Rocna Anchor Failure

[Exile]

Originally Posted by noelex 77

Yes, stainless steel chain is “slippier”. If you have a problem with the chain piling up in the chain locker and jamming the windlass a switch to stainless steel chain will often solve the problem.

There is some good quality stainless chain available, but they are not easy to find. Many are poor quality despite the cost. Good quality duplex stainless steel chain seems to hold up well from user reports, but it is expensive.

Thanks Noelex. I think I've already done most of the recommended modifications to my chain pipe & locker, or at least the ones that didn't require an extensive reconfiguration. I think I'll look into this the next time I need to replace my chain, with the best practice noted above to use a galvanized shackle(s) with a galvanized anchor, and keep any SS swivels, etc. connected further down on the chain to prevent any (minor) galvanic corrosion. Hope I got this right.

[thinwater]

Originally Posted by NorthernMac

Lol, I was actually thinking it was a little oversized

and it’s a little of both!

It's a pretty boat. Do what you like. It's about feeling good about it.

[NorthernMac]

Originally Posted by thinwater

It's a pretty boat. Do what you like. It's about feeling good about it.

Thanks
For sure, it’s on the larger end of their recommend sizes, but seems to fit ok, little bigger then the Bruce it replaced.

[hpeer]

Don’t we have a chain thread somewhere?

I’d like to talk more about it but don’t want to “drag” this anchor thread.

[noelex 77]

Originally Posted by Exile

I think I'll look into this the next time I need to replace my chain, with the best practice noted above to use a galvanized shackle(s) with a galvanized anchor, and keep any SS swivels, etc. connected further down on the chain to prevent any (minor) galvanic corrosion. Hope I got this right.

There is only a little bit of galvanic corrosion attaching a stainless steel shackle or swivel to a galvanised anchor. It is the anchor that will potentially corrode, but there is a very large mass of anchor and only a relatively small mass of stainless steel so the interaction is minor.

The recommendation of attaching a few links of chain between the anchor and the swivel is sound advice, but this is given to reduce the side loading on the swivel rather than any concerns about galvanic corrosion. There is the risk that many swivels, while strong with a straight line pull, are not as strong as the chain if subject to side loading. It is silly for such a small component to be the weak link in the system, hence the advice to connect the anchor to a few links of chain before the swivel to allow enough articulation so that the swivel is not subject to side loading.

The above is sound advice for most swivels, but there have been a few swivels that have been produced that claim they have enough articulation and/or strength that they can be safely attached to the anchor shank without the chain links. The Wasi power ball, Mantus and Ultra swivels make this claim.

In the photo below you can see the bent swivel where some previous side loading has caused distortion of the jaws. The swivel is still obviously being used by the owner (the photo was taken underwater while the anchor was in use), but it is not safe in my view. Attaching a few links of chain between the anchor and swivel prevents this type of problem.

[osprey877]

Originally Posted by Bleemus

Aside from the mystery that shackle was installed backwards. Rounded end goes on the anchor.

As I noted above, I think it is impossible to install the shackle backwards as shown in the photo because only the pin, not the shackle ends, are small enough to fit through the chain link. I have tried to find a shackle that would fit the way shown and it is not possible unless you go to a ridiculously small shackle or you have some non standard chain configuration. Hence my conjecture that the shackle was sawn through and the photo staged with the two pieces.

[CassidyNZ]

Originally Posted by noelex 77

Yes, stainless steel chain is “slippier”. If you have a problem with the chain piling up in the chain locker and jamming the windlass a switch to stainless steel chain will often solve the problem.

There is some good quality stainless chain available, but they are not easy to find. Many are poor quality despite the cost. Good quality duplex stainless steel chain seems to hold up well from user reports, but it is expensive.

If castling was a problem on my boat, I’d rather hire someone little to sit in the anchor locker and control the chain.

Where I live, SS chain is 5 x $$ compared to test link steel chain. 100m of 10mm DIN766 stainless chain would cost around NZ$8700! Standard DIN766 steel chain would cost NZ$1700.

Seven grand to stop castling is a lot of bux.

[Exile]

Originally Posted by CassidyNZ

If castling was a problem on my boat, I’d rather hire someone little to sit in the anchor locker and control the chain.

Where I live, SS chain is 5 x $$ compared to test link steel chain. 100m of 10mm DIN766 stainless chain would cost around NZ$8700! Standard DIN766 steel chain would cost NZ$1700.

Seven grand to stop castling is a lot of bux.

And $7K is a lot of lil' person hires to knock the chain down every so often! I knew SS chain was more $$$ but didn't realize the disparity. I've got mine to the point that I only have to knock it down once and at most twice every 100' of chain. Not exactly a big deal.

[Exile]

Originally Posted by noelex 77

There is only a little bit of galvanic corrosion attaching a stainless steel shackle or swivel to a galvanised anchor. It is the anchor that will potentially corrode, but there is a very large mass of anchor and only a relatively small mass of stainless steel so the interaction is minor.

The recommendation of attaching a few links of chain between the anchor and the swivel is sound advice, but this is given to reduce the side loading on the swivel rather than any concerns about galvanic corrosion. There is the risk that many swivels, while strong with a straight line pull, are not as strong as the chain if subject to side loading. It is silly for such a small component to be the weak link in the system, hence the advice to connect the anchor to a few links of chain before the swivel to allow enough articulation so that the swivel is not subject to side loading.

The above is sound advice for most swivels, but there have been a few swivels that have been produced that claim they have enough articulation and/or strength that they can be safely attached to the anchor shank without the chain links. The Wasi power ball, Mantus and Ultra swivels make this claim.

In the photo below you can see the bent swivel where some previous side loading has caused distortion of the jaws. The swivel is still obviously being used by the owner (the photo was underwater while the anchor was in use), but it is not safe in my view. Attaching a few links of chain between the anchor and swivel prevents this type of problem.

Sorry, I must have misunderstood some earlier comments. Thanks for clarifying. I had a swivel that a rigger recommended early on, but when I had a bear of a time removing it one time (red locktite) I decided it was more potential trouble than I thought it was worth. I've always just used one appropriately sized Crosby shackle btwn chain & anchor and called it good. After this thread, however, I plan on checking the amount of play the shackle has to move on the shank. If it looks problematic, I still think I'd go with a second (Crosby) shackle before another swivel. But I do see swivels on a lot of boats so maybe I'm missing some of their benefits.

[NorthernMac]

Originally Posted by Exile

Sorry, I must have misunderstood some earlier comments. Thanks for clarifying. I had a swivel that a rigger recommended early on, but when I had a bear of a time removing it one time (red locktite) I decided it was more potential trouble than I thought it was worth. I've always just used one appropriately sized Crosby shackle btwn chain & anchor and called it good. After this thread, however, I plan on checking the amount of play the shackle has to move on the shank. If it looks problematic, I still think I'd go with a second (Crosby) shackle before another swivel. But I do see swivels on a lot of boats so maybe I'm missing some of their benefits.

Red?

Why red?

I’ve used blue on all sorts of stuff, aside from installing new weapons sights I dont recall using red for much of anything. I’d think for a shackle just safety wire, no?

[a64pilot]

If you can safety wire that’s fine, if not Red Loctite is called for.
It is a PIA to remove if you don’t heat it, but if you do it comes off easy, and there should be nothing on an anchor that a propane torch will hurt

[Exile]

Originally Posted by NorthernMac

Red?

Why red?

I’ve used blue on all sorts of stuff, aside from installing new weapons sights I dont recall using red for much of anything. I’d think for a shackle just safety wire, no?

I don't recall using red locktite on anything either. This first swivel I mentioned was installed by a rigger not long after I bought the boat. Didn't find out he used red until I needed to take it off. Don't know why he chose red. Required a torch to remove. Yes, I use just safety wire on shackles. Has worked out fine thus far.

[s/v Jedi]

About swivels: I tried doing without but got a twisting and buckling chain so put it back in. I don’t have shiny stainless anchoring gear so used galvanized 7/8” bow shackle and swivel like used by the fishing fleet

The chain is 3/8” with an enlarged end link.

[Exile]

Originally Posted by s/v Jedi

About swivels: I tried doing without but got a twisting and buckling chain so put it back in. I don’t have shiny stainless anchoring gear so used galvanized 7/8” bow shackle and swivel like used by the fishing fleet

The chain is 3/8” with an enlarged end link.

Now I know what those (swivels) are for!

[TBW]

Anchor - chain. maybe a swivel. maybe more shackles than shown. That is a strange shackle.
The owner said he was a little new. Maybe there was a shackle there that he just had not "seen". If the shackle failed, the anchor would leave right now.
Non-standard shackles and fasteners of all kinds are a big problem.
Only defense is to have them made and a certificate supplied (maybe some special bolts) or use known brand-name gear - Crosby comes to mind.
I am from the oilfield and do not like shiny sailboat gear.

Failure of the anchor slot as everyone has said is not a realistic issue.
The chain is there.
Stolen - not impossible but it does strain the imagination.
A shackle can break. If you have ever watched them make shackles in India and China this is not a hard thing to imagine. Think sweeping everything off of the floor and dumping it in a big pot / cauldron. The resulting brew is poured into molds and there is your shackle - it will probably break if you hit is across the bow with a hammer.
Even certificated shackles specially made for a heavy lift have been known to break.
Russian blowout preventers that are supposed to test to 10K psi have been tested and shown to actually leak pressure through the steel.
There is a flood of this equipment out there; it gets shined up, branded and sold to us.
Maybe the owner has some pictures of the foredeck before the anchor left but there almost had to be something between the chain and the anchor that failed. The cousin of whatever shackle that is in the picture would be a good suspect.
I have several Rocna's. Have drug 4 times in 10 years; could probably be a better anchorer. Just changed an anchorlift swivel for a Mantus. May take the swivel out altogether. Use only Crosby shackles and tighten them really tight with a wrench. Still worry about the anchor falling off. (have a spare or two).