Eddy

From Wikipaddle

Eddies are areas of still or reverse (upstream) moving water. They are formed on rivers when the water comes up against an obstacle (most commonly rocks) and has to pass around it, creating a void in the flow directly downstream. They are used in whitewater kayaking to slow down the rate of descent down a river, to regroup after sections, to paddle upstream with ease, and to safely stop to look at what's coming up ahead.

Eddies can be caused by large rocks in the middle of the river, by outcrops on the sides, or indeed by any fixed obstacle in the flow of the river.

Recirculating Eddies

These eddies are commonly to the sides of other features, such as weirs or drops with stoppers. They may also be formed where the main flow runs up against a wall or obstruction and some of the current flows back upstream. In these eddies the flow is constantly moving upstream (or occasionally all over the place), usually being drawn in by a stopper. Although these can be useful for getting upstream quickly (especially for playboaters wanting to get back onto a wave or hole), caution should be taken as the flow is often erratic and novices may be unwittingly pulled into the feature.

Eddy Hopping

This is the practice of moving from one eddy to another whilst progressing downstream. It is often used in whitewater where running straight down the river may be dangerous. This allows the leader of a group to move from one safe point to another and check what's coming up ahead downstream. It also allows groups to maintain Line of Sight down a rapid by moving one at a time from eddy to eddy, following one another down.