Polypropylene Line is a thermoplastic polymer material that has a wide variety of uses. It is commonly found in many household, textile, and industrial applications. For the marine industry, polypropylene line is tough, flexible, and strong yet lightweight enough to float which makes this ideal for dinghies and small keel boats.
Polypropylene Rope Characteristics:

Light weight: when compared to similarly-sized diameter lines.
Does not absorb water, Floats, Excellent shock absorption, Easy to splice, Economical, Low tolerance to UV, Low Melting Point, Low Abrasion Resistant, Some common applications of a 100% polypropylene line include dinghy tow rope, an economy dinghy mainsheet and you may even find it as a spinnaker take down line on larger keel boats.