Rapids and weirs provide plenty of drama on a river. But it is not the weir walls or the rocks in the rapids that are the most feared obstacles. The real killers are "strainers" or obstacles stuck in the river, around which (or even through which) the river flows unabated, often resulting in the paddler getting pinned helplessly against the obstacle.
What is a strainer? As the name implies, anything that allows the flow of the river to pass through easily can be called a strainer. Classic examples of strainers are trees.
Think of the first day of the Berg Marathon. Or the first few kilometres of the Upper Umgeni below Albert Falls. Or any river in flood, where the flowing water spills into trees on the bank. The river flows fast through trees rooted in the river bed, allowing the water to flow through easily, but presenting the paddler with a frightening web of branches that can hold a person or kayak easily.
Other examples of strainers are man-made structures like poles, fences, reinforcing rods sticking out of concrete debris, or trees or poles or even low level bridges that are lying at or just above the level of the water surface. Reeds and Palmiet can be deadly strainers as well, as can hyacinth.
Step One - Spot it well in advance. So what does a strainer look like from the water? Most fixed obstacles like rocks caused the water to deviate around or over the obstacle, and whip up water formations and waves that help in identifying the obstacle's vital features.
The key identifying feature of a strainer is that it doesn't make much impact on the flow of the water at all, because the flow of the river through, around or under is not slowed or deflected at all. So the identifying characteristic is the lack of turbulent water!
Step Two- Avoid. Obviously, try to avoid the strainer as far as possible. Bear in mind that you will have to work a lot harder to cross the current, because it is not being slowed or deviated by the strainer. Anticipation, and reading the river far in advance are crucial to being able to paddle away from a strainer.
Also useful here is the knowledge that water moves slower on the inside of a corner, so if you are confronted with a tough decision about where to try and get away from the most dangerous part of a strainer (like a tree that spans the entire river), it always makes sense to head for the inside of a corner. The river flows slower, and if you are pinned, the grip of the water will be weaker and hopefully easier to get out of.
Step Three - Contact! This requires a lot of courage and control, because it flies in the face of your natural instinct. When confronted by a serious strainer that you cannot get away from, lean INTO the strainer at contact, NOT AWAY from it.
It is quite natural to want to try and avoid the strainer, but, sitting in a kayak, it is the worst possible thing to do.
By leaning away from the obstacle, you will be tilting the kayak up on the strainer-side, and down on the upstream side. The second that you slow down in making contact with the strainer, the force of the river flow will push down the upstream side of your boat, and almost certainly flip you over, and under the strainer, which is exactly where you do not want to be.
By leaning into the strainer, you will create a situation where your upstream side of the boat is higher than the side nearest the strainer, and the water will flow under the boat without tipping you over. If you are able to hold or lean into the strainer, you will be able to keep steady. And almost surf in this position.
Step Four - Getting out of there. From this stable position leaning into the strainer, and surfing the water with the upstream rail held high, you can start pulling yourself towards safety.
Think the escape route through, carefully through. If you have been pinned against a branch, it is not a good idea to try and pull yourself to the thinner end of the branch, as it will become increasingly difficult to support yourself on the thinner branch, and you may well get pushed deeper into the tree.
It is often a better idea to head for the most secure part of the strainer, and ideally claw yourself towards the bank, from where you can scramble to safety, where the water is moving a little slower.
Sometimes you do not have that luxury. The strainer might be plain nasty, the water flow too great, or maybe there is no workable escape route at either side of the strainer. Recognise that you are in a very dangerous situation, and you priority is saving your own life. From the stable position try to pull yourself up onto the top of the strainer, and out of your boat, which will almost certainly be swept under, into or through the strainer.
Be grateful that you were able to escape, and worry about trivial issues such as recovering your boat and equipment later.
Strainers are the greatest killers in canoeing. Treat the with a lot of respect!