THERE are four varieties of rope in the United States naval service: that made of the fibres of the hemp plant; the Manilla rope, made of the fibres of a species of the wild banana; hide rope, made of strips of green hide, and wire rope.
In some countries, ropes made of horse hair, of the fibrous husk of the cocoanut, called coir-rope, and of tough grasses, are quite common. In our own country, rope has been made from the flax and cotton plants. The metals have also been put in requisition, copper-wire rope being used for particular purposes, principally for lightning conductors, and iron and steel wire are in general use for standing rigging; steel wire being some fifty per cent. stronger than iron wire of the same size.
Of the many vegetable substances that are adapted to rope-making, the best is hemp-hemp-rope possessing in a remarkable degree the essential qualities of flexibility and tenacity.
Hemp in its transit from its native fields to the ropewalk passes through the operations of dew-rotting, scotching and hackling. In the first process water dissolves the glutinous matter that binds the fibrous portion to the woody core, thus partly setting the fibres free; scotching breaks the stalk and separates it still further from the fibre, and hackling consists in combing out the hemp to separate the long and superior fibres from the short and indifferent ones or tow.
The hemp of commerce is put up in bundles of about 200 lbs. each. If good, it will be found to possess a long, thin fibre, smooth and glossy on the surface, and of a yellowish green color; free from “spills” or small pieces of the woody substance; possessing the requisite properties of strength and toughness, and inodorous.
Russian and Italian hemp are considered the best, for the generality of purposes. Rope made from the best quality of Russian hemp, is more extensively used in the navy than any other kind.
Italian hemp is only used in the navy for packing for engines, its cost being more than double that of Russian hemp.
The Native American dressed hemp, easily distinguished
|by its dark grayish color, is preferred for many purposes, such as for marline, houseline, hambroline, and all cordage spun by hand, the fibre being finer-than that of the Russian hemp.Cotton is a poor substitute for hemp, in rope-making, lacking its strength and durability. It retains moisture when once wet, and is liable to rot.
Flax is used sometimes for deep-sea sounding-lines, though reeled piano wire has replaced it for this purpose where great depths are measured.
Sail Twine is made of cotton or flax.
The size of Rope is denoted by its circumference, and the length is measured by the fathom. The cordage allowed in the equipment of a man-of-war ranges from 1 1/4 (15-thread) to 10 inches inclusive.
For a brief description of the process of rope-making, see Appendix A.
Varieties of Rope. In rope-making the general rule is to spin the yarn from right over to left. All rope yarns are therefore right-handed. The strand, or ready, formed by a combination of such yarns, becomes left-handed. Three of these strands being twisted together form a right-handed rope, known as plain-laid rope. Fig. 14, Plate 7.
White Rope. Hemp rope, when plain-laid and not tarred in laying-up, is called white rope, and is the strongest hemp cordage. It should not be confounded with Manilla. It is used for log-lines and signal halliards. The latter are also made of yarns of untarred hemp, plaited by machinery to avoid the kinking common to new rope of the ordinary make. This is called “plaited stuff,” or “signal halliard stuff.”
The tarred plain-laid ranks next in point of strength, and is in more general use than any other. The lighter kinds of standing rigging, much of the running rigging, and many purchase falls are made of this kind of rope.
Cable-laid or Hawser-laid Rope, Fig. 15, is left-handed rope of nine strands, and is so made to render it impervious to water, but the additional twist necessary to lay it up seems to detract from the strength of the fibre, the strength of plain-laid being to that of cable-laid as 8.7 to 6; besides this, it stretches considerably under strain.
Back-handed Rope. In making the plain laid, it was said that the readies were left-handed, the yarns and the rope itself being right-handed. If, instead of this, the ready is given the same twist the yarn has (right-handed), then, when brought together and laid up, the rope must come left-handed. This is called left-handed or back-handed rope. It is more pliable than the plain-laid,
|less liable to kinks and grinds when new, and is allowed, in the navy, for reeving off lower and topsail braces.Shroud-laid. Rope, Fig. 16, Plate 7, is formed by adding another strand to the plain-laid rope. But the four spirals of strands leave a hollow in the centre, which, if unfilled, would, on the application of strain, permit the strands to sink in, and detract greatly from the rope’s strength, by an unequal distribution of strain. The four strands are, therefore, laid up around a heart, a small rope, made soft and elastic, and about one-third the size of the strands.
Experiments show that four-stranded rope, when under 5 inches, is weaker than three-stranded of the same size; but from 5 to 8 inches, the difference in strength of the two kinds is trifling, while all above 8 inches is considered to be equal to plain-laid when the rope is well made.
Four-stranded rope is now but little used except for lifts, preventer-parrels, Jacob’s ladders and rigging laniards.
Tapered Rope is used where much strain is brought on only one end. That part which bears the strain is full-sized, tapering off to the hauling part, which is light and pliable. Fore and main tacks and sheets are made of tapered rope.
Twice-laid Rope is made from second-hand yarns. This rope may be readily known by the different shades of color of the yarns, but it is often difficult to determine, by mere inspection, whether it is relaid from what was good rope, and, consequently, still good, or made up from junk or condemned rigging, and worthless. Twice-laid rope is only met with on board ship when necessity has compelled its purchase on foreign stations.
Manilla Rope seems to be better adapted to certain purposes on board ship than hemp, being more pliable, buoyant, causing less friction, and not so easily affected by moisture. It is used for hawsers, tow-lines, and for light-running rigging and gun-tackle falls. Manilla is now less used in the navy than formerly. The Book of Allowances states that the cheap first cost of Manilla as compared with hemp is more than compensated by the greater market value of the hemp when worn-out. This statement is not correct if applied to the current relative values of hemp and Manilla junk in this country.
Hide Rope is made of strips cut by machinery from green hides. Formerly used for topsail tyes, and for tailing on to such ropes as are exposed to much chafe in some particular part, as topsail sheets, etc., it is now allowed only for wheel ropes. Its strength is about one-third that of hemp.
Hide rope requires care to keep it in good order, and should not be exposed to the weather unnecessarily. It should be given a lick of thin tar (Swedish preferred)
|as often as may be necessary, usually about twice a year.Avoid serving the splices of hide rope. When spare wheel ropes are stowed away they should be well oiled and headed up in a barrel to preserve them from rats and mice.
One set of wheel-ropes is now supplied of flexible iron wire-rope.
Bolt Rope is the name applied to rope used for roping sails. It is made of the best hemp and finest yarns, and is the most superior kind of cordage.
Wire Rope for general use in the navy is made from one quarter to seven inches, inclusive, in circumference, those being the maximum and minimum sizes likely to be needed.
Each strand has a hemp heart, and the rope itself has a heart usually of the same material; this adds greatly to its pliability.
When first introduced, it was thought that great difficulty would be found in manipulating wire rigging, but our best riggers cut, fit and splice it as readily as they do hemp rigging.
In its less bulk and cost, wire rope has decided advantages over hemp for the standing rigging. of ships, and now all vessels of the navy are provided with standing rigging of wire.
Besides the great advantage that wire rigging possesses of not being affected by the heat and sparks from the smokestack, its durability is at least three or four times that of common rope, and, when once completely set, does not require further pulling up.
Wire rope may be used for strapping blocks, and will be found neat and serviceable.
In Appendix A will be found a table of comparative dimensions of chain cables, hemp, iron and steel rope, with breaking strains and weights per fathom.
Small Stuff is the general term applied to small rope. It is particularized by the number of threads or yarns which it contains, and is further known either as ratline stuff or seizing stuff.
Ratline Stuff is three-stranded, right-handed small stuff of 24, 21, 18, 15 or 12 threads. It is measured by the fathom.
Seizing Stuff, Is of 9, 6, 4 or 2 threads, and is measured by the pound. While all varieties of small stuff may be spoken of as “24, 18, 9, &c., thread stuff,” the smaller varieties have also special names, according to their number of threads and the manner of laying up. We have:
Hambroline, two-stranded, right-handed, and
Roundline, three-stranded, right-handed. Both of
|these are made of fine back or left-handed yarns, so that the stuff itself is right-handed.Marline, two-stranded, left-handed.
Housline, three-stranded, left-handed. Both of these are made of finer dressed hemp, and have altogether a neater, cleaner and smoother appearance than spun-yarn.
Spun-Yarn is also left-handed, and of two, three or four strands. Spun-yarn is always in great demand aboard ship, being used for seizings, service, and a great variety of purposes. In its manufacture, “long tow,” as it is termed, or the tow of the first hackling, is hackled again, and laid up loosely, left-handed, and to keep it from opening is well tarred and rubbed down.
For fine seizings and service, hambroline and roundline (right-handed), or marline and housline (left-handed) are the kinds of small stuff selected. For ordinary purposes, spun-yarn is used.
Nettles, used for hammock clews, and where very neat stops are required, are made by laying up two or three yarns in a taut twist with the thumb and fingers, and then rubbing it down smooth.
Foxes, used for temporary seizings, making mats, sennit, gaskets, reefing beckets, boat gripes, bending studding sails, &c., are made of two or more yarns, as required, laid up by twisting by hand, and then well rubbed down with a piece of tarred parcelling.
A Spanish Fox is a single yarn twisted up tightly in a direction contrary to its natural lay-that is, left-handed, and rubbed smooth. It makes a neat seizing, and is used for the end seizings of light standing rigging, and for small seizings generally.
Rumbowline is the name sometimes applied to coarse, soft rope, made from outside yarns, to be used for temporary lashings, &c.
Rogue’s Yarn is a single untarred thread, sometimes placed in the centre of the rope, or in the centre of each strand, denoting government manufacture.
Junk is supplied for the purpose of working up into various uses-such as for swabs, spun-yarn, nettle-stuff, lacings, seizings, earings, gaskets, &c.-of all of which the supply, in proper kind, is generally inadequate. Good junk is got out of such material as condemned hawsers-they having been necessarily made of the best stuff, and condemned before being much injured. Old rigging makes bad junk, not being condemned generally until much worn.
Of the worst junk, swabs and spun-yarn should be made; of the best, nettle and seizing-stuff, lacings, earings, &c.
Large junk, such as lengths of towlines, should be unlaid
|before being put below, that it may admit of being snugly stowed.Shakings are odds and ends of yarns and small ropes, such as are found in the sweepings of the deck after work. They are collected, put in a bag kept for the purpose, and at certain times served out to the watch to be picked into Oakum, a good supply of which should always be on hand for any calking that may be required, for stuffing jackasses, boat’s fenders, &c.
Use of the Ropermaker’s Winch, Fig. 18, Plate 7. A ship’s winch, which will make very fair 2-inch rope, is about 15 inches in diameter. In the frame, which is double, are placed five hooks-the three upper ones for general use, the fourth for four-stranded rope, and the centre one for hardening up large rope after it has been laid up by the upper ones (the latter not being sufficiently strong for the purpose). The shanks of the hooks, between the two parts of the frame, are inserted in cogged barrels, which are turned by the wheel, one revolution of which gives nine to the hooks-any one of which can be thrown out of gear by hauling it back close to the after part of the frame.
A loper is a swivel hook, Fig. 17 (a), which, by revolving freely, allows the strands to twine up together, by the twist put in them as the top is withdrawn.
The top, Fig. 17 (b), is a conical piece of wood, scored on the outside for the reception of the strands. Its use is to keep the strands separate between it and the winch, and to regulate the amount of twist in the rope behind it, by being moved along either slowly or rapidly. When four-stranded rope is required, a hole is bored through the centre, as a lead for the heart.
A length of junk being brought on deck, you proceed to unlay it by attaching the strands to separate hooks, and the loper to the other end-one hand holding back on it, and then heaving back-two hands following the rope down to separate the ends.
Spun-Yarn is made by hooking all the yarns that compose it (according to the size required) upon one hook. You then heave round, the reverse way to the lay of the yarns (which in ordinary rope are all right-handed) until there is plenty of back turn in them, holding on the ends by hand; then rub down and make it up.
In rubbing down, a boy puts the end of a strand over his shoulder, and walks away with it, another hand holding on the rubber (which is the end of the strand doubled up loose) round the stuff they are laying up.
As many lengths of spun-yarn can, of course, be made at once as there are hooks on the winch.
Nettle-Stuff. Hitch the yarns to separate hooks; let a couple of hands then take hold of them, and commencing close to the winch, walk back while it is hove round the
|reverse way; the yarns are thus hove up the contrary way to what they were originally, to soften them; for when drawn out of rope, they are usually hard and angular; and would not lie square, or bear an equal strain, if laid up in that condition. When thus relaid, the ends are knotted together, the loper hooked on-one hand holding on to it, the top put in, the winch hove round the same way as at first, and the top moved along towards the winch. When up to it, the top is taken out, the yarns unhooked, and hitched to a single hook, then the winch hove round the opposite way to what you have just been heaving it, to harden the stuff up; rub down and make up.Thus, the yarn will be left-handed, and the nettle-stuff right-handed; for, though the winch is hove round the same way with both, the twist in the yarns causes them to unite abaft the top with the lay of contrary denomination, and the revolutions of the loper prevent the turn coming out again.
Six (or nine) Thread Stuff: Put two (or three) yarns on three separate hooks; hold on the end by hand, keeping each of the three lengths separate, and heave round a reverse turn, as with spun-yarn. When sufficiently hove up, knot the ends together, hook on the loper, put in the top, and proceed as with nettle-stuff.
Fig. 18 gives a general idea of the winch, in operation.
General Remarks on Rope. The strength of a rope-yarn of medium size is equal to 100 lbs., but the measure of strength of a given rope is not, as might naturally be supposed, 100 lbs. multiplied by the number of yarns contained in the rope. The twist given to the yarn, after certain limits, diminishes its strength, as already stated, and with the best machinery it is scarcely possible that each yarn of the tope should bear its proper proportion of strain. The difference in the average strength of a yarn differs with the size of the rope. Thus, in a 12-inch rope, the average strength of each yarn is equal to 76 lbs., whereas, in a rope of half an inch, it is 104 lbs.
Experiment has shown that by applying a constant, or even frequent, strain equal to half its strength, the rope will eventually break. This seems to be particularly the case with cable-laid rope, which is the weakest of all.
It has been ascertained that a good selvagee, carefully made with the same number and description of yarns, as the common three-stranded plain-laid rope, possesses about the same degree of strength.
It has been shown by experiment, that where a span is so placed as to form an angle less than 30 degrees, the strength of the two parts of the rope or chain of which it is composed, is less than the strength which one such part would have if placed in a direct line with the strain.
Right-handed ropes are coiled down with the sun, or in
|the direction pursued by the hands of a watch; the left-handed ropes, against the sun. An exception to this rule is in the hemp cables and hawsers, which are left-handed and are coiled away with the sun.In taking out new rigging from a coil, the end should be passed through the coil and coiled down against its lay to get the turns out.
Avoid covering hemp rope with leather, especially green hide, unless good and well-tarred parcelling be interposed.
Rope contracts very considerably by wetting it. Advantage may be, and often is, taken of this, by wetting lashings, which are required to be very taut and solid, and are not permanent, as the lashing of a garland on a lower mast for taking it in or getting it out. For the same reason in rainy weather, braces, halliards, sheets, clew-lines, and other rigging requiring it, should be slacked up to save an unnecessary strain on the rope, and avoid the risk of springing a yard or carrying something away.
Running rigging has nothing to protect it from the effects of the weather, excepting, in hemp, the tar taken up in the process of manufacture, and after being wet the air should be allowed to circulate through it freely. Rope should never be stowed away until thoroughly dry.
Running rigging, when not in actual use, should be kept neatly coiled down near the pin to which it belays, taking care always to capsize the coil that the running part may be on top, so that it may run clear. In port, during good weather, the rigging may be coiled down in flemish coils, that is, perfectly flat, as soon as the decks are dry enough in the morning, and left so until the decks are cleared up at seven bells in the afternoon, when the ends should be run out, the rope coiled down snugly and triced up in readiness for washing decks in the morning.
When scrubbing clothes or hammocks, soap at times unavoidably gets on the rigging: it should be carefully washed off before the decks are dry.
One rope may be rove by another by putting the two ends together, and worming three yarns or pieces of spun-yarn in the lay for three or four inches on each side, and clove-hitching the ends around the rope, or opening the strands and laying them in. This is always done when reeving new braces by old ones, and with running rigging generally.
To Find the Breaking Strain of Government Rope:
Untarred Hemp: Multiply the square of circumference in inches by 1371.4 = strength in pounds.
Tarred Hemp: Use in above formula 1044.9 as the multiplier.
Manilla Rope: Use 783.7 as the multiplier.
|Iron-wire Rope: Weight in pounds per fathom x by 4480 = strength in pounds, but ifSteel-wire Rope, use 7098 as the multiplier. Or by the
Practical Rule for ascertaining the Strength of Rope. The square of half the circumference gives the breaking strain of the weakest plain-laid rope in tons, and is therefore a safe rule.
Thus, by the table, the breaking strain of a 6-inch rope is 10 tons, and by the rule (6/2)2=9 tons.
The breaking strain of a 10-inch rope is, by the table, 28 tons, and by the rule (10/2)2=25 tons.
No cordage should be subjected to a strain above one-third of its estimated strength.
For ascertaining the Weight of Rope. Three-strand, plain-laid, 25-thread yarn, tarred. Multiply the square of the circumference by the length in fathoms, and divide by 4.24 for the weight in lbs.
Ex. 2-inch rope, 113 fathoms. (22 x 113)/4.24 = 106 lbs. – actual weight, 105 lbs.
The divisor for hempen cables is 4.79.
A Practical Rule for determining the relative Strength of Chain and Rope. Consider the proportionate strength of chain and rope to be ten to one-using the diameter of the chain and the circumference of the rope. Half-inch chain may, therefore, replace five-inch rope.
The absolute strength of chain, at the breaking point, may be found by dividing the square of the diameter in eighths, by 2.4 for round link crane chain, and by 2.7 for chain cable.
To find the Weight a Rope will lift when rove as a Tackle: Multiply the weight the rope will sustain by the number of parts at the movable block, and subtract one-fourth of product for resistance.
To find the size of Rope when rove as a Tackle to Lift a given Weight: Divide the weight to be raised by the number of parts at the movable block to get the strain on a single part, add one-third of this for the increased strain due to friction, and reeve the rope of the corresponding strength.
To find what Number of parts of a parts of a small Rope are equal to a large Rope: Divide the square of the circumference of the larger rope by the square of the circumference of the smaller, and the result will be the number of parts of the smaller equal to one part of the larger.
To find the Proportionate Strength of Wire and Hemp Ropes: Multiply the square of the circumference of a hemp rope by .223 for
|iron wire, and by .12 for steel wire, and the square root of product will be the circumference of a wire rope of corresponding strength.The wire-rope referred to has a hemp heart.
By multiplying the square of the circumference of a wire rope by 4.5 for iron wire and 8.4 for steel wire and extracting the square root of the product, the circumference of a hemp rope of corresponding strength may be obtained.