The International Scale of River Difficulty defines six classes of river difficulty. Keep these in mind when deciding what river to tackle the next time you go whitewater rafting.
Class I
EASY. Moving water with minimal waves and open spaces. Few and minor obstructions. Self-rescue is easy.
Class II
NOVICE. Straightforward rapids with some manoeuvering required over the fast-moving water. Rocks are evident. Self-rescue is usually easy but assistance can be helpful.
Class III
INTERMEDIATE. Rapids with moderate, irregular waves that make complex manoeuvers necessary. Powerful currents, strong eddies, strainers, and tight bends may be present. Scouting is recommended. Self-rescue is possible but group assistance is useful.
Class IV
ADVANCED. Difficult and powerful rapids that call for experienced manoeuvering. Holes, dangerous hazards, strong rollers, unavoidable waves, and constricted passages are the norm. Scouting is essential. Self-rescue is difficult and experienced rescue is necessary.
Class V
EXPERT. Extremely difficult, long, and violent rapids. The steep chutes, unavoidable holes, and waves need to be manoeuvered by experienced runners only. Eddies are small and rare. Scouting is necessary but not always possible. Rescue is dangerous and difficult even for experts.
Class VI
EXTREME. Unpredictable, dangerous, and almost impossible. Raft control is difficult. Not recommended. Severe consequences for errors and rescue may not be possible.
These are just guidelines. Rivers don’t always fit neatly into one category; they can change quickly so always use caution.
River Dangers
As you meander or barrel down a river, there are many things to watch for. Besides fallen trees, rocks and other obvious obstructions, beware of the following river dynamics:
- Wraps – This occurs when a raft hits an exposed rock sideways. If the raft does not slide around the rock, the current plasters the raft against the upstream face of the rock, pinning it there. It can take days to get the raft “unstuck”. If the raft meets a rock, everyone needs to move immediately to the rock side to avoid a wrap.
- Holes – Water flowing over a boulder or other obstacle has a hole on the downstream side where water flows back upstream to fill the void. This causes a swirling vortex.
- Strainers – Like a giant colander, these obstacles made of trees, debris and/or boulders grab ahold of solid objects while letting water through. Go around strainers. If you capsize and can’t avoid a strainer, turn onto your stomach and face downstream, pulling yourself over the debris with as much force as possible. If you can’t get out of a strainer, hold on and await rescue.
- Eddies – Found behind some rocks and next to riverbanks, eddies are a patch of still water where rafters can “park”.
- Rollers – Big curling waves that flow upstream onto themselves are rollers. These are caused when the riverbed rapidly changes pitch. Rollers can flip rafts over or trap boats.
Understanding currents and the power of the river is essential to a safe and fun day of whitewater rafting.
Sources:
- American Whitewater
- Wildwater Rafting Ltd.
- U.S. Department of the Interior, Bureau of Land Management
- Whitewater Rafting: The Essential Guide to Equipment and Techniques by Graeme Addison
- The Complete Whitewater Rafter by Jeff Bennett
Toby Welch - Toby is a full-time freelance writer who specializes in magazine articles, online writing, e-books, and manuscript editing.
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