Roughly, the strength of ropes may be calculated by multiplying the circumference of the rope in inches by itself and the fifth part of the product will be the number of tons the rope will sustain. For example, if the rope is 5 inches in circumference, 5 X 5 = 25, one-fifth of which is 5, the number of tons that can safely be carried on a 5-inch rope. To ascertain the weight of ordinary "right hand" rope, multiply the circumference in inches by itself and multiply, the result by the length of rope in fathoms and divide the product by 3.75. For example, to find the weight of a 5-inch rope, 50 fathoms in length: 5 X 5 = 25; 25 x 50 = 1,250; 1,250 ÷ 3.75 = 333-1/3 lbs. These figures apply to Manila or hemp rope, which is the kind commonly used, but jute, sisal-flax, grass, and silk are also used considerably. Cotton rope is seldom used save for small hand-lines, clothes-lines, twine, etc., while wire rope is largely used nowadays for rigging vessels, derricks, winches, etc., but as splicing wire rope is different from the method employed in fibre rope, and as knots have no place in wire rigging, we will not consider it.
CHAPTER II
SIMPLE KNOTS AND BENDS
For convenience in handling rope and learning the various knots, ties, and bends, we use the terms "standing part," "bight," and "end" (Fig. 3). The Standing Part is the principal portion or longest part of the rope; the Bight is the part curved or bent while working or handling; while the End is that part used in forming the knot or hitch. Before commencing work the loose ends or strands of a rope should be "whipped" or "seized" to prevent the rope from unravelling; and although an expert can readily tie almost any knot, make a splice, or in fact do pretty nearly anything with a loose-ended rope, yet it is a wise plan to invariably whip the end of every rope, cable, or hawser to be handled, while a marline-spike, fid, or pointed stick will also prove of great help in working rope.
To whip or seize a rope-end, take a piece of twine or string and lay it on the rope an inch or two from the end, pass the twine several times around the rope, keeping the ends of the twine under the first few turns to hold it in place; then make a large loop with the free end of twine; bring it back to the rope and continue winding for three or four turns around both rope and end of twine; and then finish by drawing the loop tight by pulling on the free end (Fig. 4).
