Anchors - Bigger is Better ?

[foggysail]

Originally Posted by JonJo

Maybe a smaller anchor would have set more deeply

Jonathan

Hundreds of posts earlier, I half heartlessly said in a post "just maybe a small anchor would dig deeper." Now of course that is in line with your premise.

Have any tests been conducted regarding this? The anchor testing I recall seemed to indicated size mattered. It just seems that a smaller anchor in some anchorages could dig deeper. Even if that is the true, would such condition translate into having greater holding force?

Again as last time, I still wonder but I am still in the "big is better group."

Foggy

[Maine Sail]

Originally Posted by JonJo

Maine Sail

I did not go to the effort to try to bend the shank of my 15kg Mantus.

I did not either. I simply wanted to see if it would rotate in a sea bed after being HEAVILY loaded then veered 180 degrees and loaded again. This testing was.

#1 To see if the claims on forums would translate to my real world..

#2 To see how the shank would handle it, for myself.

My intent was never to bend it and I had a feeling it would not when just rotating in a set position. My test is not conclusive of anything but what I saw with my own anchor in that bottom. For me personally it was enough to satisfy my own curiosity and exceeds any real world event I envision my vessel ever repeating. I am sure this would never satisfy the net cadre. I don't have the time to sit here and defend a test like that so it will not get published. Simply not worth it.

Occasionally when a netter espouses something so outlandish, or perhaps dangerous, I will go out and conduct a test and post a video. These are often first and foremost to satisfy my own curiosity.

My physical in-water prop-drag testing was born out of my own curiosity after listening for years to netters espouse helicopter analogies etc.. There was so much factual sounding data on both sides I just had to see for myself, with a sailboat prop not helicopter blade, so back in 2007 I began constructing a fist of its kind in-water test jig. I finally did that testing in early 2009.. . After that test a LOT of those "locked is faster" guys simply fell quiet.

This was one of those tests:

Can Chain Alone Anchor Your Boat?

Originally Posted by JonJo

I did the 'ball bearing' test on the shank and disbelieving the results (as I 'knew' it was made from A36 steel, yield of 250 MPa) I took it to a commercial metallurgical lab for testing. Like you, no-one sponsors this. The lab tests and mine were in fair agreement (mine were higher) but the lab tested the steel to be a 500 MPa material, based on 6 Brinnel tests.

Based on the shank dimensions a 500 MPa steel would result in a shank not dissimilar in strength to the offspec Rocna anchors, some of which bent - but many I suspect are still in service. The 250 MPa Mantus shanks are obviously weaker.

Whether your tests simulated the conditions under which Rocna shanks bent - I have no idea - but the specified material would bend under a load of a few hundred pounds and not the load you are describing. I consequently suspect your shank and mine might be made from the same sort of steel - but maybe your is better.

I never cared about my Rocna as it is one of the good ones from well before the "China debacle"...

Originally Posted by JonJo

There has never been an explanation as to why the shank I had was twice as strong as specified but it does allow one to draw imaginative conclusions - one being the manufacturer might have had a supply issue and used whatever it was he had in stock. This is fine, unless his available stock is not as good as that specified (though difficult to get anything worse than 250 MPa). It would be interesting if you could check out your shank and define what sort of steel it is made from.

It is certainly reassuring the Mantus have offered to replace any of the old shanks, no questions asked, when they have stock of the appropriate A 514 shanks. Hopefully they will post same on their website (they might have already done so).

As I have said before Greg was brutally honest with me when I specifically asked him about shank strength as I was buying this anchor amidst the "China debacle"... Having been directly lied to by two anchor manufacturers, this alone helped me support Greg's endeavor and to get me a new anchor to play with. I liked his brutally honest approach and his insistence that he 100% would stand behind the product.

Originally Posted by JonJo

But - Maine Sail, you do yourself an injustice. Your independence and views are respected, your testing is highly regarded and consequently if you say something (or do not say something) then conclusions are drawn - simply because of the respect you engender.

I am just another voice on the net. I try to approach what ever I do without bias and always try to keep it based on science, testing or available data. I come from a sciences background and spent the better part of my life reading and living in the world of clinical trials data (pharmaceutical & biotech industries). I have a good sense of what makes for "fair" data, but I am not perfect either... Much of this stuff I have to see for myself so I often conduct my own testing. My load cell has proven an invaluable tool for testing things such as seacocks, electrical crimp terminations/tools and my anchors and mooring loads among other uses. I don't like to just shoot from the hip on stuff because then I have to eat my own words. Perhaps the reason people put trust into what I say is because I do my best to back that with actual evidence.. Still this is what I tell folks on my how to web site:

Originally Posted by Compass Marine Inc.

As I always say "Don't just take my word for it.". My site is but ONE source among hundreds or thousands of legitimate sources. Always do your homework, weigh all the options then decide what will work best for you & your boat. "

The best I can do, is the best I can do, but I don't try to put myself out there as a final authority and hope people don't see it that way (see quote above). One must ALWAYS weigh the positions of multiple authors, experts etc. before deciding what is right for themselves. When I say something one can certainly weigh it but please don't ever take it as gospel or a final word! I would HOPE people put more effort into research than just listening to one guy on the net...

Originally Posted by JonJo

If, for example, it is known you have an an anchor with (again - for example) obvious faults questions are then raised as to why you have not flagged the faults - even though the tests are for you and you alone. In the past you have shared your views - why the reticence over a specific model? Not many have your expertise nor ability - who else is going to tell them.

I have shared in multiple threads on numerous occasions that the aluminum versions of the Spade 80 (A-80) does not set nearly as well as the identical size, shape and design S-80.. This is where Alain and I tangled toes.

He went so far as to call me crazy, a lunatic and told me what I said happens can't possibly happen. "Tip weight as a percentage is what sets that anchor not the in-water weight." With the A-80, when directly compared to the S-80, this proved to simply not be true. After he saw the video he sent me a free S-80. He then asked me to not mention this. I refused as that is just not right. I even offered to pay him for the S-80 when I refused his "gag order"... He then called me an a$$hole and we never spoke again.... He never warned others about this even though he KNEW it could happen, so I do. Again, I am but one voice in the crowd and can only share what I have learned and physically see.

Originally Posted by JonJo

As an example - you have now tested your Mantus shank and made the detail public, above. This test is valid for your shank but having aired the results others might think their shanks are as good (and not bother to replace) if their shanks are 250 MPa this might not be wise if it happens your shank is a 500 MPa or better.

My results are for my shank and satisfied my curiosity. Other owners need to satisfy their own curiosity... I have no explanation for why your shank tested at better than spec and have no clue what grade mine is. I honestly don't really care because my testing, in the real world, satisfies my curiosity for my anchor...

Originally Posted by JonJo

Sadly you might have involuntarily taken on the mantle of a moral responsibility to become a harbinger of bad news - or unexpected results.

Jonathan

If people can't look beyond one guy on the net I honestly feel badly for them. Everyone needs to do their own research and this should ALWAYS include more than one source, forum, book etc. etc.......

Other avenues I will & do publish my testing because it is more cut and dry, like seacock testing. With that or crimps I have a physical standard to test them against. Anchors are more like religion and I can't test religion any better than you or Sail Magazine or YM or PS etc. etc. because there are far to many variables...... What works in Maine may not work as well elsewhere due to environmental conditions that are different....

[foggysail]

Originally Posted by El Pinguino

I would like to see photos of the hoop causing the anchor to fail to hold or to ball up with weed.
Patagonia has a reputation for heavy kelp, however some anchorages are seriously kelpie.. in others your anchor wiill come up with mud, others it will come up clean as a whistle.
A few photos to have a look at ... the first (red boat ) is using a bruce (and I don't think they had a decent kelp knife). The second is in the same anchorage a few years earlier... Rocna... still on the bottom but unless cleared there will be a BBB of weed on the anchor when it comes in sight.
Third pic... not kelp just green weed and that is my old CQR.

The local fishermen use home made grapnels... big - maybe 1 metre diameter on the business end and light, made from about 10 mm stock on the grapnel bits. For rode they use 10 or 12mm polyprop... no chain.... must see if I can find a photo somewhere...

A Swarbrick would work in kelp.

Your photos remind me of my experiences with Bruce

[Delfin]

Delfin: SS cold flows and is quite weak.

Originally Posted by foggysail

Really??? Can you provide a reference???

Yield strength of 316L stainless = 205 MPa
Yield strength of A36 mild steel = 250 MPa
Yield strength of Bisalloy 80 steel = 750 MPa

Online Materials Information Resource - MatWeb

When analogs to steel anchors are made out of SS to make them pretty, they are also quite a bit weaker than even mild steel. I still have a SS shackle that has one leg about 1/4 longer than the other framed on my desk. It elongated because the pin had come loose and the load of the halyard was just on the single 1/4" leg, which stretched like it was made of putty.

[Delfin]

Originally Posted by Maine Sail

I did not either. I simply wanted to see if it would rotate in a sea bed after being HEAVILY loaded then veered 180 degrees and loaded again. This testing was.

#1 To see if the claims on forums would translate to my real world..

#2 To see how the shank would handle it, for myself.

I think you capably proved that the shank could 'handle it' in the conditions you provided, and these are probably very typical. I think that to determine what a shank can handle when under lateral strain, however, you have to immobilize the flukes. Otherwise, I'm not sure what you would be measuring since the force in straight pull the anchor sustains is going to be very different from the force required to rotate it, at which point it can be re-loaded.

Interesting that yours tested at 500 MPa, and the manufacturer thinks it should test at 250 MPa, which would be the case if made of mild steel. I guess I would rather a manufacturer make undocumented changes to metallurgy to strengthen their product rather than weaken it like Rocna did, but my first preference would be to have accurate data on the anchor's construction in the first place.

[River Cruiser]

Bigger is better = best;-)

[foggysail]

Originally Posted by Delfin

Delfin: SS cold flows and is quite weak.



Yield strength of 316L stainless = 205 MPa
Yield strength of A36 mild steel = 250 MPa
Yield strength of Bisalloy 80 steel = 750 MPa

Online Materials Information Resource - MatWeb

When analogs to steel anchors are made out of SS to make them pretty, they are also quite a bit weaker than even mild steel. I still have a SS shackle that has one leg about 1/4 longer than the other framed on my desk. It elongated because the pin had come loose and the load of the halyard was just on the single 1/4" leg, which stretched like it was made of putty.

No disagreement in comparing SS to high quality steels. It was the cold flow that I essentially questioned. The only info I could find regarding cold flow was related to 304 where dynamic softening will occur at temperatures above 750 degrees C. I am not aware of any cold flow issue to date, that was what I questioned...... and of course there may be that issue and I am not aware of it.

Shackles--- My experience is you have to purchase the good ones. The cheepies are just junk. Once I tested a good one with a sledge hammer in an attempt to force the pin opening a few thousands wider with zero luck.

[JonJo]

Maine Sail,

I was provided with one of the offspec Chinese Rocnas, 25kg, that had bent during a severe thunderstorm in the Caribbean. The storm had passed, essentially, directly overhead veering suddenly through 180 degrees. Gusts on other boats in the anchorage were said to be 40 knots. The shank had bent and on subsequent testing was about 375 MPa, independent tests (again I paid). Obviously it was impossible to know which gust and at what angle of gust the shank had bent. The bend was found when the anchors was lifted when the owners wanted to move to a more sheltered location. The anchor did not break free and drag. The 25kg anchor was one of the early offspec modela and delivered to Europe (eventually over 1,000 offspec units were delivered). This puts the shank of the Rocna having been made from a stronger material than the original Mantus and the Rocna shank is wider (by 30%) (though of the same thickness of plate). My conclusion, simplistic though it might be, is that under similar conditions the Mantus original 250 MPa shank will also bend (and much more easily).

If the manufacture makes claims that their anchor has exceptionally high holding capacity then under severe weather conditions the shank is basically immovable - it might slip round with time, say 30 minutes but not in an instant. If the fluke does not allow easy movement it is then effectively immobile and you have perfect conditions to load a shank in its weakest orientation with a severe gust in a thunderstorm or a storm 'bullet'.

Rocna replaced the bent shanked anchor without question, unfortunately with a 33kg model, from the small batch of approx 200 offspec models that came to America, with a 450 MPa shank (again I paid for the test) - which also bent, which they then replaced with a 650 MPa shanked model (which as far as I am aware has performed flawlessly). In fact I am not aware that any of the 650 MPa shanked models (the steel quality last quoted and believed to be still used under CMP) have bent

But a shank with a propensity to bend is a lunch time hook, only.

Until Mantus put out a clear and unequivocal public recall they are going to be bugged by this issue for at least a half a decade (if the Rocna issue is any example)


I have tested extensively both the alloy and Steel spade '80' models and I can find no difference in setting ability between the 2 models. However I have been told that the alloy models have 'more' lead in the toe than originally - possibly to overcome early deficiencies? Equally it might be that your 'hard' seabeds are much harder than we have here. But personally I cannot fault the alloy Spade.


Anchor makers have a rather common habit of tweaking their models (some tweaks are bigger than others) without advising the market place and a fault in an early model is ascribed, rightly so, to the complete range - even though the fault might have been removed. The anchor makers are of course reluctant to admit the early model might not be as good as the new improved model for fear of being required to allow replacement or trade in. But its a double edged sword. Spade might have overcome the issues of poor setting of the original alloy Spade - but are bugged by historic experience being repeated again and again. Equally Ultra have gone through 2 upgrades on the internal strengthening web of their hollow shank, originally no web, then a single web, now a double web. But who has got what and when the changes filtered through to the market place - only they know. But certainly the current Ultra must surely be stronger than the original.

Jonathan

[JonJo]

Foggy Sail,

I have tested small models and large models of the same model of anchors in the same seabed. But I have been comparing 5kg models with 15kg models.

But I can completely bury 5kg models, such that the top of the horizontal of the shank is 20cm-40cm below the seabed. Contrarily with the same load and same seabed I am unable to bury the larger models with most of the shank still exposed.

But the loading capacity of both anchors is the same, its the load needed to bury them as described.

But the loading capacity of the small anchor is at or near maximum and will not increase (if loaded further the larger anchor have 'potential'). The small anchor will simply squirrel their way through the seabed, at 20/40cm depth until the fluke clogs or it hits and obstruction - it then lifts and drags.

This issue is straight forward and logical.

In harder substrates this then raises an issue - if the wind changes direction will the larger, more poorly set, anchor roll over on its side and need time to reset itself. The small anchor should simply slide round (see Maine Sails experiment). Its Noelex 'octopus' seabed - where his large anchor is hardly set at all - would the smaller anchor have been better as he would have been able to completely bury it?

In a straight line pull, lots of rode, the bigger anchor when increasingly loaded will set more and more deeply. What happens when the wind is veering, the rode is short (not enough room) and we have Miane sails very hard seabed (so hard an (old model?)alloy Spade will not set).

If the large anchor is 'too' large might the load imposed by the yacht (which will now depend on increasing wind speed) be sufficient to set the anchor deeper (or will its veering) upset what little hold it already has. Noelex octopus seabed.

The premise was 2 sizes bigger and if you have a 15kg Rocna then a 25kg Rocna is not that much bigger but a 33kg and 55kg Rocna is a significant difference, especially as Rocna are conservative to start with (so 33kg errs on the side of caution).

Its an area currently led by gut feel.

Jonathan

[foggysail]

Is it straight forward and logical? I have trouble with that.

The force required to bury each sort of represents a holding force at any particular anchor depth. Greater force only should only result in a deeper dig.

Problem is it might not dig deeper at all, it might just pop up. Am I missing something?

And I do agree with your comment---"Its an area currently led by gut feel." Shucks, I should not have revisited the small vs big after all these posts.

[darylat8750]

Bigger is better = best;-)
NOW THAT will HOLD. I just need a boat big enough to carry it!

[foggysail]

Originally Posted by darylat8750

Bigger is better = best;-)
NOW THAT will HOLD. I just need a boat big enough to carry it!

INDEED IT WILL

My 80 pound Manson Supreme also holds well

[JonJo]

Originally Posted by foggysail

Is it straight forward and logical? I have trouble with that.

The force required to bury each sort of represents a holding force at any particular anchor depth. Greater force only should only result in a deeper dig.

Problem is it might not dig deeper at all, it might just pop up. Am I missing something?

And I do agree with your comment---"Its an area currently led by gut feel." Shucks, I should not have revisited the small vs big after all these posts.

It is straight forward and logical that if the anchors are of the same design then if you apply a fixed force then the smaller surface area will set more deeply than a bigger surface area - but the hold will be that of the 'setting' force (the same for both). This becomes untrue if the setting force is sufficient that it exceeds the maximum hold of the small anchor then it will reach its max diving depth at a lower force and then squirrel through the seabed. So if in a given seabed the little anchor reaches its max diving depth at 300kg then its holding capacity will be 300kg if you were aiming at 400kg then the bigger anchor will set to 400kg and, obviously, have better hold - you might load the little one to 400kg but that will simply increase the speed of squirreling (if someone can think of a better word than 'squirreling' - be my guest)

Diving depth is a factor of a number of factors, including chain size - the bigger the chain the less depth.

The problem with my tests, 5kg and 15kg is that I have been testing an anchor 3 times the weight of the other (not sure what that is in surface area (need to check)) but the thesis is on the basis of about 60% increase in weight (not 3 times).

One thing that does happen - if you try to set an anchor in a difficult seabed and try to set too quickly such that its toe cannot engage - so it surfs over the seabed - then it might take a long time to engage (and a dragging yacht can move at worrying speeds). Fortunately most modern anchors do engage - unlike some of the older designs which could be confidently expected never to engage again.

Jonathan

[noelex 77]

Originally Posted by JonJo

I have tested extensively both the alloy and Steel spade '80' models and I can find no difference in setting ability between the 2 models. However I have been told that the alloy models have 'more' lead in the toe than originally - possibly to overcome early deficiencies? Equally it might be that your 'hard' seabeds are much harder than we have here. But personally I cannot fault the alloy Spade.

I agree with Maine Sail on this one. The steel Spade is an excellent anchor, but the aluminium Spade is not as good (it is still a reasonable anchor) In harder substrates it does not set as well as the steel version.

This experience in observing anchor performance is also shown in the independent anchor testing in the 2009 test the anchors tested in hard sand.

Steel S80 1,705 kg
Aluminium A80 1,052 kg

The aluminium Spade still put up a good result, but the test results show there are differences between the steel and aluminium versions. In very hard substrates the aluminium version will not set at all (as shown by Maine Sails video)

Spade are careful to point out that they do not recommend the aluminium version as a main anchor.

[noelex 77]

My experience has been that you do not not need to be concerned not setting a larger anchor. I dive (or occasionally check with bathoscope) so visually check the set of my anchor. It is very rare not to achieve an adequate set. The exception is where there is thin layer of sand over rock. Smaller anchors do not set any deeper in these conditions and the larger fluke area of the bigger anchor at least gives some reassurance.

If you really want to apply more force to the anchor (to set it like a larger boat would) you can use the momentum of the boat, but I don't normally do this. A steady gradual pull ending in full reverse is normally fine to set the anchor deep enough.