Sports & Utility Boats (SUBs) 

Classification of Rapids, Water Level, and Canoeists

By I. Herbert Gordon

Part of the planning of a canoe trip entails knowing what to expect on your trip. This is not so difficult to figure out when you are canoeing on a lake. For canoeing on a river, however, you should learn about the ratings given to rapids, water level, and even canoeists.



A skier is aware that a black diamond run is a lot steeper and more difficult than a green circle slope. Rapids, like ski slopes, vary in their intensity. The International Rating system classifies rapids as follows: Top Of This Page

Water Level

The characteristics of a river can change remarkably as the water level rises or falls. As you might expect, a set of Class II rapids can become raging Class IV when the water is abnormally high following spring runoff or heavy storms. Conversely, a Class IV can turn into a shallow pussycat when the water level is low in the late summer. Even normally calm stretches become turbulent and dangerous at flood stage, because the force of currents slammed this way and that by rocks and obstructions creates powerful and dangerous surface conditions.

An International Rating system has also been devised to describe river flow. The classification for a specific river may change from season to season; the following letter designations are used to describe water level and rate of flow:


The Appalachian Mountain Club rates canoeists on a scale of I through V. Check your competence against their ratings:

To the preceding list I would add a "Class A" to describe one who has virtually no familiarity with canoes or canoeing.

Should You Paddle That River?

Three elements must be evaluated before you are competent to judge your ability to handle a river: (1) your ability; (2) the class of rapids; and (3) the river flow level. You should have no trouble deciding whether you should paddle an unknown 12-mile stretch of the Foamy River when a friend tells you: Top Of This Page

"The first couple of miles are sort of flat, but then you'll run into five or six sets of Class II rapids just after you pass the old covered bridge on Route 6. There's a rock garden after the river swings past the only island you'll find on your trip. After that it's clear sailing, but the river normally runs pretty fast for the last 2 miles. Of course, you gotta keep in mind we've had a lot of rain the past two weeks, and I know before that the river was running maybe a little below Medium, but it could be Medium-High right now. If it is, you can run a set of ledges to the left of the island. Otherwise, stick to the right. And that rock garden might be a Class III set of rapids, a helluva lot of fun-it's usually just a lot of maneuvering.

A helluva lot of fun is right, that is, if you and your partner have the experience to handle this kind of water.

The moral: Know what to expect from a technical description of a river and from your own skill at the class of rapids and expected water level. Don't put yourself and your partners at risk. If in doubt, personally inspect the river first, or don't run it.

Canoe livery operators are excellent sources of information about the rivers they service and usually are quick to warn customers about any unusual situations. When the waters are dangerous because of high levels or unusual cold temperatures, most operators will cancel all rentals. The better ones will give out rain checks. Even if you have your own canoe, operators will be as ready to warn you about dangerous conditions as they are their own customers.

 (Excerpted from The Complete Book of Canoeing by I. Herbert Gordon with permission from Falcon Publishing.)

The United States Coast Guard Auxiliary is committed to reminding all recreational boaters to:


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Pages prepared by: Robert Daraio, DVC-VE 2006

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