Anchor new Gen is Roll Bar-Critical?

[a64pilot]

I'm not sure we can get much from giant anchors, I'm likely misusing the term but I've heard it called the square / cubed rule. Basically it tries to show how things change as they are scaled up. Ants can fall forever and not get hurt, but elephants can't jump and why a Piper cub the size of a 747 won't fly.
So a huge anchors design may not work when scaled down

[groundtackle]

Originally Posted by Factor

Buy an Excel. Its welded, no bolts and Steve (PANOPE) videos seem to indicate what those of us who have owned the anchor already know, there is no better anchor. If you do need demountable, they do an Excel that slots together, again no bolts. And no roll bar.

That is interesting, It suggests that even though the anchor may be well set and full dug in etc that the roll bar still has some role (pardon the pun) to play in keeping the anchor set? I would love to understand Greg's reasoning on that.



Concave is NOT a guide to new gen or other. Concave or scoop anchor is one way to arrive at a solution, convex is another. concaves seem to need roll bars, convex not so much.

Basically there different ways to ensure an anchor orients itself correctly on the sea bed. One is to use a roll bar, another is to use anchor design and weight distribution.
The Super Sarca is a roll bar design with a lighter fluke that works very well. The EXCEL uses weight distribution / design, it has no roll bar and works very well. Excel is a combination convex (70%) / concave (30%), this is not a plow, it is a deep diving anchor. Both these designs use fluke ventilation virtually eliminating fouling with substrate leaving a controlled / reliable surface. Clean anchor upon retrieval is certainly a nice thing but even more important is the ability of these anchors to reset on a tide reversal. Both features stem from the ability to shed mud.
Nick

[Jason Flare]

Coming late to this thread.

Have an 85lb. Mantus, with the rollbar removed, tucked under the bowsprit of our Formosa 41. All chain rode. We're almost 36,000 lbs. loaded.

We rarely get a slip or mooring. We've anchored from MA to FL including two trips through the Chesapeake. We've never had a problem landing upside down dragging or not setting quickly.

Currently, (pun intended,) we're in Man O' War Harbor in Key West in 30 feet of water. Anchor is holding this year and it held in an estimated 40kt. blow last year.

[Hearts Content]

Originally Posted by skipmac

One difference being the Spade was designed without the roll bar. Those that were designed with them I think might not work as well without.

Ditto.

[markpierce]

A "scooper" (concave) anchor is better than a plow. Whatever, my copy of a Bruce works fine (in heavy mud) and see no need to change. Don't see the magic of a roll bar.

[thinwater]

Originally Posted by a64pilot

I'm not sure we can get much from giant anchors, I'm likely misusing the term but I've heard it called the square / cubed rule. Basically it tries to show how things change as they are scaled up. Ants can fall forever and not get hurt, but elephants can't jump and why a Piper cub the size of a 747 won't fly.
So a huge anchors design may not work when scaled down

I think you are probably incorrect, at least in part. In fact, much or what we know about anchors comes from the big boys, not the puny leisure market. Most of the differences have to do with handling (they are lowered more carefully) and fabrication difference.

Look at the range in size (3 order of magnitude) for this Danforth look-alike.

BTW, the holding exponent for anchors is about 0.9 to 0.95, not square or cube. This is established fact.

[Steve Bedford]

Originally Posted by ranger42c

Seems to me I was reading MAX reviews on the 'net somewhere -- specifically focused on slimy mud and hurricane holes -- by Cap'n Wil Andrews (that sound right?) in approx 2001 or so, give or take a year or two either way? I think we bought our first one at least by 2004, more likely 2003...

-Chris

You are correct Chris. Actually testing of the original Max Anchor goes back to the mid 90's with the Super MAX a year or two later. It's design has always been based on setting and holding is "suspect" seabeds along with more common seabed substrates.

Regarding a quote earlier in this thread, "Any new generation anchor that has a Concave anchor fluke like a shovel is much better than any plow anchor that is designed to push the seabed to the sides. The roll bar just makes it set a bit faster."

I don't agree with the last sentence. A roll bar may help those model anchors set faster (or get into an attack position to set) that have been designed for, or require, a roll bar. However, we all know there are some fast setting anchors that are not designed with a roll bar that have fast setting characteristics.

Steve

[ranger58sb]

Originally Posted by thinwater

Look at the range in size (3 order of magnitude) for this Danforth look-alike.

BTW, the holding exponent for anchors is about 0.9 to 0.95, not square or cube. This is established fact.

Interesting chart. Seems odd there's a big drop-off starting at 80,000-lb anchors...

Also seems odd calling most of those "lightweight".

-Chris

[ranger58sb]

Originally Posted by Steve Bedford

You are correct Chris. Actually testing of the original Max Anchor goes back to the mid 90's with the Super MAX a year or two later. It's design has always been based on setting and holding is "suspect" seabeds along with more common seabed substrates.

Heh... I'm not familiar with when some of the other newer anchors were introduced,... but if MAX predates all the others... that means maybe you can claim to offer the first of the NG anchors...



-Chris

[Steve Bedford]

Originally Posted by ranger42c

Seems to me I was reading MAX reviews on the 'net somewhere -- specifically focused on slimy mud and hurricane holes -- by Cap'n Wil Andrews (that sound right?) in approx 2001 or so, give or take a year or two either way? I think we bought our first one at least by 2004, more likely 2003...

-Chris

You are correct Chris. Actually testing of the original Max Anchor goes back to the mid 90's with the Super MAX a year or two later. It's design has always been based on setting and holding is "suspect" seabeds along with more common seabed substrates.

Regarding a quote earlier in this thread, "Any new generation anchor that has a Concave anchor fluke like a shovel is much better than any plow anchor that is designed to push the seabed to the sides. The roll bar just makes it set a bit faster."

I don't agree with the last sentence. A roll bar may help those model anchors set faster (or get into an attack position to set) that have been designed for, or require, a roll bar. However, we all know there are some fast setting anchors that are not designed with a roll bar that have fast setting characteristics.

Steve

[Steve Bedford]

Sorry about the duplicate email to the list.

I can say that the Super MAX was one of the first to have a concave fluke and did not look like other anchors (still doesn't) at the time.

As I have always said, there are some really good anchors out there for the boating community to choose from. You won't go wrong if you get a quality anchor, built with quality materials and workmanship, that fits one's vessel both in size and configuration, designed to meet the needs of the captain's anchoring experiences, and follow the manufacturer's recommended deployment and setting technique. As one contributor from another list serve (who many of you know), "the only thing an anchor has to do is beat the forces of Mother Nature and not another anchor." If someone has an anchor that can beat the forces of Mother Nature then you have a great anchor.

Steve

[noelex 77]

Originally Posted by Pelagic

What a wealth of experience on new gen Anchors

My cruising grounds is the Western Pacific and Coral Triangle Area.
The more exposed anchorages are made up of course sand and broken coral....

Would that affect your choice?

This is quite an easy substrate, which is good. Coarse, corally sand basically acts like soft sand. Most anchors, even older designs, can penetrate this type of substrate and set.

One limitation is that the substrate does not provide a lot resistance. The sand does not typically increase as much in density with depth as most sand types. Anchors like the convex plow anchors without a lot of surface area and fluke resistance will be reliable in moderate wind but may start to slowly drag in stronger wind.

The other problem is there are sometimes areas of larger lumps of dead coral mixed in the substrate. The larger lumps can upset the setting. The best defence is to have an anchor that sets quickly and test the set with plenty of reverse.

The Spade works well in this sort of substrate. The surface area of the fluke is not as great as the rollbar anchors or designs like the Manson Boss, but it is still reasonable and the concave shape provides good resistance. The Spade generally sets reasonably quickly, minimising the risk of encountering one of the larger lumps of coral.

[TheThunderbird]

Originally Posted by thinwater

I think you are probably incorrect, at least in part. In fact, much or what we know about anchors comes from the big boys, not the puny leisure market. Most of the differences have to do with handling (they are lowered more carefully) and fabrication difference.

Look at the range in size (3 order of magnitude) for this Danforth look-alike.

BTW, the holding exponent for anchors is about 0.9 to 0.95, not square or cube. This is established fact.

Oops
Please consider the following.

Weight grows up with the cube power of linear measures
Surface, by the square power
Final result is a mix of the two factors, as holding power depends on multiple factors as well

In fluidodynamics shape similarity holds much better, with some corrections (edges)

[noelex 77]

Originally Posted by TheThunderbird

Weight grows up with the cube power of linear measures
Surface, by the square power
Final result is a mix of the two factors, as holding power depends on multiple factors as well

Thinwater is correct. There has been a lot of experimental data on very large oil rig anchors and some good work from Professor Knox on our sized anchors.

All the results suggest the holding power is normally roughly proportional to anchor weight, assuming the anchor design and construction remains the same. You cannot compare steel and aluminium models for example.

I think there are some anomalies. For example the Bruce anchor which seems to work less well in smaller models. For other designs there may be some substrates, like weed, where small anchors can fail to set but normal sized models work well.

There are also manufacturing issues. Steel is only available in a limited number of thickness and sometimes the effective design of the anchor alters as the size changes.

However, if you double the weight of an anchor the best guide is that you will roughly double its holding ability.

[hsi88]

A "scooper" (concave) anchor is better than a plow. Whatever, my copy of a Bruce works fine (in heavy mud) and see no need to change. Don't see the magic of a roll bar.

"a schism exists between these more open-minded boaters and those who value the ‘tried and true’ and the traditional; and who, despite the bemusement of the early adopters of what is clearly far superior technology, continue to use designs that in the case of the CQR is rather akin to the use of cotton sails and oil lanterns"

Saw the previous statement in an article about modern vs not so modern anchors. I would agree the Bruce probably falls somewhere in-between and its the CQR being singled out along with other plows for their higher failure rates.

But I find the article's mention of cotton sails and oil lanterns holds true across this forum overall. If it works, why fix it is a common reply. And some simply like the aesthetics of older equipment and therefore accept the performance as it is.

I have no problem using older equipment because some, like myself, can't afford the latest and greatest anything. I will continue to use Dacron sails and my 5 year old chart plotter and such. Some because upgrades often come with a down side. But improvements like those found with these latest anchors are worth noting. The knowledge will help me should I stumble across a Rocna or Mantis at a reasonable price or decide its worth the extra cost right now to feel a little more secure at night.