Polypropylene, buoyant rescue ropes (usually in throw bags) can be quite different from one another.
- Diameter - thicker is better to hold on to
- Stronger - if you need to unpin a canoe you want a very strong rope
- Visibility - it should be easily visible (yellow is standard)
- Stretch - only high priced ropes such as Spectra are more 'static'. Pure polypropylene stretch like a rubber band under big loads
- Easy to throw - Smaller people have trouble throwing big throw bags