Synthetic lines are lighter and stronger and more rot-resistant, generally, than natural fiber ropes. Synthetic lines are slipperier than natural fiber ropes so be sure to check your knots to make sure they are secure. Synthetic lines should be cleaned with fresh water and detergent, kept out of sunlight, inspected frequently for chafe, and stored dry. Natural fibers such as manila, sisal, hemp and cotton will shrink when they get wet and also tend to rot or become brittle. Manila is still used today on large ships and is the best natural fiber for mooring lines, anchor lines and as running rigging.
Manila has a minimum of stretch and is very strong.
Natural fiber line should be uncoiled from the inside of a new coil in order to prevent kinks. Always whip or tape the ends of natural fibers to keep them from unraveling. When natural fiber lines have been in salt water you should rinse them in fresh water and allow to dry thoroughly. They should then be properly coiled and stored on grates above deck in a dry, well-ventilated place to help prevent mildew and rot. How, Inc .