Tec-Index
Nylon has a relative density of 1.14 , which means it will sink in Water.
A good Elasticity and being robust makes braided 5mm Nylon-Rope a good Material for stage handles.
Nylon is also the Material which is most used as Cave-Line.
The Anchor-Lines of Dive-Boats are an other Application-Field where you should use Nylon-Ropes.
Nylon contracts when it gets wet.
Polyester has a low Elasticity, pre-stretched Material a even lower one.
The relative density is 1.38, so it does sink fast in Water.
Polyester does not contract when it gets wet.
Polyethylen does extend (elongate) under continual high Load.
The relative density is 0.97 , which means it will slightly swim up in Water.
Polyethylen is very slippery.
Polypropylen (also known as Water Ski Line) is a good Material for Ice-Diving- Lines, Buddy-Lines and is also the material you should use for the Current-Line on the Dive-Boat.
It does not contract when getting wet. Polypropylen has a relative density of 0.91 , which means it does swim up in Water.
You should order it in signal-red for good visibility.
The Diameter of a Buddy-Line should be at least 8mm.
5cm wide Loops, made of Shock Cord with 4mm Diameter are used to hold the Corrugated-Hoses of Wings in place.
The Stretch Capacity is about +125%.
http://Rebreather.de/technical_diving/rope.htm © Karl Kramer, 27.Feb.2000