Mailport May 2013 Issue

Mailport: May 2013


I am writing in regard to the small anchor reset test (PS, February 2013), and would like to address some omissions related to the Rocna anchor.

Given your publication’s reputation for unbiased reporting, we feel it a privilege to have this opportunity to express ourselves relative to this specific test, which we believe was conducted outside of generally accepted independent testing standards.

The surface area-to-weight ratio of an anchor is a key performance indicator, with particular relevance to holding power in soft bottom types, and is one that Rocna has taken particular care to maximize. Given that the author apparently recognized the value of presenting this ratio, it is puzzling that the Rocna is the only anchor for which this is not calculated. This omission is even more surprising considering that unlike most anchors, the surface area of the Rocna blade is included on the label of the anchor, in our literature, and on our website. Had the author chosen to present this ratio for Rocna, its ratio of 98 would have been the highest of the anchors tested.

The results of any anchor testing are strongly influenced by the seabed type. Although the table in the article includes results for two seabed types, once again the Rocna was singled out for omission with results reported for only for the sand/clay seabed, and no data for the sand seabed. Our expectation is that the Rocna would have set quickly and performed well in this seabed.

As the author noted, typical tidal or veering wind situation occur over an extended period of time, rather than presenting sudden 180-degree load reversals such as were used in this test. Based on our testing and the experience of thousands of cruisers worldwide, the Rocna design handles real-world load reversals extremely well, and will typically remain buried and rotate in place.

It is notoriously difficult to perform reliable and meaningful anchor testing, particularly with a large number of test anchors. To achieve statistically meaningful results requires large numbers of repetitions of each test condition, seabed, and anchor type, resulting in a huge amount of data. Most testers do not have the time or resources to provide this type of rigorous testing. Some of the results in this article are based on only two pulls, and the author noted that results “outside the norm” were discarded without defining what objective criteria was used for this data selection. Based on these concerns, the statistical validity of these results can certainly be questioned.

There are many factors that would lead a boater to select a particular anchor type. We urge those who are considering their choice of ground tackle to base their selection on feedback from users as well as independent tests, rather than on a single criteria.

Mark Pocock

Product manager

Rocna Anchors / Canada Metal

We regret the omission of the surface area-to-weight data for the Rocna; the table will be updated online. The main purpose of the test was to evaluate veering performance based on anchor type and to establish baselines for further testing in the two-part series on shank strength, which concludes this month. As stated in the veer-test article, we do not regard it as a definitive analysis of overall anchor performance. Based on the performance of the Rocna in the beach testing—and the general correlation of our beach testing data to what we found on the boat—we can assume that the Rocna would perform similarly in on-the-water testing.


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