A Second Look at Anchor Shanks

Posted by By Darrell Nicholson at 02:34PM - Comments: (6)

Jonathan Neeves
Jonathan Neeves

Welded bar supports the hollow shaft of the stainless steel Ultra anchor.

In case you hadn’t noticed, we’re bending anchors here at Practical Sailor. Look for Part 2 of our anchor shank-bending adventures in the upcoming May issue. Coincidentally, right when we were in the middle of bending anchor shanks, we received a 33-pound Mantus anchor for testing. The design is interesting in that it combines some attributes of a Rocna, Manson Supreme, and Wasi Bugel. The anchor has a folded fluke with a small, sharpened toe welded to the fluke. The anchor is shallowly concave but has a roll bar that is sufficiently wider than the fluke.

Here's a summary of our tester's report so far:

"The anchor is unusual in that the fluke and shank are not welded, but bolted together with high-tensile bolts (making it easier to ship and store.) One of the first things we noticed was that the shank dimensions were smaller than the equivalently sized Right Anchor, Excel, or Rocna. The shank thickness (about 1/2-inch) and length are similar to the 33-pound (15-kilogram) Rocna or Right Anchor Excel—but the 2.4-inch-wide Mantus shank is 60-percent narrower.

The shaft of the new Mantus anchor is bolted to the flukes.

"Looking only at shank strength, this implies that the Mantus shank will be noticeably weaker than the Excel or Rocna. Both of these anchors use higher-tensile steel (ASTM 514) in their anchor shanks; the material held up very well in our testing. Given the smaller size of the shank, we were curious about the grade of steel Mantus is using. Mantus makes no claims on the quality of its shank; it advertises simply that it is ‘formed out of high-quality steel plate.' The manufacturer gladly provided the information to us, saying it uses A36 mild steel in the shank. The company does imply that its anchor is as good or better than its peers such as the Manson Supreme or Rocna.

"Before hiring a metallurgist to further analyze the metal, we tested it using our quick and dirty ‘ball bearing test,’ in which a super-hard bearing or bolt is clamped between the anchor shank (cleaned of any galvanizing) and a plate metal of known tensile strength. The metal that dings first is the softer metal, and, although this is not a universal rule, in the world of galvanized steel anchors, the softer metal is generally the weaker metal. Comparing the Mantus to increasingly harder plates, we confirmed that the metal used in the shaft is probably a high-grade mild steel—but not near the tensile strength of that used in the Rocna or Manson Supreme."

Certainly, setting and holding power are paramount in an anchor, and a sailor could use an anchor with a milder steel-shaft for a lifetime and never see it bend—as many makers, like Rocna, contend. Anchors from both Fortress and Spade bent in our recent tests, and these anchors have years of use to back them. However, as we will demonstrate in the May issue, bending an anchor shank made of so called “high-tensile” steel in real-world conditions is not as hard as one may think. Fortunately, Mantus, like many makers, offers a lifetime warranty that would likely cover a bent shank. Of course, we’d prefer makers use steel with a higher yield strength in the first place. More importantly, we’d like makers to be more transparent about the type and grade of material they are using in their anchors.

Comments (6)

Having worked with both UL and ASTM, before any effort can start there much be clear vision of what the proposed standard is to prevent, and what tests would be useful. There must be clear agreement between all affected parties. Money is less important than clarity.

Posted by: Unknown | April 14, 2013 5:02 PM    Report this comment

UL Yes, Government No. Beware what you ask for. Before you know it some government bureaucrat will pick up on this and wham BIG GOVERNMENT will be there to REGULATE the makers' results in building this product, and substantially increase the prices for the same piece of equipment. Don't go to some regulated standard. Take a look at the anchor on the bow of the most seaworthy vessel in your marina, talk to the owner, and figure out what your needs are in anchoring. If any of these shafts were snapping off, I'd be worried we have a problem, we don't. When one owner will swear by their Delta and another a Rocna (or take your pick of names) and have used it for years on end, the well designed, long-lived anchors on the market are a SAFE bet. Please don't get government into this debate, it will only cost us all more money.

Posted by: Craig R | April 11, 2013 5:37 AM    Report this comment

Ok, it bends, but then how hard is it to straighten?

Posted by: Thomas P | April 11, 2013 1:00 AM    Report this comment

Have there been any studies to indicate whether a bent shank alters the holding power? It obvously will affect setting but for the anchoring in which it bends does it matter? Also, how much bending does it take to weaken the steel? i.e. One bend, straightened, does it affect function?


Posted by: Geoffrey K | April 10, 2013 1:42 PM    Report this comment

I personally find little to no comfort in any lifetime warranty illusion with so much riding on what is potentially not covered that provides no product specifications to substantiate claims to greatness. Mr. Baldwin makes an excellent point gentleman. One would think this quality requirement would have been addressed long before now.

Gerry Stanford

Posted by: Gerry S | April 10, 2013 11:51 AM    Report this comment

Maybe Practical Sailor could get a grant to establish and issue UL type certificates for anchors. There would have to be a lot of qualifications, and no doubt there would be a struggle to prevent race to the bottom (oops) of the quality requirements.

-Mark Baldwin

Posted by: Mark B | April 10, 2013 10:44 AM    Report this comment

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