The following text is by Adolph E. Peschke as presented in the 1998 printing of the 1993 edition of the Pioneering Merit Badge Pamphlet:
The craft of building with ropes and spars continues in remote areas throughout the world today. Scouts can apply the skills of knot tying and lashing to build pioneering structures that are needed to make living in camp a little more comfortable. Whether you build a simple gadget, or a bridge to provide a shortcut to the swimming pool, pioneering can be rewarding and fun.
The pioneering projects shown here, along with the suggested sizes and lengths of spars, are intended for building “boy-size” structures; that is, projects that can be built by boys of Boy Scout age.
You don’t have to build a huge tower to learn the skills and enjoy the fun of pioneering. These projects are designed so that you can build them in a few hours with a minimum of equipment and supplies. Yet, you will still learn how the basic pioneering skills of knot tying and lashing must work together with the design of a structure to produce a sound, safe pioneering project.
Building these projects will be much easier if you put together a pioneering kit first. The success of any project is directly related to the planning and preparation you put into the project from the beginning.
Here are some things to take into consideration before you build a pioneering project:
Decide on the type of project you want to build. Take into consideration the equipment, the number of people needed, and the time required to build it.
Check the site where the project is going to be built. Collect all the information that you will need when building the project. For example, are there any natural anchors for guylines? How wide and deep is the creek where a bridge is to be built?
Make a rough sketch of the project or work from an approved plan drawing. Along with the sketch, have a list of equipment that includes all the equipment you’ll need. You don’t want to start a project and later learn you need something you don’t have.
Select the necessary spars you’ll need for the project, making sure that you have enough spars with the proper butt diameter and length to build a safe project.
Determine the size and lengths of all the ropes needed for lashings, guylines, etc.
Before you start building, determine if the project can be divided into subassemblies for ease of lashing and erecting. Assign crew members and a crew leader to each of the sub assemblies, based on skill level and experience.
Go over the plans with all the crew members. Assign only one person to give signals when raising all or part of the structure.
As you’re building the project, frequently check the progress to make sure it is being done with safety in mind.
A word about the appearance of the project: Part of the skill in building with ropes and spars is to select the spars that are best suited to the structure. In some situations, the supply of spars might be limited.
It is not necessary for your project to be picture perfect, but rather that it is structurally sound. If one or two spars are a bit longer than required, that’s fine as long as the lashings are in the proper location for strength and the diameter of the spars will carry the load applied.
Try to avoid cutting off the ends of spars and ropes just to fit a certain project, especially if you’re working with spars from a pioneering kit. The next crew might want to build a different project and could use the spars and ropes at the original lengths.
The spars used for a pioneering project should have the bark removed for two reasons. Bark beetles and other boring insects can seriously decrease a spar’s strength, and inspection is easier with the bark removed. Also, if the project racks, the bark under the lashing can be loosened, which in turn makes the lashing loose and adds to the possibility of making the whole project wobbly and unsafe. (And, bark under a lashing can be rubbed off in the process of setting up a project.)
Note: Any pioneering structure that is to be a permanent camp improvement should not be left with only lashings. It needs to be bolted together for safety and maintenance.
The current Guide to Safe Scouting states, “Pioneering projects, such as monkey bridges, have a maximum height of 6 feet. Close supervision should be followed when Scouts are building or using pioneering projects.” However, under certain circumstances and in accordance with some recently revised standards, Scouts CAN again build and CLIMB ON this and other tower structures. Refer to: NCAP Circular No. 2, pages 3 and 4.
The following text is by Adolph E. Peschke as presented in the 1998 printing of the 1993 edition of the Pioneering Merit Badge Pamphlet:
This project solves the old problem of wanting to build a signal tower when there aren’t enough big spars to do the job. The double ladder tower requires four 14-foot spars and several smaller spars, but not nearly the amount needed for a four-leg signal tower. It also cuts down the number of lashings required.
This tower is not free standing. It requires the use of guylines to hold it steady. Review the sections on anchors and rope tackle if this is your first encounter with guylines.
Assemble the ladders. This project begins with building two ladders: a climbing ladder and a supporting ladder. Lay out two pairs of spars on the ground for the legs of the ladders. Be sure the butt ends are even at the bottom so that the tower will stand up straight. Before you begin any lashing, mark the positions where the spars that will hold the top platform are to be lashed onto the legs. This is about 4 feet from the top ends of the legs.
To make the climbing ladder, lash ten rungs on one pair of legs at about 1-foot intervals. The top rung should be lashed on where you marked the position of the platform, 4 feet from the top. Also the top handrail is lashed on to complete the climbing ladder.
To make the supporting ladder, lash three spars on the other set of legs to serve as the bottom, center, and top spreaders. The top spreader should be lashed at the point you marked for the platform, 4 feet from the top. Then lash on the top handrail, as on the climbing ladder.
Lash the ladders together. Now you have to join the two ladders to form the tower. Turn the two ladders up on their sides so they’re parallel to each other and approximately 6 feet apart. Check to see that the bottoms are even. Now lash on the base spreader to join the bottoms of the two ladders.
Lash on the platform supporting spar just above the top rung and top spreader on the ladders. Before proceeding, check the measurements from the bottoms of the legs to the platform supporting spar to make sure they’re equal on both legs so that the platform will be level.
Continue by lashing on the top long handrail. The lash on the two side X-braces diagonally between the legs using square lashings to lash the ends to the legs, and a diagonal lashing where they cross.
Lash the other side. To make the lashings on the other side, you have to get the whole crew together to roll the tower over 180° so that it’s laying on the X braces and the other sides of the ladders are up where they will be easier to get to.
Then proceed as before. Lash on the base spreader spar and the platform supporting spar. Again, measure to make sure there’s equal distance from both ends of the platform support spar to the bottoms of both legs. Continue to lash on the top long handrail and finish with the X-braces.
Lash on two more platform X-braces under the platform. These braces go diagonally across the legs just under the platform to help the tower resist racking (see figure 137). Use square lashings to lash them to the legs and a diagonal lashing where they cross.
Before standing the tower upright, lash on the spars to form the platform floor.
Anchors and Guylines. When all the lashings are done, move the tower to where it will be hoisted. Before actually hoisting the tower, lay out the position of the four legs on the ground. Then determine where the four anchors for the guylines will be placed to steady the legs of the tower. (Refer to the Anchors section to determine the position of the anchors.)
If the tower is positioned to make use of a natural anchor (such as a tree), prepare anchor strops to attach the guylines. For any guylines that won’t be using natural anchors, build anchors using pioneering stakes. At a minimum, you’ll need to build well constructed 1-1 anchors at all four corners.
Attach the four guylines to the legs just above the platform. The guylines should be 3/8-inch diameter manila or polypropylene rope. They’re attached to the legs of the tower using a roundturn with two half hitches and securing the running end of the rope.
Note: For safety reasons, never use a taut-line hitch on guylines, or for that matter, in any pioneering work. This hitch is used when adjustments in the tension are called for. It can slip.
Hoisting the tower. Hoisting the tower up into a vertical position is done with separate ropes. Do not use the guylines. Tie two lines on the side of the tower being lifted and one line on the opposite side to prevent over pulling and toppling the tower.
You’ll need a whole crew to do the hoisting. First there should be a safety officer who observes for all safety considerations and signs of trouble during the hoisting. There should also be a signal caller who tells the crew members when and how fast to pull on the hoisting ropes and when to stop pulling. Two or more Scouts should be on each of the two ropes. And one or two Scouts should be on the rope on the other side to prevent over pulling the tower.
When everyone is in position, the signal caller should direct the Scouts on the hoisting ropes to hoist the tower into position. As soon as it’s up, temporarily tie the guylines to the anchors using a roundturn with two half hitches.
Heeling in the legs. When the tower is upright, heel in the butt ends of the tower legs in holes about 4 to 6 inches deep. This is done to steady the tower and can also help in leveling the tower to make sure that the platform is level and the tower itself is vertical.
Tighten the guylines. To hold the tower steady, gradually apply strain to each of the four guylines at the same time. One of the easiest ways to adjust the strain is to tie a rope tackle on the anchor ends of the guylines.
As soon as the tower is in position and the legs are heeled in, go to each of the anchors and untie the roundturns with two half hitches and replace it with a rope tackle.
Do this by tying a butterfly knot in each guyline about 6 to 8 feet from the anchor. Then wrap the running end of the guyline around the forward stake of the anchor and back through the loop in the butterfly knot. When rope tackles are tied to all four anchors, gradually tighten the lines. Apply enough strain to each of the guylines to hold the tower firm and in a vertical position. Then tie off the rope tackles and secure the running ends with half hitches.
Test the structure. Before the tower can be put into general use, make a test climb while the safety officer and the whole crew observe all the lashings and anchors to ensure they are all secure.
Note: Some people are not comfortable climbing up to a high place. They should not be encouraged to climb if they are not sure of themselves. Do not pressure anyone to climb the tower if they don’t want to.
four 4-inch x 14-foot tower legs
ten 2-inch x 3-foot climbing ladder rungs
three 2-inch x 3-foot support ladder spreaders
two 2-1/2-inch x 6-foot base spreaders
two 2-1/2-inch x 6-foot platform supporting spars
two 2-inch x 3-foot platform handrails
two 2-inch x 6-foot platform long handrails
four 2-1/2-inch x 10-foot X braces
two 2-1/2-inch x 8-foot X braces
eighteen 2-inch x 3-1/2-foot platform support slats
eight pioneering stakes
four 3/8-inch x 50-foot manila guylines
thirty-one 1/4-inch x 15-foot manila lashing ropes (for 28 square Lashings and 3 diagonal lashings)
In accordance with current regulations, a fine adaptation consists of replacing the ladder rungs with support side spreaders, and dispensing with the platform floor slats. Lashing one or more long flag poles to the top of the legs and flying banners or flags never fails to elicit a rousing array of cheers, as the Scouts hoist their tower into an upright position! Click here for project description and materials.
The well-known, time-tested, traditional Monkey Bridge is perhaps the most familiar of all Scout pioneering projects. It’s frequently featured at Scout Expos, Camporees, Scout Camps, and is often a central attraction at public gatherings where Scouting is represented.
The following instructions and guidelines are provided by Adolph Peschke, taken from the 1993 edition of the Pioneering Merit Badge Pamphlet:
Using a double A-frame to build a monkey bridge is a departure from the usual X-frame that supports the foot rope and hand ropes. This new method has two distinct advantages over the X- frame version. First, the double A-frame provides a wider base making it less likely to tip over. The second advantage is that the positions of the A-frames can be adjusted so the span between the hand ropes can be narrowed for better balance as you make the crossing.
Building the A-frames. The first step in building the monkey bridge is to build four A-frames using the 8-foot spars for the two legs, and 6-foot spars for the ledger. Lay out the first set of three spars (two legs and one ledger) on the ground in position for lashing. Before lashing, drive three stakes, as follows, to help you make all four A-frames the same size: Drive a stake at the top to mark where the leg spars cross. Then drive stakes to mark the positions of where the bottom ledger crosses the legs. This will also indicate how far the legs are spread apart. Now you can lash the four A-frames together, laying them out one at a time using the stakes. Remember that all three lashings on the A-frames are square lashings, even though the spars cross at less than 90˚ angle.
Double A-frame. When you have four A-frames, you can lash two of them together to form a double A-frame. (see figure 140). Lay one A-frame on the ground and then put another on top of it so that the bottom ledgers overlap one-half their length (approximately 3 feet). The first step in lashing the A-frames together is to go up where the two legs cross (the X formed by one leg from each A-frame). Then with a good tight square lashing, lash the two legs together.
Note: The point where these two legs are lashed together is where the foot rope will rest. You can adjust the overlap of the two A-frames to adjust how high the foot rope will be off the ground. Also note where the tops of the A-frames are, because this is where the hand ropes will be. To complete the double A-frame, stand it up so the butt ends of all four legs rest solidly on level ground. Lash the two bottom ledgers together where they overlap with three strop lashings. Now repeat the entire process to build the second double A-frame.
Site preparation. Before you can erect the double A-frames, you need to prepare the site. Begin by stretching a length of binder twine along the center line of where the monkey bridge is to be built. Working from the center, measure 10 feet toward each end to mark where the A-frames are to be placed. They should be 20 feet apart. Then mark out another 10′ from each A-frame to where the anchors are to be built.
Note: These dimensions are for building a bridge with a 20-foot span. This is the maximum span for a bridge using a 50-foot rope. The extra 30 feet of rope is needed to have 15 feet of rope at each end for the proper distance from the A-frames to the anchors (10 feet) and for the knots at the anchors (5 feet).
Build the anchors. The foot rope will be attached to anchors at both ends. Before erecting the double A-frames, build a 3-2-1 anchor, or a log and stake anchor, 10 feet from where the A-frames will be erected (see figure 141).
Rope grommet. After the anchors are built, attach a rope grommet with a ring or shackle in it. (You can make the rope grommet with a 10-foot length of 1/2-inch diameter polypropylene rope. Tie the ends together using a carrick bend, and permanently secure the ends with some strong twine).
Position the A-frames. Prepare to erect the monkey bridge by moving the A-frames into position no more than 20 feet apart. Lay them down on the binder twine that marks the center line of the bridge.
Hand and foot ropes. Now you can prepare the foot and hand ropes for the monkey bridge. Lay the foot rope in a straight line off to the side of where the A-frames are laying. Then lay the two hand ropes on the ground next to each other so they’re parallel to the foot rope and 42 inches away.
Stringer ropes. Now you can add the stringer ropes that will go from the foot rope to the hand ropes. Start by tying the center of an 8-foot long stringer rope (use 1/4-inch manila rope) at the center of the foot rope, using a clove hitch. The stringer rope is tied around the foot rope so that both ends are 4 feet long. Add two more stringer ropes on both sides of the center stringer rope (so there are five stringer ropes in all), tying them about 4 feet apart. Tie one end of each stringer rope to one of the hand ropes, again using a clove hitch. Then do the same with the other ends of the stringer ropes, attaching them to the other hand rope.
Assemble the bridge. You’re just about ready to assemble the bridge. First place a piece of heavy canvas (called a “saddle”) in the V formed by both double A-frames. This will protect the foot rope and allow it to slide a little in the V without interfering with the lashing rope.
Now get the crew together to erect the bridge. You will need a safety officer to watch for any problems that might occur, and a signal caller to tell the crew members what to do. You will need two Scouts to lift and hold each double A-frame in place, two more Scouts to lift the foot rope into the V of the double A-frames, and two more Scouts to lift the two hand ropes into place at the tops of the A-frames. Lift everything into place. Then, holding the A-frames steady, temporarily tie the hand and foot ropes into the rings of the grommets using a roundturn and two half hitches (see figure 142).
Tighten the foot rope. Now you can put a strain on the foot rope. It’s not necessary to use block and tackle since this will put too much strain on the lashings, anchors, and the foot rope itself when there is a load on the bridge.* Whatever strain three or four Scouts can put on the foot rope by pulling it by hand will be enough. As soon as the bridge is used a few times, there will be a sag in the rope. This is fine because it means that you are working with reduced strain on the foot rope as a safety measure.
Tighten the hand ropes. Next, tie the hand ropes to the top ends of the A-frames. First, loosen one end at a time from the anchors. Then, use a clove hitch to tie the hand rope to the top end of the leg of the double A-frame. As you’re tying these clove hitches, adjust the strain on the sections of the hand ropes between the double A-frames to match the sag of the foot rope. Also, adjust the length of the stringer ropes so there is even strain between the foot rope and both hand ropes. After the hand ropes are tied to the tops of the A-frames, move down and retie the ends of the hand ropes to the rings in the grommets using a roundturn and two half hitches.
Final testing. With caution, one crew member can get on the bridge as all lashings, anchors, and knots are observed by the safety officer and all other crew members. Make adjustments as required. Then secure the running ends of the hand ropes and foot rope with a piece of cord. Safe operation calls for only one Scout to be on the foot rope of the monkey bridge at a time.
LIST OF MATERIALS FOR DOUBLE A-FRAME MONKEY BRIDGE
eight 4-inch x 8-foot A-frame legs
four 3-inch x 6-foot ledgers
fourteen 1/4-inch x 15-foot lashing ropes for Square Lashings
one 1/2-inch or 3/4-inch x 50-foot rope
two 1/2-inch x 50-foot hand ropes
five 1/4-inch x 8-foot stringer ropes
six 1/4-inch x 10-foot lashing ropes for Strop Lashings
six pioneering stakes for each 3-2-1 anchor
eight pioneering stakes for each log-and-stake anchor
one 5-inch x 4-foot spar for log-and-stake anchor
two 1/2-inch x 10-foot polypropylene ropes for rope grommets
two pieces of scrap canvas for foot rope saddle
binder twine for anchor tieback straps
* It has been found that a rope tackle in the foot rope at each end (not a block and tackle) tightened by one Scout is an excellent procedure to maintain the optimum foot rope tension, and an easy-to-use remedy for too much sagging due to repeated, heavy use and over stretching. There are other configurations used to initially tighten and keep the hand and foot ropes at the optimum tension during use, depending on the weight the bridge must withstand and the amount of traffic it will bear.