JibCap’s Scuttlebutt #3 Halyard Knots or Nots
Determining a precise strength value for a particular knot is difficult because many factors can affect a knot efficiency test: the type of fiber, the style of line, the size of line, whether it is wet or dry, how the knot is dressed before loading, how rapidly it is loaded, whether the knot is repeatedly loaded, and so on. Yachting Monthly has a good article on knot strength or knot efficiency. https://www.yachtingmonthly.com/sailing-skills/strongest-sailing-knot-30247
The advantage of using the eye splice is that it retains approximately 80+% of the line strength. The disadvantages are halyard splices can be difficult to make during ‘on the water situations’, especially with older line and it is likely the broken splice will slip through the mast opening because of the splice’s small profile.
The only ‘knot’ that comes close to the eye splice is the ‘Double Fisherman’s Loop’ which retains line strength at approximately 80%. The advantages of the ‘Double Fisherman’ Loop’ is that it is easy to make under all circumstances and should this knot part, it is likely it will NOT pass through the mast opening because of its much larger profile. https://www.youtube.com/watch?v=01Qp-z0T2NE
One last note on halyard splices and ‘knots’, consider using a plastic thimble or something similar to increase the bend radius of line around the shackle as much as possible. Lines are significantly weakened if they are taken around tight turns. The entire load comes on the few fibers on the stretched outer edge of the turn and they break. Even a 5:1 radius (the radius of the bend compared to the diameter of the line) results in a loss of about 15-20 percent of the line strength.
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