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The Double Braid Eye Splice


Since a splice is stronger than any knot, splicing an eye in double braid line is one of the essential marlinspike arts.  Using nylon line with its greater elasticity, dock lines and anchor rodes can be made.  Polyester double braid is the standard for sailboat running rigging.

Double braid line is made of two braided tubes, an inner core and an outer cover.  When the tubes are stretched along their length, their diameters shrink, grabbing each other like "Chinese handcuffs".

Whenever possible, use new line to make eye splices.  Used line has probably shrunk enough to make the process difficult, even if it has never been used.  I saw an attempt to splice a thimble onto the never-used end on a 7/8-inch nylon rode.  Apparently, the repeated soaking and drying caused the line to loose its elasticity so that the eye spice was impossible.  Line that has been under a strain is worse -- the working of the line causes internal heating from friction which "locks" the strands and fibers together.

Tools -- Certain items should be available, including:

Standard fids are the most frequently used.  They are sized for the appropriate line diameter.  Wire fids are shaped like a modified bobby pin, with the ends pointed in to hold the line.  They are typically 1/2 the length of the standard fid.  There are also several new designs available.

Standard Fid sizes. Modified from "Splicing Guide for STA-SET X and PCR" New England Ropes, 848 Airport Road, Fall River, MA 02720

Rope Diameter Fid Length Short Section Measure Long Section Measure
1/4 5.25 2.000 3.50
3/8 7.75 3.000 4.75
1/2 11.0 4.000 7.00
3/4 16.0 4.75 11.25
7/8 19.0 5.000 14.0
1.0 21.0 5.25 15.75


Splicing the Eye

Animated Braid Eye Splice


In this version, the links in the text will go to a "still" of the operation being explained.  Use your "back" button to return.
  1. Begin by placing one layer of masking tape around the line near its end.  Cut the line there to expose a fresh end which hasn't been melted to seal it.
  2. Next measure one full fid length from the end of the line and put a mark on the line there.
  3. Form the size of the desired loop using this mark as a start and make a second mark where the loop will join. STILL.
  4. Tie a slip knot, or cleat the line 4-5 feet from the end.  This is needed to prevent too much shift in the core and cover.
  5. The core is extracted from the cover at this second core mark.  Bend the line sharply and use the needle to tease apart the cover strands and gradually start working the core out.  Needle-nosed pliers may be useful.  STILL.  Tape the end of the core once extracted.
  6. While holding the core, push the cover down toward the knot or cleat, exposing more core. STILL.
  7. Next work the cover back up and mark the core where it exits the cover.  This process re-aligns the cover and core after movement.
  8. Now push the cover back toward the knot again exposing about 3 fid lengths of core past the mark.  From the mark on the core, measure one short fid section toward the knot and place a second mark on the core.  Then measure 1 full fid length PLUS 1 short fid section more and put a third mark on the core.  STILL.
  9. Insert the fid into the core at the 2nd mark aimed in the direction of the 3rd mark.  With new line, you should be able to get the fid to exit at the third mark without losing the end.  If not, you will need to use the push rod after inserting the cover. STILL.
  10. Insert the cover end into the hollow end of the fid (or attach the wire fid).  Use the push rod to shove the fid and cover out of the 3rd mark on the core.  Keep pulling more cover out of the core until the 1st original mark is exposed.  Count eight strands (or sets of 2 or 4 strands) down toward the end and put a 3rd mark on the cover there.  Remove the tape from the cover.
  11. At this stage, you can optionally taper the cover to produce a better looking finished eye. Details on tapering.
  12. Pull the cover back out of the core until the 3rd mark is just exposed (8 strands past the 1st cover mark). STILL.
  13. Now, starting at the 2nd mark on the cover (where you originally extracted the core), measure 1/2 fid length toward the knot or cleat and put a 4th cover mark here.  Next insert the fid into the cover at the 3rd mark (8strands past the 1st cover mark, where it exits the core) and work it past the second mark to exit at the 4th mark. STILL.  If you are making a large eye, you may have to exit the cover before the 4th mark, pull up the slack, re-enter the cover through the exact same hole and continue.
  14. Insert the end of the core and push it through using the push rod.  Pull out the core until the 1st core mark in seen (where it was originally extracted from the cover).  STILL.
  15. Next, taper the core from the 1st core mark to the end by cutting and removing every other strand.
  16. From the point where the cover enters the core and the core enters the cover, smooth the line in both directions.  The exposed end of the cover should disappear into the core.
  17. Now, put some serious tension on the core at this point.  You may want to put the slip-knot around a fixed object so you can pull hard.  What you are doing is stretching the core so that its diameter where the cover is inside of it is reduced.
  18. Now, start "milking" the cover back down over the core.  You may want to keep a lot of tension on the core.
  19. As you continue, beat on the area where the core is going into the cover to soften the line.  Also try putting a stick (hammer handle or large fid) into the eye and give some sharp, strong tugs.  STILL.
  20. Keep going until your very 1st cover mark disappears, or the eye is snug around the thimble.
  21. Finish the splice by sewing through the splice part of the eye for at least 4 diameters, then do it again with the stitch line 90 degrees off from the first row of stitches;
  22. Well done.

Copyright 1998 Bruce Tetzlaff.  Use permitted with credit.

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