Scouting founder Robert Baden-Powell believed every Scout should know how to build bridges. From designing the structure to gathering materials and putting it all together, bridge construction combines technology, teamwork and enthusiasm to complete a span that is memorable and useful.
A bridge on a hiking trail can be as simple as a log across a narrow gap. A more serious one relies on sturdier materials like rope and poles. A rope bridge Baden-Powell described in his 1908 manual, Scouting for Boys, is what today’s Scouts would call a monkey bridge.
This is a classic pioneering project, and a variety of styles and instructions have been shared many times, from a 1965 Boys’ Life article penned by Scouting leader and author William “Green Bar Bill” Hillcourt to various editions of the Pioneering merit badge pamphlet.
If Scouts don’t have a stream or small gully to cross, they can build the bridge in a meadow or backyard. Follow safety rules, ensuring the foot rope is no higher than 6 feet off the ground and no longer than 25 feet between A-frames. Using a 50-foot rope, the maximum span between A-frames should be 20 feet, with the extra length being used for anchoring the bridge.
Before building any pioneering structure, it’s necessary to first acquire the wherewithal to experience success. The skills, along with the lashing ropes and poles required to build a monkey bridge using double A-frames for better stability, can be used time and again, for a variety of pioneering projects and troop meeting activities. Here’s how to build a monkey bridge.
Eight 8-foot-by-4-inch A-frame legs
Four 6-foot-by-3-inch ledgers
14 15-foot lashing ropes for square lashings (Use 1⁄4-inch manila for all lashing ropes.)
Six steel rings or locking carabiners to join grommet and rope tackle
Two 1⁄2-inch-by-10-foot polypropylene ropes for rope grommets
Binder twine to create loops for tourniquets
Six 10-foot lashing ropes for round lashings
Two 1⁄2-inch-by-50-foot hand ropes
One 1⁄2-inch- or 3⁄4-inch-by-50-foot foot rope
Five to seven 8-foot lashing ropes for stringers
12 24- to 30-inch-by-21⁄2-inch pioneering stakes for two 3-2-1 anchors
Two pieces of scrap burlap for saddles
1. Begin by building four identical A-frames with the 8-foot and 6-foot spars. Make sure the A-frames are all uniform in size when lashed together. Lash them together with three tight square lashings. You could also use shear lashings at the top of the A-frames.
2. Once you have four identical A-frames, it’s time to make two pairs of double A-frames. Stand up two A-frames so they overlap each other one-half their length (about 3feet). Join the legs together where they intersect with a tight square lashing. Finally, lash the two 6-foot bottom ledgers together where they overlap with three tight round lashings. Do the same for the other double A-frame.
3. Drive the pioneering stakes into the ground first with three stakes together, then two, and then one. Use loops of binder twine and a small stick in between each set to form a tourniquet. Both 3-2-1 anchors should be installed about 10 feet from where the A-frames will be erected. Place a rope grommet around the front stakes, before applying the tourniquet joining the three front stakes to the middle two.
4. Position the double A-frames no more than 20 feet apart from each other. Lay the foot and hand ropes alongside the A-frames. Attach the stringer ropes to a hand rope with a clove hitch at 3- to 4-foot intervals along the hand rope. Make roundturns around the foot rope and tie the running ends of the stringer ropes to the other hand rope with a clove hitch.
5. Make two saddles by folding pieces of burlap, placing one above the square lashings in the middle of the double A-frames where they intersect. This is where the foot rope will rest.
6. With the double A-frames held in place on each side, place the foot rope over the saddles, and tie the hand ropes to the top of the A-frames with clove hitches on a bight.
7. About halfway between the anchor and the A-frames, tie a butterfly knot in the foot rope to form a fixed loop for a rope tackle (trucker’s hitch). With Scouts still holding the double A-frames in position, use the rope tackles to put strain on the foot rope. Next, pull the hand ropes tight and attach them to the anchors using rope tackle or roundturns with two half-hitches.
8. Once all the ropes are tightened, check the knots and lashings before crossing the bridge. Allow only one person on the bridge at a time.
Bridging the gap
Scouts can celebrate their bridge’s completion by crossing it and reflecting on how the project came together. What went well? What would they do differently next time? What roles did teamwork and leader-ship play in the project?
After it has served its purpose, the bridge can be dismantled: The ropes can be coiled and stored with the poles in a dry place, ready to bring out for the next pioneering project.
Helping Scouts realize they have the power to plan and construct big projects is a practical way to bridge the gap between the promise of Scouting adventure and fulfilling that promise in the field.
Robert Birkby is author of three editions of The Boy Scout Handbook, two editions of the BSA’s Fieldbook and the newest edition of the Conservation Handbook. Find him at robertbirkby.com
Troop 86 from Sumter, SC wanted to do a pioneering project and they selected the Double A-Frame Monkey Bridge. Great place to start, and a great way to illustrate sequential programming. What skills enter into the picture? A whole bunch! And with each step along the way, there’s an activity wherein each campcraft skill can be put into action, in a fun way, as reinforcement.
B.-P. wrote: “I am inclined to suggest to Scouters that in addition to the technical details of knotting, lashing, and anchorages, there is an educative value in Pioneering since it gives elementary training in stresses, mensuration, etc.” In addition to the “mensuration” skills that come into play when setting out the area for the bridge’s A-frames and anchors, a good deal of measuring takes place to assure the A-frames are as close to identical as possible, the pairs are joined together in similar fashion, an the spanner ropes are spread evenly. (Hand in hand with the building, Scouts do a lot of planning.)
Using Half Hitches to tie a Clove Hitch – A simple process always makes it easy to tie a clove hitch and finish many types of lashings. Several are used to attach the spanner ropes. — How-to Video / Activity Video —
Round Lashing – Three or four can be used to join together the bottoms of the A-frames on each side. Round lashings can also be used to attach a flag pole(s) to an A-frame(s). — How-to Video / Activity Video —
Square Lashing – This project can use fourteen of them for both building the A-frames and then joining them together. — How-to Video / Activity Video —
3-2-1 Anchor – The skill is to carefully drive in the stakes at the proper angle and applying the tourniquets to join the groupings. — Explanatory Video —
Roundturn with Two Half Hitches – You can use this pioneering knot to attach the hand ropes to the anchors. — How-to Video / Activity Video —
This short commentary is one part surmise and three parts observation. It’s composed of a series of events with a predictable outcome. Except to those familiar with Scout Pioneering, and Scout competitions, the whole scenario will appear obscure. But to the Scouts involved, it’s far from obscure. On the contrary, whenever something like this happens, it’s downright confusing, and without being melodramatic, maybe a little traumatic too. No real names are used in this account, and no fingers are being pointed at any individuals. The characters in stories like this are always well-intentioned and without malice. There are no wrongdoers involved… just victims.
Scout Pioneering is about building structures with poles and rope. They can be useful, they can be for fun, and often they’re both. Knowing how to tie knots and lashings is a basic Scouting skill that’s been a part of our movement for over a hundred years. In all bonafide Scout Pioneering settings, when two poles cross each other, but do not touch, a Diagonal Lashing is often used to spring the poles together. The lashing is so-named, because the wraps run diagonal to the poles. Additionally, those who are experienced in building pioneering structures accept the fact that joining two poles together that cross from 45º to 90º calls for a Square Lashing. There’s more contact between the rope and the poles than with a Diagonal Lashing, and hence a Square Lashing provides a better hold. The Square Lashing gets its name from the fact the wraps run square to the poles. The name has nothing to do with at what angle the poles cross.
Enter “Ned”: Without knowing any better, Ned, a well-meaning Scouting volunteer, reasons quite innocently the Diagonal Lashing should be used whenever Scouts join two poles that cross each other at less than a perpendicular angle. So from this viewpoint, which, because of its name, appears logical, Ned concludes Scouts should use Diagonal Lashings when making an A-frame. After all, the angles formed by the poles are less than 90º. Without any real, hands on exposure to pioneering, he’s not familiar with the fact the lashing is reserved for springing two poles together when they cross but don’t touch. To him, his assumption about the lashing is obvious. He proceeds to write up a description of a Scouting activity featuring his misunderstanding about the use of Diagonal Lashings. Since he’s an intelligent, well-respected Scouter…somehow, it get’s printed, and then again reprinted, in official BSA publications.
Enter the “Raccoon Patrol”: As part of a troop that regularly embraces large pioneering projects, the Raccoon Patrol is well-versed in building A-frames. During inter-patrol competitions at Scout meetings, they do well in A-frame Chariot Races. On outings they build camp see-saws where the roller bar for the plank is supported by two heavy duty A-frames. They have also helped to build several monkey bridges relying on sturdy A-frames as sub assemblies. Belonging to a unit with a successful pioneering program, they’ve been taught to make their A-frames using three Japanese Mark II Square Lashings. In addition to being supported in certain BSA publications, their grasp of Scouting skills stems from Scouters who’ve served on the pioneering staff at national jamborees and who, themselves, have learned from some of the most esteemed Scout Pioneering legends.
Enter “Nancy”: On staff at summer camp, Nancy volunteers to conduct an A-frame Chariot Race as part of the camp-wide skills event towards the end of the week. Her reference material is one of the BSA publications containing Ned’s well-meaning misconception, directing Scouts to construct an A-frame using Diagonal Lashings. Without any real experience putting together an A-frame, she’s basing her thinking on what she has read. Furthermore, since the content is featured in an official publication, she requires each patrol taking part in the activity to build their A-frame in just that way.
Reenter the “Raccoon Patrol”: Participating in the camp-wide competition, the Raccoons confidentially arrive at Nancy’s station, all revved up to be the fastest patrol in the A-frame Chariot Race. Nancy proceeds to explain her rules for putting together the A-frame, which immediately confuses the Raccoons. In their attempt to comply, they bungle the Diagonal Lashings, something they seldom use. At the top, they ask if they can tie a Square Lashing in lieu of a Shear Lashing, and Nancy acquiesces. But, they are further penalized because Nancy insists that if they’re going to tie a Square Lashing, it must start and end with a Clove Hitch. She has never seen or heard of a Japanese Mark II Square Lashing. It isn’t in the official publication she is using as her reference. At that point, the Raccoon’s performance is so poor, they don’t even bother to race. With disgruntled comments, they leave Nancy’s station. They are hurt and bewildered.
Are these kinds of scenarios rare at Scout skill events? The answer is, no. They take place at Boy Scout summer camps, district and council camporees, and OA conclaves. Scouts have been penalized, disqualified, and even politely insulted by facilitators who base their event’s rules on material that contradicts what some may have adopted from other official publications. This is a sad state of affairs. Scouts become frustrated, angry, and disillusioned—feelings that shouldn’t obtain at a Scouting event.
What about this conflicting information presented in different official publications? Are there ways around the confusion? The answer is, yes. At the time of this writing, a national task force is taking steps to assure the publications all provide compatible information pertaining to Scout skills—approaches that are sensible, practical, and proven to be the most efficient. This is a lengthy process and will take time. Everything that appears in official BSA publications should be exemplary, but change happens slowly. Until Scout skills are presented consistently across the board, the following is felt to be an advisable practice: during inter-troop, district, or council events, in competitions like the A-frame Chariot Race, let the patrols complete the challenge in anyway they can. Don’t permit their efforts to be circumscribed by a rigid set of exacting rules. As long as what they build is safe and gets the job done, the Scouts should be allowed to experience success.
We’ve seen how block and tackles and even commercial-grade come-alongs have been employed to tighten hand and foot ropes during the construction of various monkey bridge projects, especially those spanning longer distances and using larger diameter ropes. On the other side of the coin, in the presentation of his Double A-Frame Monkey Bridge, Adolph Peschke says, “Whatever strain three or four Scouts can put on the foot rope by pulling it by hand will be enough.”
The simple rope tackle provides a 3:1 mechanical advantage and is frequently used to apply the desired tension to both hand ropes and foot rope—often on both sides of the bridge. Adjusting the strain on individual ropes during use of the bridge can result in a slight complication—the spanner ropes can lose their symmetry.
A method that will alleviate this issue, and also provide a greatly increased mechanical advantage, is to utilize a Single Pull 2-Ring Configuration. After attaching the hand ropes to their respective spars with Clove Hitches, (adjusting the strain on the sections of the hand ropes between the double A-frames to match the sag of the foot rope) this approach is executed as follows:
Use a roundturn with two half hitches to attach the hand and foot ropes to a rope grommet at one anchor point. At that side of the bridge, they will remain fixed.
Pulling the three ropes so each receives the same degree of strain, attach each to one large ring at the other side of the bridge, again using Roundturns with Two Half Hitches.
With a length of 1/4 or 3/8-inch manila (preferred), using a roundturn with two half hitches, connect one end to the same large ring.
Reeve the running end of this rope through the ring in a rope grommet which is situated about four feet away and already fixed at the anchor point on this side of the bridge.
Carry the running end back and reeve it through the large ring. (If you now pull on the running end, there’s a 2:1 mechanical advantage.)
To increase the strength of this connection enabling it to withstand all the strain exerted on the bridge during heavy operation, reeve the running end back through the ring in the rope grommet and then through the large ring two or more times.
Now when you adjust the tension of the hand and foot ropes with this pull rope, the mechanical advantage is greatly increased. Secure the entire configuration with two Half Hitches cinched up against one of the rings.
Some Notes: This arrangement can be configured any way you like, e.g. when using 3/8-inch manila, attach the pull rope to the large ring, reeve it through both rings twice, and then finally secure the configuration at the large ring. Or, instead of first tying the pull rope to the large ring (the ring that’s functioning as the moving block) initially tie it to the ring in the rope grommet (fixed block). Then proceed to reeve it through the other ring, back again, etc.
With each turn on the rings, make sure the rope doesn’t cross on top of itself as this would interfere with adjusting the strain.
This kind of rope tackle can exert too much force on the bridge components, so carefully monitor how tight everything is getting and don’t just give the rope a willy-nilly pull.
An Opportunity Identified: Last spring, on April 12-14, a Scout Expo was held on the extensive grounds of the Myrtle Beach Speedway in Myrtle Beach, SC. for the purpose of increasing public awareness and celebrating Scouting throughout the eleven counties of the Pee Dee Area Council. Units were invited to camp overnight on Friday and Saturday, and from 10:00 to 5:00 p.m. on April 13, the Expo’s festivities were open to the general public. To promote Scouting, all units were invited to set up a fun, and/or informational display.
A Challenge Accepted: To contribute to the overall impact of the event and to increase awareness of the Order of the Arrow, the Chicora Chapter of Santee Lodge 116 received permission to set up their own exhibit. They wanted to communicate and share with everyone in attendance that members of the Order of the Arrow were capable of providing an outstanding activity—one that provided real interactive fun, and one that promoted camping by demonstrating advanced Scout skills.
Addressing the Opportunity and the Challenge: To take advantage of this opportunity, the chapter decided to challenge itself to assemble a Scout Pioneering exhibit—one that would engage and impress Expo attendees. It would be a special rope bridge. But, instead of the typical single or double A-frame versions, an elaborate design was developed featuring two 5’ climbing towers.
What They Did:
They formed a Pioneering crew made up of chapter members who readily volunteered to participate.
They fine-tuned the project design and gathered together all the materials needed.
They provided themselves with the pioneering skills required to build a safe structure.
They formalized a plan of action for actual project construction, with assembly procedures and building assignments.
They made meal plans and camping arrangements for all crew members.
They organized a schedule for manning the bridge to assure it was used safely and properly during the seven hours of Expo festivities.
They carried out all their plans
Who was involved: Twelve members of the chapter rendered cheerful service in building the project on Friday, maintaining and supervising its safe operation on Saturday, and disassembling the structure on Sunday.
The Costs: The only money involved was the cost of Friday evening’s dinner for the Pioneering crew, and the price of registration for those brothers who were not already camping with their troop.
The Success: The success of Scout Pioneering can be measured in two ways. One, did those building the project complete it safely and effectively? Two, did the completed project accomplish whatever it was designed to do? Their efforts were successful on both counts. The chapter brothers cheerfully worked hard and worked together building a project that was stable and strong. When the work was done, they proudly shared the fruits of their labor with numerous, appreciative Scouts and Expo guests.
The Result: For seven hours, their display enjoyed a continual stream of eager Cub Scouts, Webelos Scouts, Boy Scouts, and Expo visitors. The Council-wide Scout Expo was well-attended. Though there was not an exact count, it is easy to say that throughout the day, hundreds of people crossed the bridge, supervised and safe-guarded by the helpful Order of the Arrow attendants. The Expo organizers were very happy with the participants’ response to the OA exhibit, and the Pioneering crew regularly received high praise from Expo attendees.
The Benefit: The Chicora Chapter’s original intention in setting up a Scout Pioneering exhibit at the Expo was to benefit both Scouting and the Order of the Arrow, by contributing to the overall impact of the event, and by providing those attending with positive exposure to our Brotherhood of Cheerful Service. Because their display was so cool, and because its presentation was so impressive, the conclusion is that in both these lights, they hit the ball out of the park! In line with an honor organization that promotes camping, they wanted to have Scouts associate the Order of the Arrow with advanced Scouting skills that are functional and fun. For many, it was the first time they ever got to try a rope bridge. For everybody, it was the first time they ever saw a monkey bridge with a double platform! The exhibit was well-manned and the cheerful Arrowmen looked great with their sashes symbolizing the service they provided to their fellow Scouts and Expo visitors.
The Future: As an outgrowth of the favorable impression made at the Scout Expo, opportunities to serve their district and council are on the rise. In October the chapter was asked to build a traditional Double A-Frame Monkey Bridge at a District Webeloree. Then in November, they received a request to assist in an afternoon team-building session during a multi-district Boy Scout Camporee, by presenting Pioneering activities as patrol challenges. More and more arrowmen are becoming aware of the fun and positive impact this kind of service provides, and an increase in participation by other chapters throughout Santee Lodge is foreseen.
Plans to Grow: The more the Pioneering skills are developed through learning and application, the greater will be the capacity for sharing these skills through the construction of interactive Pioneering displays, while exampling cheerful service! Those who appreciate the fun in using only poles and rope to build a useful structure, who enjoy working together as a team utilizing specialized skills to get the job done, and who have experienced the sense of accomplishment that goes along with completing a Pioneering project that illustrates “old-school” Scouting know-how, need no coaxing when invited to do it again and again! The chapter just found out that a local pack has requested they build a simple Single A-Frame Bridge with twin walkways for their outdoor Webelos crossover ceremony this February. But, they’re most excited by the largest venture coming up in April! Santee Lodge is hosting this year’s Dixie Fellowship at Camp Coker. With the input of the Chicora Chapter Pioneering Crew and with the help of many other, eager lodge brothers, Pioneering crews will be erecting an enormous gateway flying the American flag, the Order of the Arrow flag, the World Scout Crest flag, and the state flags of NC, SC, and GA. These six flags will surround a 10’ banner welcoming everyone to the Dixie Fellowship! The OA Pioneering Crews will also build a 12’ Swing Boat and 10’ Atomic Pile for intermittent fun during the Fellowship. With over 1,000 OA brothers in attendance, sharing the satisfaction inherent in serving Scouting and promoting the Order of the Arrow through well-presented displays of Scout Pioneering will be a blast! (See: Pioneering at the 2014 Dixie Fellowship.)
Sustaining the Idea: The idea is fostered that if provided the wherewithal, in every OA lodge there are many Scouts who would enjoy building fun and useful Pioneering structures that are really cool. There are also those closely involved with Scout Pioneering who would be very happy to make it a priority to help equip and train fellow arrowmen, so they can implement their own program and serve their councils in like fashion. Building Pioneering projects provides outdoor fun that quite simply stands the test of time. The Native Americans did it in a big way, and so did the folks who settled our country. Especially today, even with a modern emphasis on the high-tech, the fascination with old school Scouting skills always persists. This is evidenced by the joyful responses well-built Pioneering projects consistently receive. The Order of the Arrow is steeped in rich Scouting traditions, and hence provides wonderfully fertile grounds for a welcome resurgence of the timeless Scouting skills that are embodied in Scout Pioneering—a golden opportunity to both promote Scout camping while exampling cheerful service during Scouting events!
Furthering the Mission and Purpose of the Order of the Arrow: For 100 years, the Order of the Arrow has inspired numerous Scouts, both young and old, by linking a love for the outdoors and camping with the cheerful rendering of service to our fellow man. When, in preparation for an organized Scouting event, arrowmen dedicate their time and skills to the building of an impressive, interactive pioneering structure, they are setting the stage for something very special. In addition to enhancing the event’s impact, their accomplishment carries with it a dual purpose. One: a properly presented and well-built Pioneering project in itself promotes a love for the outdoors and camping. Two: unselfishly giving their time to share the fun inherent in their work, by answering questions about their project in a friendly manner and providing safe guidance in its use, is the kind of action that inspires, motivates, and indeed exemplifies the cheerful service that embraces the watchwords of our order.
For those familiar with the traditional Double A-Frame Monkey Bridge design, a couple of noticeable modifications will be apparent from the outset. (Click on the photos for larger views.) Scout Engineering is a fluid undertaking, and frequently variations are necessary. Just as frequently an alteration or change can be deemed a desirable improvement. In the case of this double A-frame design, the consensus of opinion is these modifications are really neat, and I’m sure Adolph Peschke would concur.
Instead of separate shorter ledgers for each pair of adjoining A-frames, connect four legs with one longer ledger. The length can actually be the same as that of the legs, e.g. four 8-foot legs and one 8-foot ledger at the bottom, or for a larger structure, 10 or 12-foot legs and ledger. (A spar longer than the legs does yield more flexibility when lashing together the four legs.)
Ladder rungs! Lashing a couple of cross pieces between the legs of the left A-frame cancels the need to climb on board the bridge using the foot and hand ropes! Same thing of the other side. Crossers use the rungs and have a safe and easy way to get on and off the bridge, AND eliminate the often awkward balancing act on the ropes between the A-frames and the anchors. There’s an added advantage too: no more excess stress and strain on the ropes near the anchors.
It’s a pretty safe to say most Scouts love to climb things. So, it makes sense that if a monkey bridge is combined with something to climb on, it will be even more fun. The challenge in constructing a project like this is to assure the structure can safely support not only the weight of those climbing on the platforms, but also the continual stress created by repeatedly crossing the rope bridge. Building this version of a double platform monkey bridge entails quite a few subassemblies and a procedure with many steps. Basically, with the materials listed, the ropes span a distance of 25 feet between two identical square platforms 4 feet wide and 8 feet high. At the front of each platform is an X-brace just under 5 feet high, providing a V for the foot rope. The hand ropes run through the junction where the X-braces intersect the top of the front legs, and then extend down joining the foot rope at a log-stake anchor 10 feet behind the back of each platform.
Here are the materials needed to construct the project:
eight 8-foot x 4-inch spars for platform legs
four 8-foot x 3-1/2-inch spars for X-braces
four 6-foot x 2-1/2-inch diagonal side braces
eight 4-foot x 3-inch spars for side base spreaders (4) and platform supports (4)
sixteen 4-foot x 2-inch spars for ladder rungs (10), handrails (4) and X-brace leg spreaders (2)
twenty-four 4-foot x 2-inch floor spars
two 4-foot x 4-inch log and stake anchor logs
sixteen 30-inch pioneering stakes for 2 log-stake anchors
sixteen large wooden stakes for the 8 guyline 1-1 anchors
sixteen small tourniquet stakes
two rope grommets with large O-rings
one 70-foot x 1/2 or 3/4-inch manila foot rope
two 70-foot x 1/2-inch manila hand ropes
eight 8-foot x 1/4-inch manila spanner ropes
thirty-six 15-foot x 1/4-inch manila lashing ropes
twenty-six 20-foot x 1/4-inch manila lashing ropes (for X-braces, base spreaders and platform supports)
eight 25-foot x 3/8-inch manila guylines
four 35-foot x 1/4-inch manila lashing ropes for floor spars
six burlap or canvas saddles (for the foot rope and hand ropes)
two large mallots
• Participants should be well-acquainted and experienced in the skills required for building this project.
• Select a project leader who will divide the participants into work groups, assign tasks, and oversee operations.
• Before proceeding, position the materials in proximity to the location where the project will be placed. It’s good to organize the materials by the tasks for which they’re needed.
• Depending upon how many Scouts are participating (will there be a small group of 6 Scouts, or a large group of 24), many of the subassembly steps needed to finish the project can be completed simultaneously. This division of labor can enormously streamline the project’s completion.
• If the opportunity presents itself, it can very helpful to initially lay out the hand and foot ropes, in conjunction with completing Task E, before proceeding with Tasks A & B.
• The following tasks can be completed at the same time:
Tasks A 1 & 2 / B 1 & 2 / Tasks D 1 & 2 and E
Task C 1 / Task C 2
Task F 1 & 2 / Task H 1 & 2
Tasks I & J / Tasks K, L & M
• If one task is taking longer to complete, workers from other groups can lend a hand and help finish it up so the next step can commence.
• Placing a 4-foot spar underneath the spars lying on the ground, in a strategic position, will raise the project sides up and make lashing much easier.
• There are 64 square lashings in this project and, for stability and safety, they must be tight! For speed and efficiency, the Japanese Mark II Square Lashing is highly recommended.
TASK A – 1 & 2: Building the ladder sides of the platforms. 1) Lay out two 8-foot legs side by side. Space the spars apart so that the distance from the middle of each spar, at both the top and bottom ends, is 40 inches. Use a tape measure. Also, make sure the butt ends are at the bottom and absolutely even. Starting 6 inches up from the butt end, connect the legs by lashing on a 4-foot ladder rung directly above the 6 inch mark, with tight square lashings.
Using a tape measure, measure 5 feet up from the butt end of each leg, lash on another ladder rung, directly below, just touching, the 5-foot mark, ON THE OTHER SIDE (what will become the inside) of the legs. See the diagram on the right.
Right in the middle of these two ladder rungs, lash on another ladder rung, and then, between the middle ladder rung and the top and bottom ladder rungs, lash on two more. Use tight square lashings.
2) Repeat the whole process on two other 8-foot legs for the other platform.
TASK B – 1 & 2: Building the X-brace sides of the platforms.
The premise for these sides is the X-braces have to cross each other just under 5 feet for the foot rope, and they have to intersect the tops of the legs equally on each side for the hand ropes. Because of the size of the spars involved, and the necessity for very secure connections that do not shift, use 20-foot lashing ropes and two Scouts for each X-brace square lashing.
1) Lay out two 8-foot legs side by side. Space the spars apart so that the distance from the middle of each spar, at both the top and bottom ends, is 40 inches. Use a tape measure. Also, make sure the butt ends are at the bottom and absolutely even. Starting 6 inches up from the butt end, connect the legs by lashing on a 4-foot ladder rung as a leg spreader, directly above the 6-inch mark, with tight square lashings.
With a tape measure, mark 56 inches up from the butt end of each leg.
Temporarily stretch a piece of binder twine over each 56-inch mark and tie it to each leg to help define where this intersecting line lies. It’s at the middle of this line where the X-braces need to cross so that the foot rope will extend just underneath the floor spars of the platform.
Lay out an 8-foot X-brace spar diagonally in such a way that the top end lays over one leg about 4 inches from the top of the leg, and extends out approximately 6 inches from the side. Angle the spar so that it will cross the middle of the intersecting line (56 inches up from the butt ends of the platform legs). Line up the bottom end of this X-brace so that it is positioned under the bottom of the opposite leg. Lash the spar in place with tight Square Lashings.
Lay out a second 8-foot X-brace spar on top of both legs so that it creates an X. Angle this spar so that it will cross the middle of the intersecting line (56 inches up from the butt ends of the platform legs). Make sure this spar also extends out approximately 6 inches from the side and that it intersects the leg at the same distance from the top as the X-brace on the other side. Lash this spar in place over both legs with a square lashing. It’s between the top of the front legs and the extension of the X-braces that the hand ropes will be supported.
Now, with a diagonal lashing, lash the middle of both 8-foot X-braces springing them together where they cross, using a 20-foot lashing rope.
2) Repeat the whole process with the two remaining 8-foot legs.
TASK C – 1 & 2: Connecting the Ladder and X-brace sides. (If Task E has already been completed, before joining the ladder and X-brace sides, carry the two completed sides for each platform to the approximate location where they will eventually be positioned.)
1) Turn both a ladder side and an X-brace side up horizontally, parallel to one another. On the X-brace side, make sure the leg spreader and the X-brace spars are facing out. Space the legs apart so that the distance from the middle of each leg, at both the top and bottom ends, is 40 inches. Use a tape measure. Also, make sure the butt ends are absolutely even. With tight Square Lashings, join both sides by lashing a 4-foot side base spreader to the legs just below the bottom leg spreaders with a 20-foot lashing rope.
On the inside of the platform, using a 20-foot lashing rope, lash a 4-foot platform support to both legs so that the top edge comes up to 58 inches on both sides (directly under and as close as possible to the top ladder rung on the ladder side.). We will be laying the floor spars on top of this support.
Lash a 4-foot hand rail (same as ladder rung) to the top of both legs.
Lay a 6-foot diagonal side brace diagonally over both legs, between the base spreader and platform spreader, and lash in place using square lashings.
To join the other side, carefully lift and roll the platform over 180°, supporting the spars as much as possible, and repeat the above steps.
2) Repeat the whole process to join the ladder side and X-brace side of the other platform.
TASK D: Stand the platforms upright. With three Scouts lifting at the ground-level handrail, and two to three pulling on the other handrail, raise the platform to an upright position. If TASK E has been completed, we can proceed to Task G.
TASK E: Site preparation. Begin by stretching a length of binder twine along the center line of where the ropes will span. Drive a tent stake into the ground marking the center.
Working from the center, measure 12-1/2 feet toward each end and drive another tent stake to mark where the X-braces of each platform are to be placed. They should be 25 feet apart. Then with two other tent stakes, mark out another 14′ to where the anchors are to be built.
TASK F – 1 & 2: Build the anchors. The foot and hand ropes will be attached to anchors at both ends.
1 & 2) Build a log-and-stake anchor (also known as a log and picket holdfast), 14 feet from where the X-braces of each platform are to be placed. To make the log-and-stake anchors, place one of the 4-foot x 4-inch logs perpendicular to the pull of the line, 14 feet from where the X-brace side will be. Drive in a row of four pioneering stakes spaced evenly in front of the log, leaning them back at a 45° angle. Slip a rope grommet through an O-ring and then slip the ends of the grommet around the log (see diagram). Drive a second row of pioneering stakes 24 inches behind the front stakes. Then anchor the front pioneering stakes to the rear pioneering stakes with a tourniquet made of binder twine or rope using four tent stakes. After twisting the tourniquet tight, hammer the tent stake into the ground to keep it from loosening.
TASK G – 1 & 2: Position the platforms. All hands on deck! Move both upright platforms into position no more than 25 feet apart. Place them on the binder twine that marks the center line of the bridge, making sure the X-braces of each are facing each other 10 feet from the center mark.
TASK H – 1 & 2: Lash on the floor. Lay 4-inch floor spars on top of the platform supports so that the ends extend out evenly on each side. Using the Double Floor Lashing and the 35-foot lashing ropes, lash the floor securely in place.
TASK I – 1-8: Add anchors for platform guylines. For added stability, we’ll be adding four guylines to each platform. To start, measure 10 feet, 45° out from each leg and drive in a 1-1 anchor.
TASK J – 1-8: Secure the platforms. Attach one of the 25-foot x 3/8-inch guylines to each leg, directly above the floor spars, with a roundturn with two half hitches.
Extend the guyline down to the corresponding 1-1 anchor and attach it to the anchor with a rope tackle. Repeat this process at each leg.
TASK K: Foot rope. First place a piece of heavy canvas (called a “saddle”) in the top V formed by the X-braces. This will protect the foot rope and allow it to slide a little as needed.
If the foot and hand ropes are not already laid out during Task E, two Scouts will be needed to stretch the foot rope out, aligning the center of the rope with the center stake along the binder twine.
Next, lay the ends of the rope over the saddle in the V formed by the X-braces on each platform. Then, maintaining the rope’s center alignment between the platforms, extend the rope under the platforms, through the ladder sides and pulling it somewhat taut, thread the ends through the O-rings attached to the log-and-stake anchors. Tie these off temporarily with a roundturn with two half hitches.
TASK L: Hand ropes. Two Scouts will be needed to stretch the hand ropes out on either side of the foot rope, aligning the center of each with the center stake along the binder twine.
Climb the platforms and place saddles in the crotch between the X-brace extensions and the front legs. Maintaining the center alignment between the platforms, place one hand rope over its corresponding saddles. Then extend the rope down, crossing it over the outside of the top ladder rung, pull it taut, and thread the ends through the O-rings attached to the log-stake-anchors. Tie these off with a roundturn with two half hitches. Repeat the process for the other hand rope.
TASK M: Stringer ropes. Now 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 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.
TASK N: Tighten the foot rope and hand ropes. Now you can put a strain on the foot rope. Undo the Roundturn with Two Half Hitches, and make a rope tackle on each end of the foot rope. Two Scouts will need to adjust the tension at each rope tackle so that the middle of the rope stays midway between the platforms.
As needed, adjust the tension of the hand ropes by tightening them at the anchors and retying the roundturn with 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.
Safe operation calls for only one Scout to be on the foot rope of the monkey bridge and up to two on either platform at a time.
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.