Hi Shills,
Your described motive for the swivel originated (in part) by the chain not coming out of the locker smoothly and fast in a fire drill, an understandable safety concern. You also suggest prior troubles with chain twist and suggest that these problems have been alleviated by the use of a swivel.
As to chain coming out of the locker and getting jammed in a fire drill: this does not surprise me. When emerging at a moderate rate, the links can separate and flow easily, especially if there is sufficient distance from wildcat to the top of the chain pile (assuming a reasonably configured locker where chain piles do not need to be knocked over to accommodate the chain and the chain is brought in by the windlass-ie not dumped). All bets are off with a very fast rate as links will have insufficient time to separate and can easily get jammed as the chain is jumping about.
As to twist when recovering the anchor, I have never understood the forensics of how chain twist gets induced. Do you have an explanation of what takes place that your chain gets twisted?
My observation: If chain goes out un-twisted as it would if going over a free-wheeling wildcat (or even by hand) I do not see how the chain could get problematically twisted in a few days of anchoring. Maybe a few wind shifts and rotations, but these would be easily “un”-twisted when the anchor hangs free coming up to the boat and absorbed by the snubber when at anchor. So I do not see a way for twist to get induced. How do you understand it?
Probably most powerful argument for me is that in many thousands of anchoring experiences, I have yet to find a problem that makes a swivel worth the added vulnerability to my ground tackle system. The only time I wish for a swivel is when the anchor comes up in a way that makes it harder to get it onto the roller: a swivel might make this easier to remedy, but even there I am in doubt.
I would suspect that there is an alternative solution to your chain twist, but without understanding the mechanics inducing the twist, I am unable to make suggestions. I am clear that I consider swivels an unnecessary added vulnerability in a ground tackle system that should be avoided.
My best, Dick Stevenson, s/v Alchemy

Hi Shills

I may have posted this earlier, but here is a link to a page where we discuss swivels, where to place them (as you also suggest), and the problems associated with them.

http://features.coastalboating.net/Editorials/swivels/

In Flying Fish 2014/2 Red Knickers covers the loss of the anchor after the anchor swivel shackle failed with bent jaws (photo pg98). This is possibly because the swivel was attached directly to the anchor shank – in fact as shown in the photo on pg14 of the same FF. This potentially puts a great deal of strain on the swivel if there is any sideways force on the anchor shank, e.g. if it gets caught on a rock or even when it re-sets itself with a wind shift. We have a short length of chain (about 1m) between the anchor shank and the swivel to avoid this i.e. anchor, 1m of chain, swivel, rest of chain. We initially did not have a swivel and had frequent problems with twisted chain – this came to a head when we were anchored in Brazil and a moored vessel dragged onto us - we had to dump our anchor and chain to the bitter end to escape, and this was slowed down by twisted chain. Since then we have always had a swivel.

Hi Daria,
Pretty dramatic pictures.
I have seen this before, but it is not as common as the "jaws-pried-open" failures that have gotten more press. With all the publicity it is hard to believe that people still attach this style swivel directly to the anchor. It is a failure waiting to happen.
My understanding of this particular failure underlines why I believe stainless steel has no place in ground tackle. I see this failure developing when side loads (or poor manufacturing) give rise to a crevice which then blossoms into crevice corrosion in hard to inspect places. This leads to the catastrophic failure that stainless steel can be prone to.
My best, Dick Stevenson, s/v Alchemy

Here is a report on failure of a Kong swivel. It 's a type of failure I had not seen before.

http://www.latitude38.com/lectronic/lectronicday.lasso?date=2009-05-15#.VcjUivnG-PV

Vice Commodore, OCC 

Hi John,
Twists in the chain may seem inevitable, but I have not had my chain ending up twisted. This may be because I use a fairly long and small diameter snubber which may absorb more twist than most. I agree that some twist may resolve itself when the chain does its occasional jumping in the gypsy. I suspect much also gets untwisted when the anchor frees itself from the bottom and while it hangs free on the way back to the boat. In any case, we agree about the need for a swivel.
My best, Dick

Having had a catastrophic failure of a swivel some years ago I sleep much more soundly without one and with the chain connected to the anchor with a moused shackle. I have not experienced a problem in not having a swivel.

Inevitably the chain does build up twists and normally the windlass accommodates these by the chain occasionally jumping over the socket of the gypsy (wildcat). Periodically these twists should be removed by removing the anchor and veering the first 30 or 40 metres of chain normally used, and then bringing it back aboard slowly allowing the free end of the chain to rotate. Twists do not normally come out when the anchor is attached especially if it is a large or heavy Rocna or Spade.

The use of any piece of equipment on a boat should solve a problem. I used a swivel the first 5+ years of boating as that was the recommendation at the time. For the last 30 years I have not used a swivel, 13 years being full time live-aboard.In certainly thousands, probably 10s of thousands of times where we anchored, I have never come across a problem that lead to me wishing for a swivel. The consults I have done with people and complaints were tracked often to those who lock their chain down (chain lock or in the windlass). A snubber is the answer to this as it allows free rotation which is absorbed in the snubber.
Dick Stevenson, s/v Alchemy

Here 's a new post on anchor swivels that covers the pros and cons. What are your feelings on using an anchor swivel?


To Swivel or to Twist, That is The Question
To a cruiser, anchoring tackle is perhaps one of the most important pieces of gear – second only to the boat itself. As such, any mention of the pros or cons of any particular component, such as swivels, or configuration will... coastalboating.net

http://www.coastalboating.net/Features/Editorials/swivels/index.html

Vice Commodore, OCC 

Could do, Bill. Only opted for a swivel originally due to problems getting 32kg Delta aligned to come over bow roller. Twisting was a minor irritation but not a bad problem. Original swivel used in ignorance was poor quality, but nevertheless worked well with very frequent use - we live aboard and sail a lot, and do not tend to sit at anchor for weeks at a time.

The short chain between anchor and swivel, plus a high quality galvanised certified commercial shackle would seem to relieve the possibility of the sideways pull potential weakness of the swivel. Interestingly the Kong spec gives the straight line and sideways MWL of 2000kgs. This considerably exceeds both the 10mm chain and the shackle, both at around 1250/1500kgs, so is the swivel the weakest link in this configuration? I have also ensured the only removable pin in the swivel is locked with suitable adhesive. I guess if left submerged or not freshwater rinsed, corrosion could become an issue over time, but checking for that is part of the overall ongoing ground tackle maintenance.

This debate is very interesting, but the hardest part is comparing like with like - all chain or chain and rope/swivel direct to anchor or with a shackle or with a short chain and a shackle/side pull or straight pull/cheap stainless or high quality/long or short immersion/good or poor maintenance - OR any combination of the above.

Certainly there are some horror stories, but what were the combinations and was the load when failure occurred direct or sideways? Opinions seems very strong as well!! If one of the experts could assure me one way or the other that my configuration and products will work or categorically not for what I do, that would be brilliant!!