Useful Information

Grades of Water

Grades of water

The international grading system defines rapids by how difficult they are to shoot in a boat. Grade I is easy and Grade VI is very difficult. It’s important to know that difficulty is the only factor that affects the grading, though it shouldn’t be the only factor you rely on when deciding whether a river or a rapid is for you.

For a start, consider the objective danger of the rapid. Although the danger of a rapid is often linked to its grade, this isn’t always the case. For example, a grade II rapid that sweeps round a tree could be significantly more dangerous than its grade would suggest, whereas a deep grade IV into a flat pool might be a very safe proposition. Intimidation is also a factor that shouldn’t come into the equation - some waterfalls are very simple and safe propositions but are often overgraded because of their height.

Rapids can also vary in difficulty according to how much water is in the river. Most rapids get harder with more water, but this isn’t always the case. There’s been a trend to downgrade rapids as they’re paddled more and more frequently. Also, consider who’s grading the river — a grade IV to a novice club paddler might well be a very different rapid to grade IV according to a play boater.

Grade I Easy - moving water with the odd disturbances in the shape of small, regular waves and slight meanders.
Grade II Moderate - the water is faster and rapids are more frequent; rocks, waves and small stoppers are found but always with an obvious channel.
Grade III Harder - the pace quickens with fairly big waves, and stoppers which are quite capable of holding a boat firmly. Rapids are much more continuous and, although the route is fairly obvious, it is necessary to be able to maneuver the kayak well.
Grade IV Difficult - long stretches of heavy rapids and falls with irregular waves and often powerful holding stoppers. The route is not obvious from the water, and bank inspection is usually necessary. A mistake or swim could be serious.
Grade V Extremely difficult - longer rapids, large drops with very big waves, dangerous stoppers and rocks to negotiate. This is a challenge to any canoeist. Although never absent in the lower grades, in grade V, substantial danger is always a possibility. Continual inspection and/or protection is often necessary.
Grade VI Limit of navigation - a line down exists - just. Luck may often play a part. There is always a real risk to life. Very favorable water conditions and protection may make rapids of this grade feasible. Very skillful paddling and the ability to pick the ideal days are also involved. Most of the time, however, they are too dangerous to canoe.

Grading rapids is not as specific as, perhaps, we would like. There are a range of "grades within a grade" i.e. there are "soft touch" grade IV rapids, and "top end" class IV with a whole host in between. The words "grade" and "class" are used interchangeably - they mean the same thing.

Waterfalls vs Class VI

The new generation of boaters are running harder and harder falls, and at higher and higher water levels. There is a grey area where class VI runs into the, waterfall description. Many waterfalls are runnable only when the rest of the river is too low to contemplate. Often it is not feasible to run them when the rest of a river is worth doing. It is for this reason waterfalls are best portaged.

The grading of rivers is very difficult. Paddlers have argued about, chewed over and spat out the systems available. There is still no universal grading system that every paddler accepts and, even if there were, people would still grade rivers differently. Paddlers are subjective, no matter how hard they try to remain objective. It is tempting to grade a river as hard if one follows a poor line and takes a thrashing on a usually easy line: "it’s a hard IV" - "No, it’s an easy V"-type arguments are familiar to most.

Grades III, IV and V are usually where the discrepancies exist (and also most serious consequences) but this is not absolute. With harder and more dangerous rapids being tackled, there are more class VI rapids appearing. No grading system can be absolute. Where does class VI end and a new class VII start? Or, is it possible to extend grade VI as VI+, or ‘super sixes’ in order to cover all eventualities? Tunnels, sluices, and low bridges may increase the seriousness of particular rivers in particular places. Protection can, at times, make rapids and falls safer, as can prior knowledge of previous accident black spots. If a river is continuous at a particular grade, it will usually make it more serious but not necessarily more technical. The moves may be the same, but, instead of having to perform them over 100 metres, it may be necessary to do so over a few kilometres! Many paddlers survive class IV rapids but not class IV rivers. It is always harder to maintain skills over a sustained period of time. This, probably, along with the much bigger volume, are two reasons why many UK boaters get a shock to the system when launching on, for example, a comparably-graded US or even French river.


Unusual spate water can make normally safe weirs dangerous. Complacency towards weirs is always risky. There are various pointers to the presence of a weir:

  • Firstly, you may expect one because the guide say’s so. However, it is important to remember that weirs may change. New weirs may be built - eg. On the Strule River at Omagh. "Bad weirs", may be made much worse! For example, the weir on the Owenkillew is now a definite portage.
  • There may be an unnatural slowing to the river - weirs are often used to control the flow. There may be a distinct horizon line. There may be a roar or rumble on a flat section - ask yourselves why, but remember that very quiet weirs can be extremely dangerous as well!
  • There may be an old mill on the banks - eg. Upper Bann and the Lagan.
  • There may be new weir buildings or huts, or canalization as with the weirs on the Lower Bann.
  • The message is clear - keep your eyes open, scout well ahead, and if in any doubt, portage.

There are three categories of weirs:

  • Safe
  • Dangerous
  • Grey area - in which case they are dangerous!

Grey areas are anything that the particular paddler isn’t 100 percent sure about and should be treated as dangerous. The message is clear - if in doubt PORTAGE.

Information courtesy of Canoe Wales.

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