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Old 22-10-2013, 14:17   #151
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

Quote:
Originally Posted by s/v Beth View Post
+1. I had heard about these anchor threads, but this is the first one I have followed in detail. Lots of fun.
Newt, I believe you are illustrative of my point that different people care about different things. I seem to recall you intended to tear the cedar out of your boat on the basis that it was poisonous. Another person might leave the cedar in place and buy an anchor unlikely to bend. Just different priorities, I guess.
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Old 22-10-2013, 14:41   #152
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

Obviously I need to get used to the idea of anchors being built with the marine (or anchoring) equivalent of built in obsolesce.

I said in the distant past that anchors seem to bend on lifting, or retrieval. Newer design anchors would be more prone as they develop higher holding capacity and the loads necessary to retrieve them are high. Carrying a spare shank is obviously wise, but why not buy an anchor that is indestructible, like a Rocna, Supreme or Excel? Changing anchors, or shanks, is not going to a bundle of laughs in the dark in choppy water. Its cost?, over many days anchoring the cost of an anchor, that is securing an expensive assets, seems small.

Regarding SARCA shanks - on 15kg anchors built from hi-tensile steel the shank thickness is 12mm, a SARCA is 18mm (it is the square of thickness that determines strength). If the Mantus A514 shank was 16mm instead of the current 12mm the shank would be as strong as its peers. If you check your American publications you will note I still query the strength of the SARCA shank and have an image to illustrate why. In Australia the SARCA has been tested and meets Australian standards. You might not like the standards - but I am sure if you are ever in trouble near our shores and AMSA rescues you then they, who will rescue you, are the same people to set the standards and I am sure you will not question the professional way they attend to you. Every time I mention a Kobra I comment on its weak shank and have images of Kobra's with bent shanks published. I do not recall a thread on Kobra on which a comment might be appropriate. I have also said it is not easy to calculate the strength of a Ultra or Spade shank but Spade do use 2205 steel in their larger models and Ultra have reinforced the shank with 2 internal webs of steel. But of the Spade shank, the combined wall thickness of the 15kg model is 12mm (whether alloy, stainless or steel), it has a 100mm width, vs 60mm on the Mantus, it has a transverse 6mm plate (recall its square of thickness) and its a box section - it will be much stronger than the Mantus.

Jonathan
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Old 22-10-2013, 15:07   #153
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

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Originally Posted by Fortress View Post
Greg, I would not make this claim without specifically testing anchors from other manufacturers to verify it.

The gentleman who developed the Anchor Saver product did some side-load testing on the shank of our 15lb / 7kg FX-23 model (for 40' boats as well) to use with his breakway / tripline system. His exact comments afterwards:

The Fx 23 produced extraordinary results. Conclusions;

The Shank sprung back at 1850 pounds of pressure. It will probably experience failure at around 2000 pounds. I would have to modify my machine to reach that load on this type of test. I think, this is way above the boat size requirements for this anchor.


Regards,
Brian
Brian you are absolutely right, guessing, hearsay and random statements that are not backed with data are baseless... I will come back with DATA stay tuned.... By the way I do not know if you are at liberty to share, but if you are what material is the Fortress arm made off.... (what alloy ?) I am not in the business of throwing others under the buss, you have seen my behavior in this forum... especially over this issue... I will create a public data base of shank strengths that will be in the public domain... and calculations shared... and may be challenged.
Back from the jog very even kilter-ed
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Old 22-10-2013, 15:13   #154
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

Quote:
Originally Posted by JonJo View Post
I have also said it is not easy to calculate the strength of a Ultra or Spade shank but Spade do use 2205 steel in their larger models and Ultra have reinforced the shank with 2 internal webs of steel. But of the Spade shank, the combined wall thickness of the 15kg model is 12mm (whether alloy, stainless or steel), it has a 100mm width, vs 60mm on the Mantus, it has a transverse 6mm plate (recall its square of thickness) and its a box section - it will be much stronger than the Mantus.

Jonathan
Jonathan, I will help you with these complex calculations and publish them...
I am not being smart, they are complex that is why I will do my public service and do it for all shanks... on my cost and any one can challenge it. Details to follow.
I am tired of fighting, we will create a table and than the customer can look at it and make theirs choice accordingly.. give me 2 weeks....
Sincerely and always with LOVE Greg
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Old 22-10-2013, 15:22   #155
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

Try as I might, I still cannot find these Australian standards that would apply to private and recreational vessels. The only ones that AMSA seem concerned with are commercial ones. It would appear to me that there are no standards for non commercial boats in Australia.

With regards to cost etc. Having worked in a chandlery for 14 years until recently over here, I can tell you that very few people are interested in the way that anchors are made and what they are made of. The racers want alloy ones because they save weight. After that it's usually "Which is the smallest and cheapest anchor that I can get away with on my boat" type of questions.

Only very rarely would we get somebody in who had done any research and wanted a specific anchor.

None of the anchors were advertised or sold as meeting any standards.

We can all point the finger at the retail chandlers for stocking these cheap Chinese anchors, but if it is what the public ask for, then you have to supply them with it.

Coops.
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Old 22-10-2013, 15:40   #156
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

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Originally Posted by noelex 77 View Post
Its hard to believe anyone would do this intentionally
Assembled upside down, the Spade resembles a Delta - I'm surprised more people haven't done this (although it takes special perseverance to cram and wiggle the shaft in upside down).

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Old 22-10-2013, 16:11   #157
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

Two questions:

If the shank is fine as it is - why change
If the roll bar is unnecessary - why have it
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Old 22-10-2013, 16:16   #158
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

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Two questions:

If the shank is fine as it is - why change
If the roll bar is unnecessary - why have it
Dear Factor, the change is to accommodate Netters ...
No punt intended... I am not kidding... we went with mild steel because its was easier to produce a good weld without the risk of cracking.. But after the seeing what the market wants we adjusted...
Roll bar is necessary to some and is not necessary to others Please read my previouse posts on the issue...
Thank you for your Question
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Old 22-10-2013, 16:29   #159
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

Quote:
Originally Posted by Delfin View Post
Newt, I believe you are illustrative of my point that different people care about different things. I seem to recall you intended to tear the cedar out of your boat on the basis that it was poisonous. Another person might leave the cedar in place and buy an anchor unlikely to bend. Just different priorities, I guess.
Your right Delfin,
I see lung pathology on a daily basis from environmental hazards, including a few today. I guess if I dragged my anchor or saw an anchor dragged a few times a day every day then I would get really excited about it. But mostly my anchor just sits there at the end of a very long chain. And so does everyone else's mostly it seems.
So discussing improvements? Absolutely.
Getting passionate about them? Maybe.
Calling other than your favorite design inferior? Go ahead, but forgive me if I smile.
Anyone want to talk about environmental hazards?
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Old 22-10-2013, 16:29   #160
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

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Roll bar is necessary to some and is not necessary to others Please read my previouse posts on the issue...
Thank you for your Question
My plan is to remove the roll bar while I am in the marinas. Break down the anchor and stow below deck during voyaging. Use the roll bar while anchoring as I will not be needing to deploy the sprit. Very useful design.

Jack
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Old 22-10-2013, 16:55   #161
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

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Originally Posted by s/v Beth View Post
Calling other than your favorite design inferior? Go ahead, but forgive me if I smile.
Hmm, I don't recall anyone mentioning a 'favorite design'. Just a few people noting that some steel is stronger than other steel and the anchor is question isn't an anchor (yet) that could be characterized as having a robust shank.
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Old 22-10-2013, 17:12   #162
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Anchors all look the same from this angle

Anchors all look the same from this angle.
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Old 22-10-2013, 19:50   #163
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

Regards Rex.
CEO of Anchor Right Australia.

One would think developing –designing an anchor is challenging enough, doesn’t compare when it gets to being scrutinised on forums.

You Know I never thought I would be saying this as I have copped much flak from Jonathan myself, I can remember an anchor of mine he tested and it ended up in a boating mag with a bent shank, this is the thing, even though I have been on the receiving end of his findings- comments I see on this thread are no different here than when he scrutinised myself Fortress- Rocna- Manson and so on.

I think we should not get side tracked with anchors that have been around for many years as most take them at face value, New Generation is where it started, I believe this is where Jonathan is coming from, when a certain company some years back was spruiking very similar to Greg and myself, Jonathan- along with guys like Delfin- Riggamortise lead a very long campaign exposing these guys for what they were.

No complaints about Jonathan then, in playing his part he was indeed appreciated, it was not long proven that what was being said by this gremlin, was absolute lies and resulted in bent shanks with many disappointed and ripped off customers, luckily no one was hurt that I know of, just their pride, but what if, I see no different here, Greg spruiking how wonderful his anchor is, I understand why, but what if he was another gremlin and no one is suggesting he is.

Jonathans concerns-comments re anchor shanks I totally understand as he is an expert, he had firsthand experience during the process of weeding out the gremlin, so why would he not make a comparison with what he knows will bend and has been proven, Greg’s comments as to if you want a stronger shank, then go for a Bruce or CQR,
A comment like that is worthy of doubt, so Greg I think much of the criticism you are responsible for, as pointed out by some, transparency has not been your greatest asset when addressing this thread.

I think you and the many following this thread can be thank full for Jonathans input as you all know more about the Mantus anchor than ever before, more importantly you are Getting a better picture of Greg himself, and Greg be honest, earlier your video and comments supported that the Mantus was equally up to it,roll bar or no roll bar, because of Jonathans probing you have changed the goal post.

I would prefer you to bite the bullet and go one step further by saying do not anchor over night without the roll bar, if the anchor is broken there is a slim chance it will not right itself, from what I can see you supplied Jonathon to test your product, no point doing this if you are only seeking appraisal, welcome to the real world of constructive criticism, it never hurt me and it won’t hurt you.

Whatever material you put in your product I could not care, if it should fail then you will be the only one to know about it because of your warranty, myself, Jonathans finding on our products really got my back up so I went the other way and now try to build our product to the point no Jurno can pick holes in it, I wish, but never the less many of you keep on saying why single out Greg, I don’t see that, it’s not Greg that’s being singled out here, it is a man of whom takes a lot of pride in trying to ensure quality in a very important piece of equipment that has served you well in the past.

Yes I know I am a sucker for the underdog and many will rip this post apart, probably say I am also tied in with Delfin- Fortess, for what it is worth we make a stronger product because of his criticism, this can only be a good thing. Jon is a “pom” from England nothing to do with us.

Coops, you are right there are no standard for recreational boats- anchors per say, as pointed out we are a certified anchor producer catering for all, In saying this regardless of prior comment from some, bumper stickers, most standard anchors will handle higher loads anyway, extra costs past on, all of this is irresponsible as it is simply not true.

Most anchors of the shelf will fold when proof testing takes place, if not the shank then the fluke will let go, on our web site you will find a true account of the Tsunami that hit Phuket, only three boats survived those waves in the path of the Tsunamis full force, all three had the great Sarca anchors and all survived, if any one ask me what was my greatest achievement, it would be that one of those boats were able to retrieve a drowned women and revived her simply because they were on a Sarca that was strong enough proved the worthiness of certification.

Regards
Rex
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Old 22-10-2013, 21:18   #164
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

There seems to be a suggestion I am picking on Greg, this is a thread about Mantus, Greg is Mantus, or Mantus is Greg. I posted simply because I thought the video was at best disingenuous and I think the shank of the anchor is weak. But the thread is about Mantus - so I was trying to stick with the thread. If you feel the need to comment negatively about the Plastimo Kobra, or the failings in Gordon Lyall's Delta - maybe we need a new thread. I do recall that a thread on the SARCA anchor was pulled completely - I am sure if it is resurrected there might be some new input.

I note that Greg wants to define the shanks of all anchors, I think this meritorious (and hard work). I've done it for a very few anchors -and as you will note it is a thankless task and at the end of the day - no-one, or very few, actually appears to care. I have all the calculations on some anchors as calculated by the manufacturers and/or designers based on a cross section of steel types in addition to those I have completed myself - so it will be interesting to compare. But I have limited my calculations to newer designs and generally 'Lyall type' shanks.

But to return to the thread.

I am still confused, but I am very simple, as to whether Greg is suggesting it is safe to remove the roll bar 100% of the time and for 100% of situations. Maybe I can request him to define when its a good idea and when its a bad idea (if it is ever a bad idea). The video seem to strongly imply (but I reiterate I take things at face value and look at things very simply) the anchor will work without the roll bar, which to me means anytime I want to remove it - its safe. My findings contradcit this - but Maybe I made a mistake - which should be rectified (soft sand bottom, 5:1 scope 3-4m depth, 15kg Mantus, 8mm all chain, deployment by Muir Atlantic windlass (not free fall).

I am quite happy to accept that people on this thread all now know and have made a decision on the Mantus shank strength issue - though I'm not sure that CF, and specifically this thread, have quite the coverage necessary to allow everyone to make the same informed decision.

Hopefully when Greg posts the results of his findings on shank strength, 2 weeks from now is about the 7th November (just after Guy Faulkes night) it will clarify everything.

Best wishes,

Jonathan
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Old 22-10-2013, 22:49   #165
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Re: It's True! The Mantus 65-lb. hooks first time, everytime.

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Fear mongering? Really?

That would be factually incorrect. Bis 80 would absorb that load given the typical thickness of the shank, and I am pretty sure the Fortress would as well. Perhaps Brian from Fortress can confirm. The issue is as you have stated. The mild steel shank will bend, but contrary to what you have stated, the A514 steel would not.
Delfin was referring to the example of a 40 ft boat with 30 kt winds developing 1200 lbs rode load.

I promised Greg some calcs tonight, but didn't have any anchor dimensions readily available then realized Jonathan Reeves cites the 10-kg Rocna geometry in his PS article “Bends and Breaks: Anchor Shank Strength” dated April 2013.
As stated in his article:
“Bisplate 80, which has a typical yield stress of 750 MPa (minimum 690 MPa)”
“The 10-kilogram Rocna has a lever arm of 529 millimeters, a width at the end of the lever arm of 92 millimeters and thickness of 10 millimeters.”

Using simple beam theory, one can calculate the load required to yield the shank.

Sigma = M*c/I
Where Sigma is the material strength (in this case yield)
M = Moment (ie F*d); F = Force, d = lever arm
c = distance from neutral axis
I = moment of inertia (for a rectangle I=(1/12)*b*h^3

There are some limitations to using simple beam theory, namely in this case, the beam must be straight - like a Danforth or Fortress. But in the spirit of comparing apples-to-apples, I'll stick with it. Besides PS & Jonathan Neeves didn't seem to have any issues using this approximation. And I would agree it should be close enough.

So using the geometry mentioned above & a yield strength of 690-MPa, one calculates the Force required to yield the shank at:

F = 2000-N = 450-lbf.

But it is not really reasonable to compare this 450-lb load to the previously mentioned 1200-lb because that was for a 40-ft boat & certainly one would not be using a 10-kg anchor on a 40-ft boat. So going to Rocna's sizing chart it is more reasonable to compare to wind loads developed with a 30-ft boat. Reference ABYC wind chart for 30-ft boat & 30-kts wind indicates 700-lbs rode load.

450-lbs < 700-lbs. The shank is far beyond yield.

This is not a ding against Rocna. they have a great anchor. The point is the wind loads developed at 30 kts, if applied purely laterally will yield even a well-designed & well-built shank.

I feel compelled to add caveats:
1. This analysis is slightly un-conservative:
  • The applied loading assumes only pure bending, in reality there will be a combined axial, bending & twisting.
  • The shifting neutral axis induces twisting as bending load is applied - this is not accounted for. The analysis assume a straight, 529-mm long, constant cross-section shank.
  • By comparing the cited 529-mm dimension to the Rocna patterns on their website, it appears Jonathan Neeves measured the lever arm as the distance from the center of the shackle hole to the center of the trip-line hole. This is less than the full length of the shank but since the shank begins to widen & curve significantly after that point, I would agree it is reasonable to use.
2. This loading event is fairly conservative:
  • It is likely the anchor will be buried in substrate. And because the Rocna shank is thin, the arm also gets buried. This reduces the "effective" length of the shank (lever arm) thus making it more resistant to yielding.
  • It is likely that the anchor will displace/rotate & re-align itself with the load, thus increasing the axial load component (strong direction) & reducing the bending component (weak direction)
3. I did not verify the cross-sectional geometry or the Bis-80 material properties. i pulled them directly from Jonathan Neeves' article.

I believe the intention is to get full geometry for as many anchors as possible & produce 3-D analysis as opposed to this simplified 2-D analysis. But this 2-D analysis is not bad & provides a decent approximation for comparison purposes. I'll continue to post 2-D analysis while we gather the 3-D geometry.

Well, I hope you found this educational or at least enlightening. Comparing the 3-D to the 2-D should be interesting too.

D.Taylor
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