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Does anyone else just lengthen the bottom closing loop a tad if they gain a little weight and the harness feels too tight? I know I should probably know how tight the pin(s) should be by now but it is probably the thing I worry about the most on sub-terminal jumps. And even though it is probably the least likely malfunction it's the one that scares me constantly. I am just curious...

It's very unlikely that the pin is going to lock up, no matter how tight the loop is.

The usual cause of pin locks is damage to the pin itself--cuts or nicks in the metal--not tension on the loop. If you have checked the pin and it is undamaged, you are probably good to go.

If you want to re-assure yourself of this, get a spring scale and put the rig on, and then have a friend pull the pin using the scale to measure the tension. If it's below 15 pounds, I'd leave it as it is.

If your tension is above 15 pounds, you can loosen the loops (as you suggested), or replace them with a more slippery material.

There are downsides to both of these (rig closes poorly with overly long loops, pin can slip too easily with slippery loops), but mostly the downsides are only going to be a problem on longer delays. For subterminal, there won't be enough time and airflow for them to matter much.



Another thing that might be helpful in this situation is to take a spring scale and measure the opening force with the rig packed but laying on a table. Then put the rig on, tighten the harness down and measure the opening force again. That will give you an idea if the tightening of your harness has really effected the pin tension, and exactly how much. I have seen rigs that were so well designed and fit to the jumper that the pin tension didn't change at all when the rig was put on. I've also seen rigs where the pin tension changed dramatically.

Thanks. I'll do that for sure. I'm almost positive it's way below 15 lbs. And they are spectra loops so they are still pretty slippery. Guess the negatives outweigh the positives in this case. Thats what I needed to hear.

So I went out and bought a pretty nice spring scale (if there is such a thing) and ran the tests. I had just shy of 2 lbs when the rig was laying on the floor, and 11 lbs when it was on my back, arms down and relaxed. Thats a pretty big difference. What does that mean in your mind? Also, where did you get the number 15 lbs? Is that what a 42" pilot chute will drag at a 2-3 second delay? I'm really curious about these numbers, not because I am scared, but because I want to have a real understanding about my equipment and not just random numbers that people have pulled out of their head. Thanks for the response, and thanks for the help.
Cheers!

a while back I found a chart with different pcs and what force they would pull at a certain second delay...it was by no means perfect and 100% accurate...but it might put your mind at ease a little bit.
If I can't find it, it's on these forums somewhere.

here...so if you're using a 42" w/ 2 sec delay, when pc inflation comes around you're already around 45lbs

The chart assumes a "perfect" PC--meaning that 100% of the airflow is captured and converted to pull force.

The 15 pound number came from my own measurements many years ago--it's the average force needed to open a velcro rig, which takes more than a pin rig. Since I know that velcro opens with a 42", I use it as a "safe" lower limit to the possible pull force from a PC.

I'd recommend you put the rig on, crank it down, and then tuck into a ball and measure the pull force. Are you going to be doing aerials with this setup? If you are flat and stable (and arched) the required opening force is going to be a lot less than if you are tucked for an aerial.

This used to really worry me also,
esecially on jump #8. 1-7 were off the
Perrine with pin rigs and an instructor.
#8 was first jump using a new to me
used velcro rig and new 42" PC from
a 306' freestander.

A few days before the jump I practice
packed the rig, put it on backwards but
unbuckled, stood in the back of my truck,
had a friend drive me around at 20+ MPH,
chucked the PC, and was glad to watch
the shrivel flap peel.

Till you get the real experience from doing
the jumps you can always test things to feel
a little better on your way to yelling CYA.

Thanks for all the input and good advice. I'll curl up and test it that way as well.
Cheers.

not that it matters anyway, but where did you get 45lbs?

according to that chart 2 second delay with 42" = 13kg

2 seconds until pitch, about 2.5 until your pc is inflated. That's 20kg, 1kg=2.2lbs, so 44lbs.
Almost 45lbs

gotcha.

ok...
2lbs to pop the pins on the table?
did you continue pulling to see how much force would be required to lift the parachute out?

personally, I would not desire an open container and the pc hesitating to extract the parachute! if the pc can generate the 11 lbs to pop the pin while on your back, I'm betting the parachute will quickly follow.

I've never worried about a PC not being able to extract a canopy from an open container. I'm such a chicken I don't need more to worry about. I'm going to assume that it wouldn't be a worthwhile test since airspeed plays a role in helping the canopy create drag as well. Thanks for the input though. Always grateful for those who are willing to help with honest advice.
Cheers!

gear fear is a killer.

learn as much as possible. testing things on the ground has always been a quality method to prove techniques and generate confidence. (and far more beneficial than simply reading random thoughts on an internet forum!)

most people believe the faster a BASE canopy opens, the cleaner the opening. if pins pop at only 2 lbs of force, a jumper risks towing the pc (albeit briefly).