Double A-Frame Monkey Bridge Constructed using “Sandwiched” 2x4s
Yes. That’s how Venture Crew 140 out of Houston, Texas put some newly-learned lashing skills into action. They also experienced, first hand how rope tackles can put the necessary strain on thick lines used for hand and foot ropes. Though they didn’t follow the instructions for making laminated spars as provided by Scout Pioneering legend, Adolph Peschke, the 6 and 8-foot lengths of doubled 2×4 boards did the trick. Here’s the email received from Crew Advisor Russ Jamerson:
“Just wanted to show you that my Crew has already put up the double a-frame monkey bridge per your instructions at Philmont Training Center! We had trouble finding natural timber spars so we made them from 2×4’s – learned a few things in that process — I did not follow the instructions you pointed out about laminated spars exactly – for example I used 2x4s sandwiched together with edges smoothed via a router for both 8’ and 6’ spars. This creates the need for longer lashing rope in some cases such as at the top of the a-frame and the round lashings at the bottom that circle essentially 4 2×4’s. The only issue is that they are a little too smooth to properly hold lashings. We plan to roughen up the surface where lashings will go by running a sawzall lightly across the surface to scar it up.
“This has been and continues to be a great teambuilding exercise while introducing some of the Crew without a Boy Scout background to various knots and lashings.”
Using a Rope Tackle, two Scouts tighten a hand rope on their monkey bridge.Click on the image for a larger view.
We apply a rope tackle, (also known as the Trucker’s Hitch, Lineman’s Hitch, Load Binder, and Harvester Hitch) where the guylines meet the anchors for pretty much all our pioneering projects. For safety reasons, Taut-Line Hitches should never be used in any pioneering work, because if the tension is eased the knot can slip.
The rope tackle is one of the many skills learned for pioneering that can be used in a variety of situations for many years to come.
Securing a load of spars to a flatbed for transport.
Frequently, we use a rope tackle when creating a ridge line between two trees for dining flies and tarps, and love using them whenever there’s an appropriate need to hold the strain on a line being tightened.
Simple Rope Tackle for a Low Stress Application using Braided Nylon Cord.
Rope Tackle for Pioneering Use
The following drawings and text have been extracted directly from the 1993 publication of the Pioneering Merit Badge Pamphlet written by Adolph Peschke:
When you want to lift or pull more than your own strength will permit, or when you want to make a heavy lifting job a little easier, the rope tackle is a device that can be used.
The idea behind a rope tackle is similar to that of a tackle using blocks and pulleys. In a rope tackle, one lead (end) of the rope has to be fixed. That is, it has to be anchored around a spar or tied through a ring or other piece of hardware that doesn’t move.
Loop knot. Then a loop knot is tied along the standing part of the rope. The Butterfly Knot and the Bowline on a bight are suitable for making a loop knot because they can be tied in the standing part of the rope and they are both easy to tie and fairly easy to untie even after being put under a strain. If you have no other reason to become proficient in tying these two knots, the rope tackle should convince you.
Vertical display, as for lifting or pulling an object.
Connect with the load. After you’ve tied the loop knot, it forms a fixed loop that acts as the wheel in a block. If you’re using the rope tackle to lift or pull an object, pass the running end through a ring or other hardware that’s attached to the object (load). The ring (or other hardware) is used so that the rope is free to slide as you pull on the hauling end of the rope as the tackle takes effect. If you want to use the rope tackle to tighten a line, pass the running end around a fixed object such as a spar, a stake, or a tree.
Finally, the running end of the rope is passed through the fixed loop in the loop knot. The running end becomes the hauling line which is pulled to make the tackle work.
Principles. The rope tackle works on the same principles as any other tackle using mechanical blocks or pulleys. The rigging method shown on the left develops twice the lifting or pulling power that’s applied to the hauling end. In other words, you can lift a fifty-pound weight using only twenty-five pounds of force on the hauling end.
To determine how much force is needed to lift a weight, the general rule is that you count the number of ropes passing through the ring where the object (load) is. In this case there are two ropes passing through the ring that’s attached to the load. Then divide the number into the weight being lifted. Let’s assume that the weight being lifted is fifty pounds. The answer is twenty-five pounds, which is the amount of pull required to lift the fifty pounds with the rope tackle.
When you take into consideration the friction of the ropes rubbing together, you will have to apply a bit more than the twenty-five pounds to make the lift. But even with the loss caused by friction, the rope tackle is quite effective.
Sometimes it is better to actually experience the effect of how the rope tackle works than it is to understand the technical explanation of the process. Setting up a rope tackle will convince you.
Tying off the Rope Tackle & Maintaining the Tension on the Line
Tying off. When using a rope tackle, if you want to hold the position of a load being lifted or pulled, or if you want to hold the strain of a line being tightened, form a bight in the hauling end of the rope and tie it off with a tight Half Hitch below the fixed loop in the Butterfly Knot.
Types of rope. The type of rope you choose for a rope tackle should have a low stretch factor, such as pure manila rope. Ropes that stretch like polypropylene and nylon, even though they are strong, require that you pull the stretch out of the rope before your tackle takes effect.
Note: When in use, the rope tackle can put considerable strain on the fibers of the rope. Therefore, repeated use of the same section of the rope for this purpose should be avoided. The ropes used to make the tackle should be inspected for damaged fibers on a regular basis.
Uses of the rope tackle. The wide range of uses for a rope tackle by a number of different craftsmen speaks for its effectiveness. Each craft seems to use a slightly different knot or hitch to form the loop that makes a rope tackle. The Lorryman’s Hitch, the Lineman’s Hitch, the Stagehand’s Hitch, are all samples of different knots or hitches used to form the loop. The only difference between these hitches is that in some of them the type of knot used to make the loop is more easily untied than others after a hard pull. But they all do essentially the same thing. That is, they form a fixed loop for the rope to be used as a tackle.
The extent to which the rope tackle has been used by craftsmen and tradesmen in their daily work can be better understood from the following list of uses and by the various names by which it is called:
The Linesman’s Hitch is used to put strain on a line in the process of stringing electric or telephone lines. It was used as far back as the building of the telegraph lines that opened up the western states during the 1800s.
The Stagehand’s Hitch is used to adjust the height of the curtains on a theater stage.
The Wagoneer’s Hitch is an English reference to the hitch used to secure the load on a wagon or lorry.
The Load Binder is is what the farmer called the hitch he used to tie down a load of hay on his wagon.
Pulling a log. One of the uses of a rope tackle is to pull a heavy load such as a log. To do this, you need two ropes. Tie a short (6′ to 8′) length of rope to the end of the log with a Timber Hitch. Then tie a bowline at the other end of this rope.
Pulling a Log or Other Heavy Object
To pull the log, tie a long line to a tree or other anchor point with a Roundturn with Two Half Hitches. Then tie a Butterfly Knot in the long line to form the loop for a rope tackle. Run the end of the long line through the Bowline and back through the fixed loop in the Butterfly Knot. Then pull on the end of the long line to pull the log.
Pioneering Uses
To adjust the strain on the guylines of a pioneering project or a flagpole (see figures 98 and 99)
To put the strain on a picket line used for tying up horses or canoes
To tie down and secure your equipment on a trailer or truck (see figure 100)
To hoist or lower equipment in rock climbing
To tie a line to air your sleeping bag or to make a clothesline for wet clothes
To tighten hold-down ropes on large tents and flies
The following text is by Adolph E. Peschke as presented in the 1998 printing of the 1993 edition of the Pioneering Merit Badge Pamphlet:
Pioneering is the knowledge and skill of using simple materials to build structures that are used in a wide range of Scouting activities. These skills are sometimes referred to as “backwoods engineering.”
Down through the ages, people have used ropes, spars, and simple hardware to build bridges, towers, and even their own shelters. In the early development of our country, pioneering methods were used in mining and transportation, to clear the wilderness, and to build roads and bridges. So it is understandable that the term “backwoods engineering” was applied.
The same skills can be used by Scouts to build pioneering projects ranging in complexity from a simple camp gadget to a signal tower.
Whatever the project, the same applied principles of physics, geometry, and math are used to build pioneering projects and structures. But, keep in mind that all the information (in this pamphlet*) is eventually used for a practical, hands-on application—that is, to build something.
Pioneering is a good foundation for many Scouting activities. You must learn, and then use, such disciplines as planning ahead and teamwork. You can also put to use the basic skills learned in rank advancement, such as knot tying.
But most of all, pioneering provides a practical way to experience the joy of accomplishment when you’ve built something that is needed for yourself or others; it can be something that makes living in camp easier and more comfortable. Pioneering can be both fun and challenging when you use your skill and knowledge to choose the right materials (ropes and spars) and build a usable structure.
The basics of pioneering, such as tying knots, making lashings, using rope tackle, constructing anchors, and basic rope knowledge can be done at home. The projects and structures (shown in this pamphlet**) can usually be constructed with materials available at summer camp or at council camping events.
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.
STAKES
Pioneering Stakes
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.
MALLET
Wooden Mallets
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.
Buried Spar & Guyline Placement
SOIL CONDITIONS
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).
GUYLINE
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.
Angles for Guylines and Guyline Length
3-2-1 ANCHOR
Strong Anchor for Pioneering Projects
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.
LOG-AND-STAKE ANCHOR
Log-and-Stake Anchor
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.
STROPS
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).
Strops
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.
GROMMETS
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.
SCOUT PIONEERING 