Small Versus Large Anchors


The consensus among anchor makers (Fortress, Bruce, Manson, Mantus) is that holding power in soft bottoms increases in approximate proportion with anchor mass; exponents range from 0.92 to 1.0. While there are differences between models and manufacturers, a 35-pound Mantus should hold roughly 18 times more than a 2-pound Mantus, and a Fortress FX-16 should hold four times more than a Guardian G5.


If we compare our soft mud 2.5-pound Mantus holding result (35 pounds) with the 45-pound Mantus result (750 pounds), the scale-up error is about 20 percent. The same is true for the Guardian/Fortress comparison and the Claw comparison: about 20-percent scale-up error. The drag-in distance to full holding was proportional to the anchors physical size, a trend supported by U.S. Navy testing; Anchors tested at Solomons Island took 30 to 40 feet to develop full hold, while the small anchors took 4 to 10 feet. These are averages; variations between runs were often 50 percent or more, often due to trash in the mud.

Overall, the burying behavior, turning behavior, and relative holding power of the pint-sized anchors in consistent sand and soft mud is consistently proportional to full-size anchors. In other bottoms, especially those that are hard to penetrate, the results are less comparable.

Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 45 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida.


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