Rocna Anchor Failure

[thinwater]

Originally Posted by Mike OReilly

He says he lost the Rocna. I presume the one shown is the backup anchor.

Exactly. That is what it says if you read it closely. He also noted adding a back-up line.


If there is a risk factor, it is that the anchor chain is not tensioned and thus the anchor can snatch on the chain.


Why a stainless D-shackle and why the pin through the anchor (instead of an anchor shackle with a bow)? Is something else missing?



But I'm not feeling it.

[Bruce K]

Originally Posted by Simi 60

Looks like a lewmar delta to me.

Please read and understand the OPs posts before posting!!

[CarlF]

I also like Tomaz473’s theory. A shackle stuck sideways in the attachment hole of the shank could exert tremendous bending pressure. The tip of the shank is relatively weak, having been mostly drilled away for the attachment hole.

The broken shackle pin head also suggests that it too was broken off by the shackle having been heavily loaded while stuck sideways. If a force was sufficient to shear the pin head, it was likely also sufficient to bend the weak end section of the shank.

And this side loading may not have been a one time event. The shackle pin head might have broken earlier and not been noticed. Repeated bending of the shank tip would quickly fatigue the metal allowing it to crack and fatigue. This may not have been obvious without inspecting the anchor shank and may have been developing for some time.

Finally, many will remember that Rocna has had previous problems with the metallurgy of their shanks that lead to a recall. While the company has new ownership, making a shank that is stiff enough not to bend while not being brittle is probably a tricky bit of metal working to get right every time.

[SwellGuy]

Originally Posted by zboss

The anchor isn’t a rocna and that shackle isn’t the shackle on that anchor. The anchor was tied off to the boat.

Cmon. Try a little harder.

[s/v Jedi]

The anchor did not fail. It was the missing swivel, the missing 2nd shackle or even the shackle shown has a fractured pin but sprung back in shape after the anchor shank worked out.

Also, like others stated, the wrong type of swivel was used. Use every component galvanized steel or use every component stainless steel, do not mix types.

Also, do not use Wichard HD shackles, not even on stainless chain and anchor. It’s too brittle.

[Oceansailor]

Originally Posted by s/v Jedi

The anchor did not fail. It was the missing swivel, the missing 2nd shackle or even the shackle shown has a fractured pin but sprung back in shape after the anchor shank worked out.



Also, like others stated, the wrong type of swivel was used. Use every component galvanized steel or use every component stainless steel, do not mix types.



Also, do not use Wichard HD shackles, not even on stainless chain and anchor. It’s too brittle.

Could you please present technical data that supports your theory that Wichard HD shackles are to brittle?

[s/v Jedi]

Originally Posted by Oceansailor

Could you please present technical data that supports your theory that Wichard HD shackles are to brittle?

I wrote HD (or spelling changed it) but meant H.R. These (17-4 stainless) shackles are much stronger because they are hardened by heat treatment, which makes them more brittle as well. Here’s some data, look at elongation only 8% vs 50% for 316

[Auspicious]

Originally Posted by GrowleyMonster

Why would it be on deck during an ocean passage, anyway? At sea, if something is not needed on deck, it should not be on deck.

I disagree with your logic. Scenario: bad weather on landfall with your anchor in a lazerette. Will you realistically be able to get a 25 or 30 kg anchor over a heaving deck, attached and properly through the bow roller? That's not something I would like to be faced with. Chain rode to windlass, chain stopper or other hold-back, and lashing that can be readily reached and cut.

Regardless, I reread the OP's initial post

Originally Posted by alc

I wanted to see if others have had the same issue with your Rocna 20 kg anchors failing. While transiting from Aruba to Curacao our anchor broke away from the shackle and chain. The shackle is completely intact on the chain but no anchor is left. I contacted Rocna and was told that without a picture of the actual anchor, which is sitting in 2000 feet of water, there was nothing they would do for me. I was surprised first that it failed after only 3 years and appeared to be in like new condition. I am just glad it happened while we were underway and not at anchor. I always believed Rocna was a good reliable product and shocked that it gave out to begin with but even more surprised that Rocna would not honor the warranty.

Without projecting any ill intent on the OP, the only thing he can say with assurance is that the anchor went missing. That the anchor failed structurally is an assumption, and not a well-informed one unless there is additional substantiated data we don't have.

I think the two most likely causes are a second shackle that failed or theft before departure that simply was not noticed. In neither case does Rocna bear any responsibility.

Engineering and management at Rocna likely came to the same conclusion.

Originally Posted by GrowleyMonster

It could not have been stolen without its absence noticed. How could you not notice that suddenly you have no anchor?

There is a lot going on at departure. The anchor hangs down a bit from the roller. There are other boaty bits including the headsail furler up there. If the owners was driving on departure, as they usually are, and crew/spouse is tidying up dock lines and fenders and anxious to get off the bow it is very possible that a missing anchor would be missed. I think the probability of that is much higher than a structural failure of the anchor shank.

Originally Posted by GrowleyMonster

Could a second shackle have come unscrewed? Doubtful. Anyone with 5k miles under his keel would by now have learned to mouse his shackles, or use locktite blue, or peen the end threads to prevent it from backing off without applying a fair amount of torque. I agree with others who smell a troll here.

Apparently not in this case as the allen head pin (ugh) on the remaining shackle was backed partway out in one photo.

[GrowleyMonster]

Originally Posted by Auspicious

I disagree with your logic. Scenario: bad weather on landfall with your anchor in a lazerette. Will you realistically be able to get a 25 or 30 kg anchor over a heaving deck, attached and properly through the bow roller? That's not something I would like to be faced with. Chain rode to windlass, chain stopper or other hold-back, and lashing that can be readily reached and cut.

Regardless, I reread the OP's initial post



Without projecting any ill intent on the OP, the only thing he can say with assurance is that the anchor went missing. That the anchor failed structurally is an assumption, and not a well-informed one unless there is additional substantiated data we don't have.

I think the two most likely causes are a second shackle that failed or theft before departure that simply was not noticed. In neither case does Rocna bear any responsibility.

Engineering and management at Rocna likely came to the same conclusion.



There is a lot going on at departure. The anchor hangs down a bit from the roller. There are other boaty bits including the headsail furler up there. If the owners was driving on departure, as they usually are, and crew/spouse is tidying up dock lines and fenders and anxious to get off the bow it is very possible that a missing anchor would be missed. I think the probability of that is much higher than a structural failure of the anchor shank.



Apparently not in this case as the allen head pin (ugh) on the remaining shackle was backed partway out in one photo.

If I stow an anchor in the lazarette and suddenly find myself in need of it, or not so suddenly but without fair weather for moving and rigging it, I lead chain back outboard of the shrouds to the anchor, and pitch it right over from the cockpit. Even in good weather when day sailing alone, I often move the anchor and the expected amount of rode back to the cockpit so I can easily drop it as I fall away from it or back away with the engine. It saves a lot of scurrying LOL! Then stoppers or snubbers or whatever after the anchor is set. Now I have a bigger boat and a windlass soon to be installed and my routine may change a bit, TBH.


Anchor should be on anyone's pre-departure checklist. I am a believer in checklists. Even so, sometimes I get into a "why didn't I think to check that?" situation. That keeps me believing in the necessity of a good checklist before departure and also before arrival. It is done on ships. It should be done on boats, too. In checking the anchor swivel, (if used). shackles, flukes or plow, shackle hole in the shank, snubbers and stoppers, windlass if so equipped, roller or chock or hawsepipe, chafing gear if needed, and the last few feet of chain for wear and distress, the complete absence of an anchor would probably have been noticed. If stowed for extended docking, it would have been broken out and attached, after inspection.



Good point about the allen head shackle pin. I like how streamlined they are, but there is no way to get a safety wire on it and you have to keep a completely different type of shackle key in your pocket along with what you usually use. The hypothetical second shackle could have been, or probably was, the same type. But there is always Loctite blue (don't use red... trust me on that.) or a punch or chisel and hammer. Just a little dot of the loctite and that pin isn't going anywhere until considerable force is applied to it directly.



I will admit that many of these truths are only truly evident after they have bitten the skipper in the hiney, but they can be found in many popular "learn to sail and do it right" books. In the real world, nobody instantly becomes Mr Expert Sailor in just a few years, but some things are naturally learned early on. The importance of a checklist is one of them.

[NYSail]

I kind of second the stolen anchor theory...... are you sure it was there when you departed. If it fractured off where is the broken part of the shank? Looks like there is a nice slot for it to sit in on deck.

[CassidyNZ]

How many thieves would take the time to reassemble the shackle? I’d wager not a lot. In fact, why would they not just take the shackle as well?

Have to say, when I think of the slotted end of my anchors it’s inconceivable that the anchor would break before the shackle and, unless the person stowing the anchor wound the chain in really tight, how would it fail in a no-load condition on deck? If it was a forging/casting flaw, perhaps it was brought to critical mass the last time it was used and failed with last stressed event (taut chain on the windlass)?

Strange indeed.

[Smokeys Kitchen]

Thanks for coming back alc.

I am kind of with Mike on this. I do not see a 'head' on the shackle pin, so I don't even see a way to secure it to the shackle.

This isn't one of those spring loaded type pins is it?

Ron

[Breaking Waves]

Originally Posted by Smokeys Kitchen

I do not see a 'head' on the shackle pin, so I don't even see a way to secure it to the shackle.

It is almost surely an Allen head.



winchard makes a whole line of them Wichard Self-locking Allen head D shackle

They have an 'indent' in the threads, so they 'self-lock' (will not vibrate loose, at least not easily). . . but I personally would always use some locktite on them also.

[Bleemus]

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

[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.