242 



MARINE PRODUCTS OF COMMERCE 



the tissues of the leaves of certain tropical plants; soft or bast fibers, such as linen, 

 obtained from the main stalks of plants, and cotton, obtained from seed hairs; and 

 synthetic, or man-made fibers, among which nylon is outstanding. It is interesting 

 to note that all of the natural fibers are composed principally of cellulose (from 

 a vegetable origin ) . 



Manila. Aside from some use in the construction of large sized otter trawls, 

 Manila (and sisal) fiber is employed almost entirely in the manufacture of marine 

 cordage. More Manila hemp (although it does not grow near Manila and is not 

 hemp) has been used for marine cordage during the past 100 years than all other 

 fibers combined. 



The sizes of Manila twines utilized in netting are designated by the number of 

 feet of single yarn and the number of cords, or strands, in the twine. For ex- 

 ample, ^2^% means a 3-stranded twine made of Manila that runs 1,200 feet per 

 pound in the single yarn. Therefore, the 3 cord would run approximately % of 

 1,200, or 400 feet per pound. The English system describes this twine by yardage 

 of the completed twine (e.g., 75 yards/2 cord would be a 2-stranded twine 

 running 75 yards per pound, etc. ) . 



Cordage is classified by thread count and diameter or circumference measure- 

 ment. For example, a 6-thread rope is M inch in diameter and % inch in circum- 

 ference. Thread count is seldom used, however, when the diameter is more than 

 /2 inch. 



Cotton. The widespread use of cotton fibers during the past 5,000 years can be 

 accounted for by its wild growth in nearly every tropical country and its ready 



Fig. 13-2. Netting as it comes off the 

 looms, sometimes called "crosstwine." 



adaptability to cultivation in semitropical zones. This abundance, as well as in- 

 herent quality, make this fiber the most important in the United States today. 

 Over 70 per cent of all netting used in the commercial fisheries is made from 



