Ropes for River Use

In this article we will be taking a look at rope used for rafting specifically static line. For this article we reached out to both Sterling and BlueWater ropes to get some technical insight on what works best for river rescue use. There is a lot to know and a lot to understand about what rafters need on the river. If you are looking for throw ropes or throw bags you can find more info on that here. We also will be bringing you some of the top contenders for best ropes on the market.

Top Recommendations for Static Ropes

Ropes are a pretty complex topic in the river community. Both static and dynamic ropes find their way into our gear. It’s Important to know what they are and when to use them if you are unfamiliar with the purpose of each type of rope. Another important piece of terminology is what the difference between rope and line is.

What is the Difference Between Rope vs. Line?

A rope is a rope right? Not exactly, as we increase our mastery over a topic, it requires greater degrees of specificity to accurately describe and understand the topic. So the best way to understand this is: a rope is a rope, unless it’s on a boat, then it’s a line. Throw ropes are used on shore, perimeter lines ring a raft, static lines pull a raft off of a wrap, flip lines (which generally aren’t even rope) flip the boat over, but a strap secures gear to the boat. Like any sport as the community has gained mastery we have borrowed some terms from sailing, kayaking, and oceanic navigation, as well as sprinkling in some other terms of our own. So a rope is a rope, until it’s not a rope, but does that make all rope equal?

Static Rope in Rafting

Now that we understand the difference between rope and line it is important to note that not all rope is equal or the same in rafting. There are two main uses for Static line in rafting: perimeter lines and static lines for rescue applications. When rigging perimeter lines some folks prefer ropes and some prefer webbing, largely it is a matter of preference, however it is important to note that if you do chose a rope for your perimeter line it should be a static line since one of the benefits of a perimeter line is providing a pre-built system to help unpin a boat rather than pulling on 1 or 2 d-rings. In either case you will likely be using the line to pull a load.

Dynamic Rope for Rafting

If you end up using dynamic rope on the water there are a few serious applications for it: throw ropes, abseiling, and extraction. Throw ropes are the most common use of this type of rope. If you are rescuing a swimmer it is fine to have a bit of elasticity to the line. For anyone who has used a throwbag you know there is a lot of slack when you first get a swimmer on the line. When the line comes under tension, there is often a lot of abrupt force transferred to the line and can easily sweep an unbraced rescuer off a rock. Climbers use dynamic rope for this same reason, a shock to a falling climber can be disastrous if 100% of the fore of the fall is transferred to a harness. To combat this, rescuers need to brace, but having the right rope can help. More elongation can reduce the felt effects of the weight of the swimmer and the resistance their body creates in the water.

Abseiling and Extraction are two other helpful reasons to have dynamic rope on hand. These are less likely scenarios that we may encounter, but you may find yourself cliffed out in a canyon. Say you lose your boat over a waterfall, you may need to get down to it, but if you are surrounded by cliffs that could be nearly impossible. Having some dynamic rope to descend, as well as some rock climbing skills can certainly come in handy here. In the same way, if your paddle partner falls on a scout, or you have an injury in a deep gorge and need to get the victim out by raising them on a rope system this is pretty critical. If you are doing either of these you will need to be familiar with the concepts and get some training, but suffice it to say dynamic rope is helpful in those circumstances.

Tubular Webbing and Flat Webbing

Webbing is the often overlooked, yet incredibly important little brother to rope. Rope does a lot of the hero work like pulling a boat off of a rock, but webbing has some serious advantages. It’s ratio of strength to bulk is relatively low making it easy to store and keep a lot on your person. It is also softer and easier on your hands making it great for perimeter lines so you won’t tear off some skin as you paddle. Webbing is also extremely strong and has very low elasticity making it ideal for anchors and perimeter lines. Tubular webbing is ideal for the applications above, however flat webbing also finds its place on the water.

Ideally flat webbing is built into cam straps and use for lashing things to your boat. Since flat webbing tends to have lower load ratings than tubular webbing or static line it is best to make sure you are really only using it to strap gear to the raft and not in highly load bearing functions.

Questions for Rope Manufacturers

We got in touch with Jim Ewing, Product engineer and technical adviser at Sterling ropes for some more in-depth insight on the ropes they produce. We also want to give a big shout out to Liz McLellan (Sterling Ropes) and Mark Newell (BlueWater Ropes) for help with this article on the following questions:

What is the difference between Spectra, Dyneema, Nylon, and Polypropylene?

Spectra rope is a trade name for Ultra-High molecular weight polyethylene (UHMWPE) produced by Honeywell. This rope was initially produced for marine applications to replace metal cable with a much greater weight reduction.

Dyneema is also a UHMWPE with a slightly higher break strength and better durability, though it is more elastic compared to Spectra. Dyneema is about 15 times stronger than steel and 1/10th the weight.  Both materials float and are fantastic for river use since it is hydrophilic.

An important note is that Nylon is both hydrophilic and has a specific gravity greater than 1 meaning it will not only absorb water and become heavier, but it doesn’t actually float. Polypropylene on the other hand does not absorb water and with its specific gravity of .91 it floats in most conditions.

Another interesting note is that Nylon is actually 10-15% weaker when wet compared to dry strength.

The following chart from the Cordage Institute provides a fantastic insight into typical rope fiber properties. Values presented here are typical for individual fabrics and it is important to note that manufacturers will make ropes from a blend of materials in an effort to gain specific advantages for certain applications.

Why is repeated exposure to liquid water and repeated soaking so damaging to a rope? How worried should we be about mold in wet rope and what does it do to the rope?

SR: Nylon is hydrophilic, meaning it readily absorbs water.  Water is a plasticizer to nylon, meaning is softens the nylon.  Nylon is typically not damaged by water; however repeated and prolonged exposure can weaken the rope.  If a rope is stressed while wet more damage will occur than if it were dry.  Wet ropes should be dried at the earliest possible opportunity and should never be stored wet.  Other materials such as polyester and polypropylene do not absorb water and are not generally affected by exposure to water.  That said, they should also be dried at the earliest opportunity and not stored wet in order to avoid mildew and rotting.  The effects of mold and mildew on rope are not entirely known, however, no one wants to handle moldy and rotting rope.

How much does sand and other contaminants in a riparian environment reduce the life expectancy of a line?

SR: Sand and dirt is damaging to the fibers in rope.  The small sharp crystal structures of sand and dirt can cut and abrade the fibers thereby weakening the rope.  Ropes exposed to excessive amounts of sand and dirt should be washed in some fashion.  Usually just a simple fresh water rinse is sufficient.  In more extreme cases it may be necessary to use a soap product.

How would you recommend people care for their rope before, during, and after use in a riparian environment?

SR: Ropes should always be stored clean and dry.  After washing or exposure to water the rope should be air dried out of direct sunlight.

What do load ratings mean in terms of LBS and KN? Essentially, under what conditions can we expect the rope to snap?

SR: When we publish minimum break strength (MBS) it is usually a very conservative value derived from what is called a 3 sigma evaluation.  It involves some fancy math but essentially means that the rope has a 99.8% chance of breaking at that load or above.  This is of course the rating when the rope is brand new and tested without knots.  The effects of knots on break strength are well known and a little digging around the internet will reveal various tables depicting typical losses in strength due to knot type.  Other things that will affect rope strength are age, usage history, moisture level, lifetime UV exposure.

When we publish average break strength (ABS), which we typically do not do, it is merely the average of a series of break tests performed on that particular model of rope.  Because it’s an average some of the test breaks can by higher and some can be lower.  ABS is generally not used for life safety ropes.

Many people talk about shock loading in reference to ropes. What are most ropes threshold for shock loading and is this incorporated into the rating above?

SR: This is a somewhat ambiguous term used in various rope world realms.  Basically it means any rapid loading of a rope or system of ropes and components.  In rock climbing we use ropes specifically designed to absorb the energy of a falling climber.  Ropes for rock climbing are considered “dynamic” and must comply with some very specific performance requirements in order to obtain certification by either UIAA or CE.  In rescue work and rope access work there is less emphasis on energy absorption by the rope and more on the devices used in attaching the worker to the ropes or in the anchoring systems of the ropes.  Typical ropes used in rescue and rope access are considered “static” or “low stretch”.  They too must comply with very specific performance requirements in order to obtain certification by either NFPA or CE.

How does the surface area of the rope effect friction? (Specifically working with rope in your hand or if it slides over a carabiner in a mechanical advantage system)

Surface area and friction: This is a little bit of a tricky area as there are a lot of factors to consider beyond simple surface area.  Yes, in general the larger the diameter the greater the surface area but there’s more…

Material, braid pattern, stiffness, elongation, and coatings are just a few things that affect friction coefficients. It’s entirely possible to have two identical diameter ropes with completely different friction properties.

How does rope diameter and sheath thickness affect the strength of a rope?

SR:  Across similar rope designs, a larger diameter will always be stronger.  When we get into different designs, particularly different braid and core structures it is entirely possible to have a smaller diameter rope be stronger than a larger diameter.  Material type can have a lot to do with this as well as.

How do bends or turns in the rope (such as a pulley system) affect the load rating of the rope?

SR: Bends in rope always cause reduction in strength.  The amount of strength loss increases as the radius of the bend decreases.  The tighter the bend, the greater the strength reduction.

How do the stresses in a mechanical advantage system affect the breaking point of a rope? 3:1 "z-drags" and vector pulls are often employed in rafting, so what do people need to understand about how much more stress (if any) these systems place on the rope in the system?

SR: The areas of concern for stresses in mechanical advantage systems are any component or leg of rope that is subjected to the entire load of the system.  The anchoring line and the line attached to the load should be of sufficient size and strength to pull the load without any mechanical advantage system.  The goal of the mechanical advantage system is to reduce the amount of force needed by the humans employing the system.  It doesn’t change the force needed to pull the raft off the rock.  The rope inside the mechanical advantage system will see forces related to its location within the system.  Each leg of a 4 to 1 system will see a different load but none will exceed the peak load experienced by the anchor line or load line.

How does static vs dynamic rope affect the rope's ability to pull a static load (Specifically a raft off of a rock)? Static rope is the standard for that application, but why is static line more effective than dynamic line?

SR: Pretty simple. Never use a dynamic rope for pulling a static load when you can be using a static rope.  The amount of effort to take all the stretch out of a dynamic rope before it applies enough force to move a pinned raft would be astronomical. 

Not to mention that dynamic ropes are notoriously weaker than static ropes of similar diameter. Dynamic ropes and static ropes are tested in dramatically different ways and so the published evaluations are very difficult to compare. 

What kind of damage can hauling heavy static loads on dynamic rope do to the strength of the rope? Should it be retired after this?

SR: Dynamic ropes are not designed for maximum strength relative to diameter.  Therefore, dynamic ropes rarely if ever are given a break strength rating.  If a dynamic rope is stretched to its maximum extension it should be retired or at least never again used as any sort of life safety system.  Whenever rope is stressed damage occurs.  The extent of that damage is impossible to evaluate without destructive testing.

At what point should a rope be retired? 

Both Sterling and Blue Water say that rope retirement is at the user’s discretion. Rope retirement is an understandably difficult topic since there is no accurate way to test rope without destroying it. A few thoughts the manufacturers offered up though were that prolonged usage in dirty conditions can be cause for retirement as we mentioned above. Also visible mold, discoloration, UV damage, nicks, pulls in the fibers, or cuts are cause for concern. Finally if your dynamic rope has been stretched to maximum elongation it is likely not sound for load bearing applications any longer. Again this is a complex topic so its important to inspect your rope after each use to verify that it is in good shape.

Super Static 2 - Sterling Ropes

MSRP $ 157.95 (150 feet)

Lightweight and easy to handle, the 3/8" SuperStatic2 is a proven choice for rigging anchors and readily compatible with most ascending or rappelling devices.

• NFPA 1983: Technical

• Diameter (mm): 9.5

• Weight (lb/100'): 4.2

• Minimum Break Strength Rating (lb): 5,170

• MBS Rating (kN): 23.0

• Elongation at 300 lb (%): 3.6 

BWII+ Static Rope - Blue Water Ropes

MSRP $ 180.95 (200 ft)

The 1/2″ BlueWater Hybrid River Rescue Rope is a new addition from BlueWater. Designed with a unique hybrid sheath of alternating solution dyed Polyester and Polypropylene fibers it has a tensile strength rating of 5000 lbf. This rope has better cut and abrasion resistance than 100% Polypropylene sheathed ropes. The larger diameter is easier to grip especially with dry suit gloves. It features 100% Polypropylene block creel construction core strands. Buy American Act [BAA] qualified. Made in the U.S.A. Part #501900.

• Certification(s): CE EN 1891 Type A, UIAA and UL Classified to meet NFPA 1983/2017 edition standards for Technical Use rope.

• Diameter:    11.5mm (7/16″)

• Grams Per Meter:    61

• Tensile Strength:    3900 lbf. (17.3 kN)

• Weight Per 100 Feet:    6.55 lbs.

• Elongation:
  @ 300 lbf. = 1.6%
  @ 600 lbf. = 2.9%
  @ 1000 lbf. = 4.8%

Webbing

1” Tubular Webbing - Sterling Rope

MSRP $ 14.95 (30 foot wheel)

The standard in 1" webbing, Mil-Spec tubular webbing is favored by climbers and rescue specialists for slings and anchor systems as it offers exceptional abrasion resistance. As its name implies, Mil-Spec is also the standard webbing for military applications.

• Minimum Break Strength Rating (lb): 4000

• MBS Rating (kN): 17.8