Anchor design and misnomers

[noelex 77]

Originally Posted by downunder

Not sure I follow the compression logic.

I didn't think that sand could be compressed. That logic escapes me. Can't see it has anything to do with the issue.

You missed out, as a kid, building sandcastles. I seem to remember compressed sand , or more correctly a sand water mix, having different properties

Banging down and compressing the sand in a bucket was a required skill for a six year old trying to build a sandcastle that his sister, or the tide would ultimately end up destroying

[Cotemar]

Originally Posted by Kettlewell

Take a look here at at the Vryhof website and watch some of the animations too. In the side view these things look remarkably like a Delta/Excel. Yes, they don't have the center ridge, but if you took out that center flat area and joined the sides it would be quite similar to the Delta shape, though with flatter angles. I wonder if anyone has tried a yacht-sized anchor with a shape like this but with single center shank?

I say, leave the double shank, so you do not have to worry about bent shanks.

Make a 45 lb size I a can try on my boat and I am their. Not sure what would happen if it's just layed on it's back. May need a roll bar to get the tip facing down.

[estarzinger]

Originally Posted by Delfin

From the Sarca website:

"Q. Sarca Excel looks similar to a delta style or plough anchor, why is the holding power so much greater?
A Take a second look,

Sarca Excel has a single rear plain fluke that doesn’t plough, this unique design compressors the substrate and forces it over its rear, incredible pressure is applied to the convex surface area of the Excel, when this happens these forces not only multiplies the anchors holding power but drives the anchor down filling in behind it.

Excel also incorporates extended and slightly concave cutting edges. You will further notice the toe of the Excel is turned down also with extended cutting edges. The turn down of the toe allows the anchor to set in most cases within the length if its fluke, it has low resistance when penetrating and will readily bed itself in a wide variety of ocean type substrates, sand, mud, reef, gravel and many more."

Well if those are the significant differences vs the delta then it is clearly an "improved copy" and I will remain a bit skeptical about how much improved . . ..

The first (single angle rear fluke), is a simplification of a feature the delta already has (delta has a double angle rear fluke).

The second (cutting edges) probably is a clear improvement, for setting in hard sand, which is common in parts of AUS, so may in fact explain the AUS appeal. But you could take a grinder and put a better cutting edge on many anchors, including the delta, if that was a priority type of bottom. Cutting edges tend to be vulnerable on anchors and degrade over time, which is why most anchors are designed for/with blunter more durable cutting edges, and why (as you well know) ROCNA provided specially sharper edges for the anchors it sent to anchor tests.

I would be interested to know tip weight and surface area vs the same sized delta.

But if those above are the two unique selling points I wish them well and I will move on to looking at other designs.

Note: by the way, I think the delta is a pretty decent anchor, one of the major "acceptable" anchors. We carried one for a decade on hawk, and only got rid of it in the big anchor shuffle when the Bruce got cracked. So, an "improved delta" is also probably a quite decent anchor. Just not what I am looking for.

[Delfin]

Originally Posted by noelex 77

High holding power anchors (HHP) and super high holding power anchors (SHHP) are terms used by anchor manufacturers so its important to realise what they mean.

SHHP in particular sounds very impressive, but anchor corresponding to this standard only has to hold 4x the force of a standard stockless anchor. That's like the one shown in the photo. They store well in a hawse pipe, but don't work very well when scaled down to the sizes used on yachts.

Another definition is that a SHHP power anchor has to hold 6x its mass.
For say a 35lb anchor that's 210 lb. the yachting world tests showed similar sized anchors were holding over 5000lb.

These standards are expensive for manufactures to obtain, but I don't think they mean much

I didn't know that, thank you. I guess I'll have to rely on anecdotal experience, which for the Excel seems universally positive, to the point of raving, while for the Delta, somewhat more mixed, although as Evans notes the Delta is certainly in the "ok" class. Based on what I know today, when we replace the current hook I would opt for an Excel just based on the reports from users. There are a number of Aussies that post on Trawler Forum and they all seem to confirm the performance of the Excel that the company describes in their videos, and I have yet to find a negative report on that anchor anywhere else. There might be some, but I haven't seen them.

I am quite sure that the performance of an anchor can be highly variable depending on its weight. The Bruce type anchors are generally not considered much of a hook, until you get into the heavier weights. Our 176# Claw has held our 65 ton boat in 55 knots of wind without budging, and has never failed to set instantly. However, what I do assume is that if a design is highly efficient at lower weights, it will only become more so when it is sized up. Gravity reigns supreme.

[Delfin]

Originally Posted by estarzinger

Well if those are the significant differences vs the delta then it is clearly an "improved copy" and I will remain a bit skeptical about how much improved . . ..

The first (single angle rear fluke), is a simplification of a feature the delta already has (delta has a double angle rear fluke).

The second (cutting edges) probably is a clear improvement, for setting in hard sand, which is common in parts of AUS, so may in fact explain the AUS appeal. But you could take a grinder and put a better cutting edge on many anchors, including the delta, if that was a priority type of bottom. Cutting edges tend to be vulnerable on anchors and degrade over time, which is why most anchors are designed for/with blunter more durable cutting edges, and why (as you well know) ROCNA provided specially sharper edges for the anchors it sent to anchor tests.

I would be interested to know tip weight and surface area vs the same sized delta.

But if those above are the two unique selling points I wish them well and I will move on to looking at other designs.

Note: by the way, I think the delta is a pretty decent anchor, one of the major "acceptable" anchors. We carried one for a decade on hawk, and only got rid of it in the big anchor shuffle when the Bruce got cracked. So, an "improved delta" is also probably a quite decent anchor. Just not what I am looking for.

What characteristics are you looking for in an anchor other than weight efficient setting and holding in a variety of sea beds?

I agree you can sharpen the edges of any anchor and as noted, Rocna always insisted on shipping sharpened 'ringers' to test sites for that purpose. However, the tip of the Excel also points down, so perhaps that explains the difference in holding, at least the holding as reported by users.

[estarzinger]

Originally Posted by Delfin

What characteristics are you looking for in an anchor other than weight efficient setting and holding in a variety of sea beds?

I am very open to new ideas.

I think there is some value to the Bruce's multi point contact with the bottom, I think there is some value to the spade/ultra weighted tips. I like an anchor that is designed to be used in a tandom set-up. I like an anchor that does short scope well. I don't want a roll bar. And it should be inexpensive

[Cheechako]

I dont think the compressive forces on a convex holding area as being that helpful. The anchor isnt that deep and the weight of the sand above can easily move up... thus relieveing any compression benefit. Again... once dug in it's all about surface area prevented to the pulling force. Think of it this way, while you boat is moving say 5 knots, take a 1/4" x 2" piece of wood batten. present the 1/4" side to the water and there is minimal resistance. Turn it so the 2" side is against the flow and there is huge resistance.

[downunder]

Originally Posted by noelex 77

You missed out, as a kid, building sandcastles. I seem to remember compressed sand , or more correctly a sand water mix, having different properties

Banging down and compressing the sand in a bucket was a required skill for a six year old trying to build a sandcastle that his sister, or the tide would ultimately end up destroying

Certainly did not spend so much time making sandcastles but swimming/diving the islands/GBR another issue.

To my understanding we use anchors in a sand water mix and would be interested for someone to apply physics to indicate the amount of compression to sand that can occur. I would have thought under water very little if any.

Soil science texts would show it up if one could dig one up. Water just fills the gaps between the sand particles otherwise filled by air. Little if no compression. Mud/clay particles will fill that space between the individual sand grains forming a soil and give soil its water holding capacity.

No doubt Cotemar has spent considerable time on his drawings however we are definitely not playing sandcastles here.

[Dockhead]

Originally Posted by noelex 77

Someone with a reasonable knowledge of aerodynamics could do just that.

I think in a similar way we can intelligent comments about the performance of anchors based on their geometry. This is easier to do when the design is extension of an existing design rather than a radical new concept (like say the Hyrobubble).

There are a number of anchors that have a fixed convex design blade. The Delta and Kobra are very popular designs in Europe. These two anchors share many common characteristics.

In a similar way the concave roll bar anchors Rocna, Manson supreme, and Mantus also show similar performance.

We can evaluate the anchors further looking at weight distribution tip sharpness, blade area etc.

A good aircraft (or yacht) designer can predict the performance of their creation very accurately before its ever left the drawing board. We are not at at that level of sophistication when evaluating anchors, but I believe we can come to some useful predictions.
Once an aircraft is constructed its speed, climb rate, fuel consumption etc can be accurately measured. Evaluating anchor performance is far less precise, so concentration on those designs contain favourable characteristics for further evaluation is especially helpful.

This does not mean that all convex anchor will perform the same. Sharper and more complex tip profiles, better weight distribution, tweaks in the geometry can all achieve worthwhile improvements and produce class leading performance.

But I am skeptical that they can elevate themselves above the limitations of their class that are governed by the fundamental geometry.

Time will tell.

I'm afraid I can't agree. Who would have though that this:



Would be superefficient, hypermaneuverable. I really don't think that we laymen can tell by looking and guessing, whether a wing or an anchor will work well, or not.

[Delfin]

Originally Posted by estarzinger

I am very open to new ideas.

I think there is some value to the Bruce's multi point contact with the bottom, I think there is some value to the spade/ultra weighted tips. I like an anchor that is designed to be used in a tandom set-up. I like an anchor that does short scope well. I don't want a roll bar. And it should be inexpensive

Once buried, I doubt one could improve on a Bruce design, so I'm with you there. I also agree on weighted tips, which the Excel has. I believe the Delta does as well, does it not? The tandem question is a whole other conversation, although the Excel does have the attachment point where you need it to be (low) if that is your fancy. Agree on the roll bar as they act as a backboard to collect goo and work to keep the anchor from burying itself. Inexpensive? You're joking, right?

I suppose it is possible for an anchor to be too good at setting. I spoke with a Coastie who said they had to abandon their Fortress on a 100' cutter after a three day blow because it dug itself so deep they couldn't retrieve it. Perhaps it got stuck on something, but he said it was because it just went so deep their windlass couldn't handle the retrieval load.

[Kettlewell]

I suppose it is possible for an anchor to be too good at setting. I spoke with a Coastie who said they had to abandon their Fortress on a 100' cutter after a three day blow because it dug itself so deep they couldn't retrieve it. Perhaps it got stuck on something, but he said it was because it just went so deep their windlass couldn't handle the retrieval load.

That is a problem with a Fortress and a Danforth--after Hurricane Bob it took me most of a day to retrieve two Fortress FX-23 anchors. Judging from the mud on the chain where it was just caked solid I estimate that both anchors were around six feet down in firm mud. Nothing would have broken those anchors free--something would have broken first.

[noelex 77]

Originally Posted by Dockhead

I'm afraid I can't agree. Who would have though that this:

Attachment 58001

Would be superefficient, hypermaneuverable. I really don't think that we laymen can tell by looking and guessing, whether a wing or an anchor will work well, or not.

Fighter planes are designed to inherently unstable and I don't see anything incongruous in the design.
There are many things that deduced even from a simple photograph. For example the jet is shown with flaps extended. This increases the camber of the wings ( makes them more concave in anchor talk). This increases both the lift and drag and makes the wing more suitable for low speed flight ( a relative term for a supersonic jet). I would therefore deduce that the aircraft in the photograph has been optimitised for relatively slow speed flight. The jet was likely in takeoff, landing , or slow speed manoeuvring mode.

I have little knowledge of supersonic fighter jets, but some basic parameters such as details about the shape of the wing section, thrust, mass etc and I could make some predictions about the performance. An experiencienced designer given detailed parameters should be able to predict the performance characteristics within a few percent, before the plane has ever been built, or flown.

Surprisingly we have not reached this level in predicting anchor performance. Nevertheless I think can we make some useful and intelligent (and some not so intelligent ) observations.

Given the limitation of practical anchor testing, and subjective reports from users, analysing anchor geometry and theoretical predicted behaviour should be given some weight, at least in deciding which anchors are worthy of more detailed analysis.

[Panope]

I find it fascinating that the large efforts (that we are witnessing now) to improve anchors did not occur long ago. The world was making huge strides in maritime technology while the fisherman type of anchor stayed basically the same for hundreds of years. The CQR was an advancement but it took 50 or so years for the next round of improvements to come along. Certainly many lives and vessels were lost due to dragging anchors. Why is it only recently that we are seeing widespread competition in the marketplace and the resulting "raising of the bar" of anchor design? Is it because nobody lost a war due to a dragging anchor?

Steve

[Cotemar]

Most visitors to these anchor threads under estimate the power of the Cruisers Forum to bring talented people together in one place to focus on such a controversial subject as anchors.

We have great anchor designers, company CEO's, anchor manufactures and quite possibly the next great anchor designer, right here at our keyboard just for the asking. We can ask a simple question and have multiple replies form around the world in just minutes. I have never seen this on other forums as strong as it is on the Cruisers Forum.

Who knows, you may be talking to the next great anchor designer that will take us up the next step in the anchor evolution tree. In the last few years we have seen anchor design evolve faster than we have seen in the last 50 years.

These anchors threads are a very meaning full place to be if you have a passion for anchors form, fit, function and design.

Here in these anchor threads are plenty of anchor facts, assumptions, conclusions and theories.

You really can just sit and listen to the chatter or jump right in and ride along with the rest of us passionate ones.

[Kettlewell]

The CQR was an advancement but it took 50 or so years for the next round of improvements to come along. Certainly many lives and vessels were lost due to dragging anchors.

Don't forget Danforths, developed in 1939 (CQR was 1933), that still are right there at the top in terms of holding power, and still sold and used in large numbers. Add in the Fortress variant and I would venture to guess the design is the #1 most found in North America, but you have to remember that includes a lot of powerboats.

Lots of other useful designs along the way, like the Northill, don't forget Bruce and all his knock-offs, and Deltas, then there were some oddball ones that had fans at one time or another: Wishbones, the Barnacle anchor, Hans-C (still made), the Herreshoff Style but modified Luke three-piece (still made), the SuperMax (still made), the HydroBubble, the Bulwagga (I still have one, and they are quite good), etc. Point being that there has been a lot of experimentation, and I don't think you can claim that any more boats dragged than drag today--at least going back to the 1930s. I bet a properly set Danforth will outhold anything of the same weight.