The Offshore Voyaging Reference Site

Some Thoughts On The Ultra Anchor, Roll Bars and Swivels

As most of you know, I’m not a fan of stainless steel anchors, primarily because an anchor made of the right grade of galvanized steel is much stronger, size for size.

That said, there’s no intrinsic reason that an anchor that’s strong enough for purpose can’t be made from stainless as long as the designer and manufacturer take into account the properties of that alloy, rather than just build an anchor in stainless that was originally designed for a stronger material, as several manufacturers have done.

And stainless has the advantages that it sheds mud and debris more quickly when being hauled and, of course, it does not bleed rust all over the deck like a galvanized anchor will when it gets banged up, as it inevitably will on any boat that actually cruises.

Given all that, while at the boat show I spent some time at the Ultra anchor booth, most of it looking at the cut-away model above.

Two things that I really liked about the Ultra:

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More Articles From Online Book: Anchoring Made Easy:

  1. Introduction
  2. 4 Vital Anchor Selection Criteria and a Review of SPADE
  3. SARCA Excel Anchor—A Real World Test
  4. SPADE, SARCA Excel, or Some Other Anchor?
  5. Rocna Resetting Failures and Evaluation of Vulcan and Mantus
  6. Some Thoughts On The Ultra Anchor, Roll Bars and Swivels
  7. Specifying Primary Anchor Size
  8. Kedge (Secondary Anchor)—Recommended Type and Size
  9. Third Anchors, Storm Anchors and Spare Anchors
  10. Anchor Tests—The Good, The Bad, and The Downright Silly
  11. Making Anchor Tests More Meaningful
  12. We Love The Way Our Anchor Drags 
  13. Things to Know About Anchor Chain
  14. Selecting a Chain Grade
  15. Anchor Chain Catenary, When it Matters and When it Doesn’t
  16. Anchoring—Snubbers
  17. Anchor Rode Questions and Answers
  18. Q&A: Hybrid Rope And Chain Anchor Rodes
  19. Anchor Swivels, Just Say No
  20. A Windlass That Makes The Grade
  21. The Perfect Anchor Roller
  22. Install A Wash-down Pump—And Save Money!
  23. Anchoring—Kellets
  24. Anchoring—Chain: Stoppers, Termination and Marking
  25. 20 Tips To Get Anchored and Stay Anchored
  26. Choosing an Anchorage
  27. Choosing a Spot
  28. 15 Steps To Getting Securely Anchored
  29. One Anchor or Two?
  30. Two Anchors Done Right
  31. It’s Often Better to Anchor Than Pick Up a Mooring
  32. Yawing at Anchor, The Theory and The Solution
  33. Yawing at The Anchor, an Alternative Cure
  34. How To Use An Anchor Trip Line
  35. ShoreFasts—Part 1, When to Use Them
  36. ShoreFasts—Part 2, Example Setups Plus Tips and Tricks
  37. ShoreFasts—Part 3, The Gear
  38. Gale And Storm Preparation, At Anchor Or On A Mooring
  39. Storm Preparation, All Chain On Deck
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Marc Dacey

You should sell T-shirts. That’s a very funny slogan to anyone familiar with the site. A couple of points: Did you mean to say “G70 chain” in the caption under the second photo under the subhed “Chain Attachment”? And do you consider there to be any deleterious aspect to the dissimilar metals of the typical galvanized rode and shackle vs. the SS anchor? Some people want SS chain with an SS anchor, but non-SS steel and SS are fairly close galvanically and so I’m not sure if this is a real concern. SS next to zinc, however…

john stanley

Hi John
I too don’t like swivels but have just fitted the No2 Mantus swivel to my new Sarca Excel. This has solved the connection problem some people have had with this anchor. I have 8mm chain so I could only get a smallish tested bow shackle through it whereas the mantus swivel has a large oval pin on the chain connection and a whacking great 1/2” bow shackle for the anchor, so no side loading issues.
I know this is the wrong thread for this but the new Sarca is an outstanding replacement for my rocna in my current cruising grounds of the Greek Dodecanese islands where there are a lot of bays with soft mud over very hard mud.


Rob Thompson

Hi John, fyi we used an Omega link on our 33kg Excel instead of a swivel to get the strongest attachment we could, as suggested by Jonathan Neeves who writes anchoring articles for Practical Sailor. The Omega link then takes a 5/8″ Crosby G209A shackle pin, with the shackle body through the Excels shaft slot. We also use 8mm chain, but the G100 variety for maximum strength ( breaks at 8 Ton certified) and the Omega pin fits nicely through the 8mm chain link without needing an oversize end link.

Rob Thompson

We got them bare and had them Armorgalved when we did the chain.

I thought about the driven pin as well, but they’ve been used by some full time cruisers down here in Oz for years with no issues of them loosening. I was advised that if I was pedantic about it ( which I have been accused of on occassion) I could drive the corner of a metal chisel into the seam between the pin and body to “lock notch” it. But after hammering the pin home, I really can’t see it coming loose. It is meant to be a permanent connection and considerable force is needed to drift it out if you want to take the Omega link apart.

The advantage of using the Omega was that it gave a balanced break strength in the whole rode system. As you’ve said, with 8mm chain the pin size for shackles that would fit through the 8mm chain links would give an unacceptably weak component, even using Crosby G209A.

Stein Varjord

Hi John,
I’ve also looked at the Ultra anchor with interest and mostly the same questions you have.

About the low surface friction of SS steel, I’m also no engineer, but I’ve pondered it for a while, trying to use logic. I think it might actually be an advantage for the holding ability. The reason for that thinking, is that the low friction means its fluke will make less resistance when following its cutting edge into the substrate. The substrate will probably tend to stay slightly more in its previous location, rather than follow the anchor.

These issues should make it more willing to slide deeper into the substrate, and also able to slide into harder substrates. It should also be slightly more willing to rotate in its spot to realign with the rode. All of those issues are about essential anchor properties and it might seem like important reasons to choose SS anchors. However, my guess is that even if all these assumptions are true, the actual effect is perhaps quite minor. That last assumption would be nice to run by an actual engineer.

When it comes to the swivel and intended attachment method, it makes me cringe. It adds several weak links, an then a lot of leverage to increase the loads massively! It doesn’t take an engineer to see that it’s horrible engineering. Just flat out wrong. There’s no way in h**l that I would accept such a thing.

Your point about the lacking oval shank hole is another topic I agree on, of course, but I think I could live with that one. If the shackle is oversize, it can take some misaligned loads. Since it’s way shorter than the mentioned swivel, can “hinge” without restriction, and the chain can reliably align quite a bit by sliding at the arced end of the shackle, the bending leverage should be low enough.

So, what would I choose? I’d actually base it on such such a “wrong” reason as price. The Ultra Anchor is no cheaper, rather the opposite, than a galvanised Spade. I know for a fact that Spade is a great anchor. Why then choose Ultra, which is just probably a great anchor, and does have a couple of issues?

Dan Manchester

Hi John,
As an engineer who works on marine structures including buoy moorings, I disagree with you on a couple of points.
1. The strength of an structure/component/widget is a factor of its design and material, so there is no reason that an anchor designed from any particular material is worse than any other; certain grades of stainless are much stronger than galvanised mild steel, so without knowing all the details it’s not fair to make the comparison.
2. They have the shackle attachment right. The pin should go through the hole and the body through the chain. A bolt type bow shackle should be used, NOT the screw pin type shown on your SPADE set up there. Side loading to the body of the shackle is far far preferable to corner loading on the pin to body connection as you will get on your set up.
3. You are right, swivels are a weak link in any anchoring/mooring set up, unless you are anchored in a tidal area for a long time that will see you rotate around the anchor constantly. If you do use a swivel, it should be fitted with end links so that any loading is always in line with the chain.
4. I doubt very much that the mud to metal friction is at all significant (comparing SS to HDG finish), but if anything, I would think a slipperier surface would allow the blade to cut through more easily to embed deeper – I have no science on this though!

Andrew Craig-Bennett

Very interesting article for me as I am dithering over an Ultra, although I used to think of them as power boat jewellery.

The CQR doesn’t take hold as fast as a modern anchor, but in fifty years I don’t recall reading or hearing about a case where a genuine CQR failed either at the shank (drop forged!) or at the shackle. (Worn pivots are another matter! )

The CQR came with a big round at the upper end of the shank, through which the welded-on pin of a big bow shackle fitted quite closely, so that no unfair strain could come on the pin.

Of course, as soon as we wanted to carry our anchors on our bow rollers, say around 1990, we all hacksawed through that big fat pin and threw away the big bow shackle so that our CQRs would fit in our bow rollers…

So having ruled out all anchors with flat plate shanks I am left with the Spade and the Ultra and I do like the way the Ultra is put together, BUT I want that big fat bow shackle and a bow roller fitting that will take it. A good big roller with a groove will do this and will also avoid the use of a swivel.

I wonder how many of us have used a swivel just to get past the roller? (Holds hand up and looks sheepish…)

Andrew Craig-Bennett

Hi John,

I don’t want the load coming on one corner – on one end of the pin. That’s the fastest way to break a shackle!

If you put the body of the shackle through the anchor slot, then because the anchor is bigger than the chain the chain will bear on one side of the pin.

Having said that, your shackle in the slot looks very good.

Some discussion below on this.

The old CQR, with its big bow shackle and it’s pin fitting snugly into a round hole with plenty of metal round it, put an even load on the big pin and the chain was shackled to the bow shackle with a U shackle with its pin through the last link. This gave a very good lead when the chain was no longer in line with the anchor because the U shackle could slide round the bow of the bow shackle and the bow shackle could pivot on its pin.

This was a very good arrangement but it was bulky, and didn’t suit stowing the anchor in the roller.

It’s been suggested to me that Ultra have a small round hole so they can sell their swivel along with their anchor…

Stein Varjord

Hi Dan and John,
Reading your comments made me take another look at my opinions about the shackle orientation. So far I’ve wanted the biggest shackle possible to get the pin through the normal chain link. With the oversize end link John has, one could do it the other way around, since the shackle body would pass through that bigger link. This would be especially easy and strong if the end link was oval, like an elongated normal chain link, since a circular link creates more bending load on the link material.

That opens the option to put the shackle pin either at the anchor or at the chain. Either way it’s done, the reason for discussing this issue is to avoid asymmetrical loading of the shackle or other parts of the ground tackle. I think I see an advantage for having the pin at the anchor side. I don’t think it’s a big advantage, but still, here’s my thinking:

Firstly, something has to slide along the curved shape of the shackle to align the loads. The question then is; which is better at sliding along that curve? The chain has a smooth uniform well rounded shape and unlimited ability to adopt any useful orientation. It’s not able to jam into one position. Making the anchor shank hole slide along the shackle arc is also no big problem, unless the shank hole is far from the shank edge, as on some anchors, but still has the opposite of the above properties and must perform this task less reliably. I also would think that the shackle body could easier get jammed in the shank hole than in the chain link. If the pin is in the shank, that option is gone as the shank is kept between the ends of the pin.

Secondly, the load from the straight pin should be spread evenly on both legs of the shackle body. If the pin is at the chain side, the chain will rest at one end of the pin, giving the shackle a diagonal load, meaning bending loads. If the pin is in the anchor shank, the load will mostly be close to the centre of the pin. That’s because the shank is most likely thicker than the chain links, and not as rounded. It will hold the shackle more in one plane of movement, like a hinge. The load can’t get into the corner.

Either way, I think a short pin shackle is important. An Omega shaped shackle often has a shorter pin for its strength than the U-shape, and will have a rounder curve, perhaps making it easier for something to slide along it. Anyway, I think both orientations are good enough, and all this is just thinking out loud, for whatever it’s worth…

Jo Blach

As someone with little experience in the area trying to follow the discussion, I have a naive question:
Why not use 2 shackles back to back?
Wouldn’t this allow to perfectly fit the anchor hole with the best load on the pin and one on the chain to fit the maximum pin size into the chain link?
Or is this yet again an idea that has been discarded a long time as sub-standard?

Dan Manchester

Hi John,
What I meant by corner loading is where the chain slides to the edge of the pin and puts the load on the 90 degree corner where the pin meets the shackle body. This isn’t how shackles are supposed to work and results in a huge reduction in capacity. The pin is supposed to sit against a flat drilled hole, and the chain slide around the bow of the shackle. The shackle body on sharp corners of the anchor is also an issue but not too big a deal as you’ve mentioned, the anchor hole will wear before the shackle will.

The reason not to use screw pin shackles in a permanent installation is that they can unscrew as a load rotates around the pin, granted, with mousing and Loctite you are probably mitigating that, but since a bolt type can freely rotate, it is preferable (and recommended by Crosby).

Also note, when looking at shackle strengths to match the chain, we should be looking at breaking strengths of both, not WLL which is relevant only for lifting. Shackles generally have a breaking load that is 6 times their rated WLL. I also think it’s not bad to have the shackle slightly weaker than the chain so that in a worst case event the shackle breaks, not the chain, and you don’t lose the lot.

Dan Manchester

Hi John,

The problem with using a shackle with the bow through the anchor and the pin through the chain is that you cannot keep the load path centred on the shackle pin, it will always slide to the corner to find the longest internal distance within the shackle. By putting the load into the corner you de-rate the shackle significantly as a large component of the load is taken by the thread, almost with a prising motion, rather than the pin in shear, and that derating factor is likely 30 – 50% or more. See snippets from the Crosby catalogue –

So using an example of 10mm chain, where the breaking load of the chain is around 52 kN, a 1 t shackle installed pin to chain would have a breaking load of 60 kN de-rated to about 30 kN (being conservative), whereas a ¾ t shackle which the ears fit through the link, installed pin to anchor (in a suitable drilled hole) would have a rated breaking load of 40 kN with no derating applied. My view being that the smaller shackle, used correctly at full capacity is better than the larger shackle used with a large and unquantified derating.

Additionally, though I feel like I may have mentioned it previously, I would advocate using the shackle as a fuse so that in the event of worst case scenario, the system breaks at the bottom and the chain is not lost – potentially allowing you to rig another anchor quickly, if you have a spare. So having a known set of breaking load figures enables you to know (predict at least) what will happen. This is personal choice, and the flip side of it is that it is much easier to find an anchor on the seabed when 50 m of chain is attached to it!

On this drawing [ ] that was done for us by the LROS/ABS certified chain factory in China, you will see that where shackles are used pin-to-chain, a specific joining shackle is used that has a very tight fit to the chain, this is to keep the load centred for the reasons mentioned above. Note that in this case the G2130 shackle is used only because that’s the size that fits the eye in the buoy tail, not for any other reason, but used bow to chain link. As an aside, you’ll also see that the swivel used has end-links fitted during manufacture to prevent side loading.

Anyway, hopefully I may have convinced you, but more hopefully, neither of us ever find ourselves in a situation where we’ll find out who is right!

Jordan Bettis

Machining a notch in austenitic stainless steel and then suspending it in a chloride solution under load is a textbook way to induce stress corrosion cracking.

Gilberto Sanchez

John, regarding your question about the pros and cons of friction I would argue that less friction its better as it allows the anchor to set deeper. I don’t think friction on the fluke is the main force that holds the boat in place.

Friction resists motion in a direction parallel to the plane of the flukes so friction progressively resits the anchor setting deeper. But the direction of pull of the chain is not in line with the plane of the flukes. It is oblique to it, approaching perpendicular.

(Please take this as speculation from a non-practising mechanical engineer!)

William Koppe

Hi John,
When I bought my Muir 8000 anchor winch , I also bought the 16mm studlink chain.
Muir insisted that I have a swivel and it is forged in as part of the rode.
This is the same system as large ships use.
Looking at images of swivels the ship ones are much more substantial than the yacht toys.
It is a fact that if the chain twists enough it will want to lever of each link and therefore reduce its working load. Swivels avoid this.

Chuck Batson

In one of my favorite boating books, “Creative Anchoring” by Fatty Goodlander, he suggests that every so often when in the deep sea, let the anchor out nearly all the way to dangle for a bit and allow it to untwist if needed. 🙂

Harald Bjerke

Swivels – weak link
Shackle – pin on chain side
Agree with John on the above.

Screw pin entered from the right viewed from end of chain.
Especially important if you have no other option than to attach pin on shank. This has to do with the directional motion of the chain as it repeatedly tightens.

Oval shackle better than U…?

Dan Manchester

Hi John/Harald,

What Harald is describing is exactly my point about not using screw pin shackles, the tendancy for them to unscrew as the load rotates around the pin putting an torsional force on the fixed pin, whereas bolt type can freely rotate.

Bow shackles must always be used when any side loading is present or possible, Dee shackles are better when the load path is straight through.

Harald Bjerke

Glad you had me expanding on the pin orientation. I find I have to clarify/correct myself.
Envision gentle conditions when the boat rides at anchor with a breeze acting on it. Chain lies on the bottom and gets pulled taught and orients itself upwards on occasion. With the pin in chain it will exert a clockwise motion on the pin if inserted from the right viewed from chain towards anchor, a good thing as it will tighten… and now for the clarification/correction.
If inserted through the anchor shank the pin has to be inserted from the left in order to achieve the same dynamics, tightening of the pin.
Hope this can stimulate the minds eye and make sense.


Harald Bjerke

…it could be the deciding factor of whether you put a strain on the mousing.. or not.

Chuck Batson

To my naïve eye, there does not appear to be enough metal “meat” surrounding the shackle attachment hole, particularly for net tension force around the hole. Of course it would take some measurements and knowing what load the thing is designed for to say anything definitive.

Eric Klem

Hi John,

How stainless construction affects holding power gets into soil mechanics which is a pretty specialized field and not one that I have studied.  My gut reaction is that in most situations, stainless would be better as the real goal is to get the anchor as deep as possible with as much soil that would need to be dislodged as possible to drag it.  Exceptions might be situations where burying is impossible regardless but then the difference won’t be that great and holding power will be unacceptably low regardless.  

Ignoring discussion of really soft bottoms, I tend to think that the holding power discussion misses the point much of the time.  With new generation anchors, the average holding power is sufficient that boats should basically never drag if some common sense is used but we know that they still do.  Rather than the problem being the holding power of the anchor reported by the testers as many would suggest, the issues in my mind are the variability of the holding power and resetting/veering.  Yes, an anchor with more holding power will drag less but an anchor that sets rapidly and can cut down through debris in the substrate will do much better than one which is susceptible to these imperfections.  From a statistics standpoint what I am saying is that the left end of the distribution is the problem so it is better to try to cut that off or make the distribution narrower than to try to move the entire distribution to the right.  As an example, I took the raw data from one of the well known anchor tests for a few anchors and 0 holding power was way less 2 sigma away from the mean for several anchors, that is a huge amount of variability.  I am still a big believer in moving the distribution to the right but only after it has been narrowed as much as possible.  To narrow it, it comes down to picking the right anchor, then moving it is just playing with anchor size.  Ignoring boats that are small enough to not have a windless, the total anchor weight just isn’t that big of a deal and carrying a 60-80lb anchor should not be an issue on a voyaging 40’er.  Stainless has another potential advantage here which is that in terms of resetting, if it sheds material better it is less likely to become unbalanced.

One thing to think about with a fabricated shank is what type of QC is done.  In the case of the Ultra, they would need to check for weld strength as well as somehow pressure testing to ensure it is watertight.  All anchors require some form of inspection but many portions are low stress so this inspection is not as critical.  In general, inspecting items cut from plate is easiest as it is just a dimensional inspection along with a material cert while welds and castings require x-ray which can be time consuming.  Very few items have full inspection on each serial number, they are typically done on a subset determined by a standard such as AQL.  My observations suggest that the marine industry is really light on quality system implementation and a quick check of Ultra’s website does not show any common certifications such as 9001.  Therefore as consumers we can’t judge the quality of this or probably most anchors and all we can go on is how many high risk steps there are.  Ultra are working with a somewhat less forgiving material than most and have one of the more difficult construction methods out there so I hope their QC is up to the task, I can’t say either way whether it is.

I have never used an Ultra and only seen one a handful of times and never on the bottom.  The few pictures that I have seen of them set have shown sets that are not as good as I would like, the anchor is still relatively close to the surface after a significant distance.  Hopefully this is just a poor sampling of pictures and not indicative of overall performance.


Matt Philips

As Dan M. says above, “…certain grades of stainless are much stronger than galvanised mild steel…” In this review from (, the author states, “ULTRA Marine tells us that the shank is 318LN duplex stainless-steel…” That is the only reference I can find about this – can anyone confirm or deny? If true, that would mean it is stronger than 316L and also better able to resist the sort of corrosion that might happen while buried deep in a bottom substrate. Mantus’ new M2 anchor also uses duplex stainless steel for the shank and for parts of their new swivel as well (just the pin, I think), and Ketten Wälder makes a swivel (“The Twister”) out of duplex, but I won’t link to it here for fear of a “but wait it gets worse” from John.

Finally, for those looking for an all-stainless system, duplex bow shackles may be available here as custom order: – haven’t found any for off-the-shelf order.

Dick Stevenson

Hi John,
Nice report, especially as I generally do not get to boat shows anymore and I do miss the poking around new gear etc.
Agree completely about swivels and I have some thoughts about gear/ procedures evaluation that have been percolating.
I try only to add gear to Alchemy when I need it to solve a problem. I have many thousands of anchoring situations and in none have I felt like a swivel would enhance my ground tackle effectiveness. The chain twist argument falls short when the snubber is taken into consideration as the snubber will absorb any twist well before the chain is affected in the slightest. That said, I have never noticed my snubber getting twisted. The swivel can be a convenience, however. Every now and again the anchor does not wish to address the roller easily and I must align the anchor manually: a bit of inconvenience, but no big deal. I am willing to tolerate a bit of inconvenience to not have that weak link in the system. And I would likely continue to not have a swivel even if the swivel was proved not to in any way be a weak link: gear on board is to solve a problem, not to save me a bit of inconvenience. I blame, primarily, the industry for propagating the myth (my belief) that swivels serve a purpose in recreational vessel anchoring (possibly moorings, but not anchoring). They have sold the myth and proceed to sell the product.
Interestingly, the same argument applies to spliced loop (or loop with a bowline) around a cleat (or bollard) (I am speaking to recreational vessels, not commercial). A fixed loop is a bit of a convenience, but really decreases your options for adjustment and is impossible to release under pressure without a knife. A couple of back and forths over the cleat with the line and you are belayed for a gale. Take in line easily when no or moderate pressure and bleed off line when under any pressure easily: neither is possible with a fixed loop. Again, a (very) little inconvenience leads to a safer boat that can respond to condition changes readily. Again, the industry sells a lot of docklines with fixed loops and many skippers love them. But with a little less convenience, these skippers will have much more versatile dock lines that lends themselves to much safer use/adjustment when things get ornery (think of your fingers if attempting to get a fixed loop eye off a cleat when under pressure and the boat bouncing about).
It appears to me that many discussions are around this “balance”: convenience vs safety and by safety, I am thinking of outlier events rather than safety in everyday cruising life. I try to always be prepared for outlier events.
Some thoughts, Dick Stevenson, s/v Alchemy

Steve D

I’m too am no fan of swivels and I advise my clients to not use them; I have seen failures and have the photos to prove it. In most cases I find many owners have never tried to use their rode without one so they don’t know whether or not it’s needed, and of course the anchor dealers insist on selling a swivel with every anchor. I tell my clients, “Try it without it, if you feel you must have a swivel you can always add it later”.

Regarding the “slipperiness” of polished stainless steel, within the last two years or so I’ve started using a German-made stainless steel chain, whose properties meet or exceed G4. It’s not cheap, but for those who anchor often, and find themselves wearing out the galvanizing on chain more often than they’d like, it is attractive. So far no complaints, and two observations, it’s much cleaner, mud has a hard time sticking to it, and it lays flatter in the chain locker, in both cases a result of its low friction coefficient.

It only stands to reason that this would be true for an anchor as well, right? Personally, I hate stainless anchors because it’s a waste of nickle and chrome, which we need for more important things like stainless rigging, fasteners, shafts, cleats etc;-) I prefer my anchors galvanized, and my single malt neat.

Mark Wilson

I am a fan of the question “does it look right ?” There must be examples of boats that looked good but weren’t but I cannot think of one off the top of my head. To me stainless anchors and chain look frivolous and slightly pointless. And they scream marina queen.

I’m all for beauty. Could there be an opening at AAC for a beauty correspondent ? But a stainless anchor set up presents as more of a pretty boy look as than a handsome rugged one.

And as far as taking your malt neat Steve, I was a lifelong adherent of that habit until I was convinced by a scot that a dash of water releases new flavours and aromas.

Steve D

Agreed, on the single malt and water, I have been known to do that from time to time.

While I already made my point on stainless anchors being a waste of natural resources, I have many clients who aren’t marina queens who insist on stainless, I’ve endeavored to understand their point of view but thus far have failed. Now, in making the argument against it I can add the slippery factor.

Jeffrey Stander

Hopefully this doesn’t stray too far from the topic. In attaching chain to an anchor with a bow shackle the size of the shackle is limited by size of the pin which has to pass through the chain. If the anchor attachment is a hole (as shown in your image of the Ultra stock) the ears of the shackle will not pass through the anchors’s attachment hole. I believe I remember Earl Hinz recommending TWO bow shackles with the bows together. This solves the problem of where to put the bow, adds a lot of articulation, helps minimize side loading, and lets you use the biggest shackle possible.

Jeff Stander
s/v Beatrix

Jeffrey Stander

Sorry John, as usual I wasn’t as clear as I meant to be.

It took me a couple of days, but I did find my copy of Earl Hinz “Complete Book of Anchoring and Mooring” and my memory was only half right.

First of all Hinz refers to an “anchor shackle” which is also called a “bow” shackle. The other shackle he uses is a “chain shackle” which is the same as a “D” shackle. It helps my brain to use this terminology when discussing bending the chain rode to the anchor.

Chain shackles are for inline loads and are attached to the chain; the rounded anchor shackles allow loads from many directions while MINIMIZING SIDE LOADS.

So, when you cannot pass the ears of a shackle through the hole in the anchor shank, then you have to do what Hinz is suggesting: place the anchor shackle with its pin through the hole in the anchor shank. YOU HAVE TO USE AN ANCHOR SHACKLE. The rounded bow in the anchor shackle ameliorates the side (corner) load on the shackle. The chain shackle has its pin in the last link. The two shackles have their loops together. There is no point loading (as in pin-to-pin) with this arrangement.

s/v Beatrix

William Koppe

In regard to duplex stainless steel chain and shackles , please google hydrogen embrittlement.
In water warmer than 26 deg C, there will be a galvanic reaction between the zinc on the anchor, as described by Steve D and his Duplex chain . That reaction will generate more than 700 mv which then releases hydrogen into the Duplex chain. This can have serious consequences as it severely weakens the formerly very strong chain.
I also looked at the Cromox German chain but it was 10 times the price.
A stainless anchor would be a very wise idea.
Similarly the duplex anchor stocks referred to by Matt will suffer if used with galvanised chain.
Of course there are no issues in cooler waters as the reaction is below the 700 mv level.

Steve D

O have had discussions with Crosby about hydrogen embittlement. Here is a response from one of their engineers.

“I finally has a chance to talk with the design engineers. It was pointed out to me that hydrogen embrittlement is more of a long term issue in warm waters. Given the shallow depth and short term use, Engineering is more concerned about corrosion than embrittlement.

Again, sorry to have wasted so much time getting back to you.”

Carl Mayer
Technical Support
Crosby – Corporate

Taras Kalapun

Hi John!
Why can’t you attach 2 shackles between the chain and the anchor?
This could solve the problem for Ultra.
PS: This is how I attach G7 chain to my Spade anchor now.

Stein Varjord

Hi Taras,
John already answered that question before you asked it, but maybe another angle:
A shackle can be opened, it has threads, two connected parts, various shapes and angles. That means that a shackle is undisputedly a weak point. Having two shackles will double that problem. The problem can be mostly alleviated by having an overly strong shackle and checking it frequently etc, but double risk is always double risk. Thus, if we want to double a risk, we should have a reason for that choice. In this case I see no reason. We gain no advantage. With the right anchor, chain and one right shackle, we can get the minimum risk of failure.

Drew Frye

Shackles. If using high strength chain you nearly always have to use two shackles; one that fits the chain and one that fits the anchor. The one that will fit over the anchor shank won’t fit through the chain.

Stainless vs. Galv. and penetration depth. I’ve tested both (Mantus) but did not publish the results because they were not statistically significant. Same with roll bars. I took the Mantus roll bar off and the results were not much different and seemed to vary with the bottom type. The thing about anchor testing is that the data is extremely variable, even in consistent bottoms. You can see this in any test report that shows all the data. Drawing conclusions is like herding cats. So I don’t consider those factors to be important in terms of holding. Angles, balance, and area are the big levers.

I too have come to the conclusion that our modern anchors hold enough in good bottoms unless they are crazily undersized. They are really quite good. What matters for the next generation is better understanding reset and rotational behavior. Unfortunately, that’s a lot more complicated! But it is the reason I have always feared yawing and the reason I use V-anchors more than some (but not often). In some bottoms and some conditions I just don’t trust reset completely. Even if the anchor is perfect, what if it moves into a pile of trash or a soft spot? Much to learn.

Drew Frye

I suspect it depends on the anchor/chain combination and may have been somewhat unique. With my Manson there was no shackle that would fit both the chain and the anchor (if the pin it would fit through the chain, it would not span the thickness of the anchor shank). This was not strength issue, just a fit issue.

Drew Frye

I understand. Yes, with the bow through the anchor and the pin in the chain. The largest Crosby shackle that will fit the chain will NOT fit over the anchor shank. Just barely, but no.

I’m sure it is just a combination specific problem, thought it is common with grade 70 chain. Yes, it is probably something Spade got just right!

William Koppe

Hi John,

Not suggesting a failure of the G43 chain, but rather the Duplex component, be it chain a shackle or the anchor stock. What I am concerned with is mixing galvanised and Duplex components.
All galvanised or all duplex systems are fine.
The first warning sign would be the fast reduction in the galvanising.

Dan Manchester

Hi William,
I agree this can happen, but would think unlikely to occur quickly and corrosion on the galvanised part would be very evident first. Mixing any SS and galvanised components is a recipie for a short life, and should be avoided anyway.

John – you may be less happy to know that the galvanising process actually causes hydrogen embritlement in high strength steel, and needs to be baked out post galvanising. I’ve actually seen high tensile galvanised anchor bolts all laying broken on the floor 24 hours after being installed due to this – quite an eye opener.

Steve D

A quote from Winston Churchill comes to mind, “Why, you may take the most gallant sailor, the most intrepid airman or the most audacious soldier, put them at a table together- what do you get? The sum of all fears.”

Dan Manchester

Hi John,
Yes, it is very unlikely to occur on chain as even high strength chain is not that high strength relative to certain other applications. My use of the term anchor bolts was a bit careless in the context here, I’m referring to hold down bolts.

Carl Nelson

Of course, bending the anchor shank is a crude but effective way to reduce side loading strain on the shackle or swivel. The Ultra shank design is better than some but that attachment hole and swivel looks pretty strong. Do you know if Ultra tested this (e.g. side loaded the swivel until it either broke or the Ultra shank it was attached to bent?). If it bent first, then the swivel or attachement design is not really the problem.

I certainly have seen a lot of bent anchor shanks over the years – including one of my own. Is anyone aware of a test of the side loading that different anchors shanks can take before they bend?

Stein Varjord

Hi Carl,
I can’t remember where I read it, but there was a rather technical anchor test somewhere comparing lots of anchor properties. It stated that SPADE had a shank side load strength that was more than triple of the nearest competitor, which was Rockna, I think. He meant that strength was overkill, but still ended ut with choosing SPADE and meant some other anchors on the market had a too flimsy shank.

If a swivel is attached straight onto an anchor, so that it can only hinge in one dimension, there is no way to avoid occasional unacceptable bending loads on the swivel. There’s absolutely no chance that the Ultra swivel is able to withstand the same side load as the shank of the Ultra anchor. This is true even if the swivel from a much bigger anchor is chosen.

It’s easy to be fooled by looking at a swivel. It may look thick and tough, but the rotating link has a much thinner bolt inside. It can take great tensile loads, but very much lower bending loads, which will introduce serious fatigue issues, especially in SS steel. Thus, any swivel MUST be able to completely align with the loads, and do this 100% of the time. The only way to do this is to never attach it directly on the anchor shank but use a piece of chain between it and the anchor, as mentioned by John elsewhere. My main reason for not having a swivel is just that it’s a solution to a problem that I have never had.

Carl Nelson

I’m not a defender of swivels, but I looked at the Ultra swivel at boat shows. The inside ball and tapered post would seem to be far stronger under bending loads than a simple “pin”. The side of the body is shaped to support the post. They claim a 36,000lb breaking load for the one for 3/8″ chain size. Presumably that’s straight on – a shame they don’t publish a strength for side loading. Without a test it’s hard to know, but it would seem quite possible for the swivel to withstand side loading greater than the bending strength of the shank.

That’s interesting about the Spade shank bending strength – another point in it’s favor. I’m surprised Spade doesn’t make more of that in their marketing as bent shanks are clearly the most common failure mode for cruising anchors as it is rarely repairable. Shank bending strength would seem to deserve a lot of attention when choosing an anchor.

Thomas Nygaard

I can offer some first hand experience with bent shanks vs. the Ultra swivel: This summer in Greece I had a catastrophic failure and loss of a 33kg ss Rocna Vulcan anchor, its shank simply broke in two pieces by side loads from being caught in rocks. And guess what, it was attached to an Ultra swivel that survived without any signs of failure or bending! As can be seen on my pictures here, only a slight dent could be seen in the bolt that went through the shank. This I have now replaced just to be sure.

I think this is great testament to the quality of the Ultra swivel and eventually led me to put trust in and to purchase an Ultra anchor as a replacement for the broken Vulcan. (More on how the above happened and my experience with the Ultra anchor can be read in my two comments to John’s other article on resetting failures of Rocna anchors, , almost at the end).

Anyway, it is easy to agree to many of the concerns of swivels in general that John and many commenters in here put forth, but I think it is appropriate to ask if any of this is relevant as long as the pieces are properly sized. The same probably goes for the discussion about shackle arrangements. But the unique self-righting feature of the Ultra swivel in my opinion represents a huge improvement over a pure shackle solution. For my yacht ( ) it was also a bare necessity to use something slim as my bow roller channel is too narrow to accept a properly sized bow shackle, and a D-shackle alone just too easily jams.

As to the hole in the Ultra shank being round rather than oblong, this is exactly how it should be since the anchor and swivel have been designed to work together! The Rocna Vulcan I lost had an oblong hole which I had to fill with epoxy putty to make it round for the swivel to work properly! It should also be pointed out that the two pieces of the fork over the shank are connected with a solid arch, adding to its strength and reducing the chances that the fork is opened by side loads. Note also that the pin that goes through the chain is also ovale, this is not unique to the Mantus swivel.

Bottom line, I think the Ultra anchor is far from “motor boat jewellery”! Yes, it’s pretty and expensive, but together with the swivel it represents a great piece of engineering, and it is now adopted by premium sailing yacht brands such as Swan, Oyster and Hallberg-Rassy (and indeed on premium motor boats such as Fleming).

But too bad this post has not attracted more real user reviews on the holding capabilities of the anchor itself. I personally have only been able to use the Ultra anchor for four weeks in the Cyclades, with good results including riding out a Force 7-8 meltemi for five days in a row, but it would be interesting to hear more long-term users experience.

Andrew Craig-Bennett

Very reassuring.

Dick Stevenson

Hi John,
Thomas’ Vulcan anchor was of stainless steel (see
toward the end).
And I am not sure that this incident says anything at all about the strength of the Ultra swivel. It would be my guess that the SS shank fractured as a result of crevice corrosion. If that is the case, then we have no idea what kind of pressures resulted in the final break: it is my take that merely looking sideways at a cervice-d corroded piece of ss when it is ready to go is enough. So, I do not think this is in any way an endorsement of strength of this swivel.
My take, Dick Stevenson, s/v Alchemy

Thomas Nygaard

Yes, the broken Vulcan was of stainless steel (I just wrote ss). As to Dick’s comment, the dent in the shank bolt of the swivel proves that quite some forces have been in action here! (Ref. picture link above).

Stein Varjord

Hi Dick,
I totally agree that at least some stainless types have some disturbing reliability issues, especially related to fatigue tolerance. However, in this case it seems like the load has been substantial. If the shank was weakened by fatigue or crevice corrosion, that would have been in one spot, while most of the shank would have the original strength.

From the remaining piece, we can see that much of the shank has been bent a lot. To achieve that, a lot of force is needed. Enough to say it was a good test of the swivel. I still don’t like swivels, but they might actually be stronger than I suspect.

If I were to take a guess at what happened, I’d say that a heavy boat with an all chain rode did many tries at ripping it out by ramming it at a good speed. Probably no anchor would survive that undamaged. A galvanised anchor shank would resist more force without bending, and also bend further without braking off. A SS shank will sooner get to its limit of overload and by repetition, quickly develop fatigue.

I’ve seen indications of this behaviour when testing chain plates and such. I think that before this event, the anchor was probably strong enough for normal use. I doubt that normal anchoring use, even in heavy weather, can present this level of overload. Still I think I’d prefer a galvanised anchor…

Dick Stevenson

Hi Stein,
That is a nice and, likely accurate, analysis. I also see no functional purpose to swivels that makes ground tackle more effective and have lived without for decades. And the longer I am around boats, the less I like stainless steel in general and the more I find I am replacing stainless steel gear with lashings etc. where possible and practical.
Thanks for your thoughts, Dick


Hi Mr. Nygaard,
I am with ULTRA MARINE the designer and sole manufacturer of the ULTRA products. Thanks for sharing that testimonial supporting all our claims about our ULTRA Flip Swivel. I would like to use your testimony with your permission on other platforms, too. If that is okay with you, would you send an email to me confirming that it is okay with you at rt.moc.eniramartlu@yatukre so that we don’t have any copyright infringement?

Dick Stevenson

Hi John and Erkutay,
John, that feels like a good balanced stance to take and I agree completely with your thoughts on swivels.
My best, Dick Stevenson, s/v Alchemy


Hi John,
That is what we would like to do. If Mr. Nygaard is okay with it, we would like to use it on our website as a product testimonial sent directly to us without mentioning Attainable Adventure Cruising or as this is solely about our product. We will also not use the anchor brand not to hurt our competitor. Instead, we will write it as “R…. V….”
Likewise, you have the right to make your position on swivels, but I still believe you should look further to the details of the ULTRA Flip Swivel. I understand your general concerns about swivels, but ULTRA Flip Swivel is a product proven itself that there is no place for these concerns, plus it solves upside-down anchor recovery issues so we cannot say it is unnecessary to use.
Ultra Flip Swivel is one of its kind; it is a swivel and a flipping device at the same time. Therefore, it had a DAME nomination in 2011.
Technology is developing each day, so we designed it in a way that it is solving all these general concerns about the swivels. That is why when you look at the pictures in that testimonial, you see the failing anchor shank instead of the Ultra Flip Swivel, and it is not the only example.
Once again, I believe you should think further on the ULTRA Flip Swivel simply because, like Mr. Nygaard, all other users of the ULTRA Flip Swivel are so happy with it, and they don’t find it is something unnecessary and undesirable.

Dick Stevenson

Hi Erkutay,
You bring up an interesting balance that must be struck by every skipper: where to draw the line with respect to labor-saving devices that “may” introduce safety considerations. I am clear that having the anchor come up backwards is annoying, but I have worked out a quick way to “flip” mine. In other words, I am willing to do the little bit of extra work to not introduce another piece of gear into a mission critical system. Roller furling mainsails are another labor-saving area where the jury seems still to be out in balancing convenience vs. potential problems (including compromised performance). On the other hand, the labor-saving devices allowing roller furling headsails seem to have largely passed the threshold of acceptance, safety and reliability.
And there are 2 issues at hand, swivels in general and the attachment design used by your swivel to the anchor. The latter has, in my casual observation over the years, been generally criticized with the suggestion of adding another layer of chain (and more shackles etc.) to mitigate. The other issue, swivels it all, has met with some acceptance although I agree with John that it is a solution in search of a problem. I am also willing to consider that much of the limited general acceptance is a result of the advertising seen in the magazines etc.
It is interesting to me, that those who are selling swivels have largely dropped (again casual observation) the old argument that swivels take the “twist” out of the rode. I would guess that this argument was dropped as experience developed that this was not a problem and therefore, did not need a solution. Now there is the argument that “flipping” the anchor is of enough importance to warrant the introduction of a piece of gear into this crucial ground tackle system. I would suggest that this argument, over time, will find little traction among experienced skippers who anchor regularly and will trickle down from there.
And then, perhaps, over time, your “flipping” swivel will prove so robust and so convenient that it will gain general acceptance as a labor-saving device.
My best, Dick Stevenson, s/v Alchemy


Hi Dick,

Thanks for your comments.

I will use John’s first words here to make it clear. We were not a fan of swivels, primarily because the ones in the market were low quality and weaker than the chains connected. So we don’t want to add a failure point to our ground tackle. ULTRA Anchor, on the other hand, digs in more in-depth and forces these swivels more than the other anchors accordingly breaks them. That is the main reason we came up with the ULTRA Flip Swivel.

I will continue with John’s words; that said, there’s no intrinsic reason than an anchor swivel that’s strong enough for purpose can’t be made from stainless steel as long as the designer and manufacturer take into account the general problems of the swivels.

That is what we did with the ULTRA Flip Swivel.

We are using 318LN Duplex stainless steel (which probably wasn’t even available once these other swivels were designed)at the pins of our swivel. We are making sure that our body construction is more reliable than the highest side load that the strongest anchor shank can take. That is why you don’t hear of any ULTRA Flip Swivel failure plus it has the anchor flipping function, and its slim pointy design doesn’t make extra resistance at the shank of the ULTRA when it buries itself under the seabed.

You are right that over time people will appreciate that unique anchor chain connection. Here I am just giving you heads up.

Flemming Torp Petersen

When I bought my sailboat (around 5 t) – X-342 – more than 15 years ago, the bow anchor was an original Bruce 10 kg, stainless steel chain, 8 mm with SS swivel. Looked ‘sleek and nice’ … 😉
Sailing a lot in the archipelago around Norway, Sweden, and Finland, we experienced several problems when anchoring, and based on John’s articles and analyses, we decided to go for a SPADE, 20 kg – galvanized.
But I decided to keep my 80 m, 8 mm, German SS chain, and the swivel …
Until now – after four years, I don’t see any problems with that combination. Only once, have we experienced, the anchor drifted in heavy weed.
But based on the above discussion, I will most certainly consider to remove the Mantus swivel …
Today, I was looking into some articles at Cruisers Forum about anchoring, where several sailors mention, that they have had some challenges with Rocna anchors, supporting Johns comments about the “non-resetting issue”.
You may see for yourself what other sailors write about this problem at – f.ex. recent #362 and #363 and #364 …

Rob Thompson

Thanks Flemming. That video in the Youtube vlog Sailing into Freedom showing the Rocna failing to reset is quite illustrative of the issue, and confirms what John has written about the resetting issue with a clear video. Somehow seeing things makes the risk very apparent!

Kenneth McCallum

We have been using a 45kg Ultra with Ultra swivel on an Oyster 53 for eight years of cruising without a single problem or concern. Yes, it’s been stuck in rocks and side loaded a number of times… no problems. We also use an Ultra 60kg with matched Ultra swivel on our 44 ton Oyster 62 G5… no issues.

I do cut off the last two links of galvanized chain which attach to the swivels annually which show minor rust due to friction created zinc wear on the links.


Hi John,

I am surprised to see that even after all, you insist on seeing ULTRA Flip Swivel in the category of no-name swivels in general.

ULTRA Flip Swivel that has been designed from the start to eliminate weaknesses found in other designs, is a game-changer here.

I am sure you will realize that soon and make an exception for it. Because none of ULTRA Flip Swivel users think that it is a source of a problem instead they all see that it is a unique anchor chain connection solving their below three main issues;

-It is more reliable than the chain connected both at pulling loads and side loads. So it solves their security concerns.
-It is a unique ball joint swivel solving their chain twisting issues.
-It is, at the same time, a flipping device solving their upside-down anchor recovery problem.

Even here in that thread, we had three; happily, ULTRA Flip Swivel users commented counter-discourse your general statement. Soon, you will realize that there are many others out there without exception.

I may not be able to convince you with a couple of sentences here right now, but the happily ULTRA Flip Swivel users will surely do it over time.

Stein Varjord

Hi Erkutay,
I’m just a participant here, with no other connections to this site than a deep appreciation for it’s tremendous value as the worlds best source of knowledge for long distance cruisers.

I like that you’re enthusiastic about your products and want to explain why they’re good. It’s also understandable that you might feel annoyed when they receive criticism, especially when you feel the criticism is based on incorrect facts. In this case, you feel it’s fair to say your ULTRA Flip Swivel is not a weak link in the ground tackle system, since the materials and design means it can take bigger loads than the other elements.

However, it’s also smart to be a bit flexible in your attitude when discussing issues like this. If you feel that something isn’t fair, it’s smart to not show that, but rather discuss it without emotions. That’s the absolutely only way to get potentially better information through to other participants. Emotional comments will make everybody disregard everything you say, no matter how true it is. I have the impression that you go a bit off on this.

To get through to those who seem to disagree about your products, you also need to accept that they have good reasons for disagreeing. Maybe you have knowledge that means their good reasons are not valid, but the only way to get that through to them is to acknowledge that their reasons are actually good and reasonable.

The gist of this discussion seems to be:
– Having a swivel between the anchor and chain is adding one more item. Since all items can break, no matter how strong, that means added risk, although it might in theory be infinitely small.
– The benefits of a swivel are not essential, just comfortable, thus not worth the added risk of failure in mission critical equipment, no matter how small the risk is.
– Having a swivel attached directly on the anchor shank means risk of increased bending loads on the swivel or other elements, increasing the risk of failure at least to some degree.

Your defense:
– The ULTRA Flip Swivel is built from high quality materials and has dimensions that means it can take higher loads than the other elements in the ground tackle, so it will be the last part to break.
– The design of your swivel is done so that high bending loads cannot occur.
– Maybe something I missed?

– A swivel can be made strong enough to avoid significant danger of failure.
– No matter how strong it is, any swivel can fail.
– Any sailor must decide if the comfort is worth the added cost and extra risk, no matter how small those are.


Hi Stein,

Ours is a family business, and we are the second generation. You are right that we would be emotional at some points, even though I am doing my best to put away the emotions in these discussions.

Thanks for giving me a chance to explain ourselves better.

Claim: Having a swivel between the anchor and chain is adding one more item. Since all items can break, no matter how strong, that means added risk, although it might in theory be infinitely small.

Defense: There is no way you can connect your chain and anchor without adding one more item. So that risk stands the same for all shackles.

Claim: The benefits of a swivel are not essential, just comfortable, thus not worth the added risk of failure in mission critical equipment, no matter how small the risk is.

Defense: Once again, a shackle is also an added risk of failure. Plus, the ULTRA Flip Swivel, is unique in a way that it offers a solution to upside-down anchor recoveries.

Claim: Having a swivel attached directly on the anchor shank means risk of increased bending loads on the swivel or other elements, increasing the risk of failure at least to some degree.

Defense: A swivel such as ULTRA Flip Swivel having a higher breaking load than the chain connected at sideloading is not an additional risk of failure compared to a shackle passing its bow through anchor slot.

I understand you believe there is no sideloading when you pass the bow of your shackle through the anchor slot, but we made a swivel having a higher sideload breaking than the chain plus it offers the swivel function and the flipping function. So I find it unfair not to see it at all and put it in the same category of noname swivels in general. A shackle weaker than the chain can also fail at direct pulling. Okay, it doesn’t break under sideloading, but it fails at linear pulls. ULTRA broke many shackles because, unlike plow anchors or anchors with roll bars, it digs in more in-depth and creates higher holding power, so the same shackle surviving with a plow anchor failed with the ULTRA. Here the wise recommendation is to use a connection stronger than the chain. That was the reason we came up with the ULTRA Flip Swivel. We needed an anchor chain connection more reliable than the chain connected to offer with our anchor as the others were failing.

On the other hand, in maritime, there is no side load terminology for anchors and swivels. Lloyds don’t test the side loads of the anchors and the swivels because the only way the sideload takes place if the anchor gets stuck under rocks – however, neither anchors nor swivels designed to work under big rocks.

We should see anchors under rocks as an accident situation so instead of encouraging people to make accidents. I take the shackles don’t take sideloads in that category. We should encourage people to stay away from accidents or at least take better precautions, such as using the ULTRA Anchor Ring for a recovery option, for instance,

The way I see the best recommendation about the shackles and swivel, in general, would be telling eveyone put an anchor chain connector stronger than the chain connected and not to force recovery when their anchors are under rocks. Because, if they force recovery, they will eventually break something like in Thomas Nygaard’s testimonial. The ULTRA Flip Swivel survived, but they lost the anchor.


Hi John,

I hate to be pushy, so I agree to disagree with you. However, I see there are members like Stein seeing here “the best source of knowledge,” so my comments should add some new knowledge here.

-I said, “In maritime, there is no side load terminology for anchors and swivels.” If that is not true, the Llyods giving certification to these products should test their sideloading, right? The ULTRA Anchor certified by ABS, and they didn’t prove its sideloading strength. ULTRA Flip Swivel certified by RINA, they didn’t test its sideloading strength either.

-I said, “Neither anchors nor swivels designed to work under big rocks” You said, “your argument is that it’s simply not possible,” did you mean both the anchors and swivels designed to work under big rocks? Please just give me the name of that anchor and swivel so I can check that further. Because I don’t think an anchor designed to work under rocks would work on the sea bottom.

Most importantly, the reason I used these arguments was to explain why we don’t use their sideloading in marketing. Because we simply don’t find it right. However, I didn’t use these arguments as an excuse. We designed both our ULTRA Anchor and ULTRA Flip Swivel, considering, in reality, the anchor will surely go under a rock, and people force it, so they don’t fail. That was mainly for protecting our product image because, in the end, that doesn’t solve the problem.

I am happy to see that you offer a shackle stronger than the chain, but let’s say Thomas Nygaard was using that shackle with his anchor instead of the ULTRA Flip Swivel. What difference would that shackle make? Wasn’t he going to break his anchor shank either way?

Once again, our products have no issues with side loads, but you are right that we don’t like it because making an anchor and swivel that strong still doesn’t solve the main problem, like Thomas Nygaard’s case this ends up with breaking something else.

I still think the right thing to do is to warn all others about not forcing their ground tackle when their anchor is under a rock. I understand that they are not “avoidable accidents,” but we can avoid extra forcing the ground tackle and try to use another recovery option. That is a situation we studied a lot and came up with a product to help you guys. ULTRA Anchor Ring –

After all, you are right that we can argue all day about your statement that ULTRA Flip Swivel has a fundamental design flaw, but the reality is there are thousands of users in the last 15 years out there, and none of them is suffering from it. So let’s say you are right and we are wrong so there should at least “1”, I am asking only “1” user in thousands supporting your statement about our product, right? Instead, the only thing we have even in that platform is users telling how happy they are with the ULTRA Flip Swivel. Instead, we have pictures here showing the flawed designed ULTRA Flip Swivel took extreme sideloading, and unlike your statement, it didn’t break, it even didn’t deform, and the anchor shank broke.

Do you think that it is a coincidence?

ULTRA Flip Swivel designed from the start to eliminate weaknesses found in other designs, and there is not even only a “1” user who is not happy with it. So finally, you are right that it is a risk-reward ratio, so the readers can now make their calculations better.


Hi John,

That is okay. Thanks for giving us a chance to explain ourselves to others better than.

Stefan Smith

Excellent read and excellent discussion here, many thanks!

Thomas Nygaard

A rather un-mentioned but nice feature of the Ultra swivel is its very slim pointy design, offering the least possible resistance for the shank to dig itself deep into the sand while the anchor is being set. Compare this with the Mantus swivel which has a very large diameter, actually comparable to an “anchor rescue” device I tried for a while but with very deteriorating effect on anchor setting performance, it often prevented the shaft and thus entire anchor to dig in properly.

Then, as I pointed out in a previous comment above, the self-righting feature of the Ultra swivel is very attractive. However for swivel skeptics it would be interesting to hear if anybody has any experience with using a curved piece of steel inserted to the chain just before the anchor. Something along the lines of the product below which actually has a swivel function, but I have seen homemade versions just cut out of a piece of flat iron with a similar “banana shape” to make sure the anchor twists to the correct orientation in the last moments of retrieval.


I just realized that I wrote it under someone else’s comment. That is why I am rewriting.
Hi Mr. Nygaard,
I am with ULTRA MARINE the designer and sole manufacturer of the ULTRA products. Thanks for sharing that testimonial supporting all our claims about our ULTRA Flip Swivel. I would like to use your testimony with your permission on other platforms, too. If that is okay with you, would you send an email to me confirming that it is okay with you at rt.moc.eniramartlu@yatukre so that we don’t have any copyright infringement?

Stein Varjord

Hi Thomas,
You bring up very interesting points. I totally see the logic problem with extra substrate friction at the top end of the anchor shank. That might be another good reason for not having a swivel close to the anchor. The metal plate solution is also very interesting. It would probably have less friction in the substrate than even just the chain and it would apparently not be possible to give it misaligned loads. It does the most useful job of a swivel better than it, and with none of the weaknesses. Interesting item!

When it comes to the product, I like it a lot in several ways, but I’ve never tried it. I did speak to the owner of the company a week ago at the METS trade fair. Very nice guy who is continuously working with improving the product. A new version was just released. The reason I like this product is that it does not at all interfere with the normal anchor or rode setup. It’s just an addition. Some other solutions include releasing the rode from the normal attachment point, which I think is an insane concept.

Your experience with the Anchorrescue is interesting and points to potential future improvements. Perhaps by combining it with the metal plate you mention, to get the slider further away from the anchor and reduce substrate friction. That would also give an easy way to avoid slider rotation, which is important. I’ll contact the owner and ask for his view on these issues.

Albert Stahl

Great T-shirt slogan Lol, sign me up for a dozen


Sorry, but a bit late to the comments. News takes awhile to filter down to southern oceans.
The Rocna Vulcan seems to have an oblong attachment hole……any thought from the brains trust??
And John, you have probably saved my bacon. I have two lengths of chain joined by the shackle pin alone, and can now see the error of my ways, and will re-join with a proper link forthwith!

Joshua Marieholm

So… great discussion.. but at the end with 8mm chain maggi g7 and spade s100 which is the best shackle could fit in my anchor line ? Thx in advance

Dick Stevenson

Hi Joshua,
If in the US or Canada which may be unlikely from your use of Maggi chain at the 8mm size, I would mention Crosby D shackles. If using G4 I would suggest Crosby G-209-A alloy shackles with a pin size just to fit the chain link interior. Sizing to mm and to G7 may take some research, but Crosby equipment is well regarded.
You may need two shackles to make the connection to the Spade.
In Europe, I would likely consult with Maggi directly.
My best, Dick Stevenson, s/v Alchemy

Joshua Marieholm

Thx mate belive me is quite impossible here in Europe to find something like in USA… there is nothing that can Mach and also the green pin bow schakle made in Holland is about 0’75 ton BL. … could write down the brand and model of the best shackle I can buy in USA? With the imperial system I risk to make an error to order… thx in advance for this great thread!!’

Joshua Marieholm

Hey John finally after search found the solution!!!😊 they are linked with anchor Spade!! Get a look !

Joshua Marieholm

Perfect! I will make a video on my YouTube channel Sea4See regarding this soon.. and I will explain where they can find informational …At the Morganscloud website !

Joshua Marieholm

Finally arrived the connection between chain 8 mm g70 and his European shackle g 70 to match the strength!!!
Here some photos for you

Ernest E Vogelsinger

Couldn’t one use a fine drill to punch a hole through the bolt head for the wire?

Jeffrey Stander

I might have mentioned this before, but I am using Loctite Red High Strength threadlocker on my shackles instead of wire or pin. The shackle pin will NEVER come out unless heated with a gas torch; then the pin can be easily removed.
See this video.

Dick Stevenson

Hi Jeffrey,
Interesting suggestion.
I have had occasion, rarely thank goodness, of swapping shackles and cobbling together ground tackle gear on the foredeck in lousy conditions, so I would hate a shackle that I could not undo easily. With wire mousing I have what has proven over time, a reliable “lock” for the shackle that a snip or two of my dikes and a turn with a wrench releases easily.
I would not recommend a chemical lock that requires a torch to undo. It may just be me, but I like to see that my “lock” is intact visually and I am not sure how the metal in the shackle responds to the heating you suggest. Then there is the times when the shackle must be worked in lousy conditions, rain and such, and a torch is impossible or unwise.
My best, Dick Stevenson, s/v Alchemy 

Dick Stevenson

Hi John,
Is the blue Loctite for added security (as in belt and suspenders) or is the blue Loctite a preventative for the shackle pin corroding/seizing in place? (or both?)
In the very salty Med, if I did not have shackles apart once a year (better every 6 months) they could become very difficult with hand tools. I took to smearing silicone on the threads before assembly and mousing, which made a difference in that regard.
Along those lines, I also silicone the threads of the stainless shackles used on or near sails (like the headsail tack and clew where I do not want wire ends close to sail material): a trick I learned from Tom Anderson, the rigger at Hathaway R&R back in the day. I suspect Loctite has a product that would do as well.
My best, Dick Stevenson, s/v Alchemy

Rob Gill

Hi Dick, we use a trick with silicone on shackles, but I’m not sure if it is the same, or different from your rigger friend’s method…anyway we mouse the shackle with SS rigging wire, then daub the exposed twisted end to encase it with a pure silicone “knob” which when set, is remarkably permanent to anything except a pair of pliers. This prevents corrosion and damage to fingers and sails. In fact we use this everywhere we have used seizing wire. We could probably daub some on the thread too but haven’t seen the need.
Br. Rob

Eric Klem

For what it’s worth, I have never had problems undoing shackles that have been underwater with never-seize on them even after multiple years. Last spring we replaced our bottom chain and I was pleasantly surprised that I did not have to cut the 1-1/2″ shackle off which had been submerged for 10 years, the same giant crescent wrench that put it on took it off. When using never-seize, I not only do the threads but also the area on the other side of the bow where the pin contacts as this area will often seize too. Using this method, I am amazed at how well threads last, when installed dry or with loctite, I find that they corrode away much faster and you have to check them more often.

Applications where you don’t fully torque something can be a bit tricky as they are susceptible to backing out but for all other applications, I am a big fan of never-seize although it does make a huge mess. When I designed industrial machinery, every single fastener got it so that service would be able to actually take things apart again. The industry I work in these days has cleanliness rules that mean that we have to use something else so every fastener gets Loctite 243 (blue). This provides us with a more consistent K factor, helps prevent galling, helps prevent corrosion (I design a lot of aluminum housings with SS bolts but the environment is not all that corrosive) and provides some safety cushion in case the bolted joint is not as well designed as you would like. I do my best to avoid any designs which would require Loctite 263 (red) and I don’t think that I have ever put one into production, we occasionally do it for prototyping. Forcing service people to carry torches is not exactly practical for starters. Also, if an application needs 263 to work, it often means it is a poor design with too little preload or too short of unsupported bolt shank. 263 can be a real bear to get undone but I have also seen a scarily high failure rate of it. I suspect that this is due to a combination of poor surface preparation and improper handling with relation to shelf life and storage conditions once it is opened. To get around this second issue, I buy the single use containers for personal use, something which I normally hate but which makes a lot of sense when you are not on a production floor where you go through it quickly.


Jeffrey Stander

I disagree, John. I was nervous at first using red Loctite on the anchor shackle, but the big shackle with protruding pin was jamming in my anchor roller. I wanted to use a flush shackle with a flush pin that required an Allen (hex) wrench.

That meant giving up the mouse. But LOGIC, not gut-fear, lead me to use Red Loctite on the flush pin shackle.

Mouse or no mouse, the pin with Loctite is SIMPLY NOT REMOVABLE without heat. I tested it. It’s much safer than a bit of wire.

Your point that you might want to unshackle the anchor at sea (or underwater) is a good one. If that’s important, use the mouse.

For me, it is more important to have a smooth entry into my anchor roller.

Everyone gets to choose.

Eric Klem

Hi John,

Certainly, for my own use I would not rely on Loctite or any of the competitor products for keeping my anchor shackle from backing out for exactly the reasons you state. This is one of those design trade-offs and I have always been able to take the easy, known path of wiring but there may be shackle applications where that simply isn’t possible. It is certainly theoretically possible for someone to keep a shackle from backing off with Loctite but I think few cruisers will use it exactly as intended and then the effectiveness of it will be called into question. One question that I would want to speak to someone from Henkel about (great customer service by the way) is use on galvanized fittings in a corrosive environment, that is an application which I have no knowledge about. I do use Loctite 263 from time to time on personal stuff as there are a lot of products out there with poorly designed bolted connections but I try hard to use it per the manufacturer instructions and if I can’t, I do something else like drill for safety wire. I use a fair amount of 243 both for work and personal. Loctite does also specify size ranges for their threadlockers, for example switching from 243 to 222 under 1/4″ but most engineers I know don’t change the specs for small bolts. Adhesives are really incredible these days and I think most people would be shocked at some of the things that are attached that way. In most of these cases, there has been a lot of process development, testing and process control that goes into it to ensure that it won’t fail. There certainly are failures and they sometimes are even newsworthy and usually someone did not follow the process as specified, sometimes the tests are found to have not been representative too. There are people who specialize in adhesives so while someone like me has spec’ed a lot for various applications, I am far from an expert and rely on a combination of experts and testing when I get a tricky application.

I also realize that I seize shackles differently than many here. Instead of using many turns of a small diameter wire, I use 1 turn of galvanized bailing wire for most applications and 2 turns in a few places where they are more likely to get broken. This comes from having worked on boats where there were shackles everywhere that needed mousing and unmousing each year, many turns of small stuff seems to be a yachstman style solution. Note, bailing wire does corrode if submerged for a while so I would not use it to wire shackles on mooring chain but it always looks fine when I replace it each year on our anchor shackle and our mooring pendant shackle which sits on top of our mooring buoy.


Eric Klem

Hi John,

Sorry to hear about that experience. It does raise a few questions including why the shackle backed off at all, wire is the backup and I actually don’t think I have ever seen a situation where the wire was actually what kept the shackle closed (I have seen it a few times with bolts, particularly set screws going onto flats or into dimples and I have seen plenty of failed mooring gear, just not from failed seizing). Regardless, I am a firm believer that if you are going to do belt and suspenders, both have to work so that doesn’t excuse the wiring failing. Also, I wonder what they were using for wire? I would definitely not use any steel based wire on a mooring where it remains underwater for extended periods, I could see that failing in months due to corrosion. Around here, if you don’t intervene and provide something like Monel, the mooring guys seem to either use the really heavy duty zip ties or ~12 awg solid copper wire with insulation on it. To be honest, I am not totally sold on any of these seizing solutions on a mooring shackle and I am far from convinced that screw pin shackles are the right thing to be using although they are the norm.

Your story reminded me that there is actually a pitfall with using large wire so I thought that I should mention it, this could potentially have even been related to the failure you saw. The danger is that as you spin up the ends, if you don’t keep them even and laying nicely against each other, you will greatly weaken the wire. What happens is that one strand ends up wrapping in a spiral around the outside of the other which remains straight. The straight leg will undergo too much torsional strain and either be greatly weakened or actually break during tightening. Done properly with them laying evenly, the strands are not over stressed and I have never seen one fail although I still put 2 on in critical applications like the anchor shackle. I have probably wired something like 1000 shackles now and it starts to lay wrong on me maybe 1 in 50 times so I just cut it off and start over but when I first learned, it was more like 1 in 5. This can be a problem on small wire too but I find it tends to be much easier to avoid than big wire and less likely to compromise it. So this may be a little like red Loctite, possible to do right but easy to do wrong although at least this is easily visually detectable.


Henrik Johnsen

Check this video regarding the Ultra Anchor. Not a scientific investigation , but appears like an honest review.

Henrik Johnsen
Dave Warnock

I found the contrast between your comments about taking price out of the evaluation (which I fully agree with) and their view that more expensive is automatically better (particularly with Stainless Steel over galvanised).

Dick Stevenson

Hi John and all,
How appalling that a picture was lifted off your site without permission!
I agree completely with your comments with regard to swivels.
I think it is a testament to the power of advertising money that this issue of swivels in a ground tackle system keeps coming up. I must re-iterate this discussion at least once a year.
The video makes a big deal of the Spade early galvanizing issues and I agree with your comment that a little cosmetic staining will also occur in the first few feet of chain and that the effectiveness of the anchor is not at all diminished.
I would also like to note that Spade stands by their products. My first Spade (approx. 2008 t0 2013) had many hundreds of deployments and was getting pretty gnarly looking. Spade replaced it for free and let me bump up a size and only pay the differential and then shipped the new from France to England. I even kept the old anchor (still functionally fine) which took the place of my old Luke as spare. The Luke found a new home in the UK.
The “new” Spade now has many hundreds of deployments and the galvanizing has held up well.
My best, Dick Stevenson, s/v Alchemy

Dick Stevenson

Hi John and all,
And lifting your photo may be an example of the entitled-ness and slipperiness that a few cruisers exhibit: giving us a bad name in some areas.  It was going into Treguier, I believe, that a cruiser, just dropping his mooring, said that If I left before 0900 the next morning I would not have to pay for the overnight mooring. He was not pleased (and I was glad we had water between us), when I pointed out that was stealing.
My best, Dick Stevenson, s/v Alchemy

Jeff Totman

I think customer testimonials can be useful sources of info but no matter what the item being reviewed I think it’s important to try to assess the subject knowledge of the one leaving the review. It’s also important to take into account that just after someone spends a lot of money on something, it’s common to want to convince themself that spending all that money was a good move so unless an item turns out to be a complete disaster in the first few months of ownership, most people want to say good things about their recent “investment” during this honeymoon period.

I’ve never even noticed any significant anchor chain twisting and have always thought of the anchor coming up backwards as just an occasional minor annoyance that takes just a few seconds to sort. So I’ve never understood why anyone would spend money to “fix” such a minor and momentary inconvenience, especially when the swivels are made of a dissimilar metal from my anchor chain and anchor that they’re connected to. I guess if you want an Ultra anchor, since the round hole in the shank won’t accommodate the body of a shackle, you have no choice but to add a swivel. But, between the high cost of the anchor itself, and then having to also buy their pricey swivel, I guess I just don’t understand the value when there are at least a few other anchors that cost less, don’t require a swivel, and do just as well or better in independent tests such as those conducted by Steve at SV Panope. But they sure are shiny!

Jeffrey Stander

Crossing the Pacific I eschewed anchor swivels, but once we reached Australia we at times spent weeks at anchor in shallow water. The anchor chain would be twisted with every tidal cycle.

When pulling up the anchor there was not enough depth for the chain to untwist and we were finding the chain so twisted that it would jump off the gypsy.

A swivel solved the problem. The best way to connect a swivel is with a “forerunner”, 3 or 4 links of chain between the swivel and the anchor. NEVER attach a swivel directly to an anchor.

Jeffrey Stander

In the muddy waters of Australia perhaps the anchor doesn’t reset as easily as in the sandy bottoms of the Bahamas (they are sandy, I assume).
Congratulations on the new boat.

Fort Felker

Hello all – I am new here, so please accept my apologies if I’m not commenting appropriately. Regarding the loooonnnnggg discussion about the ULTRA swivel, I am struck that there is not a single failure cited by anyone after 15+ years of service in a presumably wide range of conditions. John and many others have dismissed them as bad on 1st principles, but that seems like a merely theoretical point in comparison to not a single example cited of an actual failure. You either need a shackle or a swivel – if the swivel never fails then whats wrong with that? Some sailors might be willing to pay extra for the decreased resistance to digging deep and other minor advantages. Just my 2 cents – I have no dog in this hunt.