An article from PeterSmith.net.nz, written by
www.petersmith.net.nz/boat-anchors/2011-oct-01-rocna-issues.php

A Statement From the Rocna Anchor Designer

1st October 2011: Rocna re-licensing & historical steel quality issues

The Rocna Anchors license has been re-assigned

As of 20th September 2011, the Rocna® Anchors license – including all rights to the Rocna design and brand – was terminated and re-assigned to Canada Metal (Pacific) Ltd, a Canadian company with facilities in Vancouver and China. Canada Metal produce the Martyr™ line of anodes, CMP™ chain, Octopus™ autopilot drives, and Intellisteer remote steering systems. John Mitchell, President: “We have been searching for a line of anchors and anchoring products to complement our range of anchor chain and are very excited to have brought Rocna Anchors into the fold.” For Peter’s part, Canada Metal is a company with clear and high quality standards, possessing exceptional engineering, manufacturing, and distribution expertise, and is considered to be an excellent choice for the future of Rocna.

On the issue of the Rocna anchors shank steel

Rocna anchors were produced under license by Hold Fast Anchors Ltd from January 2007 to September 2011. Questions regarding the quality of the steel used by Hold Fast for the anchor shanks have been raised in the public arena. In August and September 2011, magazines Yachting Monthly (UK) and Practical Sailor (US) published commentary without consulting Peter. The following is intended to clarify the facts on this matter.

Two anchors were found to have steel in their shanks that had tensile strengths below the advertised grade. This steel was called Q420, possessing a minimum yield strength that is up to 39% lower* than the 690 MPa indicated in literature. Preliminary investigation of manufacturing records discovered a number of anchors put onto the market in the first half of 2010 which suffered from this problem, affecting models from 4 kg to 110 kg. This issue is real, legitimate, and affects just under 700 units. No evidence has been found that calls into question units from before or since this period.

Peter has since investigated the issue independently. The following is not intended to defend the Q420 steel, but boaters unable to conveniently return anchors suspected to originate from the affected batches need not panic. These anchors, whilst below specification and certainly subject to replacement, do not represent a danger to the boat or boater and will not fail or be damaged in normal usage. Their shanks will bend at a lesser force if subjected to lateral (sideways) loading, but nonetheless remain stronger than much of the competition (the Q420 yield strength is about double that of mild steel) and these anchors remain generally fit for use. The shanks subjected to typical in-line or upward pulls in the course of anchoring will still endure greater loads without bending than the appropriately matched chain could sustain before breaking.

Some of the public controversy has been prompted by pictures of Rocnas with bent shanks. Without doubt some of these are legitimate cases, while others appear to be new and unused anchors where the circumstances are unclear, with the bends located at strange points and at angles subtly different to those expected from real world failures. Detractors have referenced a supposed incident in Venice Lagoon where a Rocna shank was reportedly bent “in 20 knots of wind”. It was found that the anchor was in fact stuck and damaged during retrieval, as was the yacht’s bow roller assembly. Peter points out that the forces from 20 knots of wind could never have damaged the anchor, even in the hypothetical event it was built from mild steel, let alone Q420.

This issue was complicated further by an unrelated and intentional change in the steels used in all Rocna shanks to a grade called Q620. This steel was accepted as meeting design tolerances although may in theory possess a yield of up to 10% less than the 690 MPa mentioned in former Rocna literature*. Subsequent testing has seen actual samples dip at most 5% below that 690 MPa figure while the average of all production samples tested is almost exactly 690 MPa. While the inconsistency in advertised numbers is unfortunate, the strength of these anchors remains well above the minimum the Rocna design allows for.

A particular problem for customers has been a conflation, in much of the online and printed discourse, of the two primary properties that define a steel’s strength: yield strength and ultimate tensile strength (UTS). The steel for the Rocna shank was referenced in literature and elsewhere as a “grade 800” steel, which referred to a high strength low alloy steel characterized by an ultimate tensile strength of 800 MPa and a yield strength of 690 MPa. While a steel might be generally talked about in these terms, the yield property is what dictates bending strength. It has been common for certain individuals and organizations to misleadingly quote the yield of tested Rocna samples and compare this to the 800 MPa UTS of the advertised steel or other anchors. The average UTS of all tested samples of the Q620 steel has been 790 MPa.

Hold Fast, the former Rocna licensees, had completed an independent and certified SHHP proof** and destruction test on a sample Rocna 55 (121 lb) in May 2011. This unit was a Chinese sample the shank of which is formed from Q620 steel (its yield was subsequently independently certified at 658 MPa) and is near the lowest yield of all Chinese built Rocna anchors with the exception of the Q420 units as above. In the test, the shank finally bent at a figure which is more than 6.5 times the proof requirement for SHHP classification, and more than 3 times the nominal breaking strength of 12 mm (~1/2″) G40 (high test) chain. This means that the appropriate chain for the anchor will fail completely before the shank is even close to starting to bend. These figures are compatible with the standards of Peter’s design and engineering of the Rocna anchor, and lateral (sideways bending) strength is similarly considered perfectly acceptable.

* This is worst case scenario; actual yields are always some margin above the minimum.
** SHHP (Super High Holding Power) classification is the highest standard available for anchors, and includes a strength test proof load requirement.

Canada Metal and the future

The above addresses the facts directly. However, the handling by Hold Fast of the consequent public relations situation was very disappointing and many customers with legitimate concerns have not received adequate support. This is going to change.

Peter will be working with Canada Metal over the next few months in order to assist with transition of production management, assist with any problems, and will also be present in person at the 2011 Annapolis, Fort Lauderdale, and METS boat shows.

Rocna owners should understand that Peter and Canada Metal value their support, and are committed to retaining it. Anchors with question marks over their steel types will be replaced. Owners with concerns are encouraged to contact Rocna under the new Canada Metal management. Phone toll free +1-604-940-2010, or e-mail support@rocna.com.

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