PussFoot launched ask a rigger a week ago. We are happy to bring you the second question in the series (line-sets). If you have a question for our very own in house rigger please email us at PussfootOG@gmail.com. If you would like your name left out please indicate when you send in your question. Don't forget to send us pics if you have them.
Hi Dave:
Thanks for reaching out and asking about your lines. Line trim is an important aspect of canopy performance. Depending on the material the lines are made of, that will determine the average "shelf life" of a lineset. There are some materials that "go out of trim" faster than others and some that will retain the proper trim until they reach their breaking point under a load and they snap and fail. Some materials have better wear characteristics than others. It really depends on what canopy you're flying, size of the canopy and what you're looking at doing with the canopy.
Without actually seeing your canopy to see what the lines look like, I'm going to guess that it has microline or "Spectra" material lines. This material is known to " go out of trim" after a few hundred jumps. The heat caused by the lines coming through the slider grommets combined with the opening shock during deployment causing stretching and/or shortening of the lines, therefore changing the flight characteristics of the canopy. While microline has very good abrasion resistant properties, you could technically have a canopy with 1,000+ jumps and the lines look fine, while they are actually out of trim and causing issues. With microlined canopies, I recommend replacing the lines between 300-450 jumps. That number is also dependent on the wear of the lines. If you notice changes in the canopy and/or visible wear prior to those numbers, always have a rigger check the trim and inspect the lines.
There are good and bad characteristics of each material and each material has its optimal applications. Certain materials have less drag while others offer less drag combined with shock absorbing characteristics. If you're unsure what material is best for you and your canopy, check with your rigger or manufacturer for their recommendations.
I have included some video links to explain the difference and characteristics of each lineset materials.
I hope this helps Dave! As always, I recommend having a rigger inspect gear prior to purchase to find issues like this and make sure that gear is airworthy prior to your jumping it for the first time. Blue Skies!
Shauna
Actually I see you left a ton of information out of line sets and the causes of wear and trim changes. Yes, everything you previously listed are contributing factors and there are many other things that contribute more to line wear. Type and shape of grommets, size of grommet, WHERE you jump, sandy Vs, dusty locations Vs clean environment all cause more wear and tear on a line set than anything else mentioned. When you speak of Spectra, (Microline TM) I can honestly say I have put more than 1000 jumps opna Spectra line set with less than a 3/8" trim change, Simple solution is NOT to change the entire line set but to re-trim the existing line set. But then you have to know what you are doing in order to do that. Riggers recommending line set changes on a line set with less that 300-400 jumps are just ripping people off because they do not know how to re-trim a line set properly, efficiently and effectively!