Knots, Bends, Splices With tables of strengths of ropes, etc. and wire rigging

Excerpt

THE CONSTRUCTION OF ROPES.

Rope, the term being used in its widest construction, is made from almost every pliable material, but is generally composed of hemp, manila, coir, cotton, steel, iron, or copper wire.

For the present we will confine ourselves to those having their origin in the vegetable kingdom, and more especially to those made from hemp and manila.

These are divided into three classes:—

(1). A Hawser-laid Rope, which is composed of three strands laid up generally right-handed (that is, the direction taken by the strands in forming the rope runs always from left to right) (Fig. 1.)

(2). A Shroud-laid Rope, also laid up right-handed, but consisting of four strands (Fig. 2) with a heart in the centre.

(3). A Cable-laid Rope, which is composed of three right-handed hawser-laid ropes laid up together left-handed, so that it may be said to consist of nine strands (Fig. 3), or it may be formed by three left-handed ropes laid up right-handed (Fig. 4).

In Fig. 4 we show a more complete analysis of its construction (in this case a right-handed cable-laid rope).

First we see the cable e formed by the three ropes d, f, and g; whilst the rope g is dissected to show the strands forming it, c, h, j; and in the strand h we see b, the yarn composing the strand, and a a yarn teased out to show the original fibre.

The end of a rope must always be secured in some way, or it is evident from its construction that it will on the slightest usage become frayed out. The commonest method is by placing on an ordinary whipping, which is done as follows:—First lay the end of a length of twine along the end of the rope, and then commencing at the part furthest from the rope's end take a half dozen or more turns around both the rope and twine end (Fig. 5). Then lay the twine in the form of a loop along the rope and over the turns already taken, as in Fig. 6. To finish off take that portion of the loop designated a, and continue taking turns tightly round the rope and part b of the twine until the loop is nearly all used up; pull through the remainder snugly by part c, and cut off short when, no end of twine will be visible as in Fig. 7.

Considering that we now have at our disposal a small sized rope with the end whipped, we will at once proceed to the formation of the most elementary knots and hitches, namely, those formed by a single rope's end.

Fig. 8 shows a common loop, by which most of the following knots, etc., are commenced. Note exactly how the loop lies, and let us letter its parts clearly for future reference. The part of rope extending from 1 to 2 is known as the standing part which we will call a, the portion included between 2 and 3 following round the loop by y and z is termed the bight which we will call b, and from 3 to 4 is known as the end e.

Then starting in each case from the position shown in Fig. 8 we make the following knots, etc:—

(1). An Overhand Knot.—Place e up through bight b, and draw taut (Fig. 9).

(2). A Figure of Eight Knot.—Back e round behind a, bring over part z and dip down through bight b and haul taut (Fig....