What does Class III-IV mean?

When I see a whitewater classification of III-IV (or any hyphenated classification,) does it mean that a given river is rated roughly between 3 and 4, or does it mean that certain rapids on the river are 3s and others rate a 4?

Nothing in the AW rapid classification
is amenable to exact translation. I suggest joining AW, going to the river descriptions, and examining them in detail, because no one is going to give you a working rule that is satisfactory in all cases.

It’s like NOAA and the percent probability of precipitation. Does 40% mean that it will rain about 40% of the day? Or does it mean there is a 2 in 5 chance that it will rain at some time in the day, for an unspecified length of time? If you read the forecasts and put them alongside of actual precipitation, you’ll see that NOAA hasn’t made up its mind.

It means three things
The river has in the normal range of water levels, from low to high (but not flood), has:

  1. At least one class 3 rapid and maybe more.

  2. At least one class 4 rapid, but perhaps only at higher water levels, and maybe more.

  3. Nothing harder than a class 4 rapid.

    The definitions of class 3 and 4 vary from person to person and region to region. A paddler should be of at least high intermediate skills with a lot of class 2-3 experience before attempting a 3-4.

For me…
it probably means that I am going to take a swim.

I consider myself to be a decent class II/III paddler. Still, I have about a 50/50 shot of making it through a tough class III rapid. I have only done one of what I consider to be a real class IV rapid - the Funnel on the Lower Millers. I got out quickly, but my boat took a long swim. :wink:

I’ll step it up on occasion and paddle a tougher rapid on a river that is otherwise within my skill level, but the rapids are usually short, and it’s always with the right group.

There are plenty of people who can do it, but you won’t find me on anything that is continuous class III/IV. For me, that would be a long and miserable day.

Sometimes flow or route dependent
The way I learned it, class III is large standing waves and or big drops with a simple downriver clean line through it. Class IV is the same thing with “sequential maneuvers required” meaning the line through isn’t so simple and you may have to go over a drop, catch an eddy behind a boulder and peel out on the other side (that’s an example, not a required set of conditions). At some water levels, the obstructions that require the special care and make it a IV may get washed out and it becomes a III. Conversely, a runnable class III drop might turn into a boat eating hole at higher water requiring skill to get around or through it and become a IV or even V. Sometimes it depends on how you run it; left side might be a III, right side a IV (again, just an example).

Are you looking at a particular run?
As others have said, while there are definitions written the exact Oh Shit quotient can vary from region to region based on what people are used to. A class II in the northeast may be regarded as a I by someone from out west or the southeast for ex. But class III-IV should require solid skills regardless of part of the country.

I suspect there are certain runs that you are looking at - am I right? If that is the case you may want to ask about those, especially if they are runs below controlled dam releases that vary based on release level and time.

No exact definition

– Last Updated: Mar-19-14 10:30 AM EST –

If you look at the American Whitewater international scale of river difficulty:


you find that the definitions are not precise and are open to individual interpretation. For example, "moderate, irregular waves which may be difficult to avoid" for some, may be easy to avoid for those with better water reading and boat control skills.

Many whitewater runs are rated according to the difficulty of the most challenging and highly rated rapid on the run. But the nature of a run with widely spaced rapids and a single Class III with a nice, big recovery pool below it is very different from one with many closely spaced rapids and fairly continuous action. The latter type of run may have no rapid more difficult than a Class III but the consequences of a misstep might well include a long swim and lost gear. Some would therefore rate such a run as Class III-IV even if there are no true Class IV rapids on the run.

Some would use a Class III-IV designation for a run that some consider Class III and others consider Class IV.

You might also see a designation like Class III(IV) which is usually taken to mean a run that is essentially Class III with a single rapid that rates a Class IV that might be sneaked or portaged.

But you will probably find as many definitions for classifications of this type as boaters you happen to ask.


no good
That link doesn’t work, even if you copy the “start” at the end.

The definitions in the wiki entry I cited are the same, however.

scottfree’s fav. paddling spot is …

– Last Updated: Mar-19-14 11:22 AM EST –

...... Ohiopile , PA.

Some here have paddled sections of the Yough scott , so if it's a certain section you're thinking about

all I know of WW is the tighter , steeper and more technical it gets ... the higher the class rating and the more dangerous

also think cl 3 is divided into increasing difficulty levels like 3.1 through 3.5 ... before cl 4 comes into it .

Just curious, really.
Yes, I live just a few miles from Ohiopyle, and am very familiar with the various sections of the Yough. What sparked my question, though, is a small creek eight miles in the other direction. (The Big Sandy) I’ve never seen a boat on the particular section I’m interested in, and I’ve never paddled it myself. There’s very little info on the net about it beyond that its a five mile run and it’s listed as Class I-II. Really, my question is just out of curiosity as to the meaning of the hyphen. For this particular case, it really doesn’t matter. In others, though, it may mean taking a particular boat instead of another.

I’ve always looked at those stupid ratings as BS!! IF you tip over in Class-1 is’nt that a Class-IV to you?

I think it is common to do that for a stretch of river. A class II stretch is kinda fun as that generally means small waves and therefore good current all the way. A I-II means a lot of flatwater, which may still have okay flow with some small waves here and there. At least that’s how I use it. Earlier I mentioned what I think III-IV is when discussing a rapid; I think there is a tweaky difference when talking about the whole run and starting with I.

You learned wrong. Go back and read
the AW classification. A clear, open line is not guaranteed in class 3. Big waves aren’t a necessary feature either.

Sorry, wrong again.

Just means you’re a crappy paddler :slight_smile:

I think I have a decent idea of the difference between the different classes, but one thing that is seldom formally taken into consideration when trying to describe a river by its classification is the volume of the river. A class III river that normally flows 500 cfs is a far different animal than a class III that normally flows 5000 cfs, or 15,000 cfs, requiring different skills and different boats. Not to mention those rivers whose classifications are highly dependent upon water levels. For instance, the upper St. Francis in Missouri may have some class III rapids when it’s flowing at 150 cfs after a June rainstorm, but it’s a whole lot different at 1000 cfs in March, even if the rapids might still be class III. I’ll take my solo canoe down it with little extra equipment or preparation in the June scenario, but I know I’m in a whole lot more danger trying that in March.

The rating system is imperfect

– Last Updated: Mar-19-14 3:22 PM EST –

Strictly speaking, Class I water is not flat water or even moving flat water but involves at least some riffles or smaller waves.

Moving flat water is actually classified A, B, or C depending on speed of the current. Class A moving flat water can easily be back paddled against. In Class B moving flat water position can be maintained by most individuals with vigorous back paddling and in Class C the current velocity is generally greater than most folks can back paddle against.

Class C moving flat water in which the current velocity is 7 knots or greater and there are rootwads, strainers, or significant deadfall in the streambed can be significantly more dangerous and challenging than Class I whitewater.

Part of the problem with the classification system is due to the fact that different people find different types of flow more or less challenging. Some folks are challenged by relatively low volume, technical Class II rapids in which precise boat maneuvering is required to avoid pins even though the water is not at all "pushy". Those same people may have good balance and bracing ability and not be intimidated by larger volume rapids with sizable waves and even non-retentive holes, even when those rapids are rated Class III.

Other problems are that many runs and rapids have been significantly down-graded over the years as equipment and skills have improved, and the fact that river difficulty can vary enormously with volume, as was mentioned.

Part of the rating system is based on the consequences of failure to make necessary moves. One thing that is certain regardless of skill level, the consequences of tipping over and swimming in a Class I rapid will almost certainly be different from those of a Class IV rapid.

Imperfect as it is, there has to be some type of system to help boaters unfamiliar with a certain run to judge whether or not it might be within their individual skill level. The rating system is better than nothing, but the best way of making this judgement is probably by asking someone, preferably familiar with your boating ability, who has made the run at a volume similar to that which you are contemplating running it at, to compare its difficulty relative to other rivers you have successfully run.

NOAA percentages
The percentages refer to coverage of an area that is likely to get rain, e.g., 40% chance of precipitation means that 40% of the reported area will get rain and 60% will not.

It’s like saying a high school senior girls class has 40% chance of being pregnant. There IS no such thing as 40% pregnant in an individual from that class.

or means or
So big waves aren’t necessary. So much of this is subjective that trying to nail it down exactly is futile. III is intermediate and IV advanced. You can pick nits if that makes you feel smarter.

still a nit, you’re still trolling
but if it makes you feel better about yourself I am all for it. Enjoy…