Anchors, Guns and Strippers!!!!

[Dockhead]

Originally Posted by rslifkin

An oversize anchor will likely be easier to set (although if the bottom is really good it might not matter much, as any anchor will start to dig easily). Design will be the biggest impact on how much distance it takes to set once it starts to bite the bottom. But on a bad bottom (weeds, dense gravel, etc.), the heavier anchor should sink through the crap more easily, meaning it will go from sliding across the crappy bottom to starting to dig in more easily (even though the big and small versions of the same will set similarly once they start to dig).

However, there is a point where given a big enough anchor, you'd have trouble getting it dug in well, which could end up causing a holding problem if you get a wind or current reversal before it gets loaded enough to dig in further. However, unless you have a particularly underpowered boat, you probably can't fit a big enough anchor for this to become a real problem.

Personally, I've found that light weight for their size anchors, such as a Fortress, hold well, but can be a little more tricky to set. The Fortress has a ton of holding power, especially for how light it is. But because it's light weight, in some bottoms you have to be a bit careful and gentle setting it, otherwise you end up just dragging it across the bottom without it really digging in. Once it starts to dig, then you can load it up a bit more to dig it in deeper.

All this exactly corresponds to my experience.


Too big to set properly? It would have to be an awfully underpowered boat and grossly oversized anchor, in my opinion. Probably not even possible.



I had a 121 pound Rocna for a couple of years. I only needed a fraction of my 100 hp to set it, even in difficult bottoms. I don't think setting it is what forms the upper limit on anchor size -- I think it's fitting it in your bow roller and handling it. The advice to use the biggest anchor you can possibly handle -- as pronounced by Dashew and others -- is absolutely correct in my opinion.



Like many of us, I use a Fortress as a kedge and love it, but your caveats are exactly correct.

[Mike OReilly]

Originally Posted by Dockhead

I like the Spade and have used Spades for decades but I'm not selling them. In my experience all the new generation anchors work well. I've never used the Mantus but have heard consistently stellar reports about them.

Thanks DH. That's been my view and experience as well. But as my old Rocna gets more beat up I'm beginning to think about my next scoop-style purchase.

As for the bigger discussion, I agree with you both (DH & rslifkin). As I said earlier, this notion that engine size limits anchor size is true in theory, but in practice is very unlikely to be a significant factor.

If your boat really is significantly under-powered, then I would consider this factor when selecting your bower. But for the vast majority of boats this is not going to be the key limiting factor.

[Izikalvo]

Originally Posted by wsmurdoch

https://amesweb.info/Materials/Density_of_Steel.aspx
Except for the tungsten and molybdenum tool steels, they all look about the same to me. (Both tungsten and molybdenum are quite dense at 19.3 and 10.3 g/cc.) What steel were you thinking of?

Bill

Carbon steel, check here https://www.westyorkssteel.com/techn...on-calculator/
or any other Mpa/Ksi table

some companies use as low as 350 Mpa yield strength steel, fairly light but not much tensile (too much plastic behavior, less elastic characteristics).

[Dockhead]

Originally Posted by Izikalvo

Carbon steel, check here https://www.westyorkssteel.com/techn...on-calculator/
or any other Mpa/Ksi table

some companies use as low as 350 Mpa yield strength steel, fairly light but not much tensile (too much plastic behavior, less elastic characteristics).

Yes, but you said:

Originally Posted by Izikalvo

Also, as harder and denser as the steel is used, its weight gets heavier.
Meaning that the steel used by the manufacturer also contributes to the general weight of the product, in this case, anchor, see here.

which seems to contradict WSMurdoch's table, showing that all carbon steel has almost the same density.


Is the table wrong, or did you mispeak?

[Izikalvo]

Originally Posted by Dockhead

Yes, but you said:





which seems to contradict WSMurdoch's table, showing that all carbon steel has almost the same density.


Is the table wrong, or did you mispeak?

Please check again, the table and calculator are right and I am not misspoken or miss wrote (checked again).
To make a long story short and to end this minor and not so important discussion a Viking 10 anchor made of Hardox 450 steel (1250 Mpa) weighs 10.7 Kg, and made of F700 steel (750 Mpa) weigh 9.5Kg, as the anchors get bigger and heavier the differences get bigger.

[Lodesman]

Originally Posted by noelex 77

The suggestion that large anchors are going to take a long time to set and therefore are unsuitable is not correct. Take a look at my anchor photos and judge for yourself.

Nice pic. What's the bottom? Soft sand? Silt?
While it looks set, looks can be deceiving. If that's a layer of loose silt over hard pan, it might not be fully set.
I don't know what to tell you - that was the verdict by PBO - did you read the article? One of the anchors tested was a Rocna, which I feel is in the same league as the Mantus. The suggestion was not that large anchors take a long time to set - it's that the larger the anchor, the greater the distance to set it; a counterpoint to some of the suggestions here that larger anchors set faster.

The connection is to the Viking anchors link - who suggest that if your anchor is too big, you'll not have enough power to set it fully, and therefore leave it more likely to unset. I'm not sure I fully buy the argument, maybe an issue with difficult-to-set-in bottom conditions.

[noelex 77]

Originally Posted by Lodesman

Nice pic. What's the bottom? Soft sand? Silt?
While it looks set, looks can be deceiving. If that's a layer of loose silt over hard pan, it might not be fully set.

The photo was taken in Greece. Most of the sand in the area is hard. At the location pictured the sand was a little softer than average for the area so I would classify the substrate as medium or medium firm sand. Nothing unusual.

You need to careful about using the term “fully set”. The setting process using the yacht’s engine only typically puts the equivalent force of about 25-30 knots of wind. After the setting process has finished you don’t want the anchor to have dived down and reached its maximum depth. If this did occur the anchor would have also reached its maximum holding capacity and there would be no reserve for a wind stronger than about 25-30 knots.

Originally Posted by Lodesman

I don't know what to tell you - that was the verdict by PBO - did you read the article? One of the anchors tested was a Rocna, which I feel is in the same league as the Mantus. The suggestion was not that large anchors take a long time to set - it's that the larger the anchor, the greater the distance to set it; a counterpoint to some of the suggestions here that larger anchors set faster.

Professor Knox has written several good anchoring articles. In the one you linked to, he comments that “Generally the UHC (ultimate holding capacity) is reached after an anchor has ploughed 10 to 20 fluke lengths”. Therefore (if he is correct with this observation) a larger anchor with a larger fluke length than an otherwise identical but smaller anchor will take a longer distance to reach its ultimate holding capacity.

However, the ultimate holding capacity of the larger anchor will of course be higher. It is inconclusive from his comments if a fixed force (for example the force generated by the yacht engine in reverse) would cause a smaller anchor to move more while setting because this fixed force is higher percentage of the ultimate holding capacity of a small anchor, or cause the large anchor to move more because its fluke size is greater. So I don’t think the article helps clarify the issue.

Personally, after many hours of anchor observation I am not sure anchor size has much impact on setting distance for most substrates. This fits in with the most likely conclusion (for a set force) from the article by Professor Knox.

Any size differences are overshadowed by the vast differences in setting distance seen with different anchor designs. For example, below is a typical convex plow anchor (in this case a Kobra). You can see the much longer setting distance compared to the Mantus design.



However, the comments above are for typical substrates. Large anchors do set much more easily in some difficult substrates. For example, in thick weed the weed roots provide far more impediment to a small anchor setting than an otherwise identical large anchor. So the large anchor will set more rapidly and with greater reliability. The same is true for many other more challenging substrates. I suspect this factor is probably responsible for the overwhelming reports in this and other threads reporting that large anchors set more rapidly than smaller anchors.

[Dockhead]

Originally Posted by noelex 77

The photo was taken in Greece. Most of the sand in the area is hard. At the location pictured the sand was a little softer than average for the area so I would classify the substrate as medium or medium firm sand. Nothing unusual.

You need to careful about using the term “fully set”. The setting process using the yacht’s engine only typically puts the equivalent force of about 25-30 knots of wind. After the setting process has finished you don’t want the anchor to have dived down and reached its maximum depth. If this did occur the anchor would have also reached its maximum holding capacity and there would be no reserve for a wind stronger than about 25-30 knots.

Professor Knox has written several good anchoring articles. In the one you linked to, he comments that “Generally the UHC (ultimate holding capacity) is reached after an anchor has ploughed 10 to 20 fluke lengths”. Therefore (if he is correct with this observation) a larger anchor with a larger fluke length than an otherwise identical but smaller anchor will take a longer distance to reach its ultimate holding capacity.

However, the ultimate holding capacity of the larger anchor will of course be higher. It is inconclusive from his comments if a fixed force (for example the force generated by the yacht engine in reverse) would cause a smaller anchor to move more while setting because this fixed force is higher percentage of the ultimate holding capacity of a small anchor, or cause the large anchor to move more because its fluke size is greater. So I don’t think the article helps clarify the issue.

Personally, after many hours of anchor observation I am not sure anchor size has much impact on setting distance for most substrates. This fits in with the most likely conclusion (for a set force) from the article by Professor Knox.

Any size differences are overshadowed by the vast differences in setting distance seen with different anchor designs. For example, below is a typical convex plow anchor (in this case a Kobra). You can see the much longer setting distance compared to the Mantus design.



However, the comments above are for typical substrates. Large anchors do set much more easily in some difficult substrates. For example, in thick weed the weed roots provide far more impediment to a small anchor setting than an otherwise identical large anchor. So the large anchor will set more rapidly and with greater reliability. The same is true for many other more challenging substrates. I suspect this factor is probably responsible for the overwhelming reports in this and other threads reporting that large anchors set more rapidly than smaller anchors.

This is just my subjective experience, but in support of what Noelex has written here, and for whatever little it may be worth, my own experience has been that smaller anchors, even of the same type, are more likely to skip or slide over the bottom before biting in. The smaller the anchor, the more careful you have to be not to have too much way on, in my experience, and the more coaxing you have to do in less than perfect bottoms. The bigger the anchor, the less this skipping and sliding. Over 100 pounds it seems there is almost no skipping unless you are on smooth stone (unfortunately not uncommon in the Northern Baltic).



And with kelpy bottoms -- the bane of my latitudes -- smaller anchors get stuck whereas larger, sharper anchors are more likely to cut through. My 100 pound Spade almost always gets through a reasonable thickness of kelp now, which previously prevented me from anchoring no matter how hard I tried.

[Mike OReilly]

For what it's worth, my experience also lines up with noelex's excellent observations (and incredible contribution to anchoring knowledge), and DH's as well.

[Izikalvo]

Originally Posted by Izikalvo

Please check again, the table and calculator are right and I am not misspoken or miss wrote (checked again).
To make a long story short and to end this minor and not so important discussion a Viking 10 anchor made of Hardox 450 steel (1250 Mpa) weighs 10.7 Kg, and made of F700 steel (750 Mpa) weigh 9.5Kg, as the anchors get bigger and heavier the differences get bigger.

Dockhead, checked again (and again), you are right, I have entered the wrong data, and for the anchors, there is a different thickness of flukes that we used while developing, I apologize, you are right, differences are minor.

[wsmurdoch]

Izikalvo,

In note no 173 of this thread you say, "Also, as harder and denser as the steel is used, its weight gets heavier. Meaning that the steel used by the manufacturer also contributes to the general weight of the product, in this case, anchor".

At https://www.vikinganchors.com/knowle...inc-in-anchors you say, "Higher tensile metals are denser and therefore heavier than lower tensile metals."

In my experience the density of all steels (except those alloyed with large amounts of extremely dense metals such as tungsten) do not deviate significantly from 7.8 g/cc.

On the internet I checked the density of steels in the SAE 10X0 series ranging from SAE 1010 to 1090 and in tensile strength from 47,000 psi to 122,000 psi. All had listed densities of 7.87 g/cc.

I contacted Tech Support at the SSAB Corporation by email, and they replied that the densities of their Hardox 450 and Stenx 750 F proprietary steels were approximately 7.850 g/cc.

I believe that your claims that the use of a higher density steel which contributes to a superior Viking Anchor in both this thread and on the Viking Anchor website are false.

Bill Murdoch

[Lodesman]

Originally Posted by noelex 77

You need to careful about using the term “fully set”. The setting process using the yacht’s engine only typically puts the equivalent force of about 25-30 knots of wind. After the setting process has finished you don’t want the anchor to have dived down and reached its maximum depth. If this did occur the anchor would have also reached its maximum holding capacity and there would be no reserve for a wind stronger than about 25-30 knots.

This is a good point. I don't know how most anchor makers define their sizing recommendations, but I believe Rocna's rec's are meant to hold in 50 kts (in good holding iirc), so assume they have allowed that leeway.


Professor Knox has written several good anchoring articles. In the one you linked to, he comments that “Generally the UHC (ultimate holding capacity) is reached after an anchor has ploughed 10 to 20 fluke lengths”. Therefore (if he is correct with this observation) a larger anchor with a larger fluke length than an otherwise identical but smaller anchor will take a longer distance to reach its ultimate holding capacity.

However, the ultimate holding capacity of the larger anchor will of course be higher. It is inconclusive from his comments if a fixed force (for example the force generated by the yacht engine in reverse) would cause a smaller anchor to move more while setting because this fixed force is higher percentage of the ultimate holding capacity of a small anchor, or cause the large anchor to move more because its fluke size is greater. So I don’t think the article helps clarify the issue.

Agreed, I alluded to that. It would be wonderful if there was a comprehensive set of controlled tests that answer all these questions. How busy are you?

Personally, after many hours of anchor observation I am not sure anchor size has much impact on setting distance for most substrates. This fits in with the most likely conclusion (for a set force) from the article by Professor Knox.

Any size differences are overshadowed by the vast differences in setting distance seen with different anchor designs. For example, below is a typical convex plow anchor (in this case a Kobra). You can see the much longer setting distance compared to the Mantus design.

Quite right, but I think our argument centres around the difference size makes in a given design.

However, the comments above are for typical substrates. Large anchors do set much more easily in some difficult substrates. For example, in thick weed the weed roots provide far more impediment to a small anchor setting than an otherwise identical large anchor. So the large anchor will set more rapidly and with greater reliability. The same is true for many other more challenging substrates. I suspect this factor is probably responsible for the overwhelming reports in this and other threads reporting that large anchors set more rapidly than smaller anchors.

I think Dockhead has also said this, and it follows logically. Heavy stalks would presumably require a given amount of force to cut through them, or to even move them out of the way. I could see how the Spade type anchor would be superior to the roll-bar types as it should tip up on a finer point, making total weight less of a factor in its efficiency. Presumably a critical mass would be required for any given vegetation bed - and any weight over that offers no real advantage. More fodder for an enterprising tester.
I was hoping someone would have been able to post an article where such a test has been done.

[Dockhead]

Originally Posted by Izikalvo

Dockhead, checked again (and again), you are right, I have entered the wrong data, and for the anchors, there is a different thickness of flukes that we used while developing, I apologize, you are right, differences are minor.

No apologies necessary. We all learn from these discussions, and even the mistakes are useful. Cheers.

[noelex 77]

Originally Posted by Lodesman

I could see how the Spade type anchor would be superior to the roll-bar types as it should tip up on a finer point, making total weight less of a factor in its efficiency.

There has been a great deal of debate about which anchor is better in weed, Rocna or Spade. There is a wide range of sometimes very strong views on both sides from people who’s judgment and experience I respect.

In many ways this is not surprising. Weed varies enormously from location to location and often the important underlying substrate is ignored. This makes a significant difference. If it is rock then no anchor design can penetrate this.

The other issue is that most anchor designs will hold in thick weed quite reliably just by gripping the weed itself, but this only applies in moderate winds. Thus someone who frequently anchors in thick weed can describe his anchor as excellent because it has reliably held the boat in 25-30 knots of wind on numerous occasions. However, to hold in strong wind the anchor typically needs to penetrate the weed and dig into the substrate below.

Even when diving, I find assesing the performance in weed difficut. The anchor can look nicely buried without penetrating the substrate below the weed. The only way to tell is to reach down and feel the fluke, working your way to the tip. Of course I cannot show this in photos.

Take a look at the anchor in the photo. It is CQR lying on its side (not that this is obvious). The anchor is basically not working as it was designed at all. Any odd shaped lump of steel with a similar weight and surface area would probably have as much grip . Nevertheless, the weed will hold the anchor up to quite reasonable wind strengths and it is easy for the owner to praise his anchor’s performance in weed without realising what a terrible job the anchor is doing.

The Spade relies primarly on fluke ballast to adopt the correct setting position. The major drawback here is that this ballast makes the fluke of the Spade very bulky. This bulky fluke has to forced between the weed roots before the anchor can penetrate the substrate below. This is the key to holding in strong wind. Despite this, the Spade does a good job in weed. Alain Poiraud did a brilliant job in designing the steel Spade and it seems to be able to overcome these fundemental design limitations. Most anchors that rely on ballast to achieve the correct setting position have poor performance in weed. The convex plow anchors are generally terrible. They don’t have design brilliance of the Spade to offset the bulkier fluke.

[noelex 77]

It is hard to show this accurately in photos, you need to really look at the anchors for yourself.

Nevertheless, the photos below give some idea. You can see the much bulkier fluke of the Spade compared to the Rocna. I will try and download a photo of the Mantus for another comparison.