How to Do a River Rapid Classification

River rapid classification is the best way to really understand what you may be in for when you sign up for a river rafting excursion. There are six classes on the International Scale of River Difficulty, ranging from I (1) to VI (6), with I being the easiest and VI being the most difficult. Understanding these classifications is a key element of choosing the right section of river to traverse.

Difficulty: Easy

Instructions

1. Determine what features are on the river. Holes or pour-overs, hydraulics, curler waves, pin-up rocks, eddies, waterfalls, drops and cataracts are all key elements that contribute to the classification of a river.

2. Estimate the weather in which you will be rafting. When air temperatures will be less than 50 degrees F, the rating of a river's difficulty will be raised by one full class, because there are serious dangers that come with rafting in cold weather. Taking a dunk on a rapid in freezing weather is far more dangerous than it would be in warmer weather.

3. Rate the river on its most difficult rapid. Even if a section of river goes on for miles with nothing more exciting than a Class III rapid, if it has just one Class V rapid along its length, it will be classified as a Class V river. You can learn more about the classification system on Raft W.E.T. (see Resources below).

4. Identify a Class I rapid by it gentle pace. These rapids are usually float easily through flatlands and have only small waves, if any. The channels are wide with no blind spots in the rafting path or obstructions in the water.

5. Spot a Class II rapid. Though still as gentle as a Class I rapid, a Class II will require a small amount of maneuvering. These are excellent rapids for beginning rafters.

6. Recognize a Class III rapid. The waves on this category of water are much higher than on a class II river and usually without any clear pattern. The rafting channels can be narrow, and maneuvering through them may require complex effort. Though there may be some blind spots on the run, the safest routes are still clear from the top of the rapids, so planning and navigating are still possible, though more challenging.

7. Skip Class IV and V rapids unless you are a very experienced rafter. In order to do proper maneuvering on these classes of rapids, you must be very attentive and able to read the river very well. Life-threatening obstructions are present on class IV and V rapids, and routes are no longer clearly visible.

8. Stay away from Class VI rapids unless you are on a team of absolute expert rafters and understand that there is very real danger while on these types of runs. Rescue efforts are nearly impossible, so do not expect to have an easy time if you are thrown from the raft.

Tips & Warnings

• Though the classifications themselves are consistent, rivers are not. While a river may be a Class IV during a rainy season, it may be only a Class II during a drought season.
• Western rivers are classified on a scale of I to X (10), so divide these classifications in half to get the International Scale Classification.

Who Can Help:

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Resources

• Raft W.E.T. for river rapid classification system resources.