Northwest Kiteboarding
Forum | Classifieds | Lost & Found | CGKA | Industry | Sensors | Forecast | Spots | Seattle | Decals | RSS | Facebook

Events | Photos | Search | Register | Profile | Log in to check your messages | Log in 

North Clickbar Kite Lines: Destructive Testing

 
Post new topic   Reply to topic    Northwest Kiteboarding -> Gorge / Portland / Oregon Coast
previous topic :: next topic  
Author Message
Nevo

Since 01 Aug 2014
117 Posts

Stoked



PostMon Aug 13, 18 6:13 pm    North Clickbar Kite Lines: Destructive Testing Reply with quote

I have a 2018 North Click Bar That I bought in April brand new. I noticed some pretty gnarly looking wear on my red steering line recently and asked for advice on retirement from several different sources (other kiters online, at the beach, and at shops). Across the board, everyone said the line looked too sketch to continue riding with so I retired the line and replaced both steering lines for stretch/balance.

I don’t know how the damage/wear occurred or what was causing the rapid degradation of the lines. I’m including details on myself and my kiting just for anyone else’s reference and to answer any additional questions ahead of time. Plus, I’m an AMGA Rock Guide and SPRAT Rope Access Supervisor so I geek out on these details frequently.

Kiter:
180lbs. Primarily riding a surfboard and flying north neo kites. Every day of use on this bar was either wave riding or working on strapless freestyle tricks.

Bar:
New 2018 North Clickbar with new lines. Purchased in April 2018, stored in a duffle bag with my older bars. Lines are always rinsed with freshwater from the hose immediately after an ocean session (8 sessions this year). Dirty lines at the river are always rinsed with river water before being packed away. Wet bar/lines are always set out to dry at home.

The Line:
All of the red Kevlar tracers were broken and the line appeared “poofy” when dry.

Use:
This bar and lines has seen 55 days on the water this season with total flight time around 100-150 hours.

Launches include:
Event Site
Lyle
Stevenson
Viento
Sauvies Island
Fort Stevens
Manzanita

Potential damage?

I’m very unsure of why the lines wore out so quickly. I reached out to North for any insight but have not received a response yet. I did have a launch that went poorly at Stevenson early season but had no noticeable damage to the lines afterwards. That’s the only moment I can fathom the lines being damaged.

Testing:
Tests were run in Bend, OR in a rock climbing equipment production and testing facility. Lines were clipped into carabiners and rigged with tensionless hitches to minimize the possibility of a line breaking at its connection to the carabiner.

Three tests were run:

Test #1: Control test.
An undamaged section of the line was tested to get a total breaking strength on the line before proceeding. We clipped the factory connection point at the base of the steering line (where the line connects to the bar) to the top of the hydraulic puller. Several feet away from that connection point a figure 8 on a bight was tied and then a tensionless hitch was added to protect the test results. This connection point was fixed to the floor.
The clean, undamaged line, broke at the end of the North Factory splice at a total strength of 364 lbs.

Test #2: Damaged Line Test.
The damaged section of line (that was the reason for retirement) was tested next. We clipped the factory connection point (where you insert a pigtail) at the kite end of the steering line to the top of the hydraulic puller. Several feet away from that connection point a figure 8 on a bight was tied and then a tensionless hitch was added to protect the test results. This connection point was fixed to the floor. The damaged section was quite long and a small portion of it was wrapped into the tensionless hitch.
The damaged section of line broke at the tensionless hitch where it contacted the carabiner. (basically that means it broke at a slightly lower strength due to compression on the carabiner). The damaged line broke at 309 lbs.

Test #3: Knotted Line Test.
I’ve seen quite a few people flying with knots in their lines that they can’t get out. I know this decreases the strength of the lines but figured this was the perfect chance to test and give us all some real world data. An undamaged central section of the kite lines was tested. An overhand on a bight was tied at both ends and a simple over hand knot was put in the middle of the line.
The knotted section of the line broke at 209 lbs.

Interpretation of results:

Test #1 – I was surprised to see such a low overall breaking strength for lines that have only been in use for a few months. I do not know what North claims as their breaking strength when the lines are brand new at the factory.

Test #2 – Despite the damaged line looking quite scary and being unnerving to both rider and others, it retained most of it’s strength. Even knowing this, I think I would replace my “damaged” lines for my own piece of mind on the water.

Test #3 – The reduction in strength was quite dramatic here. As such, I think it makes sense that even though a fuzzy, poofy, damaged line looks scarier… lines with knots in them can be far worse off.

That's it! Happy to answer any additional questions people might have. I hope this info is useful to others.

See you on the water.


Side Note:
Broken line photos and the original damaged line photo can be found in the sauvie island facebook group. Unfortunately I can't get any photos to upload to nwkite.com anymore.

View user's profile Send private message
jasonq

Since 12 Jan 2009
147 Posts
vancouver
Stoked



PostMon Aug 13, 18 6:47 pm     Reply with quote

wow, thanks for running that test.

i read on sampson's site (?) that a loop to loop splice takes about 15% off the rated strength of the line. with proper taper, etc, etc. so on a 500 lb line, the end splices would lead to a 425 breaking strength. from the tone of the article, i got the feeling this was a best case, and used larger lines that flying lines. So 364 from a 500 lb line breaking at the splice doesn't sound unreasonable. I am assuming it is a 500 lb line, could have been less. then even more reasonable.

the knot thing. i had always wondered how big an impact that was. it is a big impact. If you have a change to test again, i have been dying to know, if you knot the line, load it to say 150 lbs, then un-knot the line, and test to failure, how much strength is lost? basically, if I accidentally flew with knotted lines, then removed the knots, should i replace the lines? (or splice the knotted area).

View user's profile Send private message
Nevo

Since 01 Aug 2014
117 Posts

Stoked



PostMon Aug 13, 18 7:03 pm     Reply with quote

I won't have the chance but that would be an interesting test. The reality, in my mind, is that if you undo that knot and don't see (or feel!) damage, you should be okay. The knot causes heat when the line loads and it actually melts and breaks. So, if you undo a knot and can't feel or see any difference, I would think you're fine.


jasonq wrote:
wow, thanks for running that test.

i read on sampson's site (?) that a loop to loop splice takes about 15% off the rated strength of the line. with proper taper, etc, etc. so on a 500 lb line, the end splices would lead to a 425 breaking strength. from the tone of the article, i got the feeling this was a best case, and used larger lines that flying lines. So 364 from a 500 lb line breaking at the splice doesn't sound unreasonable. I am assuming it is a 500 lb line, could have been less. then even more reasonable.

the knot thing. i had always wondered how big an impact that was. it is a big impact. If you have a change to test again, i have been dying to know, if you knot the line, load it to say 150 lbs, then un-knot the line, and test to failure, how much strength is lost? basically, if I accidentally flew with knotted lines, then removed the knots, should i replace the lines? (or splice the knotted area).

View user's profile Send private message
Dern

Since 11 Jul 2010
498 Posts
Vancouver, WA
Obsessed



PostMon Aug 13, 18 8:35 pm     Reply with quote

Awesome work here. Thanks!
_________________
Curious about Ocean Rodeo gear? Drop me a line or visit Windance in Hood River or go to http://www.oceanrodeo.com

View user's profile Send private message
Ho-Toe

Since 30 Apr 2014
143 Posts
thread-killer; non sequitur specialist
Upwelling Specialist



PostTue Aug 14, 18 4:43 am    thank you! Reply with quote

Good stuff here. Thank you!

View user's profile Send private message
ldhr

Since 21 Jul 2009
1097 Posts
Hood River
XTreme Poster



PostTue Aug 14, 18 6:40 am     Reply with quote

Not sure what all these numbers mean - In 10 years of kiting I have never heard of a line breaking.
I've heard of people cutting lines by accident - but never heard of a line breaking under normal use.
So either we put less force on lines than we would think - or the lines are stronger than we think.
If you weigh 180 pounds - and if you get lifted off dry ground by your kite - what is the equivalent stress on the lines? And is this stress reduced by 25 - 50% as there are four lines to hold your weight?
Most of the weight is held by the front center lines.
Which lines did you test - front or back?

Finally - there was a known issue with 2017 North Clickbar lines wearing out (center lines). The new 2018 lineset has a slightly different separator and does not wear.
Are you sure you had the newest 2018 bar and lineset?
The new lines have a separator that screws tightly onto the line and is easily moved up or down.

View user's profile Send private message
Nevo

Since 01 Aug 2014
117 Posts

Stoked



PostTue Aug 14, 18 8:22 am     Reply with quote

That’s interesting that you haven’t heard of any line breaks. I’ve heard of 3 in the last few weeks. Sounds like a crappy day when it happens.

Steering lines should carry the least weight when simply cruising along. That’s what I found damaged and tested. I don’t know enough about sail/flight physics to know the load they face when doing tricks, looping, etc. We all know that sheeting in and out doesn’t take much strength.

The steering lines don’t go through a v distributor so that wasn’t causing the wear. 2018 bar.


ldhr wrote:
Not sure what all these numbers mean - In 10 years of kiting I have never heard of a line breaking.
I've heard of people cutting lines by accident - but never heard of a line breaking under normal use.
So either we put less force on lines than we would think - or the lines are stronger than we think.
If you weigh 180 pounds - and if you get lifted off dry ground by your kite - what is the equivalent stress on the lines? And is this stress reduced by 25 - 50% as there are four lines to hold your weight?
Most of the weight is held by the front center lines.
Which lines did you test - front or back?

Finally - there was a known issue with 2017 North Clickbar lines wearing out (center lines). The new 2018 lineset has a slightly different separator and does not wear.
Are you sure you had the newest 2018 bar and lineset?
The new lines have a separator that screws tightly onto the line and is easily moved up or down.

View user's profile Send private message
ldhr

Since 21 Jul 2009
1097 Posts
Hood River
XTreme Poster



PostTue Aug 14, 18 9:00 am     Reply with quote

Just for reference - Slingshot lines are considered by most to the be the strongest available.
Their lines are rated at 500lb outside lines and 800lb inside lines.

View user's profile Send private message
Nolo89

Since 21 Aug 2014
8 Posts
Seattle Area, WA
Kook



PostTue Aug 14, 18 9:57 am     Reply with quote

Great info. Thanks for posting!

View user's profile Send private message
Post new topic   Reply to topic    Northwest Kiteboarding -> Gorge / Portland / Oregon Coast All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You can attach files in this forum
You can download files in this forum