Roll-bar Anchors in Mud

Posted by Darrell Nicholson with Jonathan Neeves at 01:30PM - Comments: (12)

Tests suggest roll bars on anchors are less effective in very soft mud.

In the February 2015 report on anchoring in mud we take a slight detour from our usual process, although we have done similar reports in the past.

In the summer of 2014, Fortress Anchors, the maker of a popular aluminum Danforth-style anchor, conducted a series of anchor-holding tests in Chesapeake Bay, an area renowned for its soft mud and oyster-shell seabed.

Practical Sailor carried out its own series of anchor tests in a mud bottom in 2006 (see April 2006 and October 2006 issues), and those tests bore out a commonly known fact: Danforth-style anchors, which feature flukes that are proportionally larger than other types of anchors of the same mass, tend to hold better than older, plough-style anchors in soft mud. When Practical Sailor was invited to witness Fortress’s test, editors were initially skeptical; the playing field seemed heavily tilted in Fortress’s favor. In the end, however, it was a busy test schedule, not outright skepticism, that prevented our attending.

After reviewing the test results, including video record of the well-documented tests, we are convinced that the evaluation was carried out fairly, and that the test methodology offers some important insight on anchor performance. Although we would change some aspects of the tests to suit our own curiosity, we believe the results are worth reporting—and putting into context.

One of the most interesting results—although not entirely surprising given the nature of the bottom—was the poor performance of some reputable anchors that have done well in past tests. One anchor that has done well in our own tests and is highly praised by some well-known cruising sailors, the Rocna, did not set at all.

The fact that it never set during testing suggests that it might have landed upside down and that the self-righting effect of the roll bar does not work in a soft seabed. This effect might also occur in soft sand, and the results imply that this might be a problem for other concave-type anchors that have roll bars but lack a weighted toe. (The Manson Supreme, which has a roll bar, but also has a weighted toe, performed better.)

Most anchors rely on a firm substrate to self-right, and this seems especially true for anchors with roll bars. It is logical that a roll bar would be little or no help in a bottom that is too soft to roll on—in which case, a weighted toe would come in handy. However, the Mantus, which has a roll bar and lacks a weighted toe, seemed to defy this logic. Compared to both the Rocna and Manson, it fared pretty well in the Chesapeake mud.

As we pondered this puzzle, we were reminded that in our own tests, the hydrodynamic effect of water flowing past the flukes of the Mantus seemed to help it self-right. The Mantus’s tendency to self-right during deployment was most obvious in our tests when the boat was moving in reverse—the direction of the set. We suspect that the protocol used during the Chesapeake Bay tests ould have promoted this self-righting.

Regardless, the reliability of the Mantus and others of its ilk should be viewed with caution in soft mud. There is evidence that the weighted convex and concave anchors—Delta, CQR, and Spade—also self-righted, but the amount of holding power for all of these anchors was inadequate for anything but a lunch hook.

Based on the holding-power numbers, it is obvious that the Ultra anchor self-righted. Its holding power was 20-percent greater than its nearest rivals of similar designs—the Boss, Supreme, and Mantus—but, again, none of these anchors, which have fared well in our tests, generated reassuring numbers in soft mud.

Comments (12)

I don't know what kind of bottom my anchor will fall on next. So I don't want an anchor that excels in sand and won't set on a grassy bottom, or one that is amazing in mud but that won't hold on rocky bottoms. I'd rather have an anchor that's mediocre on all bottom types than one that is stupendous on a couple of bottom types and terrible on the rest.

Posted by: Fred M. | June 6, 2017 2:21 PM    Report this comment

I have been following reviews for some time and have to agree with the adage "it all depends." So, I've elected to stay with the two CQRs that came with my PDQ 36 catamaran. I have't dragged or lost one yet.

Posted by: James B | January 14, 2015 3:09 PM    Report this comment

Let's be realistic: No one anchor model or type will perform superbly in all wind and sea bottom conditions, and that is why having the right anchor that works best in a specific bottom and at least a few anchors aboard is the best anchoring strategy.

Posted by: BMS | January 14, 2015 2:02 PM    Report this comment

These results as with most anchor testing by various sources flies in the face of my personal experience. No wonder anchors are so controversial. In twenty years cruising the Chesapeake, we have anchored all over the Bay. And we usually travel in company with other sailboats. A number of very active friends have switched to the Rocna, and swear by their own experience. And in those twenty years, we watched many boats drag through anchorages. Of those, nearly all pulled up a Danforth or Spade. The few who didn't hoisted a CQR or Delta. I've never yet seen a modern concave anchor, nor a Bruce, drag in the Bay. Maybe not in agreement with tests, but I'm still relying on my personal real world experience.

Posted by: REX N | January 14, 2015 1:49 PM    Report this comment

That's all great, but here in Maine you are apt to get a rocky bottom, and Danforth type anchors are totally useless in rocks. A naval anchor would be best, but I use a Rocna or Mantus single point.

Comparing the weight of an aluminum anchor against steel is a bit misleading. Don't get me wrong, I intend to buy a Fortress and recognize that weight be dam.ed, fluke size determines mud holding ability. Even in a rocky bottom I've gone into a stream fed cove and found all soft mud. I also think you need two types of anchor. The Mantus has the advantage of unbolting and storing till needed.

Posted by: Jeremiah G | January 14, 2015 12:27 PM    Report this comment

The thing about any of the "lightweight" type of anchors, including the superrior Fortress, is that on a sudden hard reversal, the flukes can and often do become fouled by mud, shells, or any piece of debris that is scattered about the sea bed. They do not "flip Flop" reliably enough. For this reason, I only use my 3 Fortresses as secondaries, in opposition to another anchor. This avoids the issue altogether.

For one's PRIMARY anchor... Setting a Fortress anchor SO firmly that it will not possibly reverse itself with a strong wind/current load reversal, is not the answer. For this anchor we need good holding for sure, (and Fortress' holding IS vastly superior in non reversing loads), but the anchor also needs to be easily retrieved and fit well on the bow. This is why I still recomend your choice of the newer generation (concave or convex) "plow shaped" anchor for the primary. IF it is chosen and sized correctly, as well as set SKILLFULLY, they should hold quite well up to say... 60 knots of wind, yet they swing and even reverse direction while staying mostly "set" when needed to. Importantly... They are also easy to retrieve. They fit on the bow roller better as well.

I still use my old Delta 35 to hold our Searunner 34 trimaran, (even in up to cacagory 1 winds), but I am intrigued by Rocna's new "Vulcan" anchors. They might get around the roll bar canundrum...

The different setting technique for soft mud is described in detail my E book: It is just a matter of patiently wiggling the hook down through the soft mud, untill you get to the firm mud that usually lies underneith. It works well for us, but I doubt that any of the anchor holding tests are done after doing this, as it may take 20 minutes, and such patience when doing 50 sets a day is not Practical.

Mark Johnson "Anchoring and Mooring The Cruising Multihull"... Amazon

Posted by: Mark J | January 14, 2015 12:15 PM    Report this comment

I use Bulwagga anchors on my boats and they work excellent in mud. No matter how they land, two of their three flukes alway grab in the bottom.

David Herndon

Posted by: Delores H | January 14, 2015 11:18 AM    Report this comment

It does all depend on where you are. We have a combination on the bow also - couldn't get the Manson to set and hold in many places in Turkey last year so we unhooked the Fortress for good results.

Posted by: hogesinwa | January 14, 2015 8:54 AM    Report this comment

I agree with the above, and there is no question that a difficult bottom condition like soft mud will produce varied results. What you are looking for is some measure of a consistency for performance, and so the averages do have value.

When set at the 45degree angle, the 21 lb Fortress FX-37 (which was tested against anchors weighing 35-46 lbs) ended two pulls with the tension above 2,000 lbs and still climbing. In two other pulls, the test ended with the tension above 800 and 1,000 lbs, and during one pull it did not set.

This performance was by far superior to the results achieved by any other anchor.

Regarding reset capability, we had great difficulty breaking the FX-37 free from the bottom when we were directly above the anchor and pulling hard at a 1:1 scope. In fact, we broke the cable once at 3,500 lbs and lost the anchor. The thought that this anchor might have broken free easier with a change of pull angle at a typical scope would appear to be all but next to impossible.

Posted by: BMS | January 14, 2015 8:50 AM    Report this comment

Which is why I have one Rocna and one Fortress as main anchors. It all depends on where you are.

Posted by: DAVID L | January 14, 2015 8:46 AM    Report this comment

Bruce missing?

Posted by: Dr. C. Franklin C | January 14, 2015 8:30 AM    Report this comment

Magazines tend to report the highest average holding power instead of the lowest result; the one that lets you drag. Measured that way, Fortress, Delta, Rocna, Claw, and Spade all registered pulls below 300 pounds. Only Danforth exceeded 500 pounds on all pulls, and rest ability is poor.

No Vendor had anything to brag about, and there is so much scatter in the data as to render all judgments shaky. Clearly, problem bottoms are just that.

Posted by: Drew Frye | January 13, 2015 7:25 PM    Report this comment

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