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Ua Rigging Chapter 2 knots and hitches
- 1. Premium PowerPoint® Presentation © 2015 by American Technical Publishers All rights reserved Chapter 2 Knots and Hitches
- 2. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches Objectives 1. Explain how knots affect the strength of a rope. 2. Identify the parts of a rope. 3. List the types of knots and hitches used for rigging operations.
- 3. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches Three Parts of a Rope
- 4. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches Basic Elements of Knots
- 5. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Overhand Knot
- 6. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Figure Eight Knot
- 7. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Half Hitch
- 8. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Double Half Hitch
- 9. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Square Knot
- 10. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Granny Knot
- 11. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Thief Knot
- 12. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Pipe Hitch
- 13. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Clove Hitch
- 14. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Single Sheet Bend
- 15. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Double Sheet Bend
- 16. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Bowline Knot
- 17. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Running Bowline
- 18. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches Double Bowline on a Bight
- 19. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Catspaw Knot
- 20. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Snubbing Hitch
- 21. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches Snubbing Hitch with Double Half Hitch
- 22. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches Barrel Hitches
- 23. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches Four-Step Method to Form a Vertical Barrel Hitch Sling
- 24. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Sling Angle Determines the Sling Load
- 25. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Timber Hitch
- 26. © 2015 by American Technical Publishers All rights reserved Chapter 2 — Knots and Hitches The Becket Hitch
Editor's Notes
- When tying knots and hitches, a rope has three parts. See Figure 2-1. 1. The running end is the end of the rope that is used to tie a knot. 2. The standing part is the part of a rope that is not used in tying a knot; the long unused part that is worked upon. 3. The bight is formed by simply bending the rope and keeping the sides parallel. A “bight” is also the working part of a rope.
- Along with the three basic parts, several elements of knots can be made. See Figure 2-2.
- The overhand knot is the simplest and smallest of all knot types and the beginning of many more difficult ones. See Figure 2-3. In general, it is used only on small cord and twine, since it jams and is hard to untie, often injuring the fiber. To tie the overhand knot, make an overhand loop; pass the running end under and up through the loop and draw up tight.
- The figure eight knot is much easier to untie than the overhand knot; it is larger and stronger, and does not injure the rope fibers. See Figure 2-4. It is the best knot to use to keep the end of a rope or fall from running out of a tackle or pulley. To tie a figure eight knot, make an underhand loop. Bring the running end around and over the standing part. Pass the end under, and then up through the loop. Draw up tight.
- The half hitch is a basic knot type and is generally used for fastening to an object for a right-angle pull. See Figure 2-5. To tie a half hitch, pass the end of the rope around the object and tie an overhand knot to the standing part. A half hitch is tied with the end nipped under the turn of the rope some distance away from the standing part. This method is satisfactory for temporary use if the pull is steady and the arrangement is not disturbed. The half hitch is primarily used to finish off other knots and should not be used by itself for lifting.
- The double half hitch is used for attaching the end of a rope to some object. See Figure 2-6. It can be made easily and quickly, and is easily untied.
- The square or reef knot is used for tying together two dry ropes of the same size, and for tying the two ends of a rope together when it is used for backlashing. See Figure 2-7. In addition, the loose ends can be half-hitched for increased security. A properly tied square knot will not slip if the rope is dry and will develop 50 percent of the strength of the rope.
- When tying a square knot, the standing part and the running end of each rope must pass through the bight of the other rope in the same direction; otherwise, the unsafe granny knot is formed. See Figure 2-8. A granny knot can easily slip or jam.
- If Method 1 of tying a square knot is used, the standing part of both ropes must cross; otherwise, a thief knot is formed. This knot, like the granny knot, will slip, due to the diagonal forces that are applied under strain. See Figure 2-9.
- The pipe hitch is the fastening that should be used whenever hoisting pipe or tubing using straight rope instead of a rope sling. Although one of the simplest to tie, it is a secure knot to use because it prevents slippage and continues to tighten under strain. To tie a pipe hitch, start by placing the running end over the pipe and make three (3) round turns; keep the turns close together. Then bring the running end to the standing part and tie a double half hitch, snugging the half hitches as they are tied. See Figure 2-10.
- The clove hitch is used for attaching the end of a rope to an object for a right-angle pull, as in the case of guy lines. It is also used in making other knots. The clove hitch should not be used to hoist pipe because it is a fixed knot that will not tighten up under strain; therefore, it can allow the load to slip. This is one of the most misused knots in rigging. There are two methods of making a clove hitch. See Figure 2-11. Method 1 is used if the hitch can be formed and then passed over the object. Method 2 is used if the hitch cannot be passed over the object.
- The single sheet bend is limited in its use for tying together two dry ropes of unequal size or for tying a rope to an eye. It must be used for light loads only, because it will slip when the ropes are slackened. See Figure 2-12.
- The double sheet bend is better than a single sheet bend, and is used for joining wet ropes, or for tying a rope to an eye. It will not slip or draw tight under heavy loads. To tie a double sheet bend, first tie a single sheet bend, but do not pull it tight. Then take another turn around the knot and finish as with a single sheet bend. See Figure 2-13.
- The bowline knot is used for forming a loop that will not slip under strain. It can be easily untied. See Figure 2-14.
- The running bowline is used to make a running loop, sling, or noose that can be easily untied. See Figure 2-15.
- The bowline on a bight is used to form a loop at any point in the rope between its ends. It is easily untied and does not slip under strain. See Figure 2-16.
- The catspaw knot is used to attach a hook such as a tackle block at any point on a rope between its ends. It does not slip under strain, and comes undone when removed from the hook when the rope is relaxed. See Figure 2-17.
- The snubbing hitch is used to hold a load or to lower a heavy load slowly. To lower the load attached to the upper line, the rope is slacked off by decreasing the tension. If the rope starts paying out too rapidly, another turn is taken around the anchor. Caution: In slacking off a snubbed rope, both hands should be used and the rope should be fed back using a hand-over-hand motion. See Figure 2-18.
- When it is desired to hold a load at a given point, the snubbed rope should be secured with two half hitches. See Figure 2-19.
- The barrel hitches are used to form slings for lifting and handling barrels or drums or other large cylindrical objects. A bowline is used for fastening the ropes in the horizontal sling as well as the vertical sling. The total length of rope needed for making a barrel hitch equals two barrel lengths, plus one circumference, plus four diameters. An alternate formula would be to use eight barrel diameters plus two barrel lengths. See Figure 2-20.
- Tying a vertical barrel hitch sling involves a four-step method. See Figure 2-21. Step 1 — Diagram A. Place the running end of the rope under the centerline of the barrel as shown at Position 1 (use the formula mentioned earlier to calculate the length of rope needed for a particular size barrel hitch sling). Then raise the running end vertically until it is parallel with the standing part of the rope, as shown at Position 2. Step 2 — Diagram B. Using the running end, tie an overhand knot and draw it down to the top center of the barrel. Loosen the knot slightly and then pull it apart as shown at Points X and Y. See complete procedure on page 25.
- It is important to maintain not less than a 45-degree angle between top of barrel and vertical leg of hoisting rope. See Figure 2-22. The diagram in Figure 2-22 shows that two legs of a barrel hitch are supporting 1000 pounds each. The combined weight of the barrel and its contents is 2000 pounds. This diagram illustrates the additional strain factor placed on each leg of a sling if the hoisting ropes of the sling are located at an angle of less than 45°. It is obvious that a decrease in the angle between the top of the barrel and the vertical leg of hoisting is an important factor in determining the safe working load of a rope sling. Remember the sling angle determines the sling load.
- The timber hitch is used for hauling and lifting spars, boards, and timbers, generally by end pull. See Figure 2-23. The timber hitch forms a secure temporary tie that may be easily undone. A half hitch can be added a short distance above a timber hitch as a guard against the timber hitch becoming undone when the pull is slackened.
- The becket hitch takes its name from the fact that it is used for fastening a rope to the becket of a block or a ring. To make a becket hitch, pass the running end of the rope through the eye of the becket and bring it around the standing part of the rope. Bring the running end over both sides of the loop formed and up through the bottom half of the loop. Pull the hitch tight. See Figure 2-24.