Basic Rope Technique

[JMJones0424]

There are a few knots and techniques that everyone venturing out into the wilderness ought to know. I do not intend this thread to be a discussion of rappelling or rock climbing, rather techniques that any untrained individual can use while backpacking. This is a work in progress. I still have a few images I need to make or find, and some of my descriptions may be poor. If you have any questions, feedback, or if anything I have written is unclear, please respond and I will attempt to correct it.

 

Last Edit: 11 Dec 2010, changed link to image of bowline backed by an overhand; added links to quick release reef knot and reef knot backed by overhands. Minor editing for clarity and spelling. Added section on gloves under "Equipment" and a section on prusik loops under "Rigs".

 

Equipment

 

There are two types of kernmantle rope used for climbing and rappelling: dynamic and static. Dynamic rope has a give to it, and is usually used for rock climbing, as a fall will be less jarring and less likely to dislodge anchors. For our purposes, we are more interested in using a static line, or one that has little stretch to it. I carry 11mm static line. Rappelling line can be pricey, especially if you never intend to rappel with it, but are just carrying it for other purposes. If you look around at military surplus stores or sports stores, you should be able to find someone with static line that has been "retired" due to excessive use that you can purchase at a reduced price. Inspect the line to make sure there are no breaks in the external sheath, and no thin spots where the internal core is broken. The outer sheath will likely be "furry" with wear, but as long as there are no structural problems with the line and it isn't far beyond it's serviceable life (usually seven years), then there's no reason this line can't be used for our purposes. For general use, 150-200 feet in length is sufficient. You will need two lengths of static line of 12 to 15 feet per person to be used for hasty slings. We will also require a few prusik cords, made from line that is roughly 3/4 of the static line size. Typically, with 11 mm static line, you would use 8 mm prusik cords. Each cord should be about three to four feet in length. The ends of all line should be melted to prevent fraying. Static line is made from a load bearing core surrounded by a protective sheath. Try to avoid stepping on the line, as this will force dirt particles through the weave of the sheath into the core, where abrasion could damage the core. Keep the line as dry as possible when not in use. A frozen, wet line will drastically reduce the amount of friction available, reducing the effectiveness of our rigs. When you get back home, if the line is slightly dirty, you can soak it in the bathtub overnight, use a soft bristle brush to clean off bad spots, and air dry in the shade or away from UV light. If the line is incredibly dirty, you can daisy chain the line and run it through a few cycles in the washing machine on gentle with mild detergent. If you find your sling ropes too stiff to work with, you can run them through the gentle cycle in a washing machine with a small amount of fabric softener.

 

It is not imperative that you purchase a static kernmantle rope for backpacking through rough terrain (though I recommend it if possible). If you use an alternative, pay attention to the rope's load rating, abrasion resistance, and special handling requirements (such as UV and water exposure, etc.). To cut a length of rope, wrap tape around the location of the cut, cut the rope in the middle of the tape, and then melt the ends if synthetic, or whip the ends of natural fibers.

 

Carabiners are available in many different shapes and materials. I recommend carrying about five carabiners per person, at least three of which should be locking carabiners. I use steel carabiners out of habit, but if you are purchasing new ones, aluminum carabiners are easier to maintain (no rust) and are sufficiently strong for our purposes. Do not buy wire gate carabiners. Use only locking carabiners in any rig on which you trust your life. Non-locking carabiners are for gear only. The load bearing end of the carabiner is the end that does not contain the hinge for the gate. If you choose to purchase pulleys for the hauling rigs, make sure you buy one "prusik minding pulley". Its significance will be made clear further on down this thread.

 

Gloves come in handy any time you are working with ropes. Any glove with a durable palm and lower finger joints will do, leather is generally preferable. I usually wear weight lifter's gloves, the are elastic on the back of the hand for a tighter fit, the tips of the fingers are cut off to allow for better dexterity, but the palm and lower fingers are covered in leather for durability.

 

Knots

 

Click on the links for pictures or animations of the knots. This list is obviously not comprehensive. I have selected these knots to give the shortest number of easy to learn, effective, and safe knots. Again, this thread is not intended to be an instructional manual for rappelling or climbing. When I say free end, I mean the small section of rope left over after a knot is tied. Others may call this the pigtail, bitter end, or running end.

 

Anchoring: The bowline is the primary knot used to tie the end of a line to an object or an anchor point, or to form a loop at the end of the line. It can untie itself, so either an overhand knot or a yosemite tie-off is used to secure it.

 

Joining two ropes: A sheetbend, or for widely different diameters a double sheetbend, is the best way to join two ends of rope. The double fisherman's bend is a more permanent means of joining two ropes, but is difficult to get untied once a load has ben applied.

 

Middle of the line loop: The butterfly loop is easy to tie, untie, and can bear loads in any direction.

 

Slide and bind: The prusik knot binds when under load and slides when the load is released. This knot is used as a safety when going up or down slopes, as a "ratchet" when lifting loads, and as an adjustable anchor point for gaining mechanical advantage when winching a load. The free end(s) must be secured to ensure they don't pull through and the knot unties. Your prusik cord will usually be made into a loop with either a double fisherman's bend (permanent) or a quick-release square knot. If the prusik is not tied with a loop, the you must tie a bowline with the free end around the working end to make sure the knot remains stable. For more on prusik loops, see below under the section "Rigs".

 

Securing: The square knot (or reef knot) is used to tie around a bundle tightly. When backed by overhand knots, it holds relatively well and is still easy to untie. By feeding one free end back through it's loop, you can make a quick release that will allow you to untie the knot even when it is under tension. Doing this with both free ends makes a shoelace knot. This knot should never be used to join two lines, as the knot can fail when not under tension and can "spill" (meaning the knot shifts and fails) when a free end is pulled perpendicularly to the knot (when it isn't backed by overhands). A variation of the square knot is the surgeon's knot, used when you want to maintain better tension around the object(s) you are securing.

 

Misc: The overhand is used to secure the free ends of other knots. Any time an overhand is used to secure a knot, it should be tied snuggly against the knot. Some of the images online show the overhand away from the knot it is supposed to secure. This is done either for illustration purposes, or by mistake. The idea is to prevent slippage of the knot, so any distance between the knot and the securing overhand will allow slippage, and could allow the overhand to come undone. Also, the overhand knot is commonly misused for other applications, but should be avoided because it is very difficult to untie once a load has been applied.

 

Hasty harnesses

 

It is absolutely unnecessary to carry a single purpose climbing harness or a rappel seat if you plan on doing neither.

 

Swiss seat: Though it may seem daunting, the swiss seat is an easy to tie rappel seat that can be used to secure yourself to a line while going over steep terrain. The seat is very safe, and distributes the shock of a fall very well on your body, but it can be uncomfortable to wear for an extended period of time. Take some time to practice, and you should be able to tie it in a minute or less. Make sure to get the seat snug, and make sure to form a good "package" lest you catch some bits of your anatomy on the wrong end of the seat in a fall. There are a lot of incorrect examples of this seat on the web, I have located a step-by-step illustration, and a short

as examples.

 

Bowline on a coil:This harness is easier to move around in than a swiss seat, but if you take a long fall with this type of harness, it will hurt. The illustration I have linked to fails to make the required overhand knot to secure the bowline, so don't forget to add that. If you don't have enough rope to make three or more turns around your waist, you can get by with just one turn. This is known as an around the body bowline, and should be tied snuggly under the armpits rather than at the waist (to prevent abdominal damage in a fall). However, with only one turn, any stress from a long fall will be very concentrated on your body. If you lack the appropriate length to do a bowline on a coil, and require more than four or five feet of safety line, I suggest you bite the bullet and tie a swiss seat. A broken rib is far more of a hassle than the minor inconvenience of wearing a swiss seat.

 

Rigs

 

Prusik loops When climbing or rappelling, you would normally carry pre-tied prusik loops to expedite their use in an emergency. Because we are using these cords for a wider variety of purposes, I don't think it's imperative that you set out with the prusik loops pre-tied. I usually carry at least three prusik cords of three to four feet in length. I recommend using a quick-release reef knot to join the two ends of a cord if the loop is to be used as a ratcheting prusik. This will allow you to untie the loop even if it is caught up in a carabiner. Any other situation you may use either a double fisherman's bend for a permanent loop or a reef knot backed by two overhands for a loop that can be untied easily even after a load has been applied. When you tie a prusik around the line, make sure the quick release reef knot or fisherman's bend is located in the middle of the loop, roughly centered between the prusik and the end where the loop will attach to a carabiner or an anchor point. (More images to come.)

 

Uphill: The Z drag is the rig used to lift loads up a hill.

There are many variations you can use depending on the situation you are facing, but it basically boils down to gaining mechanical advantage by pulling through multiple carabiners instead of just tugging up a single line. Some key points to remember- the illustration has the person at the top of the hill by the anchor point. By switching the labels of the "object" and the "fixed object," you could just as easily be located at the load being pulled up the hill.

This is the z drag rig I would use to pull a heavy load uphill alone. One sling rope would be used to tie around a tree at the top of the hill. Make a few turns around the tree and secure with a reef knot secured by overhands, and hook in the two locking carabiners (through all the turns around the tree). Make sure the gates on the carabiners open in opposite directions, and that the load bearing end is facing downhill. Feed the line through both carabiners and head back down to the load carrying both ends of the line. Tie one end of the line to the load using a bowline, and hook a locking carabiner onto the load in another location. Take one prusik cord and tie a prusik on the line just above the carabiner on the load. Run one end of the free ends of the cord through the bowline that attaches the line to the load, or through another anchor point on the load, and finish the prusik loop with a quick-release reef knot leaving very little slack in the prusik loop. This will be the ratcheting prusik, and will ensure that the load does not fall downhill when you release line tension. It will slide freely as you lift the load, blocked by the carabiner, but will bind immediately once tension is relieved. The quick release is required to be able to remove the prusik cord if it becomes fouled up in the carabiner. Now tie another prusik loop further up the same side of the line that the ratcheting prusik was tied on. The loop can be finished with either a square knot backed by overhands, or by a double fisherman's bend. Attach two non-locking carabiners through this loop. Make sure the gates open in opposite directions, but the load bearing ends should both face the load. Run the running end of the line through these carabiners, and if necessary, attach your safety line to the load, or to the line between the two prusiks. Pull the running end until the two prusiks meet, release tension and move the non-ratcheting prussik further uphill. Rinse and repeat :)

Variations of this method may be used to accomplish many tasks, including tightening tent lines. For example, by replacing a prusik cord and carabiner with a butterfly loop:

 

Downhill: Going downhill is always more difficult to do safely then going uphill. Never use any rig to go down a slope you would not feel comfortable going down on your own (without equipment), unless you are comfortable with rappelling techniques. Normally you don't need to do anything special for lowering a load downhill. If you are able to stay uphill, you can use a tree as a friction brake to slowly lower a load downhill by varying the amount of line that is wrapped around the tree and slowly lowering the load down. However, let's assume that you are by yourself, and the terrain is too uneven to just lower the load down. In this case I would either tie one end of the line directly to the tree at the top of the hill using multiple turns and a bowline, or create an anchor point with a sling rope (turns around the tree secured by a reef knot backed by overhands and a locking carabiner hooked through all the turns) and tie a bowline in one end of the line that clips into the carabiner. Affix two carabiners side by side on the load to be lowered. Weave the line through the two carabiners to provide friction resistance to control the descent. You will need to test the resistance to ensure that it is enough to control the descent, but not so much that you are constantly fighting it. If needed, you can use a prusik cord to act as a safety in case you lose your footing, but it will be hard for one person to control the prusik, the load, and the line all at the same time. (Images to come)

[Turtle]

There are a few knots and techniques that everyone venturing out into the wilderness ought to know. I do not intend this thread to be a discussion of rappelling or rock climbing, rather techniques that any untrained individual can use while backpacking. This is a work in progress. I still have a few images I need to make or find, and some of my descriptions may be poor. If you have any questions, feedback, or if anything I have written is unclear, please respond and I will attempt to correct it.

...

Rigs

Uphill: The Z drag is the rig used to lift loads up a hill.

There are many variations you can use depending on the situation you are facing, but it basically boils down to gaining mechanical advantage by pulling through multiple carabiners instead of just tugging up a single line. Some key points to remember- the illustration has the person at the top of the hill by the anchor point. By switching the labels of the "object" and the "fixed object," you could just as easily be located at the load being pulled up the hill.

This is the z drag rig I would use to pull a heavy load uphill alone.

...

 

very cool!! :thumbs_up i didn't know the prusik knot, but i think i could tie it now & will have no doubt i will own it with a couple days practice. muchas gracias.

 

so some questions. because of your use of prusiks, i am having trouble calculating the mechanical advantage/velocity ratio of the illustrated rigs. :confused: is it 2 in both, or is the second 3?

 

i think pulling down is always a better posture to get the most of human effort, so i would add a fixed pulley/carabiner to get a change of direction if necessary to pull down, even though there is no additional mechanical advantage. oui/no?

 

one last bit then. if you have the option, why not carry some pulleys to use instead of carabiners inasmuch as your effort is increased for the same system if you have to overcome the added friction of the rope through a carabiner? that is to say in an ideal system the mechanical advantage and velocity ratio would be equal, but there is friction even in pulleys making the mechanical advantage always less than the velocity ratio & the amount less, dependent on the friction in the system. or so i have read.

 

my reading was originally hardcopy and specifically stated the relationship of mechanical advantage to velocity ratio i just described, but what i found for links on each subject are discrete descriptions that don't mention the other measure. :shrug: well, here's that quick search bounty.

 

 

wiki mechanical advantage of pulleys

 

Grandpa Pencil learns about The Velocity Ratio of Simple Pulleys

 

good stuffs mr jones that a peep can get a bite on! (knot that joke again! :doh:) :lol:

[JMJones0424]

After looking at the wikipedia article on mechanical advantage, I would say at first glance that the first rig has a mechanical advantage of two and the second three. I don't know how correct this is though. From experience, I can tell you the second rig (with three "pulleys") is much easier to get tension on than the first rig (with two "pulleys"). Perhaps the fact that the last pulley on the second rig is "floating" has something to do with it? I don't know if that makes a difference or not. Whatever the figures are after everything is taken into account, I would recommend doubling or tripling the line if you need to use more pulleys than used in the second rig. Prusiks work just as well around doubled static line as they do a single strand. Because we aren't using proper block and tackle, there are areas where an extreme amount of tension is placed on the line. I have broken a single strand of 11mm static line using a four pulley z drag.

 

On carrying actual pulleys, the short answer is that I don't own any. They really don't make a whole lot of difference compared to pulling through two carabiners, though obviously they are needed in order to maximize the work available from your effort. I try to stay away from single-purpose gear as much as possible, unless it is absolutely necessary. However, if I am planning to go though rugged terrain where I know I will be using a z drag or other rig frequently, I would bring some ascenders that would replace the prusik loops in the rig. Ascenders are easier and quicker to use, but they are single-purpose and they are rough on the line.

 

Certainly, you may use additional anchor points to re-route the line as needed, either at the pulling point or along the line. If possible though, try to rig the lift in a way that this isn't necessary.

[Turtle]

After looking at the wikipedia article on mechanical advantage, I would say at first glance that the first rig has a mechanical advantage of two and the second three. I don't know how correct this is though. From experience, I can tell you the second rig (with three "pulleys") is much easier to get tension on than the first rig (with two "pulleys"). Perhaps the fact that the last pulley on the second rig is "floating" has something to do with it? I don't know if that makes a difference or not.

 

the "floating pulleys" are the key i think; my book calls them "moving pulleys". as i read it, the number of ropes supporting the load is the velcoity ratio, and you get more ropes supporting the load by adding moving pulleys. the mechanical advantage then is the same value as the velocity ratio minus the losses to friction. unless you have at least 2 moving pulleys, i don't think you can get a mechanical advantage over 2. :confused: better check me on that though. :hihi:

 

 

... Whatever the figures are after everything is taken into account, I would recommend doubling or tripling the line if you need to use more pulleys than used in the second rig.

 

i don't think the number of pulleys has anything to do with increasing the load on the line; quite the opposite in fact for much of the rope.

 

Prusiks work just as well around doubled static line as they do a single strand. Because we aren't using proper block and tackle, there are areas where an extreme amount of tension is placed on the line. I have broken a single strand of 11mm static line using a four pulley z drag.

 

well, if the prusiks are just there to keep the load from slipping back, then i'd use pulleys and only one prusik right where i am pulling. i would slide it up after each pull, and then if i lost the line from my hands, the prusik would jam in the first pulley it met and stop the load. oui/no?

 

On carrying actual pulleys, the short answer is that I don't own any. They really don't make a whole lot of difference compared to pulling through two carabiners, though obviously they are needed in order to maximize the work available from your effort. I try to stay away from single-purpose gear as much as possible, unless it is absolutely necessary. However, if I am planning to go though rugged terrain where I know I will be using a z drag or other rig frequently, I would bring some ascenders that would replace the prusik loops in the rig. Ascenders are easier and quicker to use, but they are single-purpose and they are rough on the line.

 

well, let's not pretend too much that we don't know what load i plan to haul by line :wink:, and as i don't have carabiners yet, i have every inclination to buy some pulleys too.

 

Certainly, you may use additional anchor points to re-route the line as needed, either at the pulling point or along the line. If possible though, try to rig the lift in a way that this isn't necessary.

 

roger that. other than getting a change of direction so i can pull down, i agree.

 

so on ropes, what advantage -if any- would there be in buying climbing lines vs. similar strength marine anchor line? what i actually have is about 600 feet of scavenged braided nylon strap used to pull power lines through underground conduits. it's rated @2500 pounds, but it's lubricated - with silicone i think?- and it doesn't exactly tie like round cord. not sure how it would work in a pulley yet. tows cars real good though. :steering: well, it was free, but if i ever get to a point to buy new hauling rope i want to get it right.

 

guess that's it for now. thnx!

[Turtle]

Uphill: The Z drag is the rig used to lift loads up a hill.

 

here is how i would rig for a solo uphill haul with a mechanical advantage of ~2. not sure now if the prusik is the best sliding knot to jam the pulley; what do you think? ( ) . . .

 

[JMJones0424]

The ratcheting prusik prevents the line from sliding back after tension is released, and shouldn't require any action from you during the lift, unless it gets pulled through the pulley. If you plan to purchase pulleys, buy a "prusik minding pulley" to prevent this. I think you are imagining the ratcheting prusik on the wrong side of the carabiner/pulley. (You illustrated it on the wrong side as well) The other prusiks in my diagrams are used to anchor a pulley or carabiner in the middle of the line rather than having to retrace all the way back to the anchor point. The advantage of this is less trips back and forth, and less rope length needed. In my second drawing, not only is the bottom pulley moving, but one of the top pulleys is moving too. If I needed even more advantage, I would add another moving pulley on the line between the pulley on the load and the moving pulley. This calls for another diagram I think.

The problem with this is that the line connected at the anchor takes more and more strain, and can be easily overloaded if pulling a heavy load with many z's in the rig.

 

Kernmantle ropes are used in climbing and rappelling because the rope is built so that the part of the rope that undergoes friction is seperate from the part of the rope that provides strength. Standard ropes used in friction rigs will slowly lose strength over time as the individual fibers are worn through, while a kernmantle rope retains all structural strength even if the outside sheath is quite worn. I have never used a rope that had been sprayed with a lubricant in friction rigs. I don't know how well a prusik will grip to the rope you have, that's something you'll have to test. Also, your line if rated at 2500 pounds is about one third the strength of the line I carry. I suspect that when comparing equivalent load ratings, kernmantle rope is smaller in diameter and lighter, and easier to tie (this is based off of my limited exposure to different types of rope, and may be incorrect).

 

Your diagram looks good other than the fact that you have your ratcheting prusik on the wrong side of the carabiner. As drawn, the prussik will bind when you pull and slide when you release. I really should have made my own diagram rather than cheating and using the wikipedia drawing for the z drag rig with mechanical advantage of 2. Your design is better than theirs because your ratcheting prusik cord would only be supporting half of the weight of the load, while their's has to support the entire load. Once you place the ratcheting prussik on the correct side, your drawing is precisely the way I would recommend doing it if the one who pulls the line is located at the top of the hill. If you were alone and needed to be by the load, then I would recommend my diagram with mechanical advantage of three. This way, you can locate the ratcheting prusik where you are- at the load, while still using about the same amount of line, and would gain some mechanical advantage as well (at the price of having to reset the floating carabiner periodically).

 

The prusik is always a safe binding knot to use. The bachmann when used correctly is safe, but it requires another carabiner, and provides a tempting handle to pull by inexperienced people in a fall that releases the friction. The klemheist is actually easier to tie and untie than a prusik, but it only works in one direction. These are the only friction knots I know, there are probably others. I chose to illustrate the prusik because it binds in both directions, can not be accidently released, and can be used in any situation. I actually use the klemheist rather than the prusik in a most situations outside of rappelling. Bottom line is just to make sure that you know the proper application and use of any knot you use.

 

I am afraid I am making this rig seem more difficult than it is. I recommend you just go out and try a few different rigs in the back yard and see what works. It becomes second nature quite quickly. The last thing I want to do is make any of this seem overwhelming.

[Turtle]

The ratcheting prusik prevents the line from sliding back after tension is released, and shouldn't require any action from you during the lift, unless it gets pulled through the pulley. If you plan to purchase pulleys, buy a "prusik minding pulley" to prevent this. I think you are imagining the ratcheting prusik on the wrong side of the carabiner/pulley. (You illustrated it on the wrong side as well)

 

well, i think i have it illustrated correctly. i am pulling down on the line & if i let go the prusik would rush up & jam into the pulley and lock the line. now if the prusik won't lock, then i have the wrong knot, but it is still on the right side for jamming into the pulley to lock the line.

 

The other prusiks in my diagrams are used to anchor a pulley or carabiner in the middle of the line rather than having to retrace all the way back to the anchor point. The advantage of this is less trips back and forth, and less rope length needed. In my second drawing, not only is the bottom pulley moving, but one of the top pulleys is moving too. If I needed even more advantage, I would add another moving pulley on the line between the pulley on the load and the moving pulley. This calls for another diagram I think.

The problem with this is that the line connected at the anchor takes more and more strain, and can be easily overloaded if pulling a heavy load with many z's in the rig.

 

i am very confused by the drawings & i think i need some time to get out some ropes and try some of this. i am particulary confused about how you can apply more stress on the line than the load. for my illustrated rig the stress on each line is never more than 1/2 the load.

 

Your diagram looks good other than the fact that you have your ratcheting prusik on the wrong side of the carabiner.

...

I am afraid I am making this rig seem more difficult than it is. I recommend you just go out and try a few different rigs in the back yard and see what works. It becomes second nature quite quickly. The last thing I want to do is make any of this seem overwhelming.

 

as i say above, the prusik may not be the correct knot for what i want to happen. while you substituted "carabiner" for "pulley", i think they are very different systems in their mechanical advantage, even if they have the same velocity ratio. your rigs seem more complex -more parts- than using pulleys & the main advantage i see is if you don't have any pulleys. well, it's raining like hell here so i'm going to pass on the outdoor practice, but i'm going to get my rope sack & bring it in to get started.

 

one quick question: on the prusik, where do you apply the load in the loop? directly on the fishermans bend, or up against one end of it?

[JMJones0424]

well, i think i have it illustrated correctly. i am pulling down on the line & if i let go the prusik would rush up & jam into the pulley and lock the line. now if the prusik won't lock, then i have the wrong knot, but it is still on the right side for jamming into the pulley to lock the line.

 

The way you have it illustrated, the prusik is on the incorrect side. Imagine the prusik as being a fist. As the line is pulled through, and the prusik loop is relaxed, the line moves freely. Pull the line in the opposite directin, the prusik loop becomes taunt and the prusik knot tightens like a fist around the line. I suggest you practice the knots and see how they react. You are not envisioning the prusik knot correctly right now. It is not supposed to block the line from going through the pulley, rather it holds onto the line as it pulls back through the pulley.

 

I apologize, but I have to go now. I will post a better reply later tonight or tomorrow.

[JMJones0424]

First things first, lets clarify the prusik placement. I have drawn a few (poor) pictures to try to illustrate that I can upload using the scanner at work tomorrow, but I think I may have found a picture online that serves our purposes.

From: http://www.brrr.ws/docs/Boat_Rescue_Haul_Systems.htm

 

This is an illustration of the proper use of a prusik minding pulley, showing the correct use of a prusik. Never mind that they have tied their prusik a bit differently, this image just shows how the prusik slides when you pull and binds when you let go. It is not supposed to be on the side you pull, but instead on the side that feeds into the carabiner/pulley. If you don't use a prusik minding pulley, and instead use a carabiner, there is a chance that the prusik could pull through the carabiner if you pull too far out perpendicularly from the carabiner. This is why I recommend using a quick-release square knot to complete the prusik loop rather than a double fisherman's bend. I will either find a clear image of this knot tomorrow or scan in a drawing.

 

In all of my illustrations, pulleys and carabiners are interchangeable. Pulleys are of course more efficient, but two carabiners comes close to the same efficiency of most pulleys.

 

As far as mechanical advantage goes, I think I have been incorrect. According to the wikipedia entry on the z drag that I posted, it has a mechanical advantage of 3:1 (assuming zero friction). The second z drag that I posted (and assumed was 3:1) would actually be 6:1. From the same site as the prusik minding pulley image:

 

I have no way of knowing if those figures are accurate, except that I think it is more correct to say the second rig I posted is roughly twice as efficient as the first rather than 50% more efficient. This means the rig I assumed was 5:1 might actually be 12:1. I honestly don't know, I'll have to let you do the math if you wish, or I can break out my ropes on my next day off and do some measuring. I hope these diagrams are a little easier to understand than mine. The second rig I posted originally on 7 Dec that I said I would use to pull up a load by myself corresponds to rig "E" in the image above.

[Turtle]

First things first, lets clarify the prusik placement. I have drawn a few (poor) pictures to try to illustrate that I can upload using the scanner at work tomorrow, but I think I may have found a picture online that serves our purposes.

From: http://www.brrr.ws/docs/Boat_Rescue_Haul_Systems.htm

 

This is an illustration of the proper use of a prusik minding pulley, showing the correct use of a prusik. Never mind that they have tied their prusik a bit differently, this image just shows how the prusik slides when you pull and binds when you let go. It is not supposed to be on the side you pull, but instead on the side that feeds into the carabiner/pulley. If you don't use a prusik minding pulley, and instead use a carabiner, there is a chance that the prusik could pull through the carabiner if you pull too far out perpendicularly from the carabiner. This is why I recommend using a quick-release square knot to complete the prusik loop rather than a double fisherman's bend. I will either find a clear image of this knot tomorrow or scan in a drawing.

 

i see it now! danke! maybe they have the fisherman's bend on top of the prusik to avoid the bit i earlier asked about, i.e. whether the connection to the loop bears on the bend or up against one end of it. as they have it, the bend is out of the loop (:doh:) and the carabiner attachment to the loop is bearing on the single strand of the loop. hope that made sense.

 

 

In all of my illustrations, pulleys and carabiners are interchangeable. Pulleys are of course more efficient, but two carabiners comes close to the same efficiency of most pulleys.

 

As far as mechanical advantage goes, I think I have been incorrect. According to the wikipedia entry on the z drag that I posted, it has a mechanical advantage of 3:1 (assuming zero friction). The second z drag that I posted (and assumed was 3:1) would actually be 6:1. From the same site as the prusik minding pulley image:

 

I have no way of knowing if those figures are accurate, except that I think it is more correct to say the second rig I posted is roughly twice as efficient as the first rather than 50% more efficient. This means the rig I assumed was 5:1 might actually be 12:1. I honestly don't know, I'll have to let you do the math if you wish, or I can break out my ropes on my next day off and do some measuring. I hope these diagrams are a little easier to understand than mine. The second rig I posted originally on 7 Dec that I said I would use to pull up a load by myself corresponds to rig "E" in the image above.

 

i honestly don't know either. :confused: i'm going on a brief article in a an introductory text on rudimentary machines. they say to count the number of ropes supporting the load to get the velocity ratio/mechanical advantage & by that i don't get such high MA's for those rigs.

 

:weather_rain: rained 1.3" here in the last 18 hours & more coming. i'll be practicing some of these knots indoors today, but i guess if i were really a hard nut i should get out & see how wet rope works in these rigs. :omg: (never mind that i have neither pulleys nor carabiners. ):lol:

 

thnx 4 the new info & i'll get back 2 u soon. . . . . .

[Turtle]

... It [prusik knot] is not supposed to be on the side you pull, but instead on the side that feeds into the carabiner/pulley. If you don't use a prusik minding pulley, and instead use a carabiner, there is a chance that the prusik could pull through the carabiner if you pull too far out perpendicularly from the carabiner. This is why I recommend using a quick-release square knot to complete the prusik loop rather than a double fisherman's bend. I will either find a clear image of this knot tomorrow or scan in a drawing.

 

okaly dokaly neighbor! :lol: so i cut 4 feet of 9mm cheepo cord that i had in my sack. this is utility stuff, not something i use for hauling, but it works ok for practice on your knot. the core is made of compressed plastic strands with no braiding or twisting & the sheath is snaggy braided plastic thread of some kind. they both will melt, but not at the same time so i both melted & whipped the ends. i think i have the quick-release square knot right...erhm...correct, but i took shots of both sides for clarity.

 

prusik knot with quick-release square knot loop

9mm cord

 

 

 

my strapping is imprinted so i looked it up. it's called Multetape© & not recommended for lifting loads. here's the particulars.

 

product description:Muletape

tying instructions:Muletape Knotting

 

summed up:

WARNING MULETAPE®: For cable installation only. Do not strap, bind or lift items with this product

 

scratch that idea. :doh:

[JMJones0424]

:thumbs_up Looks good! Not quite perfect, but it's my fault for not finishing the relevant sections yet.

 

The prusik is tied correctly, but the quick release should be about half way down the loop, not at the end of the loop where it would hook into a carabiner. Also, the quick release reef knot should have an overhand backing up one side and a half hitch on the loop side to prevent accidental "quick releasing". I have now uploaded and linked to these images in the original post, but I will try to explain them here in case they aren't obvious.

 

Reef knot backed by overhands:

 

This reef knot was tied using the mnemonic "Right over left, left over right." If you look at the left side of the reef knot, the "bar" passes over the standing line, while on the right it passes under. When you tie the overhand to back up the reef knot, you need to make sure you use the same orientation. On the left side of the knot, where the "bar" is over the standing end, bring the free end over the standing end, down and behind, and then make the turn to complete the overhand. Notice at the bottom of the image, the overhand was tied incorrectly resulting in an overhand that does not snug up against the reef knot. On the right hand side, since the "bar" is underneath the stnading end, you tie the overhand starting with the loop behind the standing end.

 

 

Of course, we are making a quick release, so the right hand side doesn't get an overhand. You correctly placed the loop, but as you picture it, the loop may accidentally pull through releasing the reef knot.

 

 

Step one illustrates the reef knot tied with the overhand backing up the left side already. The right hand free end is looped back and fed through the hole in the middle of the reef knot. Then in step two you bring the free end back around and run it through the loop created in step one. Pull the end so that the loop snugs down on the free end, but don't tighten it. If you need to release the reef knot, even if it is under great strain, all you will have to do is pull the free end out of the loop (taking you back to step two), and then yank on the free end to pull the loop through the reef knot. You should be left with an overhand on a bight sliding freely over the other end of the prusik loop.

 

I hope this makes sense :)

 

As you noticed, the prusik in the image of the prusik minding pulley was tied so that the double fisherman's bend was the locking bar in the knot. This is not the way I was taught to tie a prusik, and I have never seen anyone else do it that way either. It may or may not be safe that way. I don't like the fact that all that bulk (and potentially loose cord) is used to make the bar of the prusik though. I tie my prusik loops so that the knot that completes the loop is half way between the prusik and the carabiner or anchor point.

 

I am glad to see that you are picking up the techniques so far, I am used to teaching by showing, not by typing, so this is difficult for me.

[Turtle]

:thumbs_up Looks good! Not quite perfect, but it's my fault for not finishing the relevant sections yet.

 

The prusik is tied correctly, but the quick release should be about half way down the loop, not at the end of the loop where it would hook into a carabiner. Also, the quick release reef knot should have an overhand backing up one side and a half hitch on the loop side to prevent accidental "quick releasing". I have now uploaded and linked to these images in the original post, but I will try to explain them here in case they aren't obvious.

 

snip...

 

As you noticed, the prusik in the image of the prusik minding pulley was tied so that the double fisherman's bend was the locking bar in the knot. This is not the way I was taught to tie a prusik, and I have never seen anyone else do it that way either. It may or may not be safe that way. I don't like the fact that all that bulk (and potentially loose cord) is used to make the bar of the prusik though. I tie my prusik loops so that the knot that completes the loop is half way between the prusik and the carabiner or anchor point.

 

I am glad to see that you are picking up the techniques so far, I am used to teaching by showing, not by typing, so this is difficult for me.

 

i will study the snipped part & work out the bugs with some more practice. :D i did wonder about the reef position and slid it around to about where you say after i took the photos. i did notice the fisherman's bend position in the illustration as well & wondered about it too. :shrug: looks nice though. :doh: i did start out the prusik by trying to do a triple fisherman's bend but got lost and none of my material has it illustrated, i don't remember it, & i was away from the pc. will print a pic & work that one out too.

 

thnx 4 your patience. :thumbs_up some of this i remember from boy scouts -like the whipping- but some is new & some i have to re-learn. what's knot to love about this stuff!? i may have to ask santa for a carabiner or two now. :xmas_santahat_happy :xmas_gift:

[Turtle]

okaly dokaly. i put the 'release' end back through its loop and took another photo of the quick-release-reef knot with the prusik knot. i have some questions now & i have added some orientation notes to the image to that end. (:doh:) :lol:

 

1) my loop is ~ 6"; is this big enough? is there an ideal loop length?

 

2) is there a preference for whether the quick release end -when out of the loop & ready to pull- is to the rope side (left in the photo) or to the outside (right & as tied on the photo)?

 

3) is there a preference whether the reef knot is on the up side, as pictured, or on the down side of the loop?

 

4) do some of those orientations change when you start actually using the rig with a load?

 

on another note, i found it intereesting that the one set of drawings you posted had as the load a large stone in a creek. i can see where that might be rough on a moving pulley attached to the load, both for rust and also getting grime in the bearings/bushing if they are not sealed. :cry: prolly would want to position a pulley up out of water using a long sling lead from the load.

 

hauling boulders out of streams i have done in prospecting/mining, but i used a single rope & a come-along or a light block & tackle made for stretching wire fence. it was the case when i was doing this -and still may be- that as long as you didn't use any power equipment, you didn't need to file an environmental impact statement or file with the fisheries for your claim. for lifting boulders & buckets of cobles out of holes i built a big lever. i never tried the lever in the stream,-too little gold & platinum to merit the work- but the cross bar bearing the arm stood about 5 feet tall & the arm about 20 feet long. worked pretty good on land though. lashed with sisal rope ( ), i could take it apart & lay it down when i was away. thought i better throw in a knot technique there so the story would hang with the topic; i have never forgotten how to tie a clove hitch. :hihi:

 

anyway, that's a wrap.

[JMJones0424]

1) Size of prusik loop: A six inch prusik loop is ideal for the uses illustrated so far: ratcheting prusik (smaller loop equals less slide back) and anchor points on the line for mechanical advantage (smaller loop equals more line to pull before having to reset prusik). If you use a prusik loop as a safety line, you would either need to clip in your line to the six inch loop, or use a much larger loop. In this case you would want the loop + line to be long enough for you to move around, but not so long that you would be injured in a fall. When using the prusik as a safety line, you have to hold the prusik to move it up and down the standing line, and when you release the prusik and fall, it binds preventing you from falling further than the length of the loop + safety line.

 

2) Direction of pull for quick release: There is no specific preference. However, as you remarked that it is usually easier to pull down hill, it is also easier to pull the quick release towards you rather than away, which usually means downhill as well.

 

3) Reef knot location on the loop: No difference which side of the loop the reef knot is on.

 

4) Do some of those orientations change when you start actually using the rig with a load? Not usually. When using a prusik on a self belay you may end up getting the loop wrapping around the line when falling on a rappel, but with a z rig everything should stay in place pretty easily.

 

Note: Your picture of the quick release is almost right, but it looks like you are missing the overhand backing knot on the opposite side of the quick release loop. To be more safe, your quick release reef should look like step three on the second illustration in post 12. Also, in the set of drawings you referenced, they are not pulling a rock ashore, they are trying to unpin a canoe. What looks like a rock is actually a canoe seen from the bow or stern with the current pinning it to a rock.

 

Continuing to reference that illustration: (the second one in post 9)

I have verified that the reported mechanical advantage ratios are correct (assuming zero friction). That picture illustrates the benefit of a z rig over standard block and tackle. You gain vastly increased mechanical advantage using far less line and pulleys than with standard block and tackle rigs, at the cost of having to periodically reset the rig. I think the following is correct, but I haven't found any confirmation online, probably because I don't know the correct terminology. A block and tackle rig has two types of pulleys: fixed (at the anchor) and moving (at the load). A z rig adds a third type of pulley (which I have called "floating"). These are the pulleys that are fixed to parts of the line that move. In block and tackle, adding a moving pulley to the load adds 2 to the mechanical advantage, adding a pulley to the anchor just redirects the pull direction. In a z rig, adding a "floating" pulley multiplies the mechanical advantage. Figure D is figure C multiplied by figure B, or 3x2=6. I have seen this rig called a "pig rig", and is a way to use two seperate lines in extremely long pulls. Figure E is figure B multiplied by figure C, or 2x3=6. Figure F is figure C multiplied by figure C, or 3x3=9.

[Turtle]

...clip...

 

Note: Your picture of the quick release is almost right, but it looks like you are missing the overhand backing knot on the opposite side of the quick release loop. To be more safe, your quick release reef should look like step three on the second illustration in post 12. Also, in the set of drawings you referenced, they are not pulling a rock ashore, they are trying to unpin a canoe. What looks like a rock is actually a canoe seen from the bow or stern with the current pinning it to a rock.

 

Continuing to reference that illustration: (the second one in post 9)

I have verified that the reported mechanical advantage ratios are correct (assuming zero friction). That picture illustrates the benefit of a z rig over standard block and tackle. You gain vastly increased mechanical advantage using far less line and pulleys than with standard block and tackle rigs, at the cost of having to periodically reset the rig. I think the following is correct, but I haven't found any confirmation online, probably because I don't know the correct terminology. A block and tackle rig has two types of pulleys: fixed (at the anchor) and moving (at the load). A z rig adds a third type of pulley (which I have called "floating"). These are the pulleys that are fixed to parts of the line that move. In block and tackle, adding a moving pulley to the load adds 2 to the mechanical advantage, adding a pulley to the anchor just redirects the pull direction. In a z rig, adding a "floating" pulley multiplies the mechanical advantage. Figure D is figure C multiplied by figure B, or 3x2=6. I have seen this rig called a "pig rig", and is a way to use two seperate lines in extremely long pulls. Figure E is figure B multiplied by figure C, or 2x3=6. Figure F is figure C multiplied by figure C, or 3x3=9.

 

ahhh...pinned canoe. that's a shame. :doh:

 

roger the missing overhand; just wanted to get the other stuff clear before i added that complication.

 

fascinating!!! thnx & i can't wait to try some of this out back. :thumbs_up

[Turtle]

just some questions while we wait for me to slowly race off to make a couple more prusik loops. i don't have any carabiners, but i have some big snap swivels that ought to work ok for practice when i get there. . . . .

 

you mentioned that in the past you broke some lines and i was wondering about the particulars of those failures. for example, what were the weight & conditions of the load, which rig did you use, what was the strength of line, and where did the break occur on the line(s).

 

it seems to me that besides the added friction of carabiners vs. pulleys, the sharp bends of the rope in carabiners is bound to reduce the strength of the line more than the line bends around a pulley. while i can find plenty on the amounts that different knots & splices reduce a line's strength, i can't find anything on the diameter of a bend in a rope affecting tensile strength. is it possible that all the knots & sharp bends in your breaking rig contributed to the failure?

 

whip it! whip it good!!