Mantus Anchor Swivel Break

[transmitterdan]

If anchored for long time tides and wind tend to cause the boat to circle the anchor. Sometimes 3-8 times a day. A good anchor will not pull out and quite often there is not a lot of force anyway because we tend to anchor in protected anchorages. So there can be many twists introduced into the chain. Short link chain, which is preferred by windlass designers, can get hockled after a few twists and reduce its working load capacity. The chain is usually the weakest part of the rode and so there is a desire to minimize hockling.

A good windlass does not add twists to the chain. At least mine does not.

I don't see much advantage to a swivel. My spade always comes up right and if not it flips over when coming into the roller.

If I have circled the anchor a lot I try to raise and reset the anchor. I agree with Thinwater that most swivels don't.

[noelex 77]

Originally Posted by BigBeakie

How many twists in say 40 meters laid out would cause a problem? Is it caused by sailing over and/or around the anchor with wind shifts, tide changes etc. or is it caused by chain being retrieved and let out by the windlass? I've read the other threads on this, but did not see what the cause is.

The boat does not need to sail over and around the anchor to put a twist in the chain. It just has to spin around. If you twist chain enough, it will begin to bunch up or hockle. It is the number of twists per unit length that determines if this will happen. For 40m of chain this is a lot of twists, but as the chain is retrieved any twists get concentrated into the last bit of chain as the windlass keeps the chain straight. Once the anchor breaks out it will spin around and eliminate the twisting, but in the final stages of retrieval it can be a problem.

Older anchor designs are often easy to break out and with some of the less roll stable designs the twisting helps break the anchor free, but with good modern designs it needs close to 1:1 before they can break out, so it can occasionally be an problem without a swivel.

It is seen more commonly with the move towards modern anchor designs, but in most locations it is quite rare especially if you only spend a short time at anchor. A shackle has no ability to rotate and to eliminate the twists, but is a simple, strong, secure, streamlined and inexpensive solution. It is what I personally use. However, it is nice to see companies producing swivels that seem to eliminate some of the traditional problems. On the rare occasions when I have experienced the chain becoming excessively twisted a swivel seemed like a good idea.

This is a photo of chain just beginning to bunch up. If you look carefully you can see some of the links are lying at right angles despite a lot of force on the chain. Chain like this will jam in the windlass.

[Kenomac]

Originally Posted by Uncle Bob

Ken, I do believe that the hammerlock was installed for the testing, the recommended install is as shown using load rated shackles.




Perhaps you didn't notice that the oversize D shackle fitted to the anchor shank is there to allow the correct size bow shackle to attach correctly, allowing the required load rating without excessive sideloading.

I realize my mistake now, I thought the hammerlock was the flip link. Maybe the company needs to re-think their marketing strategy.

[wsmurdoch]

Originally Posted by BigBeakie

Regarding chain twisting, a question please. What causes the twist in a chain rode that is laid out? How many twists in say 40 meters laid out would cause a problem? Is it caused by sailing over and/or around the anchor with wind shifts, tide changes etc. or is it caused by chain being retrieved and let out by the windlass? I've read the other threads on this, but did not see what the cause is.

In each of the last ten years we have taken our sailboat south from North Carolina to the Bahamas in January returning in June. We get twists in the anchor chain when anchored in places with the current flowing in one direction while the wind blows in the near opposite direction. If the two forces almost balance, there is little force on the chain, and the boat travels round and round in lazy circles drawing loop after loop on the GPS chartplotter.

Our worst experiences have been in Fernandina Beach in Florida and Between the Majors near Staniel Cay in the Bahamas. With 100 feet of chain out, we can accumulate a twist in the chain every five minutes during a six-hour tidal current flow. If the current and wind are just a little out of alignment, the boat only circles in one direction and the twists add up.

Our bow roller has a notch in the bottom of its groove that attempts to keep the twist from reaching the windlass as the chain is brought in. Some of the twist reaches the windlass wildcat anyway causing the chain to jump as the twist goes by. That twist passes on into the anchor locker to perhaps emerge the next time the anchor is deployed. The larger part of the twist in the chain is pushed on toward the anchor. When the chain is slack, the twist can accumulate in hockles that come up out of the water and must be worked out of the chain by hand below the bow roller. In the end, when the anchor breaks free it can rotate in the water untwisting as it comes up. Until then, the chain is a royal mess.

I tried an Acco chain swivel for a couple of years, but had little success with it. The bearing surfaces were so rough that it would not rotate with any load on it at all. I took it off. I also suspect that the hockles don't transmit any torque down the chain; they just hang there.

A swivel needs to swivel. The Acco swivel did not.

Bill Murdoch
Irish Eyes to the Bahamas

[BigBeakie]

Thanks Bill, that was a very helpful post

[zboss]

I'm revisiting my thread... Can anyone point to someone that has had a Mantus Swivel fail yet?

Last year we spent about 6 months of the year on the swivel. I have replaced the single wire mouse with multiple segments of wires moused opposed to each other and with the ends tucked into the mousing holes. So far, so good.

I did notice (and maybe it was always here and i never saw it) that you are supposed to put teflon tape around the two joined halves of the swivel before screwing them together.

[NewMoon]

Originally Posted by NewMoon

On my 37, with 5/16 chain, I have the smallest Mantus. After one summer on the Inside Passage it still seems an excellent design. I do plan to re-do the seizing wire before this years cruise. Per the advice of someone on this forum, I used a very sturdy heavier gauge wire than what came with the swivel, but it seems like cheap insurance to re-do it.

After two summers (5 months each, anchoring maybe 3/4 of the nights) the Mantus is doing fine. Almost no signs of wear. Wire will be replaced again this spring.

[Tortuga's Lie]

No failure here after a year, but I am not full time so my year isn't really a year..........yet!

[boom23]

I used the Mantus swivel for 3 seasons cruising in the S. Pacific on my ex Lagoon 450 with 12mm chain and Manson Supreme anchor. I never had a problem. I once lifted a storm swept coconut tree trunk from the ocean floor with my anchor. This was not fun as the trunk was extremely heavy. I had to unravel the anchor & chain from the trunk without getting crushed by it. The swivel did not notice... My windlass was really struggling.

I kept an eye on the Mantus swivel seizing wires but I also kept any eye on the rest of the anchoring equipment. I almost always anchor and I like to sleep well at night.

My next boat comes with oversized Ultra anchor and swivel. But, I would not hesitate to use a Mantus swivel again.

[bgallinger]

Originally Posted by zboss

Now that the Mantus swivel has been in wide use for a while, have we seen any examples of that particular swivel breaking?

This is not a "have a swivel or not" question, just wondering if all the banter about anchor swivels breaking vs. actual examples of the Mantus (in particular) breaking.

You might consider using a question (?) mark at the end of your post!

[sailingharry]

Old post, I know. But good information. I seem to have found a broken link.


There is mention in the thread of much useful testing and such at coxengineering dot com. That is a useless HVAC contractor site (OK, a good site, but not boating related).


Their information seems to now be at Cox Engineering – A technical information resource for yacht owners

[slug]

Originally Posted by zboss

Now that the Mantus swivel has been in wide use for a while, have we seen any examples of that particular swivel breaking?

This is not a "have a swivel or not" question, just wondering if all the banter about anchor swivels breaking vs. actual examples of the Mantus (in particular) breaking.

The swivel , shackle looks well engineered

Why would it fail ?

[Dockhead]

Originally Posted by slug

The swivel , shackle looks well engineered

Why would it fail ?

A hidden design defect?


It looks to me also like it is very robust and well-engineered. Particular clever is the way it avoids levering the anchor shaft.


But it's hella fat! I don't like that -- surely a big disadvantage in getting the anchor well buried.


I have never needed a swivel on well-balanced anchors.

[a64pilot]

I’ve not read the thread, but not a design defect, if it was, there would be several failures.
If one failed it’s either from overloading, which I doubt, or a material failure from an inclusion etc., which would be my bet.

On edit, went back and looked, it’s an older thread that I had commented on, and no, one hasn’t broken.
I think it theoretically possible as for example with my 5/16” chain there are two swivel sizes that will fit, if you opted for the smaller size and had high strength chain then I believe the swivels weaker than the chain, but if chose the larger size, then the chain is the weakest.
It is a big thing, which I assume it has to be be so strong, and I can see how it may not fit though all rollers, but I can’t see how it could realistically resist and anchor from setting, if you bury the shank your not in real tough / high resistance substrate.
Mine is about the size of my fist, and I think my shank may be almost an inch thick.

[zboss]

I was following the guidelines for titling after I got my hand slapped by a mod back then The thread is several years old and with enough of the mantus swivels out there we should be hearing some feedback on the robustness of the swivel.

I have had mine on and used for anchoring maybe 50% of each year since I started the thread and so far I haven't seen any rusting, pitting, or other issues you may see from stainless steel being submerged for so long and so often in a saltwater environment.

I haven't heard of them falling off or falling apart even considering the unusual design. That being said, both my spade on the Cabo Rico and my Mantus 2 anchor on my Manta both come up randomly but almost never straight on. We always have to use a gaff to push the anchor around to line it up.