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20_kN

Single or Double Stow the Locking Stows?

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During my packing class my instructor said to consider single stowing most of the stows. I was told the instructor prefers to double stow the two of the locking stows on the bag and single stow everything else. My S&TA did not seem thrilled at the idea of double stowing all the stows when I asked about it. Other packers and instructors have mentioned opinions ranging from never double stow anything (avoid bag lock) to always double stow everything (avoid bag strip).

PD seems very passionate about double stowing and in multiple videos they recommend double stowing all the stows. They claim double stows will not create a bag lock although I do know bag locks have occurred at the stow point on double-stowed bags.

https://www.youtube.com/watch?v=4Nsca5add8g

Mirage does not seem to specify one method over the other, but in their user manual the photos show the bag as packed with double stows. Icarus also does not appear to recommend any one method, but in their packing .pdf they show the bag packed with double stows as well.

I know via previous searches that many people were strongly against double stowing the locking stows 10 years ago but it's not clear if that's still valid anymore.

So here is the question. I have a Mirage semi-stowless M6 with an S-Fire 189 that has Vectran lines. Should I:

a) Single stow the locking stows w/ small bands
b) double stow the locking stows w/ medium bands?

Keeping in mind my packing skill is still at the beginner level at this point.

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Here's my take on the baglock vs linedump discussion. Linedumps (sometimes caused by not stowing properly) hurt as hell, and have been known to kill people. On the other hand, if you have a baglock, you look up, see a ball of shit that's obviously not going any place nice soon, and you chop. No pain, no death, just a difficult search for the canopy (been there, done that, still haven't found it).

If I have the feeling that my stows, especially the locking stows, are too weak, I'll double-stow them without sparing a second thought.

Also: clickyfied: https://www.youtube.com/watch?v=4Nsca5add8g

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The people recommending single stows, do they have as much research and testing behind their recommendation to do a single stow as PD has behind their recommendation to do a double stow?

Here is another vid that shows them recommending double stows and why.

https://www.youtube.com/watch?v=lbyYbXFpMQg

I will take a company's recommendation with a grain of salt if they profit doing it one way over the other. Since PD is not selling proprietary double stow rubber bands with an embossed PD symbol on them when they make this recommendation, AND they test jump more in a year than I will probably get in a lifetime, I will go with what they say.

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As you stow the lines, the groups will get smaller because cascades turn two lines into one. Thus causing loose rubber bands if all the same size bands are used. I personally mount the bands so I can grasp the flat part mounted at the bag and pull and wiggle it to snug the band around the group, no matter how small the group is. One size band works for all, and I single stow all. The snugging down is important to give more equal release pressure to all bands. Just my personal way of doing it. No problems what so ever. The "legal" way is to follow the manufacturers instructions.

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I'm OK with whichever method one prefers, as long as the lines have some restraint, and the locking stows are somewhat tighter. So if I'm not using a sem-stowless bag, I tend to go with single stows for my personal convenience.

Some may find a double stow more awkward than opening up those small stows, while others think the reverse.

Which elastics to use does depend also on line type and thickness, and as mentioned the bundle is smaller once one is past the cascades that are on most canopies.

I don't recall what numbers any company mentions for the force to undo each stow. .... Oh wait, here's Bill Booth although from back in 2006:
Quote

it should take no less than 5, nor more than 10 pounds to unstow a line group off a sport bag (7 - 15 lbs. on a large military or tandem bag)



-------------------
EDIT: I'll add what PD says in a document it had on hard openings, as they have slightly different numbers:
Quote

To check your
stows on the ground, it should take a minimum of 8 pounds,
and ideally 12 pounds of force to unstow the lines pulling the
bag across a smooth surface by the bridle. (The emphasis
should be toward 12 pounds) Use a fish scale on the bridle to
check this. Larger, heavier canopies will require more force,
as does a canopy deployed at higher speeds.


-------------------


I'm not sure a semi-stowless bag gets to the higher values -- nor do reserve freebags!

I personally am OK with forces on the lower end, as long as I think the lines aren't going to get dumped out (messily and possibly out of sequence).

Round reserves -- as used on pilot rigs -- single stow on their diapers. And they can have 20 stows per canopy. Of course a diaper lock, like a bag lock, is very bad on your last parachute.

PD does have a point that double stows have the doubled part grip the lines nearly equally from 360 degrees. The single stow tends to grip one side well but pull the lines up against the lumpy knot area, where some lines may be gripped more than others, allowing some to pull loose more easily. (There will always be a bit of that -- a line in the middle of any bundle might slide out easier than one on the outside that's in physical contact with the sticky rubber band.)

If one needs more fine tuned adjustment for single stows, one can buy intermediate length 1.5" elastics. Or one can do a sort of double lark's head knot when putting a regular elastic on the bag to shorten it up.

But yes the trend has been more towards double stowing, although I'm not sure what the ratios are out on the packing mat.

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20_kN

Vectran lines



Double stow. As already mentioned, the real recommendation is not single or double, but 8-12 lbs of force to release. How you achieve that depends on line type and cell count. Pick the configuration that comes closest to the optimal range. Most people never bother to measure the actual extraction force, and not many are using Dacron lines these days, hence the general double stow recommendation.

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Two single stows on my semi-stowless bag, with large bights.

I go with the John Sherman theory, that preventing a bag strip situation involves using the mass of the bights to create an inertia that will bend them and prevent the bag from being ripped off the canopy.

seth
It's flare not flair, brakes not breaks, bridle not bridal, "could NOT care less" not "could care less".

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If you single stow, the lines can come out unevenly, greater chance of entanglements. Double stowing holds the lines together tightly, even as the rubber band stretches, which lets them pop out evenly. I watch PD videos, and they said on all their thousands of tests, double stows have NEVER caused a bag lock!

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Justincblount

I watch PD videos, and they said on all their thousands of tests, double stows have NEVER caused a bag lock!



Yes, I recall them saying that although several people have disagreed claiming they have had bag locks on double stowed rigs. Some of them post on here. There are photos online showing a bag lock on a double stow. While I am not in a position to really argue (never had a bag lock so I would not know), I do know it's most certainly possible to wrap the stow tight enough that it wont release. Whether that is possible with two wraps is obviously debatable, but I know some people who even go as far as triple stowing their lines and that sounds like approaching bag-lock territory.

Someone once argued that a double stow cannot cause a bag lock because even if the band did not release the PC easily produces enough force to break any rubber band. On it's surface, I'd agree, that sounds logical as a PC should generate way more force than any rubber band can withstand. However in practice, there are several photos and videos showing bag locks where the bands did not release (for whatever reason) and the PC did not break the rubber band. I am wondering why that is?




https://www.youtube.com/watch?v=bmmxBP2zp9o

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20_kN

***I watch PD videos, and they said on all their thousands of tests, double stows have NEVER caused a bag lock!



Yes, I recall them saying that although several people have disagreed claiming they have had bag locks on double stowed rigs. Some of them post on here. There are photos online showing a bag lock on a double stow. While I am not in a position to really argue (never had a bag lock so I would not know), I do know it's most certainly possible to wrap the stow tight enough that it wont release. Whether that is possible with two wraps is obviously debatable, but I know some people who even go as far as triple stowing their lines and that sounds like approaching bag-lock territory.

Someone once argued that a double stow cannot cause a bag lock because even if the band did not release the PC easily produces enough force to break any rubber band. On it's surface, I'd agree, that sounds logical as a PC should generate way more force than any rubber band can withstand. However in practice, there are several photos and videos showing bag locks where the bands did not release (for whatever reason) and the PC did not break the rubber band. I am wondering why that is?


[.image]http://www.skydivewestpoint.com/skydiving-information/images/1Packing_009.jpg[/image]

https://www.youtube.com/watch?v=bmmxBP2zp9o

The video above shows the COLLAPSED drogue, not an inflated drogue or pilotchute.

Even if you triple wrap, the band has to break only in its single layer. You triple wrap, but only a single layer of the band goes to the deployment bag attachment point.

Some pilotchutes are worn out, too small, have shrunk kill-lines, or the combination of these factors. Such PCs would not generate adequate force.



.

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20_kN

***I watch PD videos, and they said on all their thousands of tests, double stows have NEVER caused a bag lock!



Yes, I recall them saying that although several people have disagreed claiming they have had bag locks on double stowed rigs. Some of them post on here. There are photos online showing a bag lock on a double stow. While I am not in a position to really argue (never had a bag lock so I would not know), I do know it's most certainly possible to wrap the stow tight enough that it wont release. Whether that is possible with two wraps is obviously debatable, but I know some people who even go as far as triple stowing their lines and that sounds like approaching bag-lock territory.

Someone once argued that a double stow cannot cause a bag lock because even if the band did not release the PC easily produces enough force to break any rubber band. On it's surface, I'd agree, that sounds logical as a PC should generate way more force than any rubber band can withstand. However in practice, there are several photos and videos showing bag locks where the bands did not release (for whatever reason) and the PC did not break the rubber band. I am wondering why that is?


[.image]http://www.skydivewestpoint.com/skydiving-information/images/1Packing_009.jpg[/image]

https://www.youtube.com/watch?v=bmmxBP2zp9o


I don't believe a tandem bag lock is a fair argument in this case. The rubber bands are considerably larger and stronger than those of standard sport rigs.
Chuck Akers
D-10855
Houston, TX

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Firebotlt w/ 725 Spectra: Double stow all with medium bands

Sharpchuter with 900 Dacron: Single Stow only locking stows, double stow others - all with medium. I like the idea of double stowing the locking stows too, but with big heavy dacron that just aint' gunna happen.

*Edited to correct the line size.
=========Shaun ==========


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skydiverek

******I watch PD videos, and they said on all their thousands of tests, double stows have NEVER caused a bag lock!



Yes, I recall them saying that although several people have disagreed claiming they have had bag locks on double stowed rigs. Some of them post on here. There are photos online showing a bag lock on a double stow. While I am not in a position to really argue (never had a bag lock so I would not know), I do know it's most certainly possible to wrap the stow tight enough that it wont release. Whether that is possible with two wraps is obviously debatable, but I know some people who even go as far as triple stowing their lines and that sounds like approaching bag-lock territory.

Someone once argued that a double stow cannot cause a bag lock because even if the band did not release the PC easily produces enough force to break any rubber band. On it's surface, I'd agree, that sounds logical as a PC should generate way more force than any rubber band can withstand. However in practice, there are several photos and videos showing bag locks where the bands did not release (for whatever reason) and the PC did not break the rubber band. I am wondering why that is?


[.image]http://www.skydivewestpoint.com/skydiving-information/images/1Packing_009.jpg[/image]

https://www.youtube.com/watch?v=bmmxBP2zp9o

The video above shows the COLLAPSED drogue, not an inflated drogue or pilotchute.

.

I see that now, thanks.


Quote

I don't believe a tandem bag lock is a fair argument in this case. The rubber bands are considerably larger and stronger than those of standard sport rigs.




Sure, but they have a drogue which is huge and can generate a massive amount of resistance. A drogue should be able to break several of those tandem bands easily.

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20_kN



Quote

I don't believe a tandem bag lock is a fair argument in this case. The rubber bands are considerably larger and stronger than those of standard sport rigs.




Sure, but they have a drogue which is huge and can generate a massive amount of resistance. A drogue should be able to break several of those tandem bands easily.



By design, drogues collapse when released. I doubt they provide much more drag than an inflated pilot chute on a sport rig. Probably just enough more to counter for the weight of the bagged canopy.
Chuck Akers
D-10855
Houston, TX

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You need to meet some minimum amount of force required to extract your stowed line, or your deployment can get chaotic. This goes for line stowed in a pouch (stowless bags) and lines stowed the old fashioned way, with rubber bands. I think I recall the extraction force that PD recommends to be 12-15 pounds. If you can get that with a single-wrapped rubber band, great.

But the people at PD have recommended double wrapping all stows you can with standard rubber bands ("medium rubber bands" are not a thing). Since I tend to think the people at PD know more than some random packing class teacher, and more than I do, I am inclined to take their advice and double-stow.

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A VERY IMPORTANT PART OF THIS DISCUSSION. There are some canopies that ball up in the center a bit more when you pack them or for whatever reason do not fill out the corners of the D-bag. You absolutely should double stow at least those outside locking stows if you gear is like this. As someone already stated, an out of sequence opening can kill you or severely injure you and this HAS happened. NOBODY has every died after properly cutting away from a bag log.
"I encourage all awesome dangerous behavior." - Jeffro Fincher

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chuckakers

***

Quote

I don't believe a tandem bag lock is a fair argument in this case. The rubber bands are considerably larger and stronger than those of standard sport rigs.




Sure, but they have a drogue which is huge and can generate a massive amount of resistance. A drogue should be able to break several of those tandem bands easily.



By design, drogues collapse when released. I doubt they provide much more drag than an inflated pilot chute on a sport rig. Probably just enough more to counter for the weight of the bagged canopy.

Alright, so was the video a legit bag lock that was caused by the bands or a lack of a functioning drogue? Someone above implied the cause of the bag lock was a malfunctioning drogue and not an issue with the bands.

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