Mantus swivel? Design flaws? Or no swivel at all?

[NormanS]

Originally Posted by LongRange

In these parts of the Med, Osculati swivels are rather popular. (Who actually makes them, I have no idea.)



To me, it seems an excellent design with no obvious defects. The body is a massively hefty chunk of stainless, far stronger than chain, and it adds a good 2 kg to the weight of the anchor, right behind the shank. The anchor is always rotated correctly in the roller, and chain twist is eliminated.

In the larger of the two sizes, the internal T-shaped lug that provides rotation is 14 mm in diameter. The pin that goes through the chain link, and the bolt that secures the end-cap, are both 12 mm, stronger than 10 mm chain.

Mine is attached to a 33 kg Rocna with a 12 mm Wichard bow shackle, which I think may be the weakest part of the system.

I have not used a Mantus swivel, but it seems like a cut-down version of the Osculati design without the hefty auto-alignment corkscrew. I cannot see any obvious advantages over the Osculati design. The comparative disadvantages look to be a lack of self-orientation in the roller, less added weight at the base of the shank, perhaps a propensity to catch that protruding hex nut on deck hardware, and a relatively thin-section sleeve with more invisible inner surface area.

I am also not sure that the oblong captive pin that goes through the foremost chain link is such a good idea. It presumably prevents free pin rotation, and thus potentially subjects that link to weird side-loading.

My "Bent Link" is similar except it doesn't have and doesn't need a swivel.

[LongRange]

Originally Posted by NormanS

My "Bent Link" is similar except it doesn't have and doesn't need a swivel.

Personally, I am concerned about the off-axis loading effects in severely twisted chain, which is the primary reason I use a swivel. By the time it gets to hocking, chain is perhaps only one-third as strong as its rating, but even before then off-axis loading can result in significant strength reductions in chain links, "rapides", shackles, carabiners...

All such hardware is designed and rated for aligned main-axis forces. Twist them, and the label rating no longer applies. The effect may be small under 99% of circumstances, but I like to do everything I can to sleep more soundly at night, and my personal gambit is that a very good swivel is worth the extra complexity.

Having said that, most generic swivels sold in chandleries are clearly terrible.

[Shenandoah52]

Originally Posted by Jimmyhenry

Only ever had one swivel. It broke. Made me ask why I would ever bother having one. I asked many engineering friends to explain why. None could. The whole concept seems flawed. The only good reason was to swivel the anchor once it reached the bow roller.

So... as someone who regularly anchored several times a week in 150' of water in a smaller boat I had times where the 150' drop would cause the danforth to spin on the way down, or the stretch of the 3/4" three strand rope coupled to 30' of 3/8" chain would cause the rope to want to hockle on the way up. It had nothing to do with the way the anchor sat in the bow roller.
Obviously having 3:1 or 5:1 chain for that depth on a 28' boat is impractical so rope was the viable option. The rope outlasted the anchor, btw. That anchor was worn out by the time I replaced it.

[thinwater]

Originally Posted by ranger42c

We use a swivel BECAUSE our anchor returns backwards about half of the time. At least the swivel makes it easier to manually orient our anchor prior to the final lift.

We have a grooved roller, too, but we also use a mixed chain/rope rode...

-Chris

If you back while hoisting, the anchor will align. Try it. If you are going forward, it will be backwards.

[Cheechako]

Never felt I needed a swivel. I have had a twisted chain in variable current conditions, but I'm not convinced swivels rotate when you want them to. I did have one many years back though. It didn't seem to resist chain twist.

[model 10]

Originally Posted by thinwater

If you back while hoisting, the anchor will align. Try it. If you are going forward, it will be backwards.

So in the real world you pull up a load of mud and need to go FWD to wash it off. Stopping and then backing up 20 minutes later is not in the plan. In addition to that problem, nobody wants me backing up anywhere near them. The big one though, is if the wind is blowing and you can't be screwing around with the anchor or you might run aground. That's the one that get's my attention.
I had one of those Italian jobs and the thu bolt cap screw had some sort of internal corrosion and the head twisted off. Now I'm using 2 shackles instead.

[Cat36Mahalo]

I think many who answer here in the negative have never seen a Mantus Swivel or looked at the design on their website. My Mantus anchor self positions it self once it hits the roller, the swivel allowed this. If you think it is a “standard run of the mill” swivel your wrong. It is a well engineered chunk of stainless, it cannot be put on backwards, which is the cause of most standard swivel failures.

[a64pilot]

https://www.mantusmarine.com/mantus-swivel/

I have the S2 swivel on 5/16” chain, ultimate breaking strength of the swivel is over 21,000 lbs.
ultimate breaking strength of 5/16” G70 chain is only about 14,000 lbs

You can’t impart a side load on a Mantus swivel, and yes a side load is often what breaks swivels.

If you want to go forward to remove mud from your anchor do so, but if you have a Rocna and I assume a Mantus anchor if your moving in reverse I guarantee you the anchor will position itself correctly.
I do this all of the time, it works every time.

[thinwater]

Originally Posted by Ecos

So in the real world you pull up a load of mud and need to go FWD to wash it off. Stopping and then backing up 20 minutes later is not in the plan. In addition to that problem, nobody wants me backing up anywhere near them. The big one though, is if the wind is blowing and you can't be screwing around with the anchor or you might run aground. That's the one that get's my attention.
I had one of those Italian jobs and the thu bolt cap screw had some sort of internal corrosion and the head twisted off. Now I'm using 2 shackles instead.

I don't mean steaming along backwards. I mean if you are steaming forwards it is going to come up backwards. Period. I've seen this time and again. If you simply stop, for the few moments it takes to land the anchor, it will help.



Obviously, I have done this many times.

[Sojourner]

I'll second it: I don't know how my mantus works, but with the rocna on it, I haven't had it come up any which way but correctly in 2 years. Also second that it is huge compared to most swivels, and looks at least beefy enough to be able to outpull the 10mm chain it's attached to.

[Dockhead]

Originally Posted by thinwater

I don't mean steaming along backwards. I mean if you are steaming forwards it is going to come up backwards. Period. I've seen this time and again. If you simply stop, for the few moments it takes to land the anchor, it will help..

This has worked for me for years -- but PROVIDED the anchor is reasonably well balanced. With Spades and Deltas, going backwards is not required -- just stop. Just don't be moving ahead, not even 0.01 knots.



With my 121 pound Rocna, however, this did not work, because the anchor wanted to lie on its back due to balance. I found I needed a swivel, and to turn the anchor around with a boathook. This was a PITA and was one of several reasons why I got rid of that anchor.


YMMV, but I would suggest to anyone thinking about adding a swivel, to try this technique at least, beforehand. Just a tiny bit of reverse -- maybe only 0.5 knot, or even less -- as the anchor comes up out of the water -- should do it. Many people who think they need a swivel probably do not -- the anchor is only flipping over the wrong way because they are drifting forward a bit, and the interaction with the water is flipping it around. I emphasize that even a tiny amount of motion through the water will turn the anchor -- either the way you want it to turn, or the way you don't.



If it's not essential for your particular anchor, it's better without a swivel. First of all, it's safer. Second, cheaper. But most of all, the anchor will be easier to retrieve without a swivel. If you have a swivel, you will mostly likely HAVE to align the anchor as it comes up. Without a swivel, it may come right in without any messing around. Mine works so well that I sometimes raise the anchor from the helm, without even being at the bow. This is very, very handy when single handing. And we're talking about a 100 pound spade.

[ranger58sb]

Originally Posted by Jimmyhenry

Only ever had one swivel. It broke.

The only good reason was to swivel the anchor once it reached the bow roller. That suggests another problem is present. Adding a swivel just avoids fixing the real problem and adds another weak link.
We have a Rocna 33kg. Sits in the roller correctly 100%. Grooved roller is the answer.

There are swivels, and then there are swivels. What specific brand/model broke? In what circumstances?

We have a grooved roller. Doesn't do squat when it comes to anchor presentation.

Originally Posted by thinwater

If you back while hoisting, the anchor will align. Try it. If you are going forward, it will be backwards.

Thanks for tip. I haven't had that experience, but then maybe we've been a bit cavalier about our attempts. And then there's usually lots of lag time while the anchor is suspended -- so I can clean mud out of the chain links. The anchor does what it will, while suspended.

-Chris

[sck5]

another vote for no swivel. Anchor came up fine every time - occasionally needed a one or two second pause to orient itself properly on the roller but I never once had to go mess with it by hand. and all the swivels that fit were rated for way lighter loads than the chains and shackles.

Just say no to swivels.

[jmorrison146]

My problem with a swivel is the potential corrosion in a part you can't see..

[daydreamer]

No swivel and our chain has never twisted.

Ten seasons in the Caribbean and the Bahamas. Privilege 42 catamaran with 300ft of half inch (12 mm) G43 chain, with Spade A200 or 65lb Mantus.