Poor little anchor

[noelex 77]

Originally Posted by Dockhead

The only disadvantage of the "heavy tip" of the ballasted, balanced anchor is cost. The weight is a benefit, right up to the point where the anchor is too heavy to manage. Weight by itself does not create holding power, but it greatly helps penetration and burying of the anchor.

Incorporating ballast into the fluke makes the toe of the anchor thicker and bulkier than it would otherwise be. This bulky structure is harder to force into some substrates, especially weed and hard sand. As the ballast forms a portion of the anchor weight it takes away from the weight of steel available to incorporate into the fluke, so anchors with substantial ballast tend to have a smaller fluke area than the same weight anchor in a design with minimal or no ballast. This reduces the performance in very soft substrates.

Of course there are also drawbacks to roll bars, in particular many boats cannot fit roll bar designs satisfactorily.

Originally Posted by Dockhead

The downside is balance, and the resistance created by the roll bar. Mantus, and it looks like, your anchor, use much thinner roll bars than the original roll bar anchors like Rocna. That looks like a good idea to me, both from the point of view of resistance to burying, and also from the point of view of balance.

The roll bar, like the ballast, does create some undesirable resistance to the anchor burying. The advantage of the roll bar is this resistance is not a factor until the anchor is well set and substantially buried. Ballast makes the toe of the anchor thicker and as this is the first part of the anchor to bury it always causes some resistance, even in the critical early stages when the anchor is just starting to grab the substrate.


Interestingly, the two approaches of ensuring the anchor adapts the correct setting position (ballast and roll bar) have examples with excellent performance. The steel Spade and the roll bar Rocna and Mantus are fantastic anchors, despite the very different approaches.

[noelex 77]

Originally Posted by Dockhead

High strength steel/fabricated sharp shank (e.g. Spade) -- not cheap at all, but really strong, maybe decent burying performance.

The fabricated shank of the Spade is a great feature and certainly contributes to the performance of this great anchor.

The Spade shank is constructed from mild steel (if I understand correctly) so I suspect the weight savings are only small (but still valuable).

It would be nice to see a roll bar anchor adopt this technology. Shank weight is most critical to an anchor that relies on ballast, such as the Spade, but there would still be significant gains if this was used on a roll bar anchor especially an even more sophisticated design, perhaps a fabricated shank from hi-tensile steel, or a flat shank from titanium. Titanium has come down in price recently so the later may be commercially viable for those prepared to pay a premium for performance.

Rocna have incorporated a sophisticated shank design into the Vulcan. I would not be surprised if they offer their original roll bar design with this as an option in the future. The bolt on shank of the Mantus also creates the possibility the company could release a superior shank design as an option for their M1 design.

Anyway, an anchorholic can dream .

[Dockhead]

Originally Posted by noelex 77

Incorporating ballast into the fluke makes the toe of the anchor thicker and bulkier than it would otherwise be. This bulky structure is harder to force into some substrates, especially weed and hard sand. As the ballast forms a portion of the anchor weight it takes away from the weight of steel available to incorporate into the fluke, so anchors with substantial ballast tend to have a smaller fluke area than the same weight anchor in a design with minimal or no ballast. This reduces the performance in very soft substrates.

Of course there are also drawbacks to roll bars, in particular many boats cannot fit roll bar designs satisfactorily.

The roll bar, like the ballast, does create some undesirable resistance to the anchor burying. The advantage of the roll bar is this resistance is not a factor until the anchor is well set and substantially buried. Ballast makes the toe of the anchor thicker and as this is the first part of the anchor to bury it always causes some resistance, even in the critical early stages when the anchor is just starting to grab the substrate.

Interestingly, the two approaches of ensuring the anchor adapts the correct setting position (ballast and roll bar) have examples with excellent performance. The steel Spade and the roll bar Rocna and Mantus are fantastic anchors, despite the very different approaches.

That's all quite reasonable (as always), however, don't forget the role of the SHAPE of structures. The bulk is not the only factor which influences the burying performance of structures. So the Spade anchor, although the "toe" of the anchor is, as you say, made bulkier by the inclusion of ballast into it, it is in this particular implementation very sharp, and long. Likewise the Spade shank, which is somewhat bulkier than a flat plate, but it's of triangular section and sharp. Based on a lot of experience with both Spade and Rocna I can say that the Spade penetrates and buries into any given seabed noticeably better than the Rocna, which has a less bulky but rather blunt tip, and a somewhat thinner but blunt shaped shank, and the plus the roll bar (which is considerably thicker than than the Mantus roll bar). Shape counts.



I have no experience with the Mantus, but without a single exception everyone I know who has used both Mantus and Rocna report that the Mantus has significantly better setting behavior than the Rocna. No doubt from similar factors -- Mantus fluke is sharper, roll bar is thinner. Wider roll bar base of the Mantus no doubt makes the roll bar more effective, too.



As to the weight of the ballast reducing fluke area per unit of weight -- I think that's also a plus, not a minus. It depends of course on what limits anchor size on your boat, so different cases will be different, but I would daresay that in most cases it is the bulk, not weight of the anchor which is the more significant limiting factor for handling, fitting in bow rollers, etc. Those on all-chain rode and using a windlass will hardly feel the difference in weight of an anchor of even tens of kg. My 45kg Spade weighs the same as only 13 meters of my chain. So I could probably increase the weight of the anchor by half again and not notice that much if the fluke area were the same -- it would just be like have out 7 meters of extra chain. It's the bulk which limits the size for me, and I guess this is true in most cases for most cruisers.



So if you compare two anchors of equal fluke area, and one of them is ballasted and heavier, then that one is going to have much better performance, all other things being equal, particularly setting behavior, even if the ultimate theoretical holding power is more or less the same.



This lines up also with what many experienced cruisers note, which is that bigger anchors, particularly when you get to 100 pounds, perform noticeably better than smaller ones. This disproportionate performance has apparently never been measured -- Alain and others have shown from testing that ultimate holding power in tests scales more or less according to fluke area. But nevertheless, is consistently reported by people with practical experience. In my opinion the reason for this is that larger anchors have LESS fluke area per unit of weight, which increases the amount of weight acting on a given fluke area, which I believe plays a large role in setting behavior, providing the downward force vector acting on the anchor during setting, something which I think must be crucial in getting the fluke engaged with the seabed, in many cases.



The other advantage of anchors ballasted with heavier materials like lead is DENSITY. In some soft seabeds, plain steel, which is about 8x as dense as water but only about 4x as dense as mud, almost floats. Lead is about half again as dense as steel, so about half again as heavy in air, but will be DISPROPORTIONATELY heavier in dense media like mud, which is about twice as dense as water. So lead, which is 1.4x as heavy as steel in air, and 1.6x as heavy as steel in water, will be almost twice as heavy as steel, 1.9x, in mud. Lead is a very good thing in anchor construction; tungsten, which is 1.6x as dense as lead, and more than twice as dense as steel, would be even much better.

[Dockhead]

Originally Posted by noelex 77

The fabricated shank of the Spade is a great feature and certainly contributes to the performance of this great anchor.

The Spade shank is constructed from mild steel (if I understand correctly) so I suspect the weight savings are only small (but still valuable). .

Actually the Spade is made of high strength steel. The point of this construction is to achieve high strength of the shank without unbalancing the anchor with a lot of extra weight above the center of gravity.


The result is described in the Mantus white paper:


"The results are presented in chart below. The HT-Steel Spade is not shown and only because its predicted Bending Strength is twice that of the highest ones shown so it falls far outside chart boundaries." https://www.mantusmarine.com/anchor-...applied-loads/


Whether being that much stronger than the shanks of other anchors is useful or not, depends on how strong the shank needs to be. For some use cases, it might be overkill.



I took the opposite side of this in a recent discussion about the strength of different through-hull constructions. I find ball valves screwed onto skin fittings to be strong enough for my use case. Groco adapter flanges make the construction stronger, but for my use case this extra strength is not needed. YMMV, as with anchor shanks.



Some people may take the same position about anchor shanks. Depending on what actually happens on your particular boat, this may be a reasonable position. But having bent a couple of anchor shanks, and having seen countless bent anchors, I think the extra strength of the Spade shank is not overkill, at least for my use case.


Now I have (maybe temporarily) retired my Spade, which is now disassembled and in my bilge; I have been given a 45kg Ultra for testing, The Ultra also has a fabricated hollow shank, but being made out of much weaker 316 stainless steel, the shank strength is only average (see the Mantus report). I will be finding out over the next year whether that's a problem or not.

[wsmurdoch]

Practical Sailor has done a little anchor shank bending. They have a few articles.



Bill

[Dockhead]

Originally Posted by wsmurdoch

Practical Sailor has done a little anchor shank bending. They have a few articles.Bill

Indeed, and highly relevant to this discussion:



https://www.practical-sailor.com/sai...ng-more-shanks


https://www.practical-sailor.com/sai...shank-strength


"However, one look at common large commercial anchors indicates some fundamental differences. Many commercial anchors have shank cross-sections with width-to-depth ratios of roughly 1:1. In other words, the cross-section is roughly square. Some large, modern commercial anchors might be rectangular in cross-section with width-to-depth ratios of 2:1.. . The shank cross-section of modern recreational anchors like the Supreme, Anchor Rights Excel, or the Rocna is a knife-blade by comparison, with long rectangular cross-sections of 10:1. Even the Fortress, which has a thicker-than-average shank to make up for the loss of tensile strength in aluminum, has a ratio of approximately 5:1."

[a64pilot]

I’m my opinion, the only “failed” anchor is one that broke loose and wasn’t holding the boat anymore.
Apply enough force and you can bend / break anything, personally I’d rather have something bend, than break.
High strength steels have a tendency to break as opposed to bend, everything is a compromise.

Poor “Little” anchor is probably correct, if it were a significantly larger anchor I doubt it would have bent, over sizing accomplishes things other than just increasing holding. Although I doubt this was bent by anchoring, plowing into the dock is more likely.

Unless you find a way to wedge an anchor into rocks, I can’t imagine bending one in that manner, now there was apparently a run of Rocna’s that weren’t correctly heat treated and many bent shanks.
Most modern anchors are just water jet cut from plate and welded together aren’t they?
There really isn’t a need for machining etc.
It’s an anchor, not a Space shutter main spar.

[Dockhead]

Originally Posted by a64pilot

. . . Unless you find a way to wedge an anchor into rocks, I can’t imagine bending one in that manner, now there was apparently a run of Rocna’s that weren’t correctly heat treated and many bent shanks.
Most modern anchors are just water jet cut from plate and welded together aren’t they?
There really isn’t a need for machining etc.
It’s an anchor, not a Space shutter main spar.

Well, having bent two different anchors in my cruising life, I think the strength of the shank is pretty important. Neither incident was associated with rocks -- both cases were sudden windshifts in strong conditions, with the anchors deeply buried. An anchor with a bent shank won't hold, so that's a failure. It would also be a serious bummer to have to spend $1000 or $2000 or whatever to replace an anchor which bent.

I don't think water cutting simple flat plates is a very good way to make an anchor shank. It might be "good enough" depending on the use case, grade of steel, actual thickness of the plate, but it is a highly inefficient way to produce strength in the lateral plane. To be really strong in the lateral plane, an anchor shank would have to be hella thick and heavy, which further unbalances the anchor. So as bad as the CQR was as an anchor, at least it had a well designed shank. I believe those were drop-forged, not machined.

Originally Posted by a64pilot

. . Poor “Little” anchor is probably correct, if it were a significantly larger anchor I doubt it would have bent, over sizing accomplishes things other than just increasing holding. . .

I agree entirely.

[Shrew]

Originally Posted by a64pilot

if it were a significantly larger anchor I doubt it would have bent, over sizing accomplishes things other than just increasing holding.

However, there is the law of "While some is good, more is not necessarily better" . There is a spot in the range of oversizing that sits between 'so large it's a mooring' and 'Properly over sized'. In that space, an anchor too large for the boat can't actually be set by the boat.

There are inherent downsides to over sizing an anchor beyond fitting on the bow pulpit.

[Dockhead]

Originally Posted by Shrew

However, there is the law of "While some is good, more is not necessarily better" . There is a spot in the range of oversizing that sits between 'so large it's a mooring' and 'Properly over sized'. In that space, an anchor too large for the boat can't actually be set by the boat.

There are inherent downsides to over sizing an anchor beyond fitting on the bow pulpit.

We can imagine that an anchor could be so big that the boat couldn't set it, but I imagine that occurs at a size which is far larger than what can fit in our anchor rollers. I don't know any sailing yachts with anchor rollers which can accomodate an anchor which is "so large it's a mooring".


So I for one will stand by my statement that cruisers who cruise long term and off piste should have the biggest anchors they can fit in their anchor rollers and can realistically handle. This lines up with what virtually all experienced remote cruisers say including Dashew, Morgan's Cloud, etc. etc. etc.

[a64pilot]

The CQR has an I beam shank, an I beam is strong in its vertical axis, not laterally, you never see an I beam placed on its side in construction, so the I beam isn’t adding much to lateral strength, it’s there for a vertical load, but I’d suspect you don’t see bent shanks on CQR’s more because of the knuckle joint than shank construction.
Drop forging, machining, whatever it all adds unnecessary expense to manufacturing.

Here are pics of my anchor, the shank is approx three times thicker than the links of the 5/16 chain it’s attached to, when you include the cross sectional area of the shank , the shank shouldn’t be bent, the chain is likely to stretch first.
Additionally if you look at the end of the anchor where it’s cut out for the swivel, that due to lack of material ought to be the weakest area, but it’s still several times more metal than the chain.

[barnakiel]

I have just measured the shank of our anchor.


It is well over 1 inch at the flukes and narrows down to 3/4 of an inch towards the shackle hole. I think it is forged. (A Belgian Bruce).



Our boat is only 26'.


Who ever designed and build that bendy anchor, as well as that boat owner, clearly acted to a cost, which is always a bad choice given the risks involved in possible failure.

b.

[noelex 77]

Originally Posted by Izikalvo

our warranty is more than generous, again I don't want to talk about it here, you can read it on our web site if you wish.

As an anchor manufacturer, if you start a thread about an opposition’s anchor that is bent, I think it is an important to clarify how the Viking warranty would apply in a similar situation.

The Viking warranty was not entirely clear from the website, but my understanding is if a Viking anchor is stuck under a rock and bent this would not be covered under the warranty (unless there was also a fundemental manufacturing defect).

Most marine goods have a similar warranty, but leading anchor brands have a much more extensive warranty that is more like an insurance policy. Typically they will replace the anchor with no questions no matter how the bend or damage occured. Some will do this at no or a very nominal charge for postage, others require the bent anchor to be returned, which adds to the expense.

The type and details of the warranty should be taken into account when anchor shopping.

[a64pilot]

Originally Posted by Shrew

However, there is the law of "While some is good, more is not necessarily better" . There is a spot in the range of oversizing that sits between 'so large it's a mooring' and 'Properly over sized'. In that space, an anchor too large for the boat can't actually be set by the boat.

There are inherent downsides to over sizing an anchor beyond fitting on the bow pulpit.

Almost by definition if it’s too large to set, then it’s too large to drag, because setting, is dragging.
As it seems the whole point of an anchor is to not drag, then it can’t be too large from an anchoring point of view.
The reality is how much can the boat and your windlass etc handle, as many boats have windlasses that the builder installed, and they don’t often overdose due to cost, they can’t handle much anchor, ditto for the roller etc, many manufacturers install quite small gear.

Then don’t forget some people are very weight sensitive and do without a lot of “stuff” to stay light and keep performance up. These people are unlikely to hang a big heavy anchor and hundreds of lbs of chain in the locker.

Then many don’t cruise, well they may cruise but it’s from one Marina to another, I walk around here at the Marina I’m at and see tiny anchors on 60’ Motor yachts, really large boats with a tiny CQR, and it’s obvious the only reason it’s there, is your supposed of have an anchor.

But for those that value holding over weight, and actually do anchor even in bad weather, they just about can’t have too big an anchor, so long as the boat can handle it.
By Rocna’s chart I should use a 20 or 25 kg anchor, I have a 25 kg as a backup and use a 40kg. Which is I think three sizes larger than recommended, and the 40 sets as easily as the 25, apply the same force and the 25 digs deeper of course, but only time I’ve ever had trouble setting the 40 is in grass, and that’s not because of its size, it’s because a Rocna doesn’t set or hold well in grass.

[Dockhead]

Originally Posted by a64pilot

Almost by definition if it’s too large to set, then it’s too large to drag, because setting, is dragging.
As it seems the whole point of an anchor is to not drag, then it can’t be too large from an anchoring point of view.
The reality is how much can the boat and your windlass etc handle, as many boats have windlasses that the builder installed, and they don’t often overdose due to cost, they can’t handle much anchor, ditto for the roller etc, many manufacturers install quite small gear.

Then don’t forget some people are very weight sensitive and do without a lot of “stuff” to stay light and keep performance up. These people are unlikely to hang a big heavy anchor and hundreds of lbs of chain in the locker.

Then many don’t cruise, well they may cruise but it’s from one Marina to another, I walk around here at the Marina I’m at and see tiny anchors on 60’ Motor yachts, really large boats with a tiny CQR, and it’s obvious the only reason it’s there, is your supposed of have an anchor.

But for those that value holding over weight, and actually do anchor even in bad weather, they just about can’t have too big an anchor, so long as the boat can handle it.
By Rocna’s chart I should use a 20 or 25 kg anchor, I have a 25 kg as a backup and use a 40kg. Which is I think three sizes larger than recommended, and the 40 sets as easily as the 25, apply the same force and the 25 digs deeper of course, but only time I’ve ever had trouble setting the 40 is in grass, and that’s not because of its size, it’s because a Rocna doesn’t set or hold well in grass.

I agree with all the logic here, and besides that, this lines up with my experience over many years.


I had a 121 pound Rocna for a while on this boat. This was just about as big an anchor as I could fit. Setting it was no problem; initial set required no more than 1500 RPM, same as smaller anchors. I have no doubt that a 176 pound anchor would set just fine, from my boat, if I could somehow stow it.


In my experience, the bigger they are, the better they cut into the seabed and hold.