Using the 14′ Double Ladder Signal Tower as a point of reference, here are the plans for a very tall campsite gateway that stands out (and up) and serves as an impressive feat of Scout engineering. One of the perks included in this project is it provides an opportunity for new Scouts to experience hoisting a “boy-sized” structure replete with their own special colors e.g. their patrol flags.
Since this 14-foot structure isn’t climbed on, the spars can be considerably thinner in diameter. Bamboo is ideal. Lashing on those flags attached to each corner creates a spectacular effect and hence the name “4 Flag Tower!”
Note: This design is not self-standing. Therefore, using it as a gateway at a camporee or Scout Expo with the necessary guylines requires an area wide and deep enough to accommodate a 16 x 16-foot space.
four 2-1/2 to 3-inch x 14-foot leg spars
six 2-inch x 8-foot X-brace spars
four 2-inch x 6-foot X-brace spars
four 2-inch x 6-foot support spars
six 2-inch x 4-foot leg spreader
forty-five 15-foot x 1/4-inch lashing ropes
four 25-foot guylines
eight 24-inch pioneering stakes
Assemble the 4-foot sides. Begin by laying out two pairs of 14-foot spars for the tower legs, side by side, 3 and 1/2 feet apart. Be sure the butt ends are even at the bottom so the tower will stand up straight.
NOTE:All lashings need to be very tight.
Lash the legs together starting with a 4-foot bottom leg spreader about 6 inches up from the butt ends. Lash on a 4-foot middle leg spreader in the middle of the 14-foot legs (7 feet up), and a 4-foot top spreader about 3 inches from the top of the 14-foot legs.
When the legs are joined with the three 4-foot spreaders, lash on two 6-foot X-brace spars using square lashings to lash the ends to the legs, and a diagonal lashing where they cross, forming a trestle in the bottom half of the legs (see diagram 1). Three of the ends are lashed to the outside of the legs, and one on the inside, so that a slight gap is created where they cross. As the diagonal lashing begins, this gap will be cinched together with the timber hitch. Repeat the whole process with the other two 14-foot legs.
Join the 4-foot sides. Turn both sides up horizontally, parallel to one another about 5 and 1/2 feet apart. Make sure the bottoms are even.
Lash on one of the 6-foot support spars directly above the 4-foot middle spreader (see diagram 2).
Lash another one of the 6-foot support spars directly under the 4-foot side spreader at the very top.
Now, lash on two of the 8-foot X brace spars diagonally between the two 6-foot supports using square lashings to lash the ends to the legs, and a diagonal lashing where they cross forming a trestle in the top part of the wide (6-foot) side (see diagram 2). Three of the ends are lashed to the outside of the legs, and one on the inside, so that a slight gap is created where they cross. As the diagonal lashing begins, this gap will be sprung together with the timber hitch.
Lash the other side. To make the lashings on the other side, you have to get the whole crew together to carefully lift and roll the tower over 180° so that it’s laying on the X-brace, and the other sides of the 4-foot sides are easier to get to.
Repeat the same procedure as before.
Lash on the middle X-brace. This X-brace is what will keep the four sides from racking. Lash the two remaining 8-foot X brace spars diagonally across the legs just under the 4-foot middle leg spreader (see Tower Gateway Schematic on the top of this page). Use square lashings to lash them to the legs and a diagonal lashing where they cross. To accomplish this, some crew members will have to hold up the top of the tower so that there is better access to all four ends of the 8′ X brace spars.
Lash on the flags. If you want a flag or flags to fly from the top of the tower, lash the flagpole(s) to the top of each tower legs using a couple of tight round lashings.
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.
Using the pioneering stakes, build four 1-1 anchors. Each should extend 16 feet, 45° out from the leg.
NOTE: Make sure the flags are unfurled before hoisting the tower.
Hoisting the tower. You’ll need a whole crew to do the hoisting. Get ready to hoist the tower by delegating the following:
One signal caller who tells the crew members when and how fast to pull on the ropes.
One safety officer who observes for all safety considerations and signs of trouble during the hoisting.
Four Scouts to serve as “Lifters” to lift the top 6′ support spar that’s on the ground. Their job is to first left and then push the tower up.
Two Scouts, one on each of the 2 guylines attached to the legs, to make sure the tower isn’t over pulled and topples over
Four “Pullers” who will use the two guylines as hoisting ropes to pull the tower until it is standing
When everyone is in position, the signal caller should direct the Scouts on the hoisting ropes (the pullers) to hoist the tower into position, while the lifters start lifting. Care should be exercised not to over pull the tower.
As soon as the tower is standing, four Scouts should temporarily tie the guylines to the anchors using a roundturn with two half hitches.
Heeling the tower. If the tower is uneven, you can heel the the butt ends of the legs 4 to 6 inches deep as needed to make it more level.
Tighten the guylines. As soon as the tower is in position, go to each of the anchors and untie the Roundturn with Two Half Hitches and replace it with a rope tackle. Use the rope tackles to hold the tower steady, by gradually applying strain to each of the four guylines at the same time. 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.
The following text and some of the drawings are by Adolph E. Peschke as presented in the 1998 printing of the 1993 edition of the Pioneering Merit Badge Pamphlet:
We could imagine the first lashing made by man was wrapping a few strips of bark around a stone to hold it to a tree branch to make an ax to hunt and build with. Even today with all our modern ways to hold things together, it is still fascinating to lash sticks or spars together to make a camp gadget or useful structure.
There are still areas in the world where lashing spars (or bamboo poles) is the basic means of building structures. In Scouting, we use the same methods but have replaced strips of bark and vines with natural and synthetic fiber ropes.
The best choice of rope to use for lashing the type of pioneering projects (shown in this pamphlet) is pure manila rope. Therefore, all references to rope used for lashing in this section refer to manila rope.
Yet, sometimes we are faced with a problem—we have to use what is available and economical to get the job done. When making camp gadgets for temporary use, you could use lesser quality, less expensive rope or even binder twine for small projects.
SQUARE LASHINGS ***
The basic type of lashing for most projects is some form of a square lashing. This lashing is used to join two spars together, usually at a right angle, but not always. For example, square lashings are used when building a trestle to join the ledger and header to the legs at right angles. But it is also used to hold the ends of the X bracing to the legs at an angle. (Refer to “Making a Trestle.”)
In this section, three different square lashings are shown: (1) the Traditional Square Lashing, (2) the Modified Square Lashing, and (3) the Japanese Mark II. All three types of square lashings accomplish the same thing by making three wraps and two frapping turns around the spars being held together.
The only difference between these three different square lashings is the type of knot that is used to start and complete the lashing. You may learn that one of these knots is easier to tie, if so, you can stick with the one you are most comfortable with.
In addition to square lashings, you will most likely need to know how to make a diagonal and shear lashings. Some methods of making these types are also shown later in this section.
No matter what kind of lashing you’re making, there are two basic terms you should be familiar with: wraps and fraps. The basic difference between the two terms is that a wrap is made around the spars, while a frap is made around the rope itself.
Wrap. A wrap is a turn made around the two spars to hold the spars tightly together. Usually, three wraps are made to form a Square Lashing. Some other lashings require more wraps.
Frap. A frap is a turn made between the spars. It goes around the wraps to pull the wraps tighter. Usually two frapping turns are made on a lashing.
Good lashings are not made in a hurry. Each wrap must be made with a strain on the rope. Frapping turns should be pulled up as tightly as possible before the final knot is tied.
When you set out to make a lashing, the size and length of the rope you need are among the first questions you have to answer. To determine the length of rope needed for a lashing, add the diameters (in inches) of the two spars at the point the lashing is being made. If one spar is 2-1/2 inches in diameter and the other is 3-1/2 inches in diameter, the total equals 6 inches. Multiply by 3 feet to get the length of the rope needed for lashing.
If you use a rope that is too short to make three wraps and two fraps for a lashing, you should add (Splice or join with a Square Knot) a length of rope to complete the lashing with three full wraps and two fraps. For safety, don’t leave the lashing short.
If you find you have extra rope, make more wraps or fraps to use up the rope to avoid cutting the rope or leaving long loose ends hanging out.
In most cases, 1/4-inch diameter manila rope should take care of lashing two spars together as long as the combined diameter of both spars is 6″ or less. When the combined diameter is over 6 inches, use 3/8-inch diameter rope.
If your troop or camp puts together a pioneering kit, it should contain lashing ropes that are cut to standard lengths: 10, 15, 20, 30 and 50 feet.
Both ends of these lashing ropes should be properly whipped. It also helps to color-code the ends of all ropes with a bit of paint to denote each length. When storing ropes, make sure they are dry and properly coiled. Never “hank” ropes for storage. That is, don’t wrap them around your hand and elbow to form a coil. Tie each coil with a short piece of cord and store the coiled rope on pegs or in a ventilated storage box.*
TRADITIONAL SQUARE LASHING
In Scout Pioneering in the United States we most often see the square lashing started with a clove hitch. The clove hitch is tied on the vertical spar, just below where you want to join the crossing horizontal spar (see 1).
Using a clove hitch to start this lashing allows for two things. First, you can rest the crossing spar on the clove hitch to help support it as you begin the lashing while building your structure. Second, the clove hitch helps keep the structure from racking (twisting out of shape), causing the lashing to loosen as it is moved or hoisted into position.
After the clove hitch is tied, wrap the excess short end of the rope around the standing part of the rope (see 2). Hold the crossing spar up to the vertical spar and make three wraps around the spars using the long end (see 3, 4, and 5). Pull each wrap tight to hold the spars together. Make two frapping turns around the wraps (between the spars) to pull the wraps tight (see 6 and 7) and finish with another clove hitch on the horizontal spar (see 8 and 9).
One other point to make about the square lashing is that you shouldn’t be fooled by or limited by its name. Although two spars can be lashed together at 90° using a square lashing, it can also be used to lash two spars together at any angle. For example, a square lashing is used to lash the ends of two light spars to the uprights of a trestle to form the X bracing. A diagonal lashing is used at the center of the X to hold the crossed spars together.
MODIFIED SQUARE LASHING
The Modified Square Lashing was developed because of the difficulty usually experienced when tying a clove hitch to complete the traditional square lashing. The clove hitch that starts the lashing is easy enough to make, but tying a clove hitch at the end of the lashing is a different matter.
As shown in figure 104, the modified square lashing starts with a clove hitch. When tying the clove hitch, let the running end of the clove hitch extend about 12″. Also do not twist the short end around the standing part of the rope as in the traditional square lashing.
After tying the starting clove hitch, proceed as usual using the long end of the rope to make three wraps (see figure 105). Then make two frapping turns (see figure 106).
To complete the lashing, bring up the short end of the rope that extends from the clove hitch and tie a square knot (see figure 107). Bring the short end up in the opposite direction of the frapping turns.
As in the Traditional Square Lashing, there is some disadvantage in having to make the complete lashing using the one end of the rope.
When putting crossed braces on a structure to keep it from racking (as used when making a trestle), the most important lashing is the diagonal lashing where the spars cross. (Refer to the “Making a Trestle” section.)
When the cross spars are properly assembled on the trestle, they will be standing apart where they cross. That is, there will be a few inches of space between the spars where they cross at the center of the X. To pull them tightly together, a timber hitch is used to start the lashing (figure 1). As the timber hitch is pulled tight, the spars are sprung together. Next, three wraps are made in each direction across the X (figures 2 thru 5). After the wraps, make two frapping turns between the spars, pulling the wrapping turns tightly together and taking up any slack (figures 6 and 7). Finally, tie a clove hitch on one spar to complete the lashing (figures 8 thru 10). When this lashing is added to the cross braces, it helps keep the trestle from racking. Filipino Diagonal Lashing.
WEST COUNTRY ROUND LASHING
The pattern you make with the rope for this lashing is the same as the one to make the whipping. The only difference is that this lashing is tied around two spars to hold them together.
To make this lashing, tie a series of half-knots (overhand knots) around the two spars (see figure 115). Tie one half-knot in front and the next half-knot in back (see figure 116). Make sure each half-knot is pulled up as tight as possible. After tying six to ten half-knots, finish off the lashing with a square knot (see figure 117). By using six to ten half-knots in this lashing, it makes it very strong and effective, but can be a little difficult to untie.
The West Country Round Lashing is used to tie two spars together to extend the overall length of the spars. When this is done, you should make two sets of lashings, not just one lashing. Make one lashing at each end of the overlapping spars.
TWO-SPAR SHEAR LASHING (Shear Lashing)
The main application for the Two-Spar Shear Lashing is when spar legs are to be spread apart to form an A-frame.
The Two-Spar Shear Lashing starts with a clove hitch on one spar (see figure 118). After making the clove hitch, wrap the excess part of the short running end around the standing part of the rope (see figure 119).
Unlike square lashings, the shear lashing requires eight or ten wraps around the spars before making the frapping turns between the spars to pull the wraps tight (see figure 120). This lashing then ends with a clove hitch on the other spar (see figure 121).
If you’re making an A-frame, start the spars side by side and tie a clove hitch on one spar, about 1 foot from the top end of the spars depending on the project. Then you can take ten wrapping turns around the spars, making the wraps somewhat loose. The legs can then be spread to the required distance. This should put strain on the wraps.
With the legs apart, you can make the frapping turns around the wraps to pull them tight. Finally, complete the lashing by tying a clove hitch on the opposite spar.
In some pioneering situations all that’s needed is a few wraps with a rope, a light cord, or binder twine to hold two small spars or sticks together. Wrap the rope or cord around the spars a few times and finish with a Square Knot. This is called a strop lashing.
A strop lashing can be drawn down tight, or it can be made as a loose wrap so that it allows movement or acts as a hinge.
The strop lashing can have several simple applications at camp. For example, if you don’t want to dig a hole for the staff of your patrol flag, drive a tall stake in the ground. Then use a light cord or binder twine to make two strop lashings about 1 foot apart to hold the staff to the stake (see figure 122).
If your patrol just completed a signal tower and you want to show who did it, lash your patrol flag to the top of one of the legs with a strop lashing.
When you’re adding walkways to a bridge, they need to be joined to the trestle to form a single unit. The way to do that is to lash the two walkways to the transom at the center of the bridge with two or three strop lashings (see figure 123).
The ends of the walkways also need to be held to stakes. Use a strop lashing to hold the ends of the walkway to the stakes (see figure 124).
* An approach that is seen as a practical way to preserve and organize your lashing ropes is to coil ropes of the same length into manageable groupings, i.e. a large coil containing more than a single rope, and then tying up the grouping at one end with a 3-foot light cord.
** Round lashings are more frequently used to very effectively extend Scout staves or smaller diameter spars.
*** In a square lashing, the wraps and fraps form a square. In a diagonal lashing the wrapping turns cross the poles diagonally. Both lashings can be used to join two poles together that cross each other from 45º to 90º. It’s the square lashing that is used most because there is more contact between the rope and the poles, and hence it is stronger. A diagonal lashing is used when there is a need to close a gap between two spars or when they spring apart, in other words, when we want to bind poles together where they cross each other but do not touch. This most commonly occurs when the ends of the spars are already lashed in place in a structure, as in forming the X-brace of an H-Trestle.
The following text is by Adolph E. Peschke as presented in the 1998 printing of the 1993 edition of the Pioneering Merit Badge Pamphlet:
Building pioneering projects often requires some type of strong point for attaching a guyline for a tower or derrick. An anchor point might also be needed to anchor one or both ends of a monkey bridge.
Sometimes nature will provide a tree or rock in just the right location or you might be able to shift the location of the project to take advantage of a natural anchor.
When nature does not provide a solution, anchors can be constructed using stout pioneering stakes.
Note: Under no conditions should tent pegs be used for pioneering stakes. They’re not long enough or strong enough to make a safe anchor.
Pioneering stakes should be made of hardwood, such as oak or hickory. The most common size of stake (for the projects shown in this pamphlet) is 2-1/2 inches in diameter and about 24 to 30 inches long (see figure 84). After cutting the stake to this size, cut a point on one end. Then bevel the top edge to prevent it from mushrooming or splitting when the stake is driven into the ground.
When driving stakes into the ground, it’s best to use a wooden mallet. Using a metal sledge hammer or an ax head will damage the stake.
To make a wooden mallet, cut a 4-inch diameter piece of hardwood, such as hickory, elm, or sycamore, about 11 inches long (see figure 85). It should weigh about four pounds. Drill a 1-1/8-inch diameter hole to mount the handle. The handle can be made from a 24-inch length of hardwood (similar to making a stake). Use a knife or ax to round the end of the handle to fit the hole in the mallet head. Secure the handle in place with a wedge placed crosswise to the length of the head.
When driving the stake into the ground, drive it at about a 20° angle. Soil conditions can vary and will dictate how large and long a stake you need. If there will be a heavy strain on the anchor, you might need additional stakes as in the 3-2-1 configuration (shown in figure 89). After the stake is driven into the ground, keep your eye on it as strain is applied to see how it’s holding.
If ground conditions are unsuitable for even the largest stake you have, use a 4-inch diameter spar that’s buried 35 inches in the ground at a 30° angle and anchored in place with a stake (see figure 86).
Always attach the guyline around the stake as close to the ground as you can get it. If the guyline is placed or slips higher on the stake, there will probably be enough leverage to pull the stake loose (See figure 87).
ANGLES FOR GUYLINES
Both the 3-2-1 anchor and the log-and-stake anchor should be positioned so that the guyline is at a 15° angle, or a maximum of 25°. To determine this, measure the height at the point where the guyline is attached. Double this distance to determine the minimum distance required between the base and the anchor. For example, if the guyline is attached 10′ up the pole, the anchor should be a minimum of 20′ from the base (see figure 88). If your line is long enough, it won’t hurt to place the anchor a few feet further out.
As the name implies, the 3-2-1 anchor is made by driving stakes in a series: three stakes, then two stakes, and then one stake to form the anchor (see figure 89). All six stakes are 30 inches long and are driven 18 inches into the ground at a 20° angle.
First drive in the set of three stakes. Next drive in the set of two stakes about 24 inches away from the first set. Then tie a rope from the top of the three-stake set to the bottom of the two stake set using at least two loops of 1/4-inch manila rope, or six to eight loops of binder twine. Then use a small stick to twist the rope tight in a tourniquet. After the rope is twisted tight, push the end of the stick in the ground to keep it from unwinding.
Finally, drive a single stake in the ground about 12 inches from the two-stake set. Once again, use a twisted rope or binder twine as a tourniquet to hold the two-stake set tightly in place.
Depending on the strain, you can use other configurations, such as 2-1-1, or even 1-1-1 for a light strain. When using any stake anchor, be sure that it is in direct alignment with the strain being applied.
The log-and-stake anchor is easy to make and can hold a considerable amount of pull. You can tie the line directly to the log, or you can use a ring-and-rope grommet as shown in figure 90.
To make the log-and-stake anchor, place a log 4 to 6 inches in diameter perpendicular to the pull of the line. Then drive in four large stakes in front of the log. Next, slip the rope grommet through the ring and then slip the ends of the grommet around the log (see figure 90).
Drive a second row of stakes 24 inches behind the front stakes. Then anchor the front stakes to the rear stakes with a tourniquet made of binder twine or rope.
It is good practice to use a device called a strop to avoid damage to your long lines. It also makes it easier to tie off your long lines and to make adjustments.
A strop can be made by using a 10-foot length of 1/2-inch diameter manila or polypropylene rope. To make a strop, splice a thimble and ring into one end of the rope (see figure 91), or use a screw pin shackle with a thimble.
The strop can then be wrapped around a rock or tree to attach the line (see figure 92). It can also be used around a spar that is anchored between two trees (see figure 93).
Note: Be sure to use a piece of canvas or burlap to protect your rope from sharp edges of a rock or to protect the bark of the tree from rope burns.
A grommet is often used in conjunction with an anchor. A large grommet can be made by splicing together the ends of a 10-foot length of 1/2-inch manila or polypropylene rope. If you don’t have a spliced grommet in your pioneering kit, tie the ends of the rope with a square knot or a carrick bend. Be sure to secure the ends of the rope.
The completed grommet is useful when attaching a long line to an anchor of stakes. It provides a strong and more convenient way to attach a guyline or other long line.
The grommet you use must be made of a larger-diameter rope than the guyline to avoid creating a weak link in the chain between the structure and the anchor.
The National Camp Accreditation Program (NCAP) Program Specific Standard PS-212 states: “Scout camp structures such as monkey bridges, obstacle courses, and pioneering towers are expected to meet safety standards in equipment and supervision comparable to COPE but are not subject to COPE standards, do not require COPE inspection, and do not require an on-site COPE Level II instructor. “VERIFICATION: If a project has participants elevated more than 6 feet above the ground, evidence of council enterprise risk management approval. This approval may be part of the general program design review in Standard PD-112.”
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.