It often becomes requisite, when loading waggons, packing animals, or loading boats, sledges, canoes or rafts, to be enabled to form some estimate of the weight about to be placed in them, and there are few aids to travel more difficult to weigh than rope, on account of its bulk and peculiar form of construction. It is well therefore to have recourse to a rough and ready system of calculation to arrive at the required information. The strength of ropes should also be approximately known before applying them.
Robinson gives the following simple rules for calculating the strength of ropes of the ordinary form of construction, and also their weights. Multiply the circumference of the rope in inches by itself, and the fifth part of the product will express the number of tons the rope will carry. For example, if the rope be six inches in circumference, 6 × 6 = 36, the fifth of which is 7-1/5, the number of tons which such a rope will sustain. To find the weight of shroud or hawser laid rope, multiply the circumference in inches by itself; then multiply the product by the length of the rope in fathoms, and divide by 420, the product will be the weight in cwts. Example—to find the weight of a six-inch hawser laid rope 120 fathoms long; 6 × 6 = 36 × 120 = 4320, which, divided by 420, gives the weight of the rope 10cwt. 1 qr. 4lb. To find the weight of cable-laid cordage, multiply its circumference in inches by itself, and divide by 4; the product will be the weight in cwts. of a cable 120 fathoms long, from which the weight of any other length may be readily reduced. Example—required the weight of a twelve-inch cable 120 fathoms long; 12 × 12 = 144, divide by 4, and the product, 36, is the weight in cwts.
To render ropes and cords available for the variety of purposes to which they are applied by the traveller, knots, hitches, splices, &c., must be had recourse to. These are so numerous in form and mode of construction, that to describe half that are known to practical riggers and sailors would require a goodly volume. We shall, therefore, content ourselves by describing some of the most useful and generally available. It is impossible to teach the art of knot-tying by written directions; we therefore give a sketch of each mentioned. It will be well for the student who wishes to acquire a knowledge of the manner in which they are formed to provide himself with a moderately stout piece of cord, and, by following out the lines of turn, twist, and direction, given in the diagrams, and repeating the operation, he will soon acquire proficiency. A, in the accompanying full-page illustration, represents a pair of hitches, which can be caused to run firmly and freely home by hauling on the standing end, or converted into a useful loop by passing a few turns of stopping round both ends. B is a fisherman’s bend, useful for an almost endless number of purposes. When the two knots in the short ends are pulled home, they run together by pulling the two main or free ends. C is a reef knot, used for knotting the reef points of sails or uniting the ends of ropes or cordage. D shows a mode by which the end of a rope may be quickly fastened to a ring. E and F are lark knots, used for fastening the painters of boats or canoes; it is only necessary, in case of sudden attack or alarm, to pull out the stop stick to instantly free the painter without untying. G is a bowline knot, which is applicable to any purpose where it is requisite to have a loop which will not run home. H is a hawser bend, which can be expeditiously made use of for joining the ends of large ropes. I is a knot commonly made use of for securing a hawser to a mooring post. J is an arrangement known as a toggle and loops, useful for a great number of purposes; the toggle, acting as a button, can be secured or released with great facility. K is a Carrick bend, useful for uniting tow ropes or large hawsers to each other. The “seizing ” or stopping, represented as securing the short ends in some of these knots, may be composed of rope, yarn, or stout twine. A. sheathing, or “parcelling,” composed of old canvas, or some other stout material, should always be placed round ropes which are subjected to friction against quay walls or rocks, in order to protect them from chafe. The annexed illustration also represents a number of useful knots, and modes of applying ropes and cords.
Fig. 1 represents a timber hitch, which will be found most useful for taking a firm hold by cord on a round spar or pole. Fig. 2 is another method by which a rope can be secured round an upright post. Fig. 3 shows a sling, useful for raising or lowering packs, bales, or boxes. Fig. 4 is known as a harness loop; several of these can be tied in a drag rope, in order that men may make use of them as shoulder collars to draw by. Fig. 5 is a twisted or tail timber hitch, adapted for securing a log or piece of round timber for lowering or raising. Fig. 6 shows how to make a loop in the end of a pack or box lashing; the knot, running home, secures the loop, and prevents its drawing close. Fig. 7 is a sheepshank, used for shortening a long rope, and thus rendering cutting unnecessary. Fig. 8 is a loop-slip, used for uniting two looped ends securely. Fig. 9 is a weaver’s or netter’s knot, much used by those who repair or make nets for fishing. Fig. 10 is a Tom Fool’s knot, very useful for forming handles to jars and pots; the mouth of the vessel is placed in the centre of the knot, the two free ends tied fast, and the two loops left for the hand to grasp. Fig. 11 is a brooch knot, used for forming the loop in rope for casting horses. (Vide “[Veterinary Surgery].”)