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Lobster Weak Link & Buoy Line Marking Techniques

November, 21  2000 

Gear Research Team
Protected Resources Division
NMFS, Northeast Region 

Hog Rings 

Tests were run in the laboratory on a variety of ropes using 5/8" hog rings to form an eye with the following results: 

5 hog rings forming an eye in 3/8" poly-dac had an average strength of 470 pounds. 

7 hog rings forming an eye in 3/8" poly-dac had an average strength of 605 pounds. 

7 hog rings forming an eye in 3/8" poly-steel had an average strength of 540 pounds. 

7 hog rings forming an eye in 5/16" poly-dac had an average strength of 580 pounds. 

No significant variation was noted between wet and dry tests.  Also, the length over which the hog rings were distributed ( from 6" to 12") didnít significantly affect the strength. [click here for picture hog.jpg

Off the Shelf Weak Links 

The Modern Mould Sliplink tm is a knotless system based on the same theory as a jam cleat.  In its present configuration its holding strength is 400 pounds. [click here for picture mm.jpg

Planteís Lobster Vents, Inc.  is currently developing a swivel that incorporates a weak link.  It can be manufactured for different strengths (500, 600, 1100 etc.) as required.  They are expected to be available around the first of the year.   [click here for picture plante.jpg

Higher Strength Weak Links 

A weak link technique suitable for higher loads is a spliced jumper.  The jumper is selected based on breaking strength data from the manufacturer.   [click here for picture jumper.jpg

Buoy Line Marking 

Buoy lines can be marked in a variety of ways.  Shown below are three simple methods that were tested and found to work satisfactorily under normal conditions.  At the top, colored twine is seized around the line and woven between the strands.  In the center the line was spray painted.  This method requires that the rope be dry.  At the bottom,  colored electrical tape was wrapped in one direction and then back over itself to form two layers. [click here for picture marking.jpg]


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