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Old 22-10-2011, 08:23   #121
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Re: A Second Wind for Rocna

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Originally Posted by Target9000 View Post
I'm shocked by everyone that is shocked.

Grant, Delfin, and plenty others had been telling us what was up for a long time. Maybe not so specifically, but the writing was on the wall. I was shocked at how many people tried to defend Rocna in the older threads.
Well, it really depends on what exactly was being said. When people are sticking to actual known facts, that's one thing. But there has not been a whole lot of those out there to this point. Yet many would extrapolate what little was there and try to spin up a witch hunt. That's why I defended Rocna.

One little example of this is the "tuned" anchor issue. This seems like a shocker to most people. Is it? In other words, is Rocna the only organization out there to do/insist on this? Or is it standard practice? Again, we'd need to know more facts about how all that behind-the-scenes stuff works to know whether this is "cheating" or not. Or do you jump straight to the conclusion that Rocna is in the wrong?

When a company is being tried, especially in the court of public opinion, it's far better to allow room for more facts, like these emails, not just someone talking about documents they might have or have seen, before picking up a pitchfork. Personally, I'd rather be wrong in defending someone than wrong in attacking them. In cases like this, people's livelihoods are at stake.

The bottom line is that it is always way more complicated than it seems, yet it will always all come out in the wash.
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Old 22-10-2011, 08:38   #122
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Re: A Second Wind for Rocna

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Originally Posted by smackdaddy View Post

One little example of this is the "tuned" anchor issue. This seems like a shocker to most people. Is it? In other words, is Rocna the only organization out there to do/insist on this? Or is it standard practice? Again, we'd need to know more facts about how all that behind-the-scenes stuff works to know whether this is "cheating" or not. Or do you jump straight to the conclusion that Rocna is in the wrong?
And here lies the problem with most anchor tests and the industry. Like Consumer Reports does, testers should ALWAYS buy off the shelf product for FAIR comparison..
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Old 22-10-2011, 09:11   #123
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Re: A Second Wind for Rocna

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So how exactly do I get one of those "specially tuned", extra sharp, extra straight anchors built only for anchor tests?????
The sort of funny thing is that we probably have and tested one of these 'tuned' anchors. We paid for our rocna, but Peter custom built and then hand delivered it to us. It would interesting sometime to closely compare it to a 'production' 50kg anchor.

This e-mail also somewhat confirmed my prior impression that Craig's real problem with our testing was that we did not focus on what they consider their anchor's prime strength (eg measuring ultimate holding/lb in medium sand/mud) (although the e-mail also suggests the production but 'out of spec' Chinese rocnas are less successful in this regards than the tuned test anchors). We use (and tested) large anchors, in order to be able to set and hold in less good bottom conditions. With these size anchors we have never had any trouble (even in extreme weather conditions) with any of the major designs setting and holding in 'good' bottoms, while we have had trouble and different performance between designs in less good bottoms. So, we believe the best way to differentiate anchor design performance is to test in a variety of less good bottoms, which is what we did. I do believe there is a valid question about how well our results scale down to smaller anchors (in fact we know that the Bruce does not scale down very well) but I do not believe that Craig's criticism (about unrepresentative bottom) is at all valid (both because we in fact tested in a wide variety of bottom conditions and because we intentionally and thoughtfully believe it is better/more efficient to differentiate anchor designs by testing in common but 'less good' bottoms rather than only testing in 'good' bottoms).
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Old 22-10-2011, 10:23   #124
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Re: A Second Wind for Rocna

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Originally Posted by estarzinger View Post
The sort of funny thing is that we probably have and tested one of these 'tuned' anchors. We paid for our rocna, but Peter custom built and then hand delivered it to us. It would interesting sometime to closely compare it to a 'production' 50kg anchor.

This e-mail also somewhat confirmed my prior impression that Craig's real problem with our testing was that we did not focus on what they consider their anchor's prime strength (eg measuring ultimate holding/lb in medium sand/mud) (although the e-mail also suggests the production but 'out of spec' Chinese rocnas are less successful in this regards than the tuned test anchors). We use (and tested) large anchors, in order to be able to set and hold in less good bottom conditions. With these size anchors we have never had any trouble (even in extreme weather conditions) with any of the major designs setting and holding in 'good' bottoms, while we have had trouble and different performance between designs in less good bottoms. So, we believe the best way to differentiate anchor design performance is to test in a variety of less good bottoms, which is what we did. I do believe there is a valid question about how well our results scale down to smaller anchors (in fact we know that the Bruce does not scale down very well) but I do not believe that Craig's criticism (about unrepresentative bottom) is at all valid (both because we in fact tested in a wide variety of bottom conditions and because we intentionally and thoughtfully believe it is better/more efficient to differentiate anchor designs by testing in common but 'less good' bottoms rather than only testing in 'good' bottoms).
Nicely put, Evans, and I agree completely.

Cheers,

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Old 22-10-2011, 15:04   #125
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Re: A Second Wind for Rocna

MarinExtreme,

Without revealing too much detail of commercial performance:

Roughly how many 420 shanked Rocna anchors are there sitting on bow rollers, or in the seabed?

Order of magnitude - how big is the problem?
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Old 22-10-2011, 15:27   #126
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Re: A Second Wind for Rocna

Testing,

We were involved in anchor testing. Unsurprisingly Rocna would not lend us a sample, but then suggested we were looking for a freebie. This was not a problem, we simply borrowed one. When we asked Lewmar, they took us into their warehouse and asked us to take what we wanted, Delta and Claw, from a pile of anchors lying on the floor. We bought our Kobra from a UK chandler. Manson delivered their anchors to us, we checked, they looked like any other anchors of the same model - but when we tested the Supreme (hand delivered one) we checked it against another we borrowed of the same size. The SARCA came from the bow of our son's motor boat. The CQR was our own, bought from a chandler in HK.

Not perfect, but as fair as you are going to get.

We found, as has been suggested, that in a decent seabed the small bruce types work well. But give them a tougher seabed and they really struggle - however given the numbers of Bruce that you see on serious blue water cruising boats - then its a size issue
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Old 22-10-2011, 15:32   #127
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Re: A Second Wind for Rocna

I love my Rocna 33 on my Hunter 42. What makes me nervous if the link and chain will hold.. in 30 knot winds. I love Rocna. Would someone please tell me about chain and links so I am not so nervous. My Rocna very rarely drags. Thanks
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Old 22-10-2011, 15:57   #128
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Re: A Second Wind for Rocna

Panamajames

The figures I have are, 8mm gal or stainless chain when new will break at 4t (and a fitting on your yacht will have failed much earlier). Shackles will be one size bigger, so 10mm, and should be as strong. Swivels, I have no idea (and do not use them). A NZ Rocna, 25 - if loaded at 90 degrees to the length of the shank - the shank will bend at about 600kg. If a 420 shanked Rocna, it will bend at about 300kg.

We have 2 x 20hp Volvos, MD2020 with 3 bladed folding props. If we reverese up gently and run both engines at 2,500 revs we can produce a load of 260kg. If we took a run at it, give us a bit of monentum, it would not stretch the imagination to think we would achieve a 300kg snatch load. We might get higher loads if we were going forward, have not measured.
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Old 22-10-2011, 16:59   #129
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Re: A Second Wind for Rocna

I used to think that perhaps Craig protests too much, now we know he did, what a pity.
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Old 22-10-2011, 17:21   #130
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Re: A Second Wind for Rocna

The
following is a quote from the original press release after buying Rocna.

"Initial information (derived from an on-going investigation) indicated that for a period
beginning 2010 the shanks of some of the Rocna anchors were manufactured using a
steel alloy that did not meet the manufacturing specification. This information was
released in the spring of 2011 which resulted in the issue of a
West Marine Specification
Notice
as well as those suspect anchors being subjected to rigorous testing. The results
of the testing confirmed that these anchors, while not meeting the design specification,
did not pose any safety concerns, and still exceeded industry proof load strength requirements."

What they are saying is that the anchors are still going to be made in China, and that they were never unsafe, nothing really wrong with them except they weren't to spec. This company will be no better than the last one.

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Old 22-10-2011, 18:44   #131
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Re: A Second Wind for Rocna

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We have 2 x 20hp Volvos, MD2020 with 3 bladed folding props. If we reverese up gently and run both engines at 2,500 revs we can produce a load of 260kg. If we took a run at it, give us a bit of monentum, it would not stretch the imagination to think we would achieve a 300kg snatch load. We might get higher loads if we were going forward, have not measured.
Those numbers seem awfully low I can see spikes over 800 pounds backing down with a single engine and can break 1000 pounds with any momentum..
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Old 22-10-2011, 19:20   #132
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Re: A Second Wind for Rocna

If the Rocna or the Manson is the best anchor in the world it still doesn't matter to me. I can't afford any of them. I have a fake Danforth, a fake Bruce, and a fake CQR. If I waited until I could afford all of the really cool stuff I'd never get to go cruising. I hope they work. If they don't I hope my engine starts quickly.

I am simply not surprised that a company that's selling a 40# lump of steel for nearly $700.00 has turned out to be dishonest. It didn't sound right to me in the first place.
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Old 22-10-2011, 19:21   #133
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Re: A Second Wind for Rocna

Load developed by an engine

Actually I agree. John Knox had an article in PBO recently and he suggested his, then, 10hp engine developed 100kg of load - so our 130kg seemed in order, but we are going backwards (and I assume that the props would be more effective going ahead). We have checked our load cell, so the figures seem to be correct. But I still agree - they do seem low.

I confess that the data is derived from putting our load cell between us and our swing mooring, we sit in 10m of water (sorry that its all metric). We ran the engines until the load was stable (or as stable as we can get it). The mooring is 10m of 25mm hawser laid nylon, attached to about 6m of a 15mm sweeper chain, attached to about 4m of 30mm re-cycled mining chain and then a 1t block. So its not a straight line pull.

I'd welcome some informed further comment.

Its a bit of a fiddle to test going ahead as we would need to moor back to front, maybe we should do it?

But if the figures you quote are correct then bending a 420 Rocna ought to be quite easy.
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Old 22-10-2011, 19:28   #134
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Re: A Second Wind for Rocna

Load developed by an engine

Sorry - should have added, if we reverse up and then allow the momentum to develop then a spike load is higher, much, than the 260kg quoted. The 260kg is the load developed when everything is in equilibrium, the engines at 2,500 revs, the yacht basically stationary. I would not want to quote spike loads, unless I was pretty sure how fast we were travelling, or how far we had travelled - and both are not easy to quote accurately.

When anchoring we would tend to spike, or snatch, load as this ensures the anchor is well set. Though with a decent anchor you need be careful - they set quickly and snatch loading results in the same impact has hitting a sand bar at speed! It can spill your drink!!
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Old 23-10-2011, 05:34   #135
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Re: A Second Wind for Rocna

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Load developed by an engine

Sorry - should have added, if we reverse up and then allow the momentum to develop then a spike load is higher, much, than the 260kg quoted. The 260kg is the load developed when everything is in equilibrium, the engines at 2,500 revs, the yacht basically stationary. I would not want to quote spike loads, unless I was pretty sure how fast we were travelling, or how far we had travelled - and both are not easy to quote accurately.

When anchoring we would tend to spike, or snatch, load as this ensures the anchor is well set. Though with a decent anchor you need be careful - they set quickly and snatch loading results in the same impact has hitting a sand bar at speed! It can spill your drink!!
We use chain/rope rode so the stretch disallows a perfect equilibrium like you'd possibly see with all chain, though with prop cavitation / slip I think you'd still see the surging in the load cell. It stretches, spikes, drops, stretches, spikes. At full stretch I suspect I am getting prop slip and some cavitation then the rode rebounds and it starts over. Anchor does not move but the boat never reaches a "consistent" pull strain as one would imagine it does.... I suspect my mooring would be similar due to the 15 pounds/ft bottom chain wanting to keep some caternary..
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