Blood knot to join 2 pieces of Q-Power line?

[Sarda]

In my experience and using the image from above, those are the points where I would expect to see the line fail. I have no idea of what use that may be to anyone!

[sarc]

So I've been kiting on my frankenbar since November and I tried the blood knot and the double uni and the answer it blood knot all the way!
DISCLAIMER this is for Q-Power line that cannot be spliced. For normal kite lines always use splices, not knots!
The reason not to use the figure of 8 loop or double figure of eight was that they are snag magnets for Q-Power line. Unwinding the line in 30kn guarantees you'll be spending more time untangling than unwinding. The fact is, whenever the knot ends with the working end along the kite line, it forms a hook that snags anything in the vicinity like a tangle magnet. The blood knot has ends at 90 deg to the kite line and to my surprise this makes them very snag resistant. I didn't cut the extra line because it does not cause any trouble.
I messed up my blood knots real bad - I did 4 turns based on animated knots, but this prevented the knots from capsizing and forming the very neat and tight proper blood knot. Also the Q-Power line is very old (hence the need for knots) and it slips less than new line that I used for the tests. So remember to use 3 turns in the knot and maybe lubricate with some soap to help the capsizing. Also leave at least 15cm free working end because the knots need to creep and use a lot of working end to settle. Mine settled after 5 or 6 sessions. ps for the line beginning and end use only double figure of 8 loops! I've tried other knots over the years and they all failed on Q-Power.
WARNING this is a picture of the worst blood knots in the history of blood knots - I just can't be arsed to replace them because they still work fine

[evan]

Still in doubt if this shows the strength of knotted Q-power lines or that it is revealing that the average lines are never seeing loads close to the rated breaking point.

Can't test it at the moment as I destroyed my testing rig, but my guess would be the latter as I did run into used lines sets with front lines that failed as low as 100kg when exploring their breaking point.

[vakiter]

What about shrink wrap on the fig8 knots? If the only problem is snag?

[Herman]

Shrink wrap has been used in the past at the base of sleeved and sown line ends. Rightly or wrongly, this got a reputation of causing premature wear and failure at this point. Never seen any real test data on it but i concluded that it was a good idea to avoid anything stiff enough to cause a hinge point in the line. I would sooner use a flexible tape to fair things if necessary. Obviously not an immediate effect but over time………..

[faklord]

Still in doubt if this shows the strength of knotted Q-power lines or that it is revealing that the average lines are never seeing loads close to the rated breaking point.

Can't test it at the moment as I destroyed my testing rig, but my guess would be the latter as I did run into used lines sets with front lines that failed as low as 100kg when exploring their breaking point.

Just done a couple of pull tests:
3 wrap blood knot failed at 140kg. Tested 2 samples, one with standard fig 8 loops and one with double fig 8 loops. In both cases loops were ok and failed at blood knot at approx same load.

2 wrap blood knot. Knot slipped at about 80kg. Only did this as I had tied this knot in error and thought I might as well give it a test.

I’ve previously tested the same line using bollard terminations and it failed at about 250kg.

[evan]

250 sounds ok for kiting, 140 for the front lines is already on the sketchy side for heavier big air riders but could be ok for wave/foil.

[Sarda]

Still in doubt if this shows the strength of knotted Q-power lines or that it is revealing that the average lines are never seeing loads close to the rated breaking point.

Can't test it at the moment as I destroyed my testing rig, but my guess would be the latter as I did run into used lines sets with front lines that failed as low as 100kg when exploring their breaking point.

Just done a couple of pull tests:
3 wrap blood knot failed at 140kg. Tested 2 samples, one with standard fig 8 loops and one with double fig 8 loops. In both cases loops were ok and failed at blood knot at approx same load.
IMG_5734.jpeg


2 wrap blood knot. Knot slipped at about 80kg. Only did this as I had tied this knot in error and thought I might as well give it a test.
IMG_5729.jpeg


I’ve previously tested the same line using bollard terminations and it failed at about 250kg.

Try a double fisherman. It is similar to the blood knot. I wouldn't expect any miracles.

Does it fit into the 32%?

[faklord]

Try a double fisherman. It is similar to the blood knot. I wouldn't expect any miracles.

Does it fit into the 32%?

Did this a while back. Same line. Failed at 113kg.

Also (for info) fig 8 loop failed at about 145kg, so much the same as the blood knot.

[sarc]

Farklord thanks for your tests! So your breaking strength for blood knot is close to that of double figure of 8. Given that we must have double figure of 8 at the end of the line, I don't see much of a problem using blood knot elsewhere in the line! BTW what knot would you recommend to join 2 pieces of q-power without snagginess?