Lets dream about the perfect throw rope for SWR. This throw rope would have the following properties:

• Floats - What good is the rope if it sinks well below the water surface?
• Strong - Unpinning canoes and rafts take a great deal of strength
• Easy to handle - The rope has to be thick enough to grab and not slippery
• Lightweight - If it is too heavy, you will not carry it
• Durable - Avoids rotting and lasts awhile
• Reasonably Priced

Stretches (Dynamic) or doesn't (Static), it depends on the usage. When retrieving swimmers, some stretching is ideal. When hauling or unpinning a boat, stretching can be a real nuisance or even dangerous. Climbers prefer dynamic ropes, cavers don't. SWR shares more caving uses than lead climbing. Just like cavers, SWR may involve careful lowering of a rescuer and certainly top roping.

Throw ropes typically are made of some type of synthetic material like Nylon, Polypropolene, Polyester or Dyneema(Spectra). Many throw ropes use a combination of these materials. Here is a chart comparing rope fibers:

If you can afford it, it is pretty hard to beat a Dyneema throw rope. Nylon with a Polypropylene sheath isn't a bad second choice. All throw bags have foam in the end of the bag to ensure the end of the rope floats. The Polypropylene sheath also adds some flotation. Nylon throw bags have been in use for many years and are great for rescuing swimmers. Nylon also has high abrasion resistance and holds knots quite well. Sterling Rope also has an extra strong polypropylene line (4,000 Lbs) with a nylon sheath called Swiftwater Response that costs $56.80 that is a very reasonable alternative to either Nylon or Dyneema. Here are the specifications for various rope types: Sterling Rope Specifications. This article from Sterling Rope covers greater detail on rope construction: Rope Construction.

The next consideration is the length of rope. Fire fighters have the luxury of large rafts/boats to carry their equipment. They also handle major floods and very heavy load conditions. A 300' 1/2" line is standard equipment for them. There is no way we can properly throw a 300' line or even fit one in our boats. Most kayak throw ropes are between 50' and 75'. 50' is fine for a rope you carry on your person in a waist belt or in a PFD pocket bag. The ideal length for your primary bag is 75'. This length is still quite easy to throw and handles most small streams and rivers quite well. Since each boater typically carries a throw rope, you can easy tie two together when you need a longer line.

The final consideration is the diameter of the rope. Although 1/4" is more challenging to grab hold of, this diameter isn't a bad temporary measure for waist or PFD pocket bags rescuing swimmers. This thinner diameter is totally unsuitable for hauling or vertical lowering. A 1/4" Polypropylene line has a breaking strength of 950 pounds versus 1900 pounds for 3/8". A common rule of thumb for knots is 50% strength loss, this brings you down to 500 pounds breaking strength. A couple of strong paddlers pulling on a Z-Drag can easily snap this line thickness. 3/8" line is much easier to hold and pull on and is the best choice for your main throw bag.