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  1. #71
    Anonymous Guest

    Default Re: Rocna or Manson Supreme??

    It depends what you mean by 'long-term' There is an incompatibility problem and the closer the dissimilar metals, the greater the problem. You are likely to lose zinc in the vicinity of a stainless component. However, when we discussed this in the forum in, I think, late 2007, there was little evidence that it was a serious problem for cruisers -- even liveaboard long-term cruisers -- who only anchor in the summer. At least one photo was shown that suggested that zinc might have been lost as a result of the stainless but it wasn't 100% conclusive.

    In any case, stainless in the absence of oxygen corrodes quite fast and that can happen underwater. It tends to form in little nooks and crannies -- called 'crevices' hence 'crevice corrosion'. I have never (yet) experienced it personally but I have friends who have, and one friend has a little 'rogues gallery' museum of failed parts that gave way in service (or very nearly did). For this reason, some people won't use stainless for critical components either above or below the waterline.

    For long-term moorings it is recommended that dipped-galvanised components are used, not stainless.

  2. #72
    Goldie's Avatar
    Goldie is offline Registered User
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    Default Re: Rocna or Manson Supreme??

    Many thanks for that fast and comprehensive response!

  3. #73
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    Default Re: Rocna or Manson Supreme??

    Dear Forum readers, it has come to our attention that Ancor Latina have posted a number of untrue comments about the Manson SUpreme Anchor on the YBW website as follows.

    http://www.ybw.com/forums/showthread...16/page/0/vc/1

    Their comments are below this post.

    We have for the last 35 years been manufacturing anchors in New Zealand. Now, in terms of anchor manufacturers that makes one of the oldest recreational anchor manufacturers in existence anywhere in the world. We do tend not comment on forums they are for anchor users not manufacturers, and when we decide to, it is to mainly correct blatantly misleading information, usually from people that believe they know more about our products and our company than they actually do.

    Firstly, we have 30 permanent staff employed solely for the purpose of making anchors. It is all we do. Secondly all our welders are Lloyds Certified. The highest certification a welder can achieve in the marine industry.

    Thirdly the comments Ancor Latina coments on the Manson Supreme are totally incorrect and misleading.

    1. The slot doesn't weaken the shank, please explain how it does.?
    2. With regards to the slot, if the anchor pulls out (normally in all our tests it crabs around)if there is a shift in the wind, it resets immediately as the weight of the anchor makes the shackle slide back to the end of the shank immediately. if you don't want to use the slot, simply put, don't. We give consumers the option by having two slots. Note: A year ago Rocna came out with the RRR, Rocna Rock Slot. Who would you say they used for inspiration for this design?
    3. The Supreme Blade is not rolled as you indicated. It is pressed using one of the three presses our company owns. Each size grouping uses a different one, there is a 80tonne H-frame Hyrdaulic, an 80 tonne pressbrake and a 120tonne mechanical press. It is then welded to a second fluke to laminate. Laminating the fluke in this method is dual purpose, it is stronger, and also the weld hardening around the edge is harder than ordinary steel. The rocna is not pressed. It is cast in that shape. If you knew about castings you might choose to retract your comments on which is stronger.

    There are two roads to be taken in the Anchor business. The high road, where you promote your product on it's merits and sell with a conscious, or the low road where you say everyone else's product is terrible and yours' is the best and mislead the public at any opportunity. It is up to you to decide which path you will take. A word of warning. Craig has does a lot of damage to his company by saying the blantently untrue things he has about our product.

    Yours faithfully.
    Manson Anchors <span style="color:red"> </span>


    Any anchor manufacturers care to comment?


    --------------------------------------------------------------------------------


    Yes, I do although its somewhat difficult to criticize the competition

    1 First about anchor connectors: I fully support the comments of vyv Cox: Never use a swivel connector directly on the shank of the anchor:
    - they dont turn under load
    - they are not designed to support any lateral load

    2 - Im completely AGAINST the slot on the shank for me its only a marketing advantage.
    - It weakens the shank
    - If your anchor is wedged somewhere, it will not work
    - But if there is a shift of wind or current, then it will ALWAYS work and pull your anchor out!
    - This slot can be useful only for fishermen who are often temporarily anchoring in rocky areas (and stay aboard to check the mooring)

    3 - About the interesting Noelexs photos: make a very simple experience:

    - take a glass (bier?) put a rectangular sheet of paper on the top of it and then put a money coin on it, the weight of the coin will bend the paper and the coin will fall down into the glass.
    - Now, take the same piece of paper, fold it in the middle once or make several accordion folds, put it back on the glass and put the money coin again on it... It will not fall down!
    - This is a very well known principle, always used in cars panels!
    - Now look at the shape of the Supreme blade, it is made of a rolled sheet of metal. To cylindrically curve a sheet of metal is a very easy manufacturing process made with a very cheap machinery.
    - At the tip level, the sheet of metal is nearly flat and will easily bend!
    - If you look now at the tip of the Rocna, the tip is folded in the middle!

    Now make your own mind about the comparative solidity of both!

    Joo

  4. #74
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    Default Re: Rocna or Manson Supreme??

    [ QUOTE ]
    Here's how to avoid lateral loads and wedged shackles with a plate steel anchor shank. Two chain links would also be OK. In the photo the three links are 10 mm, the main chain 8 mm. I believe this to be just about the strongest and most versatile arrangement available.



    Don't use a galvanised shackle, use a Wichard 17/4 PH countersunk. In the YM destructive tests the stainless shackles were almost all stronger than the galvanised ones. Use Studlock with the countersunk pins to prevent unscrewing.

    [/ QUOTE ]Whoah down there Vyv, on your advice, well, PBO test advice I changed all my load bearing critical shackles for coloured pin calibrated jobbies..

    Galvanised though.

    I don't know which way to turn now, I was happily smug that I had followed expert advice and at the very least my pick was safely connected to the boat. Then this...

    I am not angry here, I'm just losing confidence again..

    OTOH, after buying some calibrated (big) mooring shackles from a fellow forumite in 2006, I am pleased to advise they are not showing any signs of corrosion after coming up 3 years permanent use; and been removed 4 times (this is often a hacksaw job, but not with these). So sticking with your original advice, coloured pinned quality shackles are worth the extra money... and they were about 5 times what I would normally pay... but then, I would have been on my 4th set of the cheapo chinese types usually found in the chandlers. The anchor shackles from Jimmy Green are also in fine fettle, the 1 year old cheapo shackles they replaced had rusted at an alarming rate.

    So... hopefully you might agree that quality is just as important, as just choosing SS. I am not looking for you to say it will 'probably' be ok, I need to be confident in my pick. Also, I have always been taught not to mix metals, I have seen links alongside the ss shackle almost disappear when the rust is knocked away and, not to be confrontational, you know more than me on this, but isn't stainless prone to load fatigue, a bent shackle must be better than a snapped shackle surely.

    maybe I should have started a new thread... sorry Richard.

  5. #75
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    Default Re: Rocna or Manson Supreme??

    [ QUOTE ]
    [ QUOTE ]
    Never use a swivel connector directly on the shank of the anchor:
    - they dont turn under load
    - they are not designed to support any lateral load

    [/ QUOTE ]

    Not true. The Kong connectors are specified to take a defined lateral load -- this is clearly marked on the data sheet. In my case, for my Kong, the lateral load rating of 1.5 tonnes is actually greater than the SWL of a steel shackle that you would intuitively choose to connect the anchor.

    Since you are an anchor mfr/rep I strongly urge you to check this point with Kong. The data are on their website, and they speak English.

    [/ QUOTE ]There is a definite difference between a shock load and load exerted by the test gear to destruction.

    I have seen some amazing gear breakages on trawl gear, have a look at the metal work on a trawler next time you are about the harbour, I have seen cringles (the triangles) break or bend beyond recognition and only felt a minimum bump on the boat. I am talking of 1/2 or 3/4" round bar, and 40ft trawlers. (just to explain we are not just talking about big boats which also suffer serious gear failure)

    the cringle I talk of is fitted at the bridle in the pic below.


    I worry about the safe working loads presented by manufacturers, maybe a test dropping a 50kg weight off a pier with a side on swivel might by eye opening, do you think?

  6. #76
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    Default Re: Rocna or Manson Supreme??

    [ QUOTE ]
    That's the one that tested well. In the majority of cases it was the pin or its thread that failed first on galvanised shackles, so there is logic in increasing the pin size.

    [/ QUOTE ]I posted the post above this before reading the whole thread, where you have now mentioned coloured pin shackles and my confidence is returning a bit.

    To make a comment on your quote, I have lost count of the number of cheap chinese crud that litters the sea bed around my mooring from knackered threads. In no way should I be able to strip a thread with a standard shackle key which has happened on numerous occasions now. Bow shackles seem to be the worst offenders (I am talking 10mm shackles here, though I have also stripped a big brand new mooring shackle in the past, bearing in mind most boats in the harbour on these naff copies, it is rather worrying) .&gt;&gt;&gt; Arghhh bugger......plop! seems to be par the course on Chinese metal, even on a some branded ones, well, plastimo anyhow. Hence now I only use calibrated shackles where trust is needed.

    The big problem seems to be lack of choice, most chandlers I visit only sell cheap rubbish out of a cardboard box. Very exciting that they are only 75p, so we are to blame expecting quality for pennies and a shop to compete with tinternet. It is hard to find quality shackles as we are too tight and shopkeepers seem scared to carry gear that on the face of it is too expensive, should I spend 8 or 75p.

    OTOH, 8 or my yacht... kind of helps the decision a little.


    p.s. Sorry if my posts have Knowledgeable <span class="small">(spelt correctly)</span> or opinionated characteristics, I learn by asking questions and sharing learnt knowledge, I am always ready to be corrected.

  7. #77
    Anonymous Guest

    Default Re: Rocna or Manson Supreme??

    [ QUOTE ]
    I worry about the safe working loads presented by manufacturers, maybe a test dropping a 50kg weight off a pier with a side on swivel might by eye opening, do you think?

    [/ QUOTE ]What is the basis for that test? Kong is a highly reputable manufacturer of high-quality components. Their anchor connectors are designed to be anchor connectors. The lateral force is stated clearly on the packaging. Manson's comment above is entirely incorrect and I urge him to contact Kong and get the facts.

    The problems with shackles are two-fold. First, the quality of the shackle. Second, the effect of the sharp edge of the slot on the shackle pin. No problem on a straight pull but the stress on the pin if the pin presents to the slot with the sharp edge in contact with the pin will be many times greater than the stress you'd expect from loading. If anchor manufacturers intend us to connect with shackles then they should shape the 'slot' so that a shackle can be used safely.

    The designer of the Spade anchor used to take part in anchoring discussions in this forum. His suggestion was to use a rigging toggle as a connector and he posted a photo. Looked like an excellent idea -- very professional.

  8. #78
    Anonymous Guest

    Default Re: Rocna or Manson Supreme??

    It's good to see a manufacturer taking part in a forum discussion. That you are prepared to answer your critics in public says more for your company than any publicity material ever can.

    I have two questions:-

    1. A photo of a Manson Supreme in a very rusty and bent state was posted earlier in this thread. Could you speculate on how it came to be in that condition?

    2. It is often said that anchor connectors should not be used as they are not designed for a lateral force. The Italian manufacturer, Kong, one of the most reputable in Europe, if not the world, make a two-piece anchor connector-swivel which has a quoted safe lateral force stated. Mine is 1.5 tonnes, I think. I have always assumed that on any bottom I am likely to anchor on the anchor will crab round or break out long before we get to 1.5 tonnes force. The alternative of a shackle is, to my mind, a potential risk as the pin can present to the sharp edge of the slot.

  9. #79
    vyv_cox's Avatar
    vyv_cox is offline Registered User
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    Default Re: Rocna or Manson Supreme??

    Sorry, advice in the post you picked up was based on my 'best in test' and the one I use, as shown not very well in the photo. The yellow pin shackle was the best of the galvanised ones, from memory. The combination of large pin in a standard D or bow seemed to be very effective so far as strength is concerned.

    I haven't seen steel chain links corrode badly in a galvanic couple with stainless shackles or connectors. The galvanising soon disappears on the first three or four links but that's a s far as I've seen things decay.

    The fatigue limit of 316 and 304 stainless is almost exactly the same as for low carbon steel, both in the same metallurgical condition. It's a myth that stainless is more prone to fatigue. OTOH a polished surface will have better fatigue resistance than a rough one, and possibly than a galvanised one although I couldn't be certain about this. A hot dipped galvanised component would almost certainly be better in fatigue than an electroplated one. Fatigue is a surface-initiated phenomenon, so anything that leads to pits, roughness, nicks, etc will theoretically reduce the fatigue limit. This is not a suggestion that everyone starts polishing their shackles!
    Answers to some technical queries at http://coxengineering.sharepoint.com

  10. #80
    Rogershaw is offline Registered User
    Location : Me: Johannesburg South Africa Yacht: Durban East Coast Africa
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    Default Re: Rocna or Manson Supreme??

    I have tended to keep away from commenting on anchor threads but as having a mechanical and electrical degree I would like to put my view into the pot.

    The attachment of the chain to the anchor in all the modern anchors IMHO need improvement. I think a large ring should be fitted into the hole through the stock in the way the fisherman anchors had / have. this would remove any lateral load on the anchor/chain/swivel attachment. The alternate is to fir a bow shackle with the bow through the anchor shank and the pin through the chain, like in vyv's pic but turned round. West marine in fact call bow shackles anchor shackles A dee shackle could be used but would not allow as much free movement that a bow shackle would

    I agree about the sharp corners of the hole digging into the pin/shackle helce the ring or the hole must be countersunk to reguce the sharp effect. If a swivel is fitted this could be fitted between the shackle and the chain and there would be no lateral load on the forks of the swivel.

    I also have several types of swivels including the kong and one from baseline plus several galvanized ring swivels with large bolts for the swivel. The kong uses a solid swivel with the jaws through bolted around the swivel for assemble this could be considered to be stronger that the bolt type but I do wonder what the failure mode is it may not be the swivel but the opening up of the section champing around the swivel. I would love to see some test samples tested like this.

    IMHO the loading on anchors can be very large and it would be the snatch loading that is the important one but difficult to determine.

    Now to be shot down in flames
    Life is too short not to have a sea view

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