Snubber Diameter for Larger Sailboats

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We recently had a letter from Teun and Chantal Bos, who were trying to determine what diameter anchor snubber to use. Practical Sailor did extensive testing in this area, but unfortunately some of the formulas used to determine the right size snubber—strong and chafe resistant yet elastic enough to absorb shock loads —were lost in translation as we migrated to the new website.

As a result, the equation online yielded some clearly absurd results. In the case of the Bos’s, it recommended a 12-inch diameter snubber for their 49-foot Oyster pilothouse, Beryl, clearly out of wack with reality.

As a result, we reviewed the equation and the table, and increased the range to include larger boats.. You can see the full report online (https://bit.ly/2VH64BZ). The correct equation is now online and is:

Diameter (inches) = 0.00067 x (length overall in feet) x (loaded weight in pounds)^0.3

When in doubt, round up to the next larger size. For moorings or use in consistently windy conditions, go up one size. In general, the snubber will be one size smaller than the ABYC recommended anchor rode.

Alternatively you can pick from a chart. You will need to make a judgment call regarding whether your boat is light, medium, or heavy, bearing in mind that a boat with high windage or that yaws excessively at anchor, will have higher rode tension.

In truth, there are a range of right answers. Stronger lines last longer but absorb less shock. Lighter lines will need to be retired sooner but will put less stress on the anchor and rode. As long as you stay in the range, you should be fine.

 

Drew Frye is technical editor of Practical Sailor, he blogs at his website www.sailingdelmarva.com.

SNUBBER SIZING EXAMPLES

BOAT MAKE & TYPE BOAT LENGTHDISPLACEMENT SINGLE SNUBBER DIAMETERBRIDLE DIAMETER SNUBBER LENGTHTYPELENGTHDIAMETER
MONOHULL
PACIFIC SEACRAFT 3434 Feet13,500 lbs. 3/8” /9mmN/A44 feet3-strand45 feet1/2” / 13 mm
MORGAN 41.6 42 feet27,000 lbs. 1/2” / 13 mmN/A54 feetClimbing rope50 feet3/8” / 10 mm
CABO RICO 38 38 feet21,000 lbs.7/16”/ 11 mm3/8” / 10 mm49 feet3-strand bridle30 feet5/8” / 16 mm
VAN DE STADT 4747 feet30,000 lbs. 1/2” / 13 mmN/A61 feetClimbing rope20 feet7/16”/ 11 mm
CATAMARAN
LIGHTWAVE 38 38 feet12,000 lbs.9/16” / 14 mm3/8” / 10 mm49 feetClimbing rope bridle25 feet3/8” / 10 mm
PDQ 32 32 feet7,800 lbs. 1/2” / 13 mm3/8” / 10 mm 42 feetClimbing rope bridle35 feet5/16” / 8 mm
STILETTO 2727 feet1,700 lbs.1/4” / 6 mm1/4”/ 6 mm35 feetDouble braid15 feet5/16” / 8 mm
bridle
Drew Frye, Practical Sailor’s technical editor, has used his background in chemistry and engineering to help guide Practical Sailor toward some of the most important topics covered during the past 10 years. His in-depth reporting on everything from anchors to safety tethers to fuel additives have netted multiple awards from Boating Writers International. With more than three decades of experience as a refinery engineer and a sailor, he has a knack for discovering money-saving “home-brew” products or “hacks” that make boating affordable for almost anyone. He has conducted dozens of tests for Practical Sailor and published over 200 articles on sailing equipment. His rigorous testing has prompted the improvement and introduction of several marine products that might not exist without his input. His book “Rigging Modern Anchors” has won wide praise for introducing the use of modern materials and novel techniques to solve an array of anchoring challenges. 

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