Navigation and Seamanship (1+1)

Synthetic fibre ropes

1. Poly propylene

It is a lightest synthetic rope, 60% stronger than manila. It stretches 40% and absorbs only 0.1% water. Melts at 165^oC. A 48mm pp rope will break at 27.5 tonnes.

2. Polythene

Twice the strength of cotton. As a rope, its strength lies midway between manila and nylon. It absorbs only 0.01% of water and float in water. Melts at 135^oC and shrinks about 4% at 60^oC. It is unaffected by most of the industrial chemicals and microorganisms. It offers good resistance to sun light and abrasion. A 48mm polythene rope weighs 252kg per 220m coil and has a breaking stress of 22.4 tonnes.

3. Nylon (Polyamide)

Strong, soft and pliable. They are water proof and their surfaces dry very quickly. They are equally flexible when at extremes of temperatures and when wet or dry. They are pest and chemical resistance. They are virtually impervious to rot and mildew and have a low fire resistant. Due to low meeting points. They are not so easy to handle compared to manila, due to their very smooth surface. Resistance of these ropes to abrasion is extremely good. 48mm rope weights 330kg.