Knots/Rope splicing

Rope splicing is the forming of a semi-permanent join between two ropes or two parts of the same rope by partly untwisting and then interweaving their strands. Splices can be used to form a stopper at the end of a line, to form a loop or an eye in a rope, or for joining two ropes together. The resulting join is stronger than the equivalent using knots although it usually results in a thickening of the line and if subsequently removed a distortion of the rope. Most types of splices are used on 3 strand rope, but some can be done on 12 or greater strand braided rope.

A line eye-spliced to a snap shackle.

Types of splices

  • back splice (also called an end splice) - A splice where the strands of the end of the rope are spliced directly back into the end without forming a loop. It is used to finish off the end of the rope to keep it from fraying. The end of the rope with the splice is about twice the thickness of the rest of the rope. With nylon and other plastic materials, the back splice is often no longer used; the rope strands are simply fused together with heat to prevent fraying.
A cut splice
  • cut splice (originally called cunt splice) - A splice similar to the eye splice. It is typically used for light lines (e.g., the log-line) where a single splice would tend to come undone, the rope being frequently wet. It makes a very strong knot. A cut splice is a join between two ropes, made by splicing the ends slightly apart, to make an eye in the joined rope which lies shut when the rope is taut.
Some examples of splices and splices in progress. a) a long splice almost complete b) the steps in a tapered short splice c) an eye splice d) a short splice
  • eye splice - A splice where the working end is spliced into the working part forming a loop.
  • horseshoe splice
  • long splice - A splice used to join two rope ends forming one rope the length of the total of the two ropes. The long splice, unlike most splice types, results in a splice that is only very slightly thicker than the rope without the splice, but sacrifices some of the strength of the short splice. It does this by replacing two of the strands of each rope end with those from the other, and cutting off some of the extra strands that result. The long splice allows the spliced rope to still fit through the same pulleys, which is necessary in some applications.
  • short splice - Also a splice used to join the ends of two ropes, but the short splice is more similar to the technique used in other splices and results in the spliced part being about twice as thick as the non spliced part, and has greater strength than the long splice. The short splice retains more of the rope strength than any knots that join rope ends.
  • side splice

Tapering is also sometimes done to make the thicker splice blend or taper into the rest of the rope. It is does either by cutting off a lengthwise part of the end of each strand to make the end of the spliced part thinner or by staggering the strands so that the 2nd strand is interweaved one more time than the first and the third is interweaved an additional time after the 2nd. The staggering brings the splice from twice as thick as the rest of the rope to nearly the same thickness.

A fid is a tool (basically a hollow spike) that can be fit over the end of a strand and used to feed it through each loop as needed. It may be required for very tightly wound or large ropes.

A marlin spike is a tool, commonly part of a sailor's pocketknife, used to separate strands of rope from one another. It is basically a 3"-4" steel spike, slightly curved, with a non-sharp point that tapers quickly out to a 1/4" to 3/8" shaft in the space of the first 1" length.