"Difficulty does not always reflect consequence, and the consequence does not always reflect difficulty. Calling a rapid “a chill class V” or “a big class IV” does not change the physical rapid; the terms only change our expectations and our perception. Some will underrate a rapid not to scare a friend, others will overrate a rapid to inflate their egos, and others still will give you their honest classification and be wrong in your opinion."
paddlingmag.com

Difficulty Demystified: A Modern Guide To The Rapids Rating Scale
The scale is not an exact science. Here’s what you need to know.
