There are certain skills that won’t benefit you right away in the P.A.W. Knowing how to build a rope bridge is definitely one of them. If you’re on your own and still wandering around looking for a safe location, this skill will be of almost no use to you. However, if you’re traveling in a group with more gear than everyone can carry on their backs or you’ve made a permanent settlement and you cross that particular stream/chasm frequently, knowing how to build a rope bridge and cross it is an invaluable skill.
There are more types of rope bridges than you can shake a stick at, so I’m going to go over some of the most basic varieties: the one-rope, two-rope, three-rope, and simple suspension bridges. All of them rely on several fundamental basics.
- Anchor all ropes on both sides of the bridge to a solid, permanent anchor point, like a large rock embedded in the ground or an old tree (big trunk). In the military, they call these “bombproof” anchor points, as in if you were being shelled, your anchor points wouldn’t give way and leave you high and dry.
- You need a suitable loading platform on both sides of the bridge. The loading platform is where you get on or off of the bridge. With the more permanent bridge types, this is less of a concern because you can always build a suitable platform. The platform needs to be relatively flat and close enough to the anchor rope that it isn’t difficult for anyone to attach themselves or any equipment to it.
- When constructing the bridge, make sure there is some space between your rope and the anchor point. Once your bridge is complete, the ropes will all be incredibly taut but they’ll still move around a little bit once the bridge is in use. If you don’t leave a gap, this can cause the rope to rub against the anchor abrasing the rope, weakening it, and risk the rope snapping.
- When tightening the ropes, be careful to not overtighten them. This will put undue stress on the rope at the knots which could cause the rope, knots, or both to fail while using the bridge.
- Never let more than two people cross any of the bridges at a time, especially if they are carrying equipment with them. The more weight placed on the system, the more likely it will fail.
Transport Tightening System
The anchor mechanism on the near side is referred to as the “transport tightening system” because it is tied in such a way that all the slack can be taken out of the rope, thus tightening the whole system. It is a rope and series of knots tied around the anchor point in such a way as to secure the bridge and tighten the ropes to the desired tautness.
The first knot you will tie is a static knot (like a wireman’s knot or a figure-eight slip knot) around three to six feet from the anchor point. Clip a carabiner through the knot with the gate facing upward. Continue wrapping the rope around the anchor. At this point you need to decide whether you’re going to do a “dry crossing” or a “wet crossing”. A dry crossing is when everyone but the first person cross over the bridge. A wet crossing is when the last person is required to dismantle the bridge prior to crossing.
If you decide to perform a dry crossing, you will need to add a transport knot into the system. I personally prefer this method because you only have to have one strong swimmer/climber to initially take the far side rope end to the far side.
Now that you’ve brought the rope around the tree, go back to the part of the rope on the other side of the tree and make a loop with the piece of rope coming from the far side crossing over the piece that goes around the tree. Now go back to the part that you just looped around the tree. Make a bight in the rope and pass it through the back of the loop you just made and clasp it into the caribiner on your static knot further down the rope.
Tightening and Anchoring the Rope
If you didn’t tie the transport knot into the system, clasp the rope into the carabiner attached to the static knot. Now you need to tighten the bridge. Pull the loose end of the rope coming out of the carabiner until the bridge is the appropriate taughtness. Tie the rope off on the anchor point. You can tie the rope off with any number of knots, but the easiest on to use is a round-turn with two half-hitches.
Collapsing the Bridge
For a dry crossing,after everybody but the last two people have crossed, untie your rope anchor knot and tie it to the second-to-last crosser and have him cross. As long as the slack end is directed toward the far end from the loop in the rope, the tension will be maintained. If you want to be doubly safe, you can twist the rope at the carabiner to bind all the rope. Once that person has crossed, pull the loop from the transport knot out of the carabiner and let the transport knot collapse. At this point, you basically have a rope tied on the far end anchor point, that crosses to the near end, loops around the near anchor point and back across to the far end. Have several people on the far end pull the rope tight and anchor the rope to the far end anchor point as described above. After you cross, untie the rope at both end and pull on the end until all of the rope is on your side.
One-Rope (Commando) Bridge
The one-rope, or commando, bridge is the simplest to build and tear down, but the most difficult and physically demanding to cross. As the name hints, you only use one rope to traverse your obstacle, meaning you’ll be in an awkward position, using pure muscle strength to drag yourself along the length of the bridge. This is ideal if you’re only crossing with minimal gear and able-bodied individuals, and in a hurry. Also, this is probably what your going to need initially when building a permanent bridge in order to move things back and forth during construction.
Crossing the Bridge
Crossing a bridge made with one rope can be tricky.
Two-Rope (Postmans) Bridge
If you have a lot of equipment or people incapable of crossing a Commando Bridge, but you still need your bridge to be temporary and/or hastily constructed and dismantled, then the Postman’s Bridge is your best bet. It is a reasonable balance of stability and expediency. When constructing this bridge, you are basically just building 2 Commando Bridges at different heights.
Three-Rope (Monkey) Bridge
The Monkey Bridge requires a bit more preparation, and because of the required resources and investment of time in this bridge, it is likely that you will use this in a semi-permanent capacity. One benefit that this bridge has over the previously discussed is that it can be used to span further distances.
Fortunately, the construction process is not overly complicated. Lay your hand and foot ropes out and tie stringers onto them so that the strings wrap each rope at approximately three foot intervals.
Build the shears by laying out two equal-length pieces of wood and tying them 2/3 of the way up. Spread them apart at the feet and lash them to a cross brace.
Lay the foot rope in the crux of the lasher, tie it to the anchor on one end and then tighten and tie at the other end. Do the same with the hand ropes, looping them over the tops of the shears first.