FIBER LINE

Fiber line is made from either natural or synthetic fiber. Natural fibers, which come from plants, include manila, sisal, and hemp. The synthetic fibers include nylon, polyester, and polypropylene.

SYNTHETIC-FIBER ROPES

Synthetic-fiber ropes, such as nylon and polyester, have rapidly gained wide use by the Navy. They are lighter in weight, more flexible, less bulky, and easier to handle and store than manila lines are. They are also highly resistant to mildew, rot, and fungus. Synthetic ropes are stronger than natural-fiber rope. For example,

Figure 6-19.\Crane rigged with boom and lifting hook.

nylon is about three times stronger than manila. When nylon line is wet or frozen, the loss of strength is relatively small. Nylon rope will hold a load even though several strands may be frayed. Ordinarily, the line can be made reusable by cutting away the chafed or frayed section and splicing the good line together.

SIZE DESIGNATION

Line that is 1 3/4 inches or less in circumference is called SMALL STUFF, and the size is usually designated by the number of THREADS (or yarns) that make up each strand. You may use from 6- to 24-thread strands, but the most commonly used are 9- to 21-thread strands (fig. 6-20). You may hear some small stuff designated by name without reference to size. One such type is MARLINE, a tarred, two-strand, left-laid hemp. Marline is the small stuff you will use most for seizings. When you need something stronger than marline, you will use a tarred, three-strand, left-laid hemp called HOUSELINE.

Line larger than 1 3/4 inches in circumference is generally designated as to size by its circumference in inches. A 6-inch manila line, for instance, would be constructed of manila fibers and measure 6 inches in circumference. Line is available in sizes ranging up to 16 inches in circumference, but 12 inches is about the largest carried in stock. Anything larger is used only on special jobs. (See fig. 6-20.)

Figure 6-20.\Some commonly used sizes of manila line.

If you should be tasked to order line, you may find that in the catalogs it is designated and ordered by diameter. The catalog may also use the term rope (rather than line).

ROPE YARNS for temporary seizings, whippings, and lashings are pulled from large strands of old line that has outlived its usefulness. Pull your yarn from the middle, away from the ends, or it will get fouled.