Is there a good reason for a beginner to use dynamic over static? I'm just getting into repelling and can't justify spending so much on rope.

Posted by citrusleak Is there a good reason for a beginner to use dynamic over static? I'm just getting into repelling and can't justify spending so much on rope.

Dynamic rope is what you want to use for rock climbing where the rope's stretch will help absorb the energy of a climber's fall. Static rope is best when you are rappelling or using mechanical devices to climb the rope. The lack of stretch makes it much easier (and possibly a bit safter since you aren't bouncing.) However, a fall on static rope can quickly generate loads that can kill you. Don't ever use static rope when the possibility of a fall is present.

I would REALLY recommend that you see if your local library has "On Rope" available. Reading though it will give you a great understanding of rope work.

Also in this same forum I started a thread for getting started in vertical climbing. I posted links to a caving tutorial that gives a lot of great information about vertical rope work.

When money is tight, knowing exactly what to buy will help those dollars go as far as possible.

Abby

Thanks, I've been reading those guides and I'm looking to purchase On Rope.

I guess the chance of a fall is always possible, and I know dynamic is best. I think static will work well for me for now. When I start getting into bigger drops and higher-level stuff, I will definitely be getting some dynamic rope.

for any type of rappelling, static is always best. dynamic is only ever beneficial when you're climbing above the anchor and could potentially experience a high fall factor (read more in On Rope, or online at some place like http://www.ukclimb...es/page.php?id=647)

Basically, unless you're lead climbing, stay away from dynamic. On really long drops the stretch of the rope can make for a bouncy unpredictable descent, and make ascension nearly impossible.

thanks for the link to that site Abby....lots of good deals. I've been looking into a Petzl Falcon or Yates tactical harness, but that Singing Rock Sit Worker harness looks pretty decent too, especially for the price. Never heard of them before, but it looks pretty legit.

For all of the vertical access world : static rope
For climbing where you expect to take falls, or rope swings : dynamic rope

That makes it pretty easy.

Technically, when doing vertical access (rappelling / ascending) you should always be *statically* connected to the rope and never put yourself in a situation where you can "fall" and create dynamic load forces anyway.

If you're going to ascend a dynamic rope that is 100' long, and it's elongation is rated at 29%, then you will end up ascending 129' as your weight pulls the stretch out of the rope as you ascend up it.

Conversely, static rope is closer to 3% - 5%, by standards. (roughly, I don't recall the exact standards)

If you haven't read the book yet, this means that a "static" rope will only stretch a very small amount (roughly 3 to 5 feet at 2.70kN (600 pounds of force), per 100' of rope (so 6 to 10 feet for a 200' length).

Dynamic rope runs (I think) somewhere around 24% to 30%. This stretching of the rope takes up the dynamic *force* generated when an object connected to the rope has slack, then falls and quickly takes up all that slack and loads the rope "dynamically" (multiplication of forces).

Think of it this way.
Static load = weight hanging from rope, not moving (relatively)
Dynamic load = weight being dropped and the rope "catching" that weight = multiplication of forces

Static rope is *supposed* to have some stretch to it. That 3% to 5% is important, and it is a good thing. As you rappel or ascend, you tend to put minute load forces on the rope when you stop, bounce, tug, or vary your speed. Each time you do that you're creating small dynamic forces which would otherwise be transferred straight into your anchor point, which would cause undue stress on it. That small amount of stretch in a static rope alows the rope itself to dampen and absorb those forces, protecting both you and your anchor point from taking the beating instead.

Read the book though, it explains it better.

Therrin,

Thanks for filling in the blanks that I left open!

The second shaft on the main level in Delamar has an overhang like you describe about 200 feet down and about 40 feet above the stope floor. The shaft opens right into the ceiling so you have to lean wayyy back with your feet over your head before dropping into the chamber. Down is fun. Up is a bear trying to get past the lip. There's nowhere to put your feet so you can't hold the rope away from the lip to pass it.

You going to be there over Labor Day?

Abby Normal

That 300' anthill shaft I descended out in Joshua Tree, at the Lorman Mine & Mill site was not the same, but it had 3 wicked overhangs. Each one you have to fight on the way up. And the whole time you're very aware that your rope is rubbing on them and you wish you'd brought along some extra protectors for it.

You kinda have to ascend till your upper handled ascender is right up under where the rope hits the rock, then cram yourself up underneath it. Then either lunge upwards and try to scoot your ascender above the lip; or try to get a foot up high enough to push off of it. It's pretty crappy.

The incline at the Union Mine near Atollia is the same. I took my new boss and his g/f (before he was my boss) out there for her first time descending & ascending. Dropped 2 ropes side-by-side, and went down it next to her to guide and instruct. Hit the overhang that I didn't know was there and she did a great job going over it and getting down. Going back up sucked cuz it pushed us into eachother. I had to get a few feet above her so we weren't fighting eachother for space. She managed it though. Helluva first ascent =P


I've been working A LOT lately at my new job. (which, incidentally, is largely on fire right now, work cancelled till Monday at least).

I'm trying to convince my boss to go on the trip. If he goes, I can definitely go

SD

I'm getting out of the steel mfg. industry and moving into composites....before I go, I decided it's time to make a few things with the tools I've had available to me, but rarely used. Figured I'd try my hand at some steel rigging plates and rescue figure 8's

The figure 8s are made from 3/8" A36/44W mild steel and the rigging plates will be 1/2" 50W. Only just started on the figure 8's, but this is what I've got so far. The edges will be CNC machined with 3/16" radii in the next few days and I'll hand polish them to remove any rough edges. Will probably sand blast and then give them a semi-smooth final polish with a medium grit sandpaper to ensure a fair amount of friction. Might have them powder coated or zinc plated....we'll see what I have time to accomplish.







I'll post progress photos as I go.

And for all those concerned about the safety or wisdom of making my own gear - dont worry, these things are strong enough to lift a car with. Of course I'm not marketing them to the public and selling in retail stores without testing or certification, but for personal use I'm 1000% confident they're more than strong enough to be safe. Probably 3 or 4 times stronger than any aluminum rescue 8 you can buy over the counter.

This is really cool! I'd love to be able to build my own gear!

Holy cow Batman, home made gear?

Ummmm...Robin...all our gear is home made. Now shut up and get back to waxing the Batmobile.


terapr0, nice work on the descenders. After carrying around a few steel mallions in my rigging bag, I'm not sure I would want to carry around a steel descender. I'm sure it's not a problems for you young guys. Heck, I wouldn't hesitate to lift my truck with one of those.

Just a quick thought, powder coating will negate any friction surface you create by sanding. It would be fun to do a side-by-side test of one with powder coat and one with zinc coating to see the difference. I'm guessing the powder coat would be a bit faster. Wheeee

Are the rigging plates the steel blocks in the upper portion of the photo or are those used on the machines you use? I'm trying to figure out how the carabiners would fit though that.

I'm looking forward to seeing photos as you go and hearing about your "product testing".

Abby Normal

thanks for the comments everyone. funny how I've had access to laser cutters, water jets, cnc mills & lathes, brake presses and all sorts of other industrial goodies for almost 7yrs at my current job, yet its only as I'm 2 weeks from leaving that I've had a flurry of ideas and motivation to follow through with them. doh!

Abby: the blocks in the background are machined surface blocks used for positioning parts on a CMM machine (a really, really, really accurate measurement device)...I havent gotten around to cutting the rigging plates yet. Dont want to max out my favors with the laser department so soon. And yea I think the powdercoating would slightly decrease the friction over raw or zinc plated steel, but probably not by much, especially if I sandblast it first. The powdercoat wont fill or gloss over the pits and valleys created from blasting - the end product will be somewhat matte and have a similar finish to the substrate.

Update on the rescue 8s - I got them back from the CNC mill today which machined all the edges round. On my lunch break I used a die grinder and belt sander to smooth at least one of them out and get it semi-polished. Unfortunately I also realized just how quickly they're going to rust. So instead of using mild steel for the final pieces, I asked to get 2 more cut from 3/8" 316L stainless steel. They should be cutting tonight. Machine dept. is pretty swamped, so I might just round the edges by hand with a die grinder. It'll take longer, but the end result will be about the same. good enough for me

here are some pictures of the nearly-finished mild steel ones. One is more complete than the other, neither are 100% finished.







A few coworkers were concerned about them being "strong enough", so I ran some calculations and determined they should be able to hold at least a 10,000lb static load. Good enough for me

I'm more worried about the edges.

After the blank was cut I had the edges cnc machined with a 0.125 radius and then hand polished them with a die grinder and sanding wheel....they're actually quote smooth. Still need to finish the 2nd stainless one, but thats about another hr of polishing and sandblasting.

I think they look really good! A test run or two and you'll know if it works the way you want. If there's too much friction or it wears on the rope sheath, you'll find out pretty quick.

Back "in the day" much of the gear was home crafted. I started when descending meant two carabiners with brake bars. "Harnesses" were 1" webbing around your back and up through your legs. It was all that was available and we didn't know any better. Now days there are all sorts of options available (with much better fit and safety I might add). Still I use a rack because I'm comfortable with it.

It will be interesting to see photos of your stainless units and hear your product testing results.

Abby Normal

So when are you taking orders? =)

I love to see people's "self crafted" stuff. So awesome.

You should have made some ATS-type devices!


How're the rigging plates coming along?