Whitewater - Classification of Whitewater

Classification of Whitewater

The most widely used grading system is the International Scale of River Difficulty, where whitewater (either an individual rapid, or the entire river) is classed in six categories from class I (the easiest and safest) to class VI (the most difficult and most dangerous). The grade reflects both the technical difficulty and the danger associated with a rapid, with grade I referring to flat or slow moving water with few hazards, and grade VI referring to the hardest rapids which are very dangerous even for expert paddlers, and are rarely run. Grade-VI rapids are sometimes downgraded to grade-V or V+ if they have been run successfully. Harder rapids (for example a grade-V rapid on a mainly grade-III river) are often portaged, a French term for carrying. A portaged rapid is where the boater lands and carries the boat around the hazard.

A rapid's grade is not fixed, since it may vary greatly depending on the water depth and speed of flow. Although some rapids may be easier at high flows because features are covered or "washed-out," high water usually makes rapids more difficult and dangerous. At flood stage, even rapids which are usually easy can contain lethal and unpredictable hazards (briefly adapted from the American version of the International Scale of River Difficulty).

• Class 1: Very small rough areas, requires no maneuvering. (Skill Level: None)
• Class 2: Some rough water, maybe some rocks, small drops, might require maneuvering. (Skill Level: Basic Paddling Skill)
• Class 3: Whitewater, medium waves, maybe a 3–5 ft drop, but not much considerable danger. May require significant maneuvering. (Skill Level: Experienced paddling skills)
• Class 4: Whitewater, large waves, long rapids, rocks, maybe a considerable drop, sharp maneuvers may be needed. (Skill Level: Advanced Whitewater Experience)
• Class 5: Whitewater, large waves, continuous rapids, large rocks and hazards, maybe a large drop, precise maneuvering. Often characterized by "must make" moves, i.e. failure to execute a specific maneuver may result in serious injury or death. Class 5 is sometimes expanded to Class 5+ that describes the most extreme, runnable rapids (Skill Level: Expert)
• Class 6: While there is some debate over the term "Class 6", in practice it refers to rapids that are not passable and any attempt to do so would result in serious injury, near drowning or death (e.g. Murchison Falls). If a rapid is run that was once thought to be impassible, it is typically reclassified as Class 5.