thin shank (made from higher cost higher tensile steel, etc etc). Swivels cost money - lots - but don't actually add any value - except they can be weak link, reduce the performance of your anchor and don't actually swivel.

At all

There are number of articles - this is one:

https://www.practical-sailor.com/blog/How-Well-Do-Swivels-Reduce-Twist-11938-1.html

google "Practical Sailor Swivels' for some horror stories - and expose of construction

and for a bent link, boomerang

http://www.mysailing.com.au/cruising/how-to-boomerang-your-anchor-right-back-at-you

You can make your own, cheap as chips and much more reliable than a swivel. Some of the dimensions are there - and if galvanising seems a bit of a faff - make one from duplex stainless. All you need is an angle grinder and a decent bench drill.

Members here have made bent links - it not rocket science.

Independent tests on a Boomerang show that the device reduces the impact of veering on an anchor, when chain is buried.

Jonathan
 
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Summary. Some of the better swivel-making companies have a good track record with few
or no failures. My own experience includes 15 years cruising with a big SS Kong swivel
that still shows no sign of deterioration. It gets taken apart, greased and carefully inspected
at least once a year. Spade claims over 10 years with no breaks and no returns for their SS
Wasi Powerball. Other quality SS swivels include the Ultra Flip and Mantus, both are welldesigned of quality material but have a relatively short use history. Crosby (who also makes
SS swivels) and Acco/Peerless both make forged, galvanized, bail-to-bail “positioning
device” swivels, and have a good reputation.
Google “Anchor Swivels” for additional information on this important issue. Just remember
that not everything you read on the internet is true, and some of the shorter negative
comments on forums are based entirely on unsubstantiated opinion. Unfortunately,
there is little firsthand, well documented or laboratory analysis on the internet regarding
swivel failures. What is there, as you would expect, mostly involves incorrect installation,
undersized models, poor design, or flawed metallurgy.
A swivel, like other parts of your ground tackle, is not necessarily a weak link unless you
make it so.
Click to expand...

Like everything else on your boat - understand the weaknesses and benefits, inspect and service regularly and do what you feel is best for yourself and the boat. Opinions and horror stories abound, I just spent a week cruising in Scotland and one of the non-sailors had a problem with his mother - she thought it was too dangerous and he was going to die. Just as well we didn't listen to her - we had a great time.
 
RichardS said:
Kong rules, once again. :)
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The report by R L Jensen that is linked in the article was especially interesting. It is nice to see a proper scientific analysis of a failure.

The Kong swivels are more expensive than the very similar looking “no name” alternatives, and many must be tempted by the low cost option. Reading the report shows that some of these “no name” products are not what they claim to be.

Quality brands such as Kong are worth the extra cost.

Don’t forget Vyv’s excellent advice to use a short length of chain between the anchor and swivel to reduce the risk of side loading.
 
Interesting reading thanks. In the past week I have been advising a member of Ocean Cruising Club who suffered a total failure of a swivel. Its design was the two ring type joined by a bolt, probably, as noelex' article says, due to stress corrosion cracking. Like the author, I have a Kong that is now well over 13 years old and in perfect condition.
Despite Jonathan's prejudice against them, having gone a season without one, we find ours most beneficial and will continue to use it.
 
vyv_cox said:
Interesting reading thanks. In the past week I have been advising a member of Ocean Cruising Club who suffered a total failure of a swivel. Its design was the two ring type joined by a bolt, probably, as noelex' article says, due to stress corrosion cracking. Like the author, I have a Kong that is now well over 13 years old and in perfect condition.
Despite Jonathan's prejudice against them, having gone a season without one, we find ours most beneficial and will continue to use it.
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Good to hear yours is 13 years old , mine coming up to 10 years and although there no mark of wear , I did wonder if it was time to buy a new one .
 
The article has some interesting references to galvanizing. It mentions hot dip galvanizing, hot flame spray galvanizing and cold galvanizing. The latter two are mis-nomers promoting their products by naming them after a superior process. Not that metal spraying and zinc rich paint (so called cold galvanizing) have no place, just not appropriate in this marine environment.
Hot dip galvanizing is a metallurgical reaction between zinc and iron that forms alloys on the surface of the steel. It is metallurically bonded to the steel. The corrosion protection is two-fold, a barrier (like paint is) and an anode - electrolytic protection. It is sacrificial, that is it disappears with time, gets consumed.

Flame spray zinc coating is where zinc wire is melted and blown by a gas onto the surface where it solidifies. It forms no more bond that similar to throwing mud, but for a static item, with no flex, and no impact damage can be effective corrosion protection. It is electrolytic protection but not normally a barrier unless combined with paint. For a swivel that would be quite inapproporiate.

"Cold Galvanizing" is paint. The paint contains zinc particles that give a small amount of electrolytic corrosion protection, and is mostly a barrier. Manufacturers add aluminium also to give it shine and some brands have been found t have little zinc (the desirable active ingredient). You can tell the difference by weight. If you hold a can of good quality zinc rick paint it should feel decidedly heavy. If it doesn't, don't buy it!


On swivels: I use one. It will rotate under partial load, but that's the only time rotation is required. Usually when the anchor is being weighed, and off the seabed, the anchor can turn allowing the chain to straighten up over the windlass.

There's wide variety of prices of Kong swivels. That's the only brand we will stock at Knox.
 
Geoff - I'm glad you mention throwing mud - it did seem appropriate.

I am happy to flaunt my prejudices.

The punter has just walked along the pontoons admiring the tethered yachts and identifies he is missing that common shiny addition - the swivel. He goes into the chandler (and obviously not Knox Anchor) and asks for a 'decent' swivel. The chandler seeing a sale offers a Kong. The punter raises his hands in horror at the price and leaves bearing a nice shiny product (probably from Asia) at 25% of the cost. The chandler identifies quickly that if he is to make a sale he needs to gild the lily - or miss some salient features (of the product he, eventually, sells)

Not everyone frequents this forum or other similar sites.

I'd rather we discouraged use of swivels entirely - than have another failure - when there are fail safe options.

My analysis is that people use a swivel to allow them to manually rearrange the orientation of the anchor when the anchor is in close proximity to the bow roller, usually with the aid off a broomstick. Those who actually use a bent link don't need any manual intervention. A bent link can be stronger, if you follow the instructions, stronger than your chain. Its fool proof, no moving parts. Its cheap. The trouble is - people damn them without using them - based on no scientific evidence at all (which is one reason there are few scientific articles - people decide based on gut feel (and prejudice). But we all have these prejudicies - though why anyone damns an item that is cheap as chips, works, is safe, that they have never used - beggars belief. But this is the internet - and anything goes.

You can make one in a couple of hours.

I am more than happy to accept that a Kong or Ultra swivel does exactly the self same thing, is safe - costs a rather large amount of money and needs manual intervention (to 'swivel') - which somehow contradicts the common perception (that swivels actually swivel).

For more evidence of failure - nothing scientific about this - simple observation and reporting. That does not make it, I hope, in any way less valid.

https://www.practical-sailor.com/issues/37_57/features/Anchor-Swivels-Caution-Required_11797-1.html

These massages have been published numerous times, threads on this forum have come to the same conclusions - buy a Kong (or nothing else) but the message simply is not sinking in. Do what my fictitious punter was doing and walk round your nearest marina - you will count the Kong swivels on the fingers of one hand and the Ultra swivels only, or predominately, used with Ultra anchors. These quality (expensive) swivels are outnumbered factorially by cheap Asian stainless swivels and cheap galvanised swivels from the lifting industry - accident waiting to happen. An open mind to a cheap alternative, the bent link, which could be much cheaper, even on the chandlers shelves, than the Asian stainless product might help encourage a change of view - but I doubt my sincerity will be supported by many.

Jonathan
 
Neeves said:
I'd rather we discouraged use of swivels entirely - than have another failure - when there are fail safe options.
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While I respect your motives, I don't need an anchor policeman thank you. I like my swivel because it allows my anchor to spin (which it usually does as it comes out of the water) and my experienced crew can whip it onto the bow roller in the correct orientation 90% of the time. The other 10% they need to "manually rearrange the orientation of the anchor when the anchor is in close proximity to the bow roller, usually with the aid off a broomstick" --- well it's actually the pole for the gypsy clutch ;) .. it's also useful to be able to spin the anchor if you need to remove mud, fouling or other debris.

I don't have the cutting and drilling tools to build a bent link myself but I'm happy to accept that they work .... wouldn't fit in my anchor locker though ... I'm pretty certain the distance from shank to the windlass is too small.

If you never hear from me again, my swivel failed and I ended up on the rocks ;)
 
Jonathon,
I did make one of your boomerangs and it worked exactly as described and was cheap. But not with any anchor with a rollbar, as they don't fit my bow.
I don't keep my anchor on the bow roller / stemhead, so it fulfills no real function of benefit for me.
I see where you're coming from, but if we extended that thinking we'd have to discourage the use of many inferior products, not just swivels. LEDs, turnbuckles, shackles, fenders, ropes, even, ... anchors!
 
Geoff - thank you for the support - you have provoked a comment you possibly did not expect.

I am the first to accept that a boomerang, bent link, only works if you have 'enough' room. I think this issue is mentioned in the article. I had a specific problem (and lots of room). That negative is not enough for anyone to damn them outright - but should be incentive for someone to look at how to overcome that issue - and for those with room - they work.

I do have a 'short' boomerang, about half the length of the one in the article. People have said you can use less links between Boomerang and anchor. I have made a Boomerang that does not need shackles. But I, and others (NormanS for one) have offered a lead...maybe others can pick up the ball.

Work that I do and others, I think Vyv - there may be many others, we do at our cost (and I for one enjoy the work and find it stimulating). An article seldoms offers a commercial return. To have an armchair critic on your back who has never seen nor tried the product is not the support to engender further work.

But I do discourage use of inferior products of which I know - shackles being one - I test them, scientifically (the same way industries test them and or how they are used). We might be winning that battle, but at the bottom of my heart - I doubt it.

I wish others would question product quality. I wish others would question testing technique - with positive input. its easy to be critical, damned difficult to be constructive. Its easy to make fanciful claims - sadly not often supported, scientifically or otherwise.

I know anchor testing is not perfect - I accept the criticism - but come up with a better way - or accept the way it is done. We now have untested anchors - point the finger there, not at those who are doing the best there is and trying to fill in some of the gaps.

Sorry Geoff

Whinge over.

Hopefully - lets move on - and upwards

Jonathan
 
KellysEye said:
I have mentioned this before, there was a wind reversal in a Greek bay and three charter yachts were washed ashore when their swivels broke.
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The probability of this alone beggars belief .... if swivels were so bad that 3 boats can be lost to swivel failure, all on the same night, in the same bay, then I would be looking very closely at the circumstances - were they all from the same charter company with the same swivel? To be honest this sounds improbable at least. Do you have any links or analysis you can share?
 
Baggywrinkle - I don't mean to be an anchor policeman, or any sort of policeman. If this is how I appear, please accept my apologies (but I will not change - accept that I don't mean it like that). I, too, dislike being told what to do and how to do it.

I also realise that not everyone has bench drills and angle grinders - and maybe are not au fait with making.*anything, but lots are capable and have the equipment - so I try to share - I'm not trying to offer a solution to everyone. If I don't share - why do it???...

Jonathan
 
This is an Osculati cranked swivel, not a 'Boomerang', but it does illustrate my reluctance to try this particular type of device. I bought the Osculati for trial purposes and fitted it to the anchor before launching a couple of years ago. There were no instructions with it, leading to some confusion as to which way around it should be installed, but in the end I tried it both ways. Results were disappointing, in that our always faithful Rocna dragged on several occasions. After a week of repeated re-anchoring, during which diving on it revealed no particular problem, we reached an anchorage where this was found and photographed. Astonishingly, the swivel was pointing almost vertically upwards, with the chain somehow wrapped around its foot. Presumably on previous anchoring attempts it was pointing downwards, hiding the problem.

We abandoned the Osculati trial immediately and reverted to the Kong plus three chain links.
 
The Oscaluti is a strange device - it is a bent link with a swivel (why the bent link (that should obviate the need for the swivel) and then include a swivel). The way you have it installed - its connected direct to the shank. A Boomerang cannot stand vertically as shown different animals. As you have mentioned Vyv - you need some articulation, a few links between the device and the anchor. Looking at the device I would not have had much confidence in the swivel mechanism either. I was going to test one, as you did, but decided it was not worth the investment (as you had already damned it).

Strangely I met the man who makes these things, he appears to own the factory, (and lots of other components), for Oscalutti this morning. He has a stainless processing facility in Qingdao and regularly attends the Sydney Boat Show.

I tested, a couple of years ago the chain hook, claw, he makes for Oscalutti - it was a load of rubbish also. The test was simply defining the tension at which it failed - I am sure the results would not meet the scientific scrutiny of our resident expert - but it was good enough for me. Tested with the correctly sized chain on a Wirop 100

https://www.wirop.com.tw/style/fram...2&name_id=136451&Directory_ID=78719&id=416776

With a continuous stress strain display offering yield and failure point.

Photographs taken of how the device was secured in the test machine, and what it looked like at failure and samples kept of a new claw and the one that had failed, all labelled. The stress strain details retained. All data available for anyone to examine. The same protocol is used for all my tests to failure.

Personally I'd like to see even this inadequate level of data for claims of 'a big anchor is more secure at short scope' or information on a Mantus holding capacity.

Jonathan
 
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Thanks for the post, Vyv. I think it is important to point out the downside with these devices.

I have watched a lot of anchors underwater noting how they behave. Personally I would be wary of using any of these anchor straightening devices if anchoring overnight. The danger of upsetting the anchor performance, as Vyv has noted, is very real in my view.

The added resistance near the end of the shank is significant. The models with a flat plate are particularly concerning. If you believe a flat plate will always stay vertical then I have a very nice bridge for sale at a bargain price :). Even the manufacturer’s web page shows the plate lying horizontally in some photos.

Then there is the issue of the bent link or the connecting shackles become caught or jamming on the anchor when the boat rotates around the swing circle. This latter issue is a very real problem that can even happen with a simple single shackle. Add two more shackles and a flat plate and there is lot more hardware that can become caught and cause an unfair pull on the anchor as it rotates.

Modern anchors work well. Don’t risk hampering their performance. A shackle, or good quality swivel with a few links of chain, is a simple an effective solution for connecting the anchor and chain.
 
Now let me explain some of the realities.

The Boomerang was developed with help from NormanS who simply provided his version as an image on this Forum.

The device was developed and a number of different prototypes made, all by hand, all Bis 80. They were made using an angle grinder, drill and file. The eventual design was that published in Cruising Helmsman. It was provided open source. A number of people here in Australia made their own and a consortium from a Yacht Club got together and had a batch made. From memory all were Armorgalv coated, Thermal Diffusion Galvanising. I know the operator and we got some group prices. I was involved at most stages of the process as I had the CAD drawings that they needed to have the Boomerangs cut (our daughter is a graphic designer).

Anchor Right saw the article and decided to make their own, I did not particularly object - as I had made it open source - and as I could hardly stop it I was simply flattered. I was upset, later, that neither me, the magazine nor the publisher were acknowledged - but no point in being upset - it was open source. Maybe I should have made that stipulation clear at the outset - being flattered reduces ones negotiation skills. We live and learn. And no - I derive no benefit from Anchor Right, even now and never have.

I do remain flattered at the success of the device. it is used in Bass Strait on big work boats - with big anchors, 100kg for example. It is sold in New Zealand, by Chains, Ropes and Anchors and in the Pacific Northwest by Ground Tackle Marine, who are based in Vancouver. Obviously it is used on yachts in Australia.

As I say - I am flattered that such a simple device has been so successful. No-one has complained - as Geoff, or Knox Anchors says - it does what it is meant to do - out of the box!

Next time it will be different - I will be more careful of how I publish, less detail, and be more careful when someone asks if they can produce. We all learn by our mistakes.

This is the relevant link to the product at Anchor Right:

http://www.anchorright.com.au/news/anchor-right-australia-introduces-innovative-flip-link/

This is a quote from Noelex:

'Even the manufacturer’s web page shows the plate lying horizontally in some photos.'

That photograph, to which Noelex refers, was taken by me on a sister yacht to our own, another Lightwave catamaran, that is kept in a marina about 1km away (Royal Prince Alfred Yacht Club). I know the owner - we compare notes.

He bought a Flip Link made by Anchor Right and I helped with the installation. We live so close I can be there in a few minutes - and I am more than willing to help - with something I developed (sorry if I have a bit of pride and commitment). Our, Boomerang, is simply the best of my prototypes, slightly different in design but the same principal. As I had the photograph and I was still in the 'being flattered' mode I was happy to provide an image, or 4 to Anchor Right

When I took the photograph I wanted the shape of the Flip Link to be obvious and I simply tipped or twisted the chain so that the side view of the device was obvious. If I had left it as was - the side view would have been distorted. Under tension the Flip Link is vertical - and surprise surprise when you set an anchor - the chain is under tension. it is important when you attach the Boomerang, Flip Link, you ensure there are no twists in the chain.

I don't know, I have no idea, how many have been sold - but not one has had problems as outlined by Noelex.

This is what Noelex said

'Then there is the issue of the bent link or the connecting shackles become caught or jamming on the anchor when the boat rotates around the swing circle'.

There is simply nothing the link, nor the shackles, can get caught on.

It pays to check before you are critical - especially when you seem to be doing so without basis - it seems emotive and spiteful, in fact trolling. A quick PM to me - might have saved Noelex the embarrassment of being wrong.

I am sorry to have a pride in what I do and in being defensive - but when criticism is made without basis, with no knowledge of the product nor seeing one in use - then my offspring (the Boomerang) needs to be defended and the true position outlined

Independent tests on a Boomerang in America have found that a buried device reduces the impact of veering - as it provides an impediment to the chain sweeping from side to side - when the chain is buried. The Boomerang has a lower surface area as it is pulled into the seabed - so it increases chain burial - all swivels are larger than the chain and reduce chain burial. There are no moving parts and a Boomerang for 8mm chain failed, under test, at around 9t - a strength no comparable swivel (nor shackle) can match.

Rant over, again.

edit,

There have been a few minor developments, and improvements (for example Omega links are better than shackles). You do need 'room' but a shorter Boomerang will work and though the suggested number of links between Boomerang and anchor is advantagous - you can reduce the number. One downside - if you have a grooved bow roller the Boomerang can lock in the slot - because it i 'always' vertical :). This can be over come using thinner plate (there is more than enough strength).

Now if this found to be like an advertorial - you are meant to make it yourself!!

There are a couple of other new devices in the pipeline. All based on a thorough, maybe even, technical if not scientific investigation for the rode - watch this space.

Jonathan
 
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