Anchor - Mantus M1 (apologies for the extended opening post - don't read if you have a train to catch).
- Thread starter Neeves
- Start date
RichardS
N/A
Neeves
Well-Known Member
Good to see a win
Maybe you did not need a new anchor.
If my posts make people think, differently, I'm happy. I have no illusions - there is no perfect anchoring - each person's needs for reliable ground tackle are different. Consequently it is unlikely one person's post will provide THE answer to a problem. A healthy, to many, unhealthy, debate on a problem, in this case anchors, is to me a mechanism to air different views and for readers to question those views. Sometimes those views are based on hard quantitative evidence, sometimes on very subjective conclusions - but they are all grist to the mill. Some subjective idea when tested with data - are found to be validated and built on to good effect (sometimes not)
If you don't like the thread - don't complain - just don't read it. I find it very strange when people complain about threads - what possesses them to read a thread they dislike (for whatever reason) and wish to establish themselves as some sort of volunteer Moderator - what's wrong with the Mods we have?
If threads make you think and alters your views, if they make you question dogma - the thread has had value. And just because you don't agree - does not mean the view with which you do not agree is wrong - maybe you should question your own thinking (a bit more deeply).
Just think howe long the cult of catenary reigned and now many use a long snubber instead. Just think how long it took for people to question the use of swivels and how 3 simple (with no disrespect to Mr Cox
) links made swivels safer.Jonathan
KompetentKrew
Well-Known Member
I absolutely do need a new anchor, as my current one is undersized and I have dragged on more than one occasion.
All this bickering has been incredibly unhelpful, with participants ignoring genuine questions about the subject.
All this bickering has been incredibly unhelpful, with participants ignoring genuine questions about the subject.
Poey50
Well-Known Member
No disrespect to KompetentKrew, just an alternative viewpoint. I don't much like bickering in general but I do learn a lot from evidence-based bickering. It makes me think and weigh up the arguments. Before that, all we had on anchoring was received-'wisdom' - very little of which turns out to have been wise.
noelex
Well-Known Member
Hi KompetentKrew, I see the question was directed to me. My apologies, I should have replied to your earlier question.
I think this thread has run its course and descended into person attacks, so rather than inflame things further I have sent you a private message, which will hopefully answer your query.
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Neeves
Well-Known Member
Its good of Noelex to tell us when the thread has run its course, he seems to forget he is not a Moderator at YBW - much as he would obviously like dissent to be suppressed.
I have just measured the 'toes' of both the Mantus and Rocna.
The extra bulk in the Rocna extends from the toe to the middle of the shank/fluke weld - call it the centre of the crown (and coincidentally the point conventionally used to measure the angle of the shank)
The extra thickness on the Mantus is only in the extreme point off the toe and looks, to me, to have been incorporated to give the toe strength, rather than weight. The Mantus extra steel extends only 12cm back from the toe whereas on Rocna it extends 29.5cm.
I have a Mantus 15kg version and as I don't have a 15kg Rocna I have taken the dimension direct from an engineering drawing (signed off by Peter Smith). So I did not measure the Rocna - simply copied the dimensions.
The Mantus fluke is made from a 9mm plate to which the toe plate is welded, the toe plate adds 5mm in thickness. The extra toe thickness of the Mantus has a volume of 8cm^3
The Rocna fluke appears to be made from 6mm plate, or rather the heel is made from 6mm plate. and the toe portion, which is a large area, is made from 16mm plate. Some of the steel in the toe is demanded for strength (and I suspect 6mm plate would be inadequate so I am assuming a similar strength demand as Mantus, 9mm, and the rest being ballast (7mm)
Based on using 7mm for ballast the volume of the ballast is 173cm^3
To suggest that Mantus has the same 'ballast' looks to test credibility too far for me.
My conclusion remains that Mantus is an unballasted fluke anchor with the crown in the wrong location. The location of the crown on the Mantus leads to compromised ability to maximise hold, see the link to Kim's research. If you believe that Mantus has no or minimalist ballast then note the location of the crown on Bugel, Danforth, Fortress, Knox, SARCA, Bruce etc. Obviously if you think the ballast illustrated on Noelex image is equivalent to the ballast in a Spade, Excel, Delta, CQR, Kobra - then I have made a significant error. Noelex pictures in his thread on CF show the fluke/seabed angle to be 16 degrees which is half the fluke/seabed angle of 'all' other anchors and the quantified reduction in hold is defined in the 'book' link I provided, specifically the graphs on page 40, where holding capacity is halved when the angles is reduced from 30 degrees to 17 degrees. The impact of fluke/seabed angle is also in agreement with publications from the US Navy research department and by extrapolation Fortress use of variable fluke angles. None of this data is mine - it all depends on research independent of me. I have validated my analysis by testing the hold of a Mantus, as designed, and have also moved the shank back (simply drilling 4 new bolt holes) and developed a commensurate increase in hold. The hold of a Mantus as designed is slightly higher than a well set Delta of the same wight (or about half the hold of a Rocna - of the same weight).
A summary of the background to the research will be found in the Practical Sailor article in the link provided in the opening post. The article has had peer review - effectively the final paragraph above summarises the article. Practical Sailor provide a copy of their articles to manufacturers of products that is the subject of their articles and the article was given to Mantus for comment. Valid comments were answered or errors corrected in the script. As you can imagine this review and subsequent work with PS and Mantus was thorough, very. This is not say that Mantus were happy. The holding capacity tests I have made were conduced after the article was published.
The data missing is independent holding capacity testing. It is notable that despite the conclusions Mantus has not conducted holding capacity tests themselves - as contradictory results from them would raise questions as to my work.
I don't need to 'sell' my conclusion with PMs - I, with the peer review, stand by my assertions and I have seen no evidence since the article was published that I have erred with my conclusions.
I am more than happy to enter into Private Messaging - but might desire to publish the correspondence in the public domain, with permission of the correspondent - I do not have anything to hide.
If anyone has queries I am more than happy to provide information until comfort is engendered. I prefer it to be made public - knowledge is not much use if it is not shared.
Burning books, suppression of debate is not my style - and NEVER works - the truth will our, even if eventually.
Jonathan
I have just measured the 'toes' of both the Mantus and Rocna.
The extra bulk in the Rocna extends from the toe to the middle of the shank/fluke weld - call it the centre of the crown (and coincidentally the point conventionally used to measure the angle of the shank)
The extra thickness on the Mantus is only in the extreme point off the toe and looks, to me, to have been incorporated to give the toe strength, rather than weight. The Mantus extra steel extends only 12cm back from the toe whereas on Rocna it extends 29.5cm.
I have a Mantus 15kg version and as I don't have a 15kg Rocna I have taken the dimension direct from an engineering drawing (signed off by Peter Smith). So I did not measure the Rocna - simply copied the dimensions.
The Mantus fluke is made from a 9mm plate to which the toe plate is welded, the toe plate adds 5mm in thickness. The extra toe thickness of the Mantus has a volume of 8cm^3
The Rocna fluke appears to be made from 6mm plate, or rather the heel is made from 6mm plate. and the toe portion, which is a large area, is made from 16mm plate. Some of the steel in the toe is demanded for strength (and I suspect 6mm plate would be inadequate so I am assuming a similar strength demand as Mantus, 9mm, and the rest being ballast (7mm)
Based on using 7mm for ballast the volume of the ballast is 173cm^3
To suggest that Mantus has the same 'ballast' looks to test credibility too far for me.
My conclusion remains that Mantus is an unballasted fluke anchor with the crown in the wrong location. The location of the crown on the Mantus leads to compromised ability to maximise hold, see the link to Kim's research. If you believe that Mantus has no or minimalist ballast then note the location of the crown on Bugel, Danforth, Fortress, Knox, SARCA, Bruce etc. Obviously if you think the ballast illustrated on Noelex image is equivalent to the ballast in a Spade, Excel, Delta, CQR, Kobra - then I have made a significant error. Noelex pictures in his thread on CF show the fluke/seabed angle to be 16 degrees which is half the fluke/seabed angle of 'all' other anchors and the quantified reduction in hold is defined in the 'book' link I provided, specifically the graphs on page 40, where holding capacity is halved when the angles is reduced from 30 degrees to 17 degrees. The impact of fluke/seabed angle is also in agreement with publications from the US Navy research department and by extrapolation Fortress use of variable fluke angles. None of this data is mine - it all depends on research independent of me. I have validated my analysis by testing the hold of a Mantus, as designed, and have also moved the shank back (simply drilling 4 new bolt holes) and developed a commensurate increase in hold. The hold of a Mantus as designed is slightly higher than a well set Delta of the same wight (or about half the hold of a Rocna - of the same weight).
A summary of the background to the research will be found in the Practical Sailor article in the link provided in the opening post. The article has had peer review - effectively the final paragraph above summarises the article. Practical Sailor provide a copy of their articles to manufacturers of products that is the subject of their articles and the article was given to Mantus for comment. Valid comments were answered or errors corrected in the script. As you can imagine this review and subsequent work with PS and Mantus was thorough, very. This is not say that Mantus were happy. The holding capacity tests I have made were conduced after the article was published.
The data missing is independent holding capacity testing. It is notable that despite the conclusions Mantus has not conducted holding capacity tests themselves - as contradictory results from them would raise questions as to my work.
I don't need to 'sell' my conclusion with PMs - I, with the peer review, stand by my assertions and I have seen no evidence since the article was published that I have erred with my conclusions.
I am more than happy to enter into Private Messaging - but might desire to publish the correspondence in the public domain, with permission of the correspondent - I do not have anything to hide.
If anyone has queries I am more than happy to provide information until comfort is engendered. I prefer it to be made public - knowledge is not much use if it is not shared.
Burning books, suppression of debate is not my style - and NEVER works - the truth will our, even if eventually.
Jonathan
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RichardS
N/A
Neeves
Well-Known Member
Geem made this pertinent comment on the Vulcan - seagrass thread, Post number 55
'With all this talk about Mantus I decided to watch the Matus introduction video of their anchors setting. I was suprised to see how long it took for the Mantus to set. It drags along for some distance before it sets. I guss if it has a shallower angle then its dive to a full set takes longer. In my experience both Spade and Rocna set repeatedly within their own length. Something is different about the Mantus and it appears to be the shallower fluke angle. I have no way of knowing how good the anchor is as it hasnt appeared in any tests against its rivals so guess what? I just bought a new Spade. Not oversized. Its the same weight as the last one and selected straight off the Spade selection chart for the weight of our boat as the last one was several years ago'
At least someone took the trouble to, understand, look and analyse
Look at any video of a Mantus and it takes a long time to set - and if you check some of the (promotional) videos the videos are terminated with the anchor still moving.
With a shallow setting angle the anchor will take, in the case of a 16 degree trajectory in comparison with a 30 degree trajectory, of anchors of a similar size twice the distance to set. So the idea the Mantus anchor sets quickly is - well rubbish (or being kind - misleading. Simple geometry will prove the issue.
Of course if you are using a large anchor this will not hold true.
For example a 49' yacht might be recommended by Rocna to use a 33kg anchor. If you choose to use a much larger one, say 60kg, your auxiliary engine will set the Rocna quite deeply but the bigger (16 degree) anchor will lock up as quickly - because you do not have engine power to pull it more deeply into the seabed. The question then is would you rather have shallow set anchor in the low sheer strength surface seabed or a deep set anchor....?
The idea of Mantus setting quickly needs some qualification, which along with the omission of mention of the unique setting angle and the strange idea of how one defines ballast should increasingly raise questions. What is also strange is that regular criticisms of, say, Kobra is common (though not used by the individual), despite members here being happy with its performance but a barrage of complaint develops when objective criticism is made of Mantus.
Anchors are a safety item, they secure valuable bits of kit (and owners valuables , wife and children). I don't understand the defense of the indefensible.
Jonathan
'With all this talk about Mantus I decided to watch the Matus introduction video of their anchors setting. I was suprised to see how long it took for the Mantus to set. It drags along for some distance before it sets. I guss if it has a shallower angle then its dive to a full set takes longer. In my experience both Spade and Rocna set repeatedly within their own length. Something is different about the Mantus and it appears to be the shallower fluke angle. I have no way of knowing how good the anchor is as it hasnt appeared in any tests against its rivals so guess what? I just bought a new Spade. Not oversized. Its the same weight as the last one and selected straight off the Spade selection chart for the weight of our boat as the last one was several years ago'
At least someone took the trouble to, understand, look and analyse
Look at any video of a Mantus and it takes a long time to set - and if you check some of the (promotional) videos the videos are terminated with the anchor still moving.
With a shallow setting angle the anchor will take, in the case of a 16 degree trajectory in comparison with a 30 degree trajectory, of anchors of a similar size twice the distance to set. So the idea the Mantus anchor sets quickly is - well rubbish (or being kind - misleading. Simple geometry will prove the issue.
Of course if you are using a large anchor this will not hold true.
For example a 49' yacht might be recommended by Rocna to use a 33kg anchor. If you choose to use a much larger one, say 60kg, your auxiliary engine will set the Rocna quite deeply but the bigger (16 degree) anchor will lock up as quickly - because you do not have engine power to pull it more deeply into the seabed. The question then is would you rather have shallow set anchor in the low sheer strength surface seabed or a deep set anchor....?
The idea of Mantus setting quickly needs some qualification, which along with the omission of mention of the unique setting angle and the strange idea of how one defines ballast should increasingly raise questions. What is also strange is that regular criticisms of, say, Kobra is common (though not used by the individual), despite members here being happy with its performance but a barrage of complaint develops when objective criticism is made of Mantus.
Anchors are a safety item, they secure valuable bits of kit (and owners valuables , wife and children). I don't understand the defense of the indefensible.
Jonathan
JRCO26
Active Member
LOL it all becomes clear now. You are an anti-Mantus zealot, spending much of your time on this forum dissing the anchor as "no better than a delta". Post, after post , after post after post.
What a lonely sad life having to apply yourself to your anti-Mantus crusade.
MapisM
Well-Known Member
Mmm... Dismissing anyone's negative views on a product based on how sad you think his life is, that doesn't make the product itself any better, I reckon.
In fact, in this specific case, it just comes across as a comment from a pro-Mantus zealot, if you see what I mean.
In fact, in this specific case, it just comes across as a comment from a pro-Mantus zealot, if you see what I mean.
lustyd
Well-Known Member
To be fair I'm pretty sure half of the users on this forum are AI bots designed to argue one specific point eldlessly. Often they don't even relate to the thread!
For some reason there are multiple "that's not a long keeler" bots.
For some reason there are multiple "that's not a long keeler" bots.
Neeves
Well-Known Member
As MapisM said you seem to have taken on a crusade to resurrect old threads for the purpose of attacking an individual - not quite what the role for which the forum was intended.
Jonathan