Jun 26, 2001, 3:18 PM
Post #1 of 28
Line stows breaking
Is there any chance or should I say what are the chances of a tube stow (rubberband) breaking inside the container. I heard that one of most nastiest mals is a line dump and it just got me thinking what if your stow broke inside the container while it was just sitting there at your house. How would you know? Couldnt that cause so major problems? Just wondering if anyone heard of such a problem.
I think as long as you keep an eye on them and make sure that they are not hanging on by a millimeter of rubber, they wont break. Just replace them as they need it. There is not really much stress put on them when they are stowed, just the process of stowing them is when they break, as they are being stretched over the lines. Also only the locking stoes are critical, some systems dont even have stoes for the lines other than the locking stoes, they are just s-folded inside a pocket of sorts outside of the d-bag.
Does the out-of-sequence unstowing cause other malfunctions?
It can cause a bag lock or tension knots. I think I would consider line dump a mal. i.e. stow bands not holding lines due to being worn out, or prematurely "dumping" the lines cause they are weak and break.
The biggest cause of line dump (IMHO) is not the stows breaking, but rather them being too loose and the lines slipping out too easily. The easiest way to prevent this is to keep an eye on your rubber bands/tube stoes and when they start getting too worn out and loose, replace them. In the case of rubber bands, if I think they're too loose, I'll double it up. The nice thing about the rubber bands over the tube stoes is they're designed to break if you get them too tight. If all your rubber bands are handing by about 1 angstrom of rubber, you might have line dump problems as well. I guess the bottom line is, keep an eye on your stows, and when the retaining bands are getting too worn out, replace them.
-the purpose of the stow bands (rubber bands, tube stoes, whatever) is to hold each line stow so that the lines deploy in an orderly manner. "Line dump" can cause OSDs, tension knots, bone-cracking openings, & damage to components due to undue stress.
-their secondary purpose is to do their part in staging the deployment so that the jumper decelerates to a speed at which the opening shock will be comfortable (once the slider comes down).
-tube stoes don't hold the lines as well as rubber bands, thus the lines deploy much faster. Notice that PD recommends rubber bands instead of tube stoes. Tube stoes DEFINITELY last longer because they are built to flip the stow out rather than roll up like rubber bands do.
-I help out fellow skydivers who are having hard openings in part by having them switch to rubber bands, make longer bights of line for each stow, and ensure that each stow is "clean;" the lines at the inside of the loop being stowed well enough so you can see through each stow.
-rubber bands are only 3 bucks a pound. IMHO the money you save in silicone spray will buy you enough rubber bands to last you a good while
-as for storing parachutes for extended periods in a packed condition - don't. If you know that you won't be jumping it for a while, have your Rigger help you open both containers and "Rigger roll" the canopies for storage. Keep 'em in the back of your closet where it's cool & dry, not in the basement.
-personally, I would compromise . . . use the heavier "locking" tube stoes for the locking stoes (the bulk above the cascades), and rubber bands for the rest. Make sure you are using the proper size stoe/band for the line type. A friend had a bone-cracker because he used regular tube stoes on his Silhouette with microline.
-my opinion on rubber bands on a (round?) reserve . . . rubber bands should be changed out every pack job so that they are fresh and do their job. The customer deserves the most bang (but least whack) for his buck.
I wans't implying it was not legal (what you do with your main is your business), I just question why you would want to have the bands more slippery... In my mind, it still does not make sense...
If they produce less friction, then it has to increase the chance of line dump (I'm not saying it will cause it, but if 1+1=2, then less friction = the stows are held less) if you keep the other variable of the pack job the same (stow length, band tightness...)
I don't mean to take sides ('cause I am not), but I thought I would give an objective opinion about the silicone idea being discussed here.
I have BRAND new dacron lines on my main and I would go through 3-4 rubber bands on EVERY jump. For the last couple of weeks though, where he got the idea I don't know, our dzo has been spraying his rubber bands with silicone and they work BRILLIANTLY!!! I go through about 2-3 rubber bands every second to third jump. While this is still a pain in the ass (new main with vectran/spectra lines here I come!!) it is a marked improvement!
So, whether or not it is good, bad, or otherwise...I am convinced that it can't be a BAD thing.
Seems that no one here has mentioned the most important factor in preventing line dump, and that is, large line bites. I don't object to Silicone on bands, but I do object to line bites smaller than 2.5 inches for locking, and 3 inches for post locking. (preferably 3.5") There is a HUGE difference in line dump potential between a 2 & 3 inch line bite, because of the "mass/lever effect" outside of the stow band.
BTW guys,--this topic/thread, belongs be in- "Gear and Rigging"
I agree about long bites being better, but why smaller for locking stows?
I guess it depends on the layout of the stows on the bag, but I tend to use progressively slightly shorter bites after the locking ones in order to minimise the chance of a loop of line getting round a bite which will release later in the deployment sequence, and so cause a baglock. (I hope that makes sense - not my best explanation!)
Anyway - I agree that roughly 3 inch stows are good.
I agree about long bites being better, but why smaller for locking stows?
DB> The "line span distance" between the locking stow points is much less than the span distance between the post locking stow points. This means there is much less line mass between the stow points,--It's the line mass between the stows that causes line dump.
Also, the locking stows are more consistently tighter because of the stretch of the band between the band attachment point and the grommet in the flap, which makes for a tighter stow. Combine both of these facts---ya dig.
In the event of catastrophic line dump at bag launch of the non locking stows, the locking stows would then more than likely "un-stow" before line stretch. (un-stow--as apposed to line dump) This is because of the inertial factor of the mass of the prematurely un-stowed line mass pulling on the locking stow. ('s) Critical bottom line--Prevent line dump of the non-locking stows with large line bites. Yes, higher band tightens will help, but larger line bites will come closer to balancing the span mass, which is the larger positive factor. As a matter of fact, if the bite sizes were half of the line span distance between the stow points, there could not be line dump even with loose bands, because of equal line mass on each side of the stow!
In the case of my prototype sleeves, I can go with 2.5" bites that do have equal mass on each side of the stow, only because of my "center span lifting loops," but in the case of a standard D-bag, you would need 5" bites which is not practical--and some would say, would increase the chance of a bag lock--but that's a whole other issue.
I have read every post on this thread, every line, every word, and I know I speaka da gud englishe, but I am so utterly lost!!!!!!!!!!!!!!
Perhaps after my 6th jump I will understand (well, a girl can hope)! I will be revisiting this thread in the future, and maybe a miracle will have happened and I will be able to comprehend this vast world of line stoes (or stine loews, which is what my eyes insist, because they are crossed now!)
OK, you sold me. Since I have no hard opening or line dump issues, I shall silicone my rubber bands to see how long they last. Sounds like it definitely reduces the "pain-in-the-ass factor." A little on the closing loop sounds like a good idea too.
Because of this thread, I went down to the dz yesterday - not to jump, but to watch the packing. I lurked, and I watched, and finally someone I knew needed to pack his chute. I got down on the ground, and really stuck my face in his chute, asking all the questions I could think of. What should have taken him about 10 minutes turned into more like 40, because he kept stopping and explaining, undoing and re-doing, showing and letting me touch, talking and teaching the whole time. I even got to help with the folding of the pilot chute (not a big deal to you, but huge to me.)
I now know what line stoes are!!!!!!!!!!!!! Thanks, Pete!