We have never seen the point of anchor swivels. In our opinion all they do is add a potential point of failure to the anchoring system and provide no benefits in return.
Sure, very occasionally our SPADE anchor comes up with the flukes facing forward so it is a bit difficult to stow, perhaps one time in 20. But all we have to do to solve the problem is surge a little chain and bring it in again. And we have been anchored for as much as a month on as little as 80 feet of chain without having any twisting problems that would require a swivel.
Our concern about swivels has always centered on the possibility of one of the two screws backing out, as happened to a friend nearly costing him his boat. And the fact that the swivel shaft—made of stainless and therefore subject to work hardening each time it is torqued over the bow roller every time the anchor is hauled.
All of that was enough to make us eschew anchor swivels, but now we have seen the ultimate reason:
A visiting cruising friend showed us this massive swivel—it is just under 4″ inches (10 cm) long—that failed when his boat was subjected to some nasty katabatic gusting that caused her to surge back and forth and then come up hard on the anchor.
A close examination shows a disturbing weakness in the design that caused the threads holding the pin to strip when a shock load was applied off axis to the anchor shank.
You can see exactly how this failure happened by looking at another anchor swivel, this time in situ, in the photograph below. When the hard jerk from off to the side (as the boat came up short) was combined with the swivel’s inherent inability to align to the load and the lever-arm imposed by its own length, something had to break.
In comparison, an ordinary bow shackle would have simply aligned to the new load without problems.
If you have an anchor swivel, we strongly recommend that you remove it and replace it with the appropriately sized bow shackle.
Carter September 12, 2010 at 3:09 pm
John
Perhaps the problem is due more to poor design rather than the swivel itself. What think you of the WASI?
http://www.swisstech-america.com/powerball.html
A quick look around my marina revealed all boats with high test chains using standard half strength shackles. Just an observation not an excuse.
Your recommendation might be better stated as an appropriately sized high test strength shackle.
I always enjoy your thoughts and ideas. Thanks
John September 12, 2010 at 5:28 pm
Hi Carter,
Thanks for the comment and link.
I can’t say I like the WASI much either. While it would seem to be very strong and an improvement on the swivel that failed, it will still be subjected to the same forces and potential failure when the ball joint reaches the limit of its travel.
The bottom line is that I just can’t see a good reason to use any swivel in an anchor rode. A good quality galvanized bow shackle will always be stronger, size for size, and in addition costs a small fraction of the $200-400 that these swivels will set you back.
David Nutt September 13, 2010 at 9:52 am
In over 100,000 miles of sailing including a circumnavigation and a recent trip to Greenland we have never used a swivel. I have never found a need for one and as John points out it is just one more expensive piece of equipment in the long chain of items that can fail. It won’t fail if you don’t have it. Also, if I search really hard I am sure I can find another more reliable and utilitarian item on which to spend that elusive $400.
Matt Marsh September 13, 2010 at 11:34 am
I always thought these things looked untrustworthy, unnecessary and ridiculously overpriced. My chain gets twisted all the time, and it never causes a problem- just let it hang and straighten itself out for a few seconds before hauling the rest of it in.
An extra $300 gets you a bigger anchor…or more rode…or a better windlass…any of which would do a lot more for anchoring securely than a swivel fitting.
Ross Mann September 13, 2010 at 2:03 pm
I’ve found that swivels can be a safe means of allowing rotation of the chain rode. Examples can be found here on the West Marine site: http://www.westmarine.com/webapp/wcs/stores/servlet/ProductDisplay?productId=101922&catalogId=10001&langId=-1&storeId=11151&storeNum=10105&subdeptNum=10424&classNum=10426
Ross
Andy Fennymore-White September 13, 2010 at 4:28 pm
An interesting post but consider this; Three years back I was on the market for 200m of 1/2″ chain. I contacted a British manufacturer who claimed to make their chain in the UK, (and is a big name here). I asked for a sample of their chain that was supposed to be 100% proof tested to 4t. I had it independently tested as I am a paranoid skeptic and guess what? It yielded at 3.5t failing totally just over 4t, when its supposed minimum break was over 8t. When I told the company they just said;” Oh do you still want to place the order?”. They did not even bat an eyelid or ask to see the results; the sales assistant even admitted that they just brought it in. (And guess from which part of the world?) You need to be very careful with everything even if it meets all the specs and costs proper money.
Martin September 14, 2010 at 12:09 am
Good to get the benefit of experience from multiple high mileage sailors, and even better to realise this means less equipment.
If exceptional circumstances should require consideration of a swivel (perhaps prevailing wind shifts, or tides, tend to rotate a vessel the same way every day), perhaps inserting the swivel a few chain links away from the anchor itself can avoid the lever arm illustrated above.
For myself, I have a faint feeling of unease with stainless steel being immersed, although we trust the manufacturers of such swivels are confident no crevice corrosion will occur in any part of the device. Apologise for thread drift, but does anyone here have an opinion on stainless chain (and stainless anchors)?
Martin
John September 14, 2010 at 5:59 pm
Hi Martin,
Our recommendation is no stainless steel whatsoever in the anchoring system.
Ideally, we like to see good quality high tensile chain from a recognized manufacturer, like Acco, who stamp every link with an imprint and who will provide a proof certificate.
Paul September 14, 2010 at 6:09 pm
It’s clearly a case of not knowing how the swivel should be connected to the anchor. As mentioned, there should have been a large shackle attached to the shank of the anchor; then any swivel can be attached to the shackle. But better still, is to put about six links of chain between the shackle and the swivel. This ensures a straight pull on the swivel. FWIW, this is not a swivel I would have chosen. Not all swivels are created equal!
Adam September 17, 2010 at 4:59 am
In my case, there was no simple way to connect 3/8″ chain to a 121 lb. Rocna anchor other than to use a swivel. No shackle that would fit through the chain had even 1/2 the rated strength of the chain itself (I don’t have an oversize final link, and don’t trust a welder to put one in).
As I am well aware of the failure modes of traditional swivels as pictured above, I hunted around for something built strong enough to exceed the next weakest item in the ground tackle system.
Quickline’s Ultra Swivel fit the bill. Its design is similar to the WASI and the breaking strength of the 13mm version *at 90 degrees to the swivel axis* is 26,000 lbs. I’m comfortable that the chain would break (or the anchor would pull out) before the swivel parted, even if the latter somehow is forced to take a purely perpendicular load.
Nick Kats September 18, 2010 at 6:27 am
Hi Adam
I looked at the Quickline swivel by Ultra. It is made of 316 stainless. This, I understand, has much less strength than regular galvanized steel. I did not pursue this any further. Have you researched the strength of the Quickline swivel, or did you accept Ultra’s statement at face value?
Nick
John – splendid article on swivels. Like you, I was never able to see a reason to put one on an anchor rode. Thanks.
Craig Smith September 18, 2010 at 2:56 pm
Since the WASI PowerBall and its copy by Ultra was mentioned: in addition to my response below, my opinion on these “ball-and-socket” designs is that they’re pointless.
The objective is ostensibly to alleviate the lateral loading on the swivel joint. However the more important issue is not this but rather the lateral leverage on the jaw sides when attached directly to the anchor, which both these ball designs still do!
Furthermore, the ball-and-socket allows an articulation of only 30 degrees. Hardly the 90 you might think is required. What is the point? It is a gimmick.
As to the Quickline specifically, it is produced in Turkey by the same outfit that make the “Ultra” copy of the Spade anchor (from only weak 316 stainless). Given the character of most imitators I would consider the quality suspect unless proven otherwise. There is a promo video which purports to demonstrate a supposed self-righting feature of this swivel in action, but it is really total nonsense, and the contents of their other literature does not inspire confidence.
John September 18, 2010 at 7:37 am
Hi Adam,
I assume that you are using schedule 70 chain? Otherwise if G40 or BBB a high tensile shackle from Crosby will equal the SWL of the chain.
If G70, then I agree that a swivel might be better than getting a local welder to add a link of unknown strength. However the Ultra Swivel is still at risk for the type of failure shown in this post if attached directly to the anchor and a snatch load is far enough off axis that the ball joint reaches the end of its travel.
And I think the strength claimed maybe meaningless in this scenario since it was probably measured in an on axis pull test.
Maybe you could get Acco to to make you a short length of G70 with an oversize link in one end that could go between the swivel and the anchor as suggested by Paul and Martin, above.
John September 21, 2010 at 7:42 am
After I closed the comments on this post, Adam wrote to us to say:
“John, I wanted to respond to a point that you made about my comments on the Quickline swivel. You suggested that the load limit that I quoted for the swivel — 26,000 lbs. — was measured axially. It was not. According to the president of QL — whose veracity you can evaluate for yourself — the swivel was tested to breaking with a 90 degree off-axis load. That was what gave me the confidence to choose his product.”
Craig Smith September 18, 2010 at 2:42 pm
This example is much more an example of a poor product – poor design combined with inadequate materials – rather than any fundamental issue with swivels that will cause the sky to fall. The boater in question needs to seriously examine his product selection process/criteria, rather than erroneously conclude that he has proven that swivels per se are to be avoided.
Buying a cheap shackle of dubious quality from the sale bin in the chandlery is likely to prove equally disastrous.
Swivels are considered useful or even necessary by some, depending on the particular combination of anchor, bow-roller design, and anchoring habits. The general advice should be that if you don’t know you need one, you probably don’t… but to rule against them because there are some poor quality examples out there is great over-reaction.
Jaw-to-jaw swivel designs such as pictured are fundamentally flawed in the way they are designed to attach to the anchor. Do NOT use them in this manner; the failure mode is typically that pictured. They can have a length of chain installed regularly between them and the anchor, or at least a shackle. The ideal swivel design is an eye-to-jaw configuration, with a pin through the chain and a regular eye to be shackled to the anchor shank.
Regarding stainless steel in anchoring components. There is nothing wrong whatsoever in stainless used for anchor gear (with the one exception that it shouldn’t be used permanently immersed and is a no-no w.r.t. mooring set-ups for example). The problem is again one of quality. Stainless steel is very expensive – quality 316 chain costs around 4x that of stronger G40* galvanized from the same manufacturer. The price of more useful stronger G50 stainless is just ridiculous. In general stainless items should cost between 3 and 5 times the equivalent (in terms of both quality and strength) galvanized product – if not, you are getting what you pay for. The typical cause of many of the stainless steel “horror” stories is not some evil character of the metallurgy, but rather this factor in action.
*316 has roughly the same strength as mild steel, weaker than the 400 grade steel used in G40 or what Americans call high test chain, and far weaker than true high tensile 600-700 grades used in high tensile chain, high load shackles, or quality anchor shanks. John’s comments about brittleness are wide of the mark, 316 is fairly ductile with the exception of poor quality castings or very work-hardened fabrications; and the issue of laterally loading the swivel joint during recovery over the roller is not a serious matter – even a poorly designed swivel of inferior material will handle these relatively small forces without problem.
Of course the pricing discrepancies between stainless and galvanized products of comparable strength/quality means that the stainless option is one of greatly reduced value to the vast majority of people. However some small components like shackles, and indeed swivels, remain affordable and stainless brings good advantages. Just make sure the quality is good!
John September 19, 2010 at 8:13 am
Hi Craig,
All good info, thanks.
One additional negative point about stainless steel. It is, I believe, very much more difficult to do high quality welds in SS. Any error in the feed of inert gas during the welding process can result in a brittle weld or one that is subject to very fast crevice corrosion.
I myself have seen a piece of SS chain where the welds corroded horribly in just a few weeks. Whereas, at least in my experience, even cheap no-name far east galvanized chain does not go that fast. (We are testing a piece out of interest on our foreshore in Nova Scotia as I write.)
So my point is that yes, as you say, there may be nothing theoretically wrong with the stainless steel for anchoring, but on a practical basis there seems little point in paying four times the price of say G40 chain to get a product with a higher potential manufacturing defect risk.
So to keep thinks simple, our recommendation at AAC remains: good quality brand name galvanized chain and shackles for anchoring. In North America we like Acco G40 chain and Crosby alloy shackles.
Craig Smith September 19, 2010 at 8:44 am
Of course it’s perfectly feasible to weld stainless, again it’s just a matter of quality. There was a Chicken Little piece published in a Caribbean centered magazine just recently where the author complained bitterly of a stainless steel chain failure, and screamed to high heaven about the need for everyone to learn from his tale of woe and avoid stainless or else…
His chain had failed where the weld of a link had totally vanished, probably as a result of sensitization from welding leading to what’s called inter-granular corrosion which essentially occurs because the all-important chromium in the stainless is depleted and permits subsequent rusting. The weld possibly also used the incorrect filler materials (the likely cause of such fast corrosion that you mention in your own example). Additionally welds must be properly passivated then cleaned. All of this is basic and standard and should not be an issue with any competent manufacturer. Basic rhetorical question: did the chain cost what it should have.
Near the end of the piece, it becomes clear that the author has no idea who manufactured the chain or where it came from. Ostensibly it was 316Ti, similar to 316L, but the veracity of this was not investigated.
Similarly, poor quality steel welding with pin-holing or the wrong materials can lead to problems with galvanizing and ultimate early failure. It is just a matter of having faith in the origin and quality of your gear.
Of course stainless is (or should be, as my much labored point boils down to) much more expensive, and obviously there’s little benefit to the vastly increased cost to the majority of boaters. If you can’t afford quality stainless, buying cheap junk is hardly an improvement over quality galvanized gear.
John September 19, 2010 at 10:45 am
Anyway, back to the original point of the post: swivels.
I have certainly enjoyed all the different views and learned a lot from them.
Having said that, nothing has changed my view that anchor swivels are at best an expensive solution looking for a problem and at worst a dangerous potential failure point.
Never mind all the theory, I personally know two people that nearly lost their boats due to the failure of an anchor swivel. Sure we could debate for days on whether those skippers installed their swivels wrong, or used the wrong swivels.
Fact is that all the swivels I have ever seen have been installed directly onto the anchor shank and have been fork/fork designs.
Bottom line, as circumnavigator David Nutt said so well, “It won’t fail if you don’t have it”.
And on that note I think I will close the comments on this post. That’s the great thing about owning the site: you get to have the last word.
John December 23, 2010 at 1:15 am
Here is yet another reason not to use anchor swivels.
Mark Hoenke March 2, 2013 at 1:34 pm
I am not impressed with the usual (boat jewelry) swivels chandleries push at recreational boaters. My windlass has trouble with twist and the chain jumps in the wildcat so I needed to find a viable swivel. I looked for swivels where commercial operators shopped. What is needed is called a swivel forerunner.
http://www.google.com/search?q=anchor+forerunner&hl=en&rls=com.microsoft:en-us:IE-SearchBox&tbm=isch&tbo=u&source=univ&sa=X&ei=XigyUf-BFIWFyQHHioCQAQ&ved=0CD8QsAQ&biw=1144&bih=607
Wow – that’s a long link. A forerunner costs a lot less and is made down to about 7/16 as the smallest. Note that attached with a Kentor link, the swivel is some distance form the ancchor, as it should be. I am buying one this winter for my new Rocna 55. I was quoted 180 bucks galvanized. Try these sources:
http://wachain.itsb.us/
http://anchormarinehouston.com/catalog/fittings/swivel-assembly
http://www.maritime-deck-pros.com/index.html