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Old 23-08-2011, 13:59   #76
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Re: New West Marine Recall on Rocna Anchors

bending a rocna video


looks easy to bend for that category anchor. Looking at the steel thickness it also makes sense it would bend. Would you do that to a new anchor?
That particular size anchor is meant to go on what sized boat?

ok found it
http://www.boatersworld.com/product/...ntent={adtype}
Quote:
Boat Length: 16 ft.(<11,000 lbs.) - 26 ft.(<2,200 lbs.)
Weight: 13 lbs.
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Old 23-08-2011, 14:09   #77
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Re: New West Marine Recall on Rocna Anchors

Well, I watched that video. OK, it is a smallish anchor. And yet ... should it bend THAT easily?

b.
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Old 23-08-2011, 14:15   #78
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Re: New West Marine Recall on Rocna Anchors

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Originally Posted by sdowney717 View Post
bending a rocna video


looks easy to bend for that category anchor. Looking at the steel thickness it also makes sense it would bend. Would you do that to a new anchor?
That particular size anchor is meant to go on what sized boat?
It is a 6kg "fisherman" type and is recommended for between a 16' boat of up to 11,000lbs and a 26' boat of up to 2,200lbs.
The sizing chart can be found here: Sizing Chart Rocna Anchors

Why bend it: it was a test conducted in 2010 after being informed by a customer that his had bent like butter.
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Old 23-08-2011, 14:24   #79
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Re: New West Marine Recall on Rocna Anchors

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Originally Posted by barnakiel View Post
Well, I watched that video. OK, it is a smallish anchor. And yet ... should it bend THAT easily? b.
Interesting question. How much weight do you think the average bloke can apply by pressing down with his foot? 100lbs perhaps?

If the 6kg Rocna is designed for up to 26ft yachts, what is the load in say 30 knots? Well the Fortress anchor website says you need a holding requirement of 490 lbs. Whether this is the same as the pull or has a safety margin built in I am not sure, but interesting.

The steel trailer wheel looked a lot thinner and didn't bend. Perhaps they should make them out of old bits of steel instead.

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Old 23-08-2011, 14:39   #80
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Re: New West Marine Recall on Rocna Anchors

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Originally Posted by barnakiel View Post
Well, I watched that video. OK, it is a smallish anchor. And yet ... should it bend THAT easily?

b.
One way to find out, stick a few different 6kg anchors in a wheel and try it. Then stick lever arm into google. The youtube doesn't really provide anything useful. I've heard that yaching monthly magazine in the uk are doing an investigation into the shank steel, maybe they'll test to see how bendy the shanks are.
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Old 23-08-2011, 18:33   #81
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Re: New West Marine Recall on Rocna Anchors

Even though the 'test' in the video is crude, it illustrates the point of the importance of HT steel in the shank pretty well. It also illustrates how dishonest Rocna is continuing to be by touting their straight pull load testing, when the only metric worth considering for the purposes of this discussion is side loading. Based on this video, it doesn't take much to bend a new Rocna when side loaded.

Big surprise.
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Old 23-08-2011, 18:35   #82
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Re: New West Marine Recall on Rocna Anchors

its a thin flat piece of steel so its weak in that direction. If the steel had a profile like an I beam or a z shape or if it was a box beam of the same thickness, it would not have easily bent.
If the steel was spring steel as in a car or trailer leaf spring then there is no way that shank would have bent with him pushing on it against the wheel.

spring steel is designed to take a large force and spring back to its original shape, but make it too brittle and it will simply crack off. So there is a middle ground here, you want it springy and durable all at the same time, so make it of a higher temper and make it thicker.

I could see how that thin shank would bend in a storm if the anchor is stuck fast and the boat is pulling several hundreds or a thousand pounds it is going to bend. there is nothing in that video that tells me that steel is anything special than from a standard mild steel.
Scaling up to a bigger anchor of the same design and a heavier boat, will produce larger forces and it would still bend.
I think the hoe shape of these anchors hold well and the shanks are not beefy enough or of the proper kind of steel, so when a lot of pressure is on them they will yield.
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Old 23-08-2011, 19:54   #83
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Re: New West Marine Recall on Rocna Anchors

OK, I think I've got a good Rocna, but thought I'd ask the forum (or at least folks who follow this Rocna anchor stuff).

I bought our Rocna sometime in 2006 or 2007 - coulda been as late as November 2007 or so - it was shipped from Canada, maybe from an outfit called Suncoast or something like that.

So, do I have a Canadian Rocna, built to original specs, with no worries? It does not have the ROCNA stamped/cast into the fluke that I see on new ones.

We've spent a lot of time on that hook and like it a lot, waaay more than our old original Bruce (that we still have on the bow roller as our secondary).

Dave
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Old 23-08-2011, 20:05   #84
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Re: New West Marine Recall on Rocna Anchors

WTF? The anchor shown in the video is obviously a Manson Supreme because of the extra slot, in spite of the labeling. ???
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Old 23-08-2011, 20:06   #85
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Re: New West Marine Recall on Rocna Anchors

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In the hurry to denigrate ROCNA, if one reads the original notice from WEST Marine, very few models, in not many usual sizes, were objects of the recall. Please, folks, read before blathering. It might help to foster more considerate discussions.
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WTF? The anchor shown in the video is obviously a Manson Supreme because of the extra slot, in spite of the labeling. ???
Nope, it's a Rocna.
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Old 23-08-2011, 20:07   #86
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Re: New West Marine Recall on Rocna Anchors

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Originally Posted by SV Liberty View Post
OK, I think I've got a good Rocna, but thought I'd ask the forum (or at least folks who follow this Rocna anchor stuff).

I bought our Rocna sometime in 2006 or 2007 - coulda been as late as November 2007 or so - it was shipped from Canada, maybe from an outfit called Suncoast or something like that.

So, do I have a Canadian Rocna, built to original specs, with no worries? It does not have the ROCNA stamped/cast into the fluke that I see on new ones.

We've spent a lot of time on that hook and like it a lot, waaay more than our old original Bruce (that we still have on the bow roller as our secondary).

Dave

Dave, rest easy you have one of the best around.
Mark Pocock of Suncoast Marine was very strict and precise about sticking to the designers specs and as far as I know there has never been a BC one returned as bent.
He is an honest manufacturer and distributor and unfortunately is going to suffer greatly through loss of sales now, something he had no hand in causing.
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Old 23-08-2011, 20:08   #87
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Re: New West Marine Recall on Rocna Anchors

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WTF? The anchor shown in the video is obviously a Manson Supreme because of the extra slot, in spite of the labeling. ???
It is a rocna fisherman model, 6kg.
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Old 23-08-2011, 20:09   #88
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Re: New West Marine Recall on Rocna Anchors

Ah, I see it is a Rocna Fisherman, not a Rocna Original. Didn't even know they made that one. Looks like the copying goes both ways.
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Old 23-08-2011, 20:11   #89
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Re: New West Marine Recall on Rocna Anchors

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Originally Posted by sdowney717 View Post
its a thin flat piece of steel so its weak in that direction. If the steel had a profile like an I beam or a z shape or if it was a box beam of the same thickness, it would not have easily bent.
If the steel was spring steel as in a car or trailer leaf spring then there is no way that shank would have bent with him pushing on it against the wheel.

spring steel is designed to take a large force and spring back to its original shape, but make it too brittle and it will simply crack off. So there is a middle ground here, you want it springy and durable all at the same time, so make it of a higher temper and make it thicker.

I could see how that thin shank would bend in a storm if the anchor is stuck fast and the boat is pulling several hundreds or a thousand pounds it is going to bend. there is nothing in that video that tells me that steel is anything special than from a standard mild steel.
Scaling up to a bigger anchor of the same design and a heavier boat, will produce larger forces and it would still bend.
I think the hoe shape of these anchors hold well and the shanks are not beefy enough or of the proper kind of steel, so when a lot of pressure is on them they will yield.
The shank is 8mm thick
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Old 23-08-2011, 20:39   #90
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Re: New West Marine Recall on Rocna Anchors

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Originally Posted by sdowney717 View Post
its a thin flat piece of steel so its weak in that direction. If the steel had a profile like an I beam or a z shape or if it was a box beam of the same thickness, it would not have easily bent.
Even anchors with box beam shanks can bend:
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