Boats & Gear

TANDEM ANCHOR SYSTEM: An Anchor Within An Anchor

Tandem Anchor illo

This new anchoring system, developed by Peter Weber in Slovenia, was formally introduced at the METS (Marine Equipment Trade Show) extravaganza in Amsterdam this month, where it was nominated for a DAME Award, and was also on our shortlist at SAIL when we put our heads together this week to pick winners for the 2013 Freeman K. Pittman Innovation Awards. It is a fascinating concept. The drawing up top gives a clear idea of the basic principle: a pair of anchors that can be deployed together on a single chain rode, designed so that one can nest inside the other when stowed.

Deploying two hooks in line on one rode has long been recognized as the best way to maximize holding power when anchoring, but very few people actually go to the trouble to do it unless confronted with an extreme event like a hurricane. Usually when setting two anchors folks set the hooks on separate rodes in a V-formation and try to adjust the rodes so that the load is carried evenly between them. This significantly reduces a boat's swinging range, and often you may want to set two anchors like this for just this reason. Your boat, however, will still swing to some extent and the load will cycle between the rodes, being carried first by one then the other and rarely by both, so it's not as secure as it might seem.

Anchored on twin rodes

Two anchors deployed on separate rodes

Twin anchors in line

Two anchors deployed in line

Traditionally, the problem when setting two hooks on a single rode has been making the connection between them. It's tempting to simply shackle a length of chain for the lead (or tandem) anchor to the little hole found in the crown of many plough or Delta-type anchors, but these in fact are intended only for rigging trip lines. The best practice is to shackle the tandem anchor's rode directly to the main rode just behind the main anchor, something like this:

Connecting a second anchor in line

Which is more secure, of course, but still a bit problematic, as the tandem anchor's tether rode must run alongside and over the main anchor and could conceivably foul it.

The key innovation in Weber's system is that the main rode--the only rode--runs right through the stock of the main anchor. As you can see in the photo below, the stock itself is a channel designed to receive both the rode and the stock of the tandem anchor and even has a roller incorporated into its front end.

Tandem Anchor set

The main anchor can be secured to the chain rode at any point along its length with a special clutch set about two-thirds of the way down the stock. You can see the clutch plainly in this next photo, which shows the two anchors properly set in series:

Tandem Anchors down

The following video, which shows a Tandem Anchor being retrieved, gives some sense of how the clutch operates:

The potential benefits of anchoring this way are (or should be) obvious. It allows you to routinely set and retrieve two anchors in line without going to very much trouble. This will increase security in strong weather, when you may worry about dragging even with maximum scope out, and more commonly when you're anchoring on short scope in a crowded harbor. In that the main anchor ensures that the load on the tandem anchor is always perfectly horizontal, or at least nearly so in a worst-case scenario, it seems it should be almost as secure as lying to a mooring. Note, too, the system is flexible. You can, if you like, always keep the main anchor in your bow roller and just set the smaller tandem anchor.

Tandem Anchors in roller

Tandem anchors poised in a bow roller. You can set one and not the other, but note that your bow roller must be wide enough to accommodate the stock-within-a-stock design

The big question, of course, is how hard is it to get the two anchors to set properly. Will there be problems with them piling up on one another? Will one anchor usually end up carrying most of the load? Will off-line side loads end up distorting the stock of the main anchor? How will the anchors reset themselves in a big wind shift? In our FKP discussions at SAIL we batted around these and a few other scenarios and agreed that the only way to definitively answer such questions was to get our hands on a pair of anchors and mess around with them, preferably in very warm water with good visibility.

In the end we booted the Tandem Anchors off our list, simply because Weber Marine isn't quite ready ship them to the United States. Peter Weber tells me the clutch on the main anchor is configured only to handle metric chain sizes, not the imperial sizes used here in the States. He's working on developing a modified clutch and is talking to a potential distributor in Florida, so hopefully we FKP judges will again be arguing about the merits of this product next year.

Meanwhile, if you're using metric chain, you can order up a Tandem Anchor System at the Weber Marine website and start conducting your own experiments. The anchors are available in various sizes in both galvanized and stainless steel. The galvanized ones seem very reasonably priced. The stainless ones are, not surprisingly, egregiously expensive.

If you do conduct your own tests, be sure to get an underwater camera and send me some pix and a report!

PS: You can check the February 2013 issue of SAIL to see which products did win FKP awards this time around.

PPS: The Tandem Anchor System did not win a DAME award, but my sources in Amsterdam tell me it did make it to the final round of judging.

[Note: The drawings above (except the lead illo) come from Peter Smith in New Zealand, who developed the Rocna anchor. Check out his website for some excellent dissertations on various aspects of anchoring. All photos (and the lead illo) come from the Weber Marine site.]

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