Mailport July 2013 Issue

Mailport: July 2013

Sizing Ground Tackle

In response to your snubber test (PS, June 2013): How does a boat owner determine the load on their anchor gear for sizing chain, snubbers, and anchors? I understand that displacement, windage, wind speed, and sea state all play a significant role, but is there a general guideline?

Richard Lewis Via

All ground tackle should be sized for shock loads in storm conditions; shock loads require much more holding power than typical anchoring. In her “Voyager’s Handbook,“ PS contributor and bluewater voyager Beth Leonard explains that most cruisers use anchors sized for a boat 10 to 20 feet longer than theirs actually is. A similar rule is applied to anchor rodes. A standard rule of thumb, according to Leonard, is to choose anchor line that is 1/8 inches in diameter for every 9 feet of boat length; chain should be half the line diameter. For more, check out our May 2012 article on anchor testing and rode loads, as well as the ABYC table referenced in this issue.

Next: Anchor Bending

Comments (1)

I fully agree with PS's response here and use of more logical metric system. The relative numbers are far more important then the units, and psi would be wholly inappropriate. We may have a sense for a few hundred psi, but what is 50,000 psi? And since the US Imperial system does not scale easily, we would be force to use something convoluted like tons per square inch. In American engineering schools, material science is taught with megapascals because it is widely used and of appropriate scale.

Posted by: DAMON L | July 14, 2013 6:59 PM    Report this comment

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