Knots - Tail length - any authority for recommendations

[Charles Kenyon]

I teach Marlinespike Seamanship at the Hoofer Sailing Club at the University of Wisconsin in Madison.


I have been told by people I trust that for most knots there should be a tail in the working end of six times the diameter of the line. For bowlines, the tail should be twelve times the working end.


The only authoritative statement on this I've found is in Animated Knots instructions on the bowline. There it is mentioned along with the statement that it is seldom seen.


Here is a temporary link to my calculator for these lengths for lines from 1/8" to 1". https://www.dropbox.com/scl/fi/qdjhj...fvif010cu&dl=0


Does anyone know of any authority for these?


Note: I cross-posted this in the International Guild of Knot Tyers forum and do not expect there is much overlap in viewers. If I get anything useful there, I will post it here as well.

[thinwater]

Originally Posted by Charles Kenyon

I teach Marlinespike Seamanship at the Hoofer Sailing Club at the University of Wisconsin in Madison.


I have been told by people I trust that for most knots there should be a tail in the working end of six times the diameter of the line. For bowlines, the tail should be twelve times the working end.


The only authoritative statement on this I've found is in Animated Knots instructions on the bowline. There it is mentioned along with the statement that it is seldom seen.


Here is a temporary link to my calculator for these lengths for lines from 1/8" to 1". https://www.dropbox.com/scl/fi/qdjhj...fvif010cu&dl=0


Does anyone know of any authority for these?

Go question.


First, animated knots said X times the circumference (you said diameter above). You used circumference in your calculator.


Climbers use a back-up knot with a bowline; they tie the tail about the working part with an overhand or double overhand. Although the rational has to do with slippage, the real reason for backup knots is to make sure the tail is long enough (can't tie the back-up knot if the tail is too short). Additionally, a bowline can shake loose, but this is far more a concern for sailors than climbers (no flogging jib ... but you do die).



---


Obviously, the need for the tail is to allow for slippage as the knots pulls up. The amount relates to material (hemp least, polyester little, nylon more, Dyneema will just keep moving with most knots if the load is high enough). Also, how dressed and snugged the knot is matters; a sloppy figure 8 draws up more than a well-dressed one. Some knots, such as a half hitch, never really draw up and can always work loose, no matter how long the tail, unless the tail can is secured in some manner, such as a seizing.

[thinwater]

Originally Posted by Charles Kenyon

I teach Marlinespike Seamanship at the Hoofer Sailing Club at the University of Wisconsin in Madison.


I have been told by people I trust that for most knots there should be a tail in the working end of six times the diameter of the line. For bowlines, the tail should be twelve times the working end.


The only authoritative statement on this I've found is in Animated Knots instructions on the bowline. There it is mentioned along with the statement that it is seldom seen.


Here is a temporary link to my calculator for these lengths for lines from 1/8" to 1". https://www.dropbox.com/scl/fi/qdjhj...fvif010cu&dl=0


Does anyone know of any authority for these?

Go question.


First, animated knots said X times the circumference (you said diameter above). You used circumference in your calculator.


Climbers use a back-up knot with a bowline; they tie the tail about the working part with an overhand or double overhand. Although the rational has to do with slippage, the real reason for backup knots is to make sure the tail is long enough (can't tie the back-up knot if the tail is too short). Additionally, a bowline can shake loose, but this is far more a concern for sailors than climbers (no flogging jib ... but you do die).



---


Obviously, the need for the tail is to allow for slippage as the knots pulls up. The amount relates to material (hemp least, polyester little, nylon more, Dyneema will just keep moving with most knots if the load is high enough). Also, how dressed and snugged the knot is matters; a sloppy figure 8 draws up more than a well-dressed one. Some knots, such as a half hitch, never really draw up and can always work loose, no matter how long the tail, unless the tail can is secured in some manner, such as a seizing.



---



update: I dug into this for a while. Abandon all hope of a meaningful answer.

[capt jgw]

I embarrassed the hell out of myself once at work when they replaced the halyard on the flag pole out front. I tied the ends with my best sailorly knot not realizing how slippery the hardware store rope was and the first time we raised the Flag the knot pulled out and the whole works came down. Ever since on critical things I tie an overhand knot in the tail. That can't pull through the knot. Well, maybe with Dyneema it could but I don't use that.