This is about some fishing line that was being "talked" about, in another forum, that didn't seem to be performing as expected, 50# PowerPro with knots that were breaking at 20-25 lbs. There were many theories advance about why this line wasn't as strong as expected: bad line, worn line, too old line, and some cures suggested: replace line, reverse line on spool, try a different knot. The favorite theory was that the line came from a Junk Spool.
Feeling that it might have something to do with their test methods, I offered to check the ABS (actual breaking strength) and KBS (knotted breaking strength) of the line. I communicated with "The Poster" enough to know that he was tying his knots properly and being systematic about his testing approach.
About a week ago, "The Poster" sent me 10 yards of the 50# PowerPro that had been giving them the problems. As part of the experience that got me into building leaders for casting to large gamefish on light tackle, I've spent a lot time researching the science of knots and destructively testing them--too much time if you ask my family.
The first thing I did was to visually inspect the PowerPro. It had the same feel and appearance of several other spools of 50# PP that I have on hand.
Next I tied an 8-turn Uni Knot to a large swivel. The knot was pulled up carefully and seated fully. I hooked the swivel to a weight load that I use for testing, and wrapped the loose end of the PP around a two inch diameter puller so that I didn't put any stress on the pulling end of the line. I started by lifting 15 lbs. and added weight 2.5 lbs. at a time. The line sample successfully lifted 37.5 lbs., and broke at 40 lbs. So I would say the KBS of the line is about 38 lbs., best case. If I were using the line I would plan on 35 lbs. or less for some safety margin.
The next knot I tried was a 50-turn Bimini (usually I get almost 100% of line strength). In fact I tied two. Both failed at 40 lbs., very surprising. I decided to set that test aside and went straight to an ABS test.
I measure ABS by splicing a 90 lb. hollow-weave line onto the end of the test sample by this method: Hollow Spectra Techniques: Splicing Hollow-Weave line to Solid Line. Then I attached it to the weight bar and started lifting weights at 30 lbs. I was able to hold 57.5 lbs., and the line broke at 60 lbs. So lets call this a 58 lb. ABS line.
The ratio of KBS/ABS is about 65%, which is what I've experience for Uni Knots tied in PowerPro 50# before. And in almost every line I've tested, the Uni knot performs like dozens of other usual knots (meaning not a Bimini Twist, PR Knot or SIG Knot). I called this group the 60%-class knots.
I then went back and tied a very carefully make Bimini at 60 turns. The twists were still slipping a bit, and the knot broke in the low 40 lb. range. Finally, wanting success, I tied a 100-turn Uni and lifted 50 lbs. Not that good but I didn't feel like going further.
Summary of PowerPro 50# Sample:
ABS: 58 lbs
KBS: 38 lbs.
Uni Knot strength: 60%-class
Bimini Twist 100 turns: 85% strong (unusually low)
Number of threads in weave: 4 (better lines use 8, hollow-weave lines use 12 or 16)
Although I have used PowerPro for years and have nothing against the line, I have switched to 60# Jerry Brown hollow weave (90 lbs. ABS in White color) for light tackle. It's smoother and can be spliced, so no line strength is lost while making connections. (I don't sell any lines, nor do I get any fees for making this recommendation.) With a lot of experience tying good knots in Spectra braids, I would have to say that PowerPro is among the more difficult lines to tie strong knots--most likely because of 4-thread design and perhaps due to the coating they use, which seems slippery to me.
Feeling that it might have something to do with their test methods, I offered to check the ABS (actual breaking strength) and KBS (knotted breaking strength) of the line. I communicated with "The Poster" enough to know that he was tying his knots properly and being systematic about his testing approach.
About a week ago, "The Poster" sent me 10 yards of the 50# PowerPro that had been giving them the problems. As part of the experience that got me into building leaders for casting to large gamefish on light tackle, I've spent a lot time researching the science of knots and destructively testing them--too much time if you ask my family.
The first thing I did was to visually inspect the PowerPro. It had the same feel and appearance of several other spools of 50# PP that I have on hand.
Next I tied an 8-turn Uni Knot to a large swivel. The knot was pulled up carefully and seated fully. I hooked the swivel to a weight load that I use for testing, and wrapped the loose end of the PP around a two inch diameter puller so that I didn't put any stress on the pulling end of the line. I started by lifting 15 lbs. and added weight 2.5 lbs. at a time. The line sample successfully lifted 37.5 lbs., and broke at 40 lbs. So I would say the KBS of the line is about 38 lbs., best case. If I were using the line I would plan on 35 lbs. or less for some safety margin.
The next knot I tried was a 50-turn Bimini (usually I get almost 100% of line strength). In fact I tied two. Both failed at 40 lbs., very surprising. I decided to set that test aside and went straight to an ABS test.
I measure ABS by splicing a 90 lb. hollow-weave line onto the end of the test sample by this method: Hollow Spectra Techniques: Splicing Hollow-Weave line to Solid Line. Then I attached it to the weight bar and started lifting weights at 30 lbs. I was able to hold 57.5 lbs., and the line broke at 60 lbs. So lets call this a 58 lb. ABS line.
The ratio of KBS/ABS is about 65%, which is what I've experience for Uni Knots tied in PowerPro 50# before. And in almost every line I've tested, the Uni knot performs like dozens of other usual knots (meaning not a Bimini Twist, PR Knot or SIG Knot). I called this group the 60%-class knots.
I then went back and tied a very carefully make Bimini at 60 turns. The twists were still slipping a bit, and the knot broke in the low 40 lb. range. Finally, wanting success, I tied a 100-turn Uni and lifted 50 lbs. Not that good but I didn't feel like going further.
Summary of PowerPro 50# Sample:
ABS: 58 lbs
KBS: 38 lbs.
Uni Knot strength: 60%-class
Bimini Twist 100 turns: 85% strong (unusually low)
Number of threads in weave: 4 (better lines use 8, hollow-weave lines use 12 or 16)
Although I have used PowerPro for years and have nothing against the line, I have switched to 60# Jerry Brown hollow weave (90 lbs. ABS in White color) for light tackle. It's smoother and can be spliced, so no line strength is lost while making connections. (I don't sell any lines, nor do I get any fees for making this recommendation.) With a lot of experience tying good knots in Spectra braids, I would have to say that PowerPro is among the more difficult lines to tie strong knots--most likely because of 4-thread design and perhaps due to the coating they use, which seems slippery to me.