Have you wanted a halyard with strong and light High Modulus line like Amsteel aloft but know it needs a cover so it wont slip on the cleat but find stripping Warp Speed just too expensive and still too thin to get a good grip on? This may be your answer. I have spliced 1/8 Amsteel to 1/4 inch Sta Set and have tested it to the breaking point of my 1/4 inch StaSet* as it goes over a Barient 22 Winch. These dimensions scale to 3/16 Amsteel and 3/8 Sta Set (or Samson XLS) making for a halyard as low stretch as wire yet easy on the hands and pocketbook. If you pick your vendors from the sources page, you can make a 100 foot halyard with 3/16 Amsteel and 3/8 XLS for $70 (and some time). Put a Brummel Splice in the end for the shackle and you are done.
We are going to bury 9 inches (seventy-two diameters) of 1/8 inch Amsteel in the 1/4 inch double braid. 7 inches will be between the core and cover. 2 inches will be inside the core. On the other side, we are going to bury 9 inches of cover inside the Amsteel. This part of the bury provides the holding force for the first part. The cover bury will be in two parts. The part closest to the splice will be braided as it normally is and the part furthest from the splice will be unbraided to ease the construction of the splice. Be sure to click on the thumbnails for a closer look.
Splice Instructions(click on image for larger version)
Theory of the Splice
A splice is held together by the friction between the different parts of the line in the bury. Frictional force is dependent on the coefficient of friction of the material, the contact area, and the holding force pressing the materials together. The contact area goes up as the length of the bury increases. The holding force comes from the constricting force of the braid diameter shrinking as it is pulled tight. The same force that wants to pull the splice apart provides the holding force that keeps it together. What we need is for the constricting force, contact area, and coefficient of friction to add up to more holding force than the pulling force on the line.
The problem with Class 2 ropes like Amsteel is that they are slippery and have low coefficients of friction. With all of this in mind, the Amsteel was placed between the double braids so that there would be twice the contact area than there is in a normal single braid splice. The bury of the cover inside the Amsteel provides the constricting force as the lines are stretched. It turns out that because the cover is relatively thick, the Amsteel is forced to open up and the weave angle increased to allow the space for the cover. When the pulling force is applied, the Amsteel weave angle tends to revert toward its normal angle and it squeezes very hard on the buried cover. It is likely that this splice needs far less cover buried to work because of this. But this is what I did so it is what I described.
The visualization is that as the line is pulled the first thing that happens is that the Amsteel weave over the buried cover constricts holding the cover tight. As things stretch more, the cover is pulled tight over the splice and that provides the constriction force that holds the splice together.
Testing of the Splice
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