Classification of White Water
The International Scale of River Difficulty is a standardized scale used to rate the safety of a stretch of river, or a single rapid. The grade reflects the technical difficulty and skill level required associated with the section of river.
There are six levels each referred as "Grade" or Class followed by a number. The scale is not linear, nor is it fixed. For instance there can be hard grade twos, easy grade three, and so on. The grade of a river may change with the level of flow. Often a river or rapid will we given a numerical grade, and then a plus (+) or minus (-) to indicate if it is the higher or lower end of the difficulty level. also note that while a river section may be given an overall grading, it may contain section above that grade, often noted as features, or conversely, it may contain sections of lower graded water as well. Detail of portages may be given if these pose specific challenges.
The specific grading system in Indian River:
Grade I - Easy
Sit back, relax swimming and go with the flow Small, easy waves: mainly flat water
Grade II - Medium
Practice for the big ones “Jail no Bail Mainly clear passages: some areas of difficulty
Grade III - Difficult“Golf Course”
Difficult passages: narrow in places and with high waves.
Grade IV - Very Difficult Long Rapids:
Waves high, irregular; dangerous rocks; boiling eddies; powerful and precise maneuvering required. Demands expert boatman and excellent boat and good quality equipment.
Grade V - Extreme Difficult
Long and violent rapids, following each other almost without interruption: riverbed extremely obstructed; big drops; violent current; very steep gradient.
Grade VI - Unraftable
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. If a rapid is run that was once thought to be impassible, it is typically reclassified as Class 5.