Bomb-Proof vs. Substantial Anchor Systems

Added: 2026-05-26

[00:00:00]I say okay. Well, what if this was just a belay system? I say this is just a belay system.

[00:00:05]Well, the belay system is rigged and we anticipate like the worst case scenario just as a planning factor. We I mean we aren't always operating in that worst case scenario. The worst case scenario being the belay competency drop test which turns into the ASTM standard which turns into the NFPA 1983 standards for belay devices. The peak force on that was 15 kilonewtons or I think 3400 lbs. I think that's in that standard for NFPA.

[00:00:32]And so if we assume that our anchor system needs to be able to handle that peak impact force of a worst case scenario 15 kilonewtons, but not only that within a reasonable safety factor.

[00:00:45]So if we take 15 kilonewtons or 3400 lbs and we apply like a 1.5 to one safety factor on that, that becomes 22 kilonewtons or 5000 lbs.

[00:00:56]That seems like a reasonable number especially if you look at OSHA and Z2 A10.48 standards and regulations, anchorages are 5000 lbs or 22 kilonewtons. So I think that's I Was that a coincidence? I I don't know.

[00:01:11]But it seems reasonable. So what is a bomb proof anchor in my opinion is any anchor system where you can operate a belay device or a belay system that's going to be at that uh 22 kilonewton breaking strength or 5000 lbs in simplistic terms. Let's talk about the components.

[00:01:32]Would you say that the components were bomb proof? I'd say yeah, of course the components are bomb proof. If I build a belay system with a device that's manufactured right, tested, and stamped and I have a carabiner that's manufactured by a reputable source and I use like software that's made and manufactured by a reputable source and has known breaking strengths and characteristics and working load limits. I could say that yeah, all the components that make up that belay system are bomb proof.

[00:02:00]So, the only thing I truly don't know for a fact, maybe would be the anchor itself. But, certain amount of logic and reasoning goes a long way and I can say, yeah, I'm pretty sure this especially the base of this tree can handle 5,000 lbs or 22 kN.

[00:02:17]Okay. The human element is is when we say, oh, it's not bomb it's the human element that plays into the factor cuz we can defeat these devices by incorrectly operating them and we can just fail our system that way.

[00:02:31]We can maybe not even tie a right knot that just slips the material through and that's a human error. It's not the material, it's us. So, we are our own worst enemies. So, again, bomb proof anchor, any anchor that you think is going to be able to handle your worst case impact forces associated with a belay. Worst case defined as the belay competency drop test NFPA standards, the ASTM standards and it's peak force of about 15 kN. But, we apply a 1.5 to 1 safety factor, we get 22 kN or 5,000 lbs. Okay, so, if this is an anchor that I deem bomb proof, can I operate not only my belay device, but can I also operate a working line like a main line off of the same anchor? Yes, you can.

[00:03:17]Because the working load is never going to see the potential peak forces that the belay system will see, but this rigged out on the anchor that's it's not like I add the force of the working load here plus the force of the worst case scenario to the belay and get a new number. It doesn't work that way.

[00:03:31]The belay only is under no tension, no force unless this one fails and then and only then does do we see impact forces. That was in the context of single man single belay, but what about a two tension rope system? So, in theory, okay, like now you have both devices that are mirrored, they're dual capability, if they're being operated correctly to make it dual capable.

[00:03:53]And you're sharing the load, and it's you could say, "Yeah, if it's bombproof, absolutely. You're splitting the load in half, and then the belay forces would not be as high as like a single man single belay." So, yeah, absolutely. You can operate both of your two tension rope systems on a bombproof anchor. Now, substantial anchor.

[00:04:14]Okay, in a single man single belay context, if I said that this anchor was substantial, meaning that I don't know or I don't have confidence that it could handle those impact forces on belay line. Okay, that means that a substantial anchor is one that I can operate a single working line from, but I don't have confidence that it's strong enough to handle a belay system.

[00:04:35]That's in the single man single belay context. Now, a substantial anchor in the two tension rope system context, what does that mean? Well, that's a big gray area, because if I operate a single working line, I have a certain amount of force, but if I share the force 50/50 on two working lines that are mirrored two tension rope system, the force doesn't really change on the anchor. I'm just throwing all my eggs in one basket. And if one side fails, yeah, there could be some if you want to call it an impact force or arrest force, but it's nowhere near the magnitude of a single belay system for having to absorb those impact forces.

[00:05:17]So, big gray area on a two tension rope system, what is a substantial anchor for a two tension rope system?

[00:05:22]Maybe it's where I don't want to put all my eggs in one basket, and I only want to operate half of my working load on one anchor, and then the other half of my working load on the other anchor. But in a single man single belay context, I can operate the entire working load on the substantial anchor, and my belay anchor needs to be bombproof.

[00:05:43]So, that's how I delineate bombproof versus substantial. So, marginal anchors combine to form substantial anchors, then substantial anchors combine to form bomb-proof anchors. And marginal anchors are, in general, things that you just wouldn't want to put any part of your system solely on. So, any working line that you have, you're not comfortable putting that working line that one part. So, usually marginal anchors we combine in groups of about three to four to be manageable. Anything beyond that, we do it in pairs. So, if we want to take maybe three to four marginal anchors into one focus, and then three to four marginal anchors into another focus, and from those two focuses, we bring those two in again to another one.

[00:06:30]So, that's just how we build them. Here, I don't have the landscape uh that I want, but if this was in the recreational rock climbing context, this is just recre- recreational rock pro. And so, you could imagine that, okay, like I chose four places that were in distinct locations that weren't like part of it, and then I combined everything into a focus. This would be my substantial focus anchor point that I would put a working line, and then I [snorts] have four as a general rule. Now, recreational rock pro depends on the types and the kinds. Some of these things will have a 22 kN breaking strength per piece of gear.

[00:07:13]Others will have like 15, some will say 10, eight, whatever. We don't really care. We're just arbitrarily going to de-rate any one piece down to 5 kN or 1,125 lb. And that's to compensate for the variability in placement, the type, like if it's rock pro, the type of rock that we're putting it in, the interface between the piece of gear and that natural uh anchorage and then the skill of the person putting the gear. So, all those are variable and unknown. And if we just try to be a little bit on the safe side within reason and say that each piece of gear we put in is going to be We're just going to say we can only trust it to about 5 kN. That means that if you multiply 5 by 4, you get 20 20 kN. So, you could just arbitrarily to make it simple, you say four pieces of like rock pro to make a substantial anchor would give you a 20 kN substantial anchor in general. Let's revisit our bomb-proof or what I deem bomb-proof tree anchor.

[00:08:26]And let's figure out how we can make our rope systems, not just the anchor, but everything else bomb-proof in the sense of satisfying a lot of those uh anchor principles.

[00:08:41]Like redundancy, for example.

[00:08:43]So, if I decide that a single sling of webbing around a tree was adequate strength to operate my system, that's my whiteboard analysis. It's my choosing. I can say, "Yeah, I can I can say, 'Yeah, the single strand is or a single wrap is fine.'" Or I can do like the whole wrap two pull twos, wrap three pull twos, or whatever.

[00:09:11]But let's look at the webbing here as we come around.

[00:09:15]Just so you can kind of see a little more clearly. Okay, so long piece of webbing. And so, we just did a Frost variation of a water knot to make a single Basically, I just tied a wrap one pull on around this tree and it's a single sling. I just made a single sling for this anchor.

[00:09:30]And then I had excess and I did the same thing down here. So, it's a single sling for the other device down here. So, each one of these devices are independent, they're on their own single sling. This is perfectly fine.

[00:09:43]There's a faster way to do it.

[00:09:45]But, if I decided to If this is a bomber anchor and I decided to operate both of my systems on the one strand, I'd say that as far as redundancy, I'm not there.

[00:10:02]I I I would not be happy with this setup because all my eggs are in one basket on this one sling. So, I'd want to separate that out.

[00:10:11]I could separate it [clears throat] out completely.

[00:10:14]Or, I could just tie two slings and have everything hooked into all the slings together.

[00:10:20]And so, what that looks like is just taking Oh, I just did two slings, two carabiners, two devices so that everything is interlinked and intertwined, and I could probably get away with this.

[00:10:31]And this will be just fine, too.

[00:10:36]Okay, so I have two wrap one pull ones going to two carabiners going to their second devices.

[00:10:43]And I would feel comfortable that now that this would definitely be a little bit more secure, more bomb-proof like. I just have to make sure that my slings were of the same length as now this is a little bit loose because I tied this one a little bit tighter than this one. So, that's the a con of doing it this way.

[00:11:03]But, if you got it right, you can now say that 1 2 3 4, you have four strands.

[00:11:08]The knots are on the back side of the tree, so they're at the place where they're going to see the least amount of tension, and so this would be pretty bomber. Is there a faster way to do this with just a single piece of webbing? And yes, there is.

[00:11:21]So, got a long piece of webbing here, and I found the midpoint, and I just tied it into an overhand. This is my skeleton water knot.

[00:11:31]And I'm going to do a basically this is a called a redundant wrap two pull two.

[00:11:37]So, folded into a bite, I'm basically doing a single wrap around the tree but with two strands.

[00:11:45]When I come around these strands, again the frost variation of the water knot, I fold this into a bite. And when I fold this into a bite, I'm actually like creating like four strands. So, it's a pretty big knot.

[00:12:01]But I give myself enough tail to complete it all the way around.

[00:12:09]And what I've just done is made two separate slings of the exact same diameter around the tree.

[00:12:22]Completely redundant. So, if I rotate this knot around to the back side of it where it sees the least amount of tension, I have a redundant wrap two pull two.

[00:12:33]So, if I cut if I cut this strand here, it's not like a in theory like a wrap three pull two or a wrap two pull one where it's all interlinked to this one and it all loosen up. This is completely independent of this. Even though they share the same knot, they're two separate slings that I tied together with just one knot. So, a redundant wrap two pull two. And now I can use this.

[00:12:59]I only tied one knot and they're both the exact same length. So, they both will share that load.

[00:13:05]And I can operate both of my systems off of this sling if I decide that this was strong enough. In this case, I decided that yes, it was. So, a redundant wrap two pull two. And I'll operate my Maestros or my devices right here.

[00:13:22]Anchor plates are great.

[00:13:25]If we want to shark fin or twin stick something, if you got clutches, cool. Swiss weiners are my favorite.

[00:13:34]In this application I have devices and I'm going to figure out is this bomb or as far as redundancy in my system, like are all my eggs in one basket? Like, am I missing something?

[00:13:48]So, let's figure it out. Okay, a redundant wrap two pull two, which I deem was perfectly acceptable to a single carabiner, to a single anchor plate, and then each system has its own device with its own carabiner.

[00:14:03]So, let's figure out what's acceptable and what's not in general.

[00:14:09]Okay, do I need to double up anchor plates to make it redundant by stacking them in like that? The answer is no, you don't need to do that. These are the exceptions.

[00:14:19]And the reason why, the rationale behind why you don't need to do double on things like this is because there's no moving parts, so it can't really be manipulated. It's just a solid piece of thing. And so, this is the exception to the rule. So, the anchor plate's plenty fine. Now, the carabiner can be manipulated and so, in this case you would not want to just use one carabiner, but you'd want to stack them.

[00:14:42]You stack them on an anchor plate like this.

[00:14:48]I could argue that I am good to go. So, bomb-proof anchor, redundant components, and I can operate a single man separate belay or two tension rope system off of this and be just fine. Let's talk about two-point anchors.

[00:15:03]Now, I'm operating both devices at a single focus. So, this single focus I'm going to deem as bomb-proof. And so, let's look at our redundancy.

[00:15:14]We have one system on one device with a carabiner to a bomb-proof anchor plate that I only need one of.

[00:15:21]And then, we have dual carabiners on that anchor plate because of the other system has its own setup. So, at least from here to here, I'd say, "Yeah, this is redundant. This checks out. I'm I'm okay with what I have going on here."

[00:15:35]Okay, so we've got two-point anchors.

[00:15:38]And let's back it up and fit and really like why do I build two-point anchors? To simplify things, there's two main reasons why I would build two-point anchors or multi-point, but we'll just keep it simple and say two-point. One is based on strength where I don't have confidence that one single anchor point will do. And the other reason is based on alignment. My direction of pull or the projected load line doesn't sit on a path that's favorable for just one anchor point. So, I have to bring things together into an ideal alignment. So, in this case I'm going to say that this focus is bombproof cuz I'm going to bring two trees together that I think aren't bombproof on their own, but they could be substantial. So, I'm going to bring two substantial anchor points together into a focus.

[00:16:30]And I'm going to call this focus bombproof. Okay, so we know that this checks out on the front end.

[00:16:38]The knots just an overhand of BFK. So, the rope itself plenty strong. One strand will be fine for this because this is the same life safety rope we're going to use for our actual rescue systems.

[00:16:49]And my angle is fine. All that checks out. And let's go back to our anchor points.

[00:16:55]So, I'm operating a single man single belay, let's just say single man single belay bombproof system up front. And here I'm putting all my eggs in one basket.

[00:17:06]Now, we have two strands going here.

[00:17:08]However, these two strands aren't isolated. So, if I lose one in theory, I lose the other. And so, there's no redundancy here. There's definitely no redundancy here or here because I would need to double it up since I'm putting all my eggs in one basket at the system.

[00:17:27]I would actually have to do a separate sling around the tree with its own separate carabiner. So I've covered my bases on the anchor point itself, but I still haven't addressed this problem right here.

[00:17:40]A fast way to address that problem it's an option. It's probably not what I would go to, but you could just isolate it. And here I'm just going to do like a quick knot for simplicity. Probably a figure eight would be better or bowline.

[00:17:58]And I'd still have to put both my carabiners in the loop.

[00:18:03]And you could say that, "Okay, now I've isolated each strand. So if the strand fails, this one doesn't cuz it's knotted here. So this would be acceptable."

[00:18:13]Same thing for the other tree.

[00:18:15]Let's take a look at the other tree. So same thing here. Okay, I used webbing. I would have to figure out how to isolate these strands by separating them out, figure eight, overhand, bowline, whatever. It It all will work just fine.

[00:18:33]So now I've covered my bases and I can operate a two-rope system.

[00:18:43]Whether that's single main, single belay, or two-tension rope system, doesn't matter. I can operate everything just like that and I'm fully redundant and ready to go.

[00:18:54]And I've covered all my bases.

[00:18:56]Okay, let's do a a more streamlined and efficient way to rig a two-point anchor with our ropes this way without having to use webbing, a bunch of carabiners, or anything like that. So here we're just going to use rope and nothing else to make a two-point load sharing bomb-proof anchor system where we're going to operate both rope systems at the same point in space.

[00:19:19]Whether that's single main, single belay, or two tension rope system, who cares? We're going to make it all bomb-proof just with the rope.

[00:19:27]I have my rope laid out. It's life safety rope. I take the two terminal ends and I go to my substantial anchor, this case a small diameter tree, and I'm going to create an anchor just with one knot. I'm just going to make these two rope ends one and treat this as if it was just one rope.

[00:19:51]Okay, so in this case, it's just a simple bowline.

[00:19:58]And since I don't have anything else going off of the tails, I just do a Yosemite retrace and call it good.

[00:20:10]So, that's one. So, now what I have is two two strands that are isolated.

[00:20:20]So, for the redundancy factor, even though one is plenty strong, now we have two. So, if something did happen to this, we wouldn't pendulum on the other anchor. So, that's one side. Let's go to the other.

[00:20:35]Based on the angles that I want to operate at, I'm going to probably equalize it somewhere back in here. And then I take the bite maybe somewhere along approximately the midpoint of the rope over, do the same thing, and we retrace.

[00:21:16]And we bring this one back.

[00:21:23]So now I have two completely redundant strands. I bring them to wherever I want to operate my focus, and then I tie my BFK.

[00:21:36]So bring this into a focus. This is going to be a big pretty big knot.

[00:21:40]Pull some stretch out. Fold this over on itself.

[00:21:47]It's going to be something like that.

[00:21:55]And I'll just do an overhand since it's really big.

[00:21:59]Pull all that through.

[00:22:12]Pull every strand coming out. Make sure it's taut and tight.

[00:22:18]Okay.

[00:22:20]And now I have one, two strands. So if I lose one, it doesn't pendulum.

[00:22:26]And same thing on the opposite side.