The river’s dificulty to do rafting is determined by a “class or category” that is given to the river, according to the International Scale of Degree’s Difficulty of the Rivers.
This scale was developed by the AW (American Whitewater Society), a non-profit organization, founded in 1954 and whose mission is “to conserve and restore the resources of American White Waters and improve the opportunities to enjoy them safely”.
This scale, besides evaluating the American rivers, was created with the aim of being applied to all the rivers of the world; hence its international character. The AW promotes, that rowing sports are done with the greatest possible safety, and therefore, in addition to the scale of difficulty of the rivers, they have also made a Decalogue of Safety for the practice of rowing sports that we will develop in another post If I want to explain, what are the White Waters I have named above. It is the set of waters of the earth that are the basis of the production of water for human consumption. They are the waters of rivers, lakes or springs, which originate and will be treated for that purpose.
This International Scale is used both to measure the degree of difficulty of a river and a stretch of a river, or the rapids of the river, which ultimately is the main thing.
Each level or grade of the Scale reflects the technical difficulty and the level of skill required, associated with the stretch of river to which we are referring. It is used for different activities and water sports, not only for rafting, but also for canoeing, canoeing, paddle-surfing, hydrospeed …
Levels or Classes to classify the river
There are 6 categories that are called “Class” followed by a number and sometimes they can be associated with a + or a – depending on whether within the level or class, the rapid or the river, is of greater or lesser difficulty, thus representing, example: class III + or class III- that would mean, that it is a river or fast of Class III of high difficulty or Class III of low difficulty.
Class I (easy): They are waters that move quickly, with small or almost nonexistent waves and rapids. Little or no obstruction in the course, all of them if any, easily recognizable and obvious. They are easily overcome. The risk if there is a rollover or someone falls into the water, is minimal, you can even get out easily and just swimming, with the help of the life jacket normally.
Class II (beginner): Rapids with wide and clear channels, which are predictable without having made an ocular inspection on the ground before making the descent.
Sometimes, during the descent, maneuvers will have to be done, and medium-sized rocks and waves are easily avoided by the guides. If any of the crew of the boat falls into the water, it will rarely be injured, and the assistance of the rest, will rarely be necessary as well.Within this class, there may be rapids that due to their greater difficulty, are classified as Class II +.
Class III (intermediate): In this class, the rapids have moderate, irregular waves, and they can be difficult to avoid; In addition, they will easily flood the boat. Here complex maneuvers are required in the rapids, and also to avoid colliding in certain tight steps or with curves or plateaus.There are big waves, but they are easily avoidable.
They are characterized because there can be considerable eddies, especially in large rivers.Rarely injured someone who falls into the water, self-rescue is usually easy if this happened, but may be necessary assistance from the entire group of the boat to prevent the person who has fallen into the water, is dragged a considerable distance. Depending on the difficulty, rapids can be classified as Class III + or Class III-.
Class IV (advanced): There are intense and powerful rapids, but predictable, and that require a precise handling of the boat. Depending on the character of the river, large, unavoidable waves and eddies or narrow passages with demanding evasive maneuvers can be presented, under pressure for the guides of the boats.
Rapid turns may also be necessary to initiate such evasive maneuvers. It is advisable to take a reconnaissance tour of the section before making the first descent. The risk of injury to the crew of the boat if they fall into the water, is moderate to high, and the water conditions, could hinder the rescue.
If there is a fall to the water, the entire crew will have to collaborate, and an instruction on the part of the guides about how to undertake the rescue maneuvers should have taken place beforehand. Skill knowledge is highly recommended. The rapids, depending on their difficulty, may be classified as Class IV + or Class IV-.
Class V (expert): In this class, the rapids are extremely large, obstructed, or very violent, and expose the components of the boat to added risks.They are not predictable, and they have very large waves and complex, narrow and demanding steps. A certain aptitude is needed to be able to carry out the descent, since they are rivers with a lot of intensity level; that is, they are very dynamic, there are rapids continuously along the route.Ocular inspection is recommended in the field before the descent. From this class, included, we can make subclassifications of rapids; class 5.0, 5.1, etc …
Class VI (extreme unexplored rapids): This type of channels, has never been tried or almost never. If you decide to take a descent on a river of this kind, it can have very serious consequences, and rescue can be impossible. The descent of this type of rivers, only carried out teams of experts, and with favorable water levels, after having made a thorough ocular inspection at the foot of the river, and having made an intense preparation and planning of what is will realize. All precautions that are taken will be necessary. If there have already been enough descents of a river or section of Class VI, its change to the appropriate Class 5.X may be considered.