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Reading Water: Using Rocks, Flakes

Updated: Dec 9, 2022

Photo: A nice cheat line over the left flake at David From Behind, Upper Quartzville Creek, Oregon.

Flakes are shallow rocks that have fast current going over them, and typically display air pockets on the downstream side. The speed of the current traveling over a flake allows rafts to ride over the top better than a similar depth pour- over rock in slower moving current. Some features related to flakes are called rooster tails or slides. Rooster tails refer to the water fanning off an underwater rock or obstacle. Flakes are considered hazards to rafts if they create a feature known as a rooster tail, which indicates the rock forming the feature is ramped up vertically, and possibly has sharp protruding rock pointed upward. Some flakes have their own names that sound something like the “can opener.” Obviously we want to avoid using a can opener on our inflatable floor. Besides being potentially sharp, another way a flake can become hazardous is if it is shallow enough to knock your raft off line or change your angle. Flakes come in all sizes, some just large enough to poke a hole in your floor and some huge enough to create a slide.

Photo: Lining up for the flake at the bottom of Rainie Falls, Rogue River, Oregon.

Rooster tails are easier to spot from upstream than most other river hazards, as water will be shooting vertically in a fan shape, literally sometimes taking the shape of a rooster’s tail or turkey tail. The more light you can see through the rooster tail veil, the more likely it is an extremely shallow rock creating the feature. Root wads and submerged trees are also likely to create this vertical ramp effect. A veil is the part of a waterfall that covers the air pocket behind it, but the term can be applied here to mean the part of the water flowing over the flake which we can see light through and air behind. Rafters should avoid running over any obstacle that creates a rooster tail.

Don’t confuse a pour over with a flake. Pour overs can be sticky and vertical on the backside and will look humped up and rounded when viewed from upstream. A friendly flake should look like a ramp from above. Look for an air pocket under the flake as well as more of a horizontal than vertical aspect to identify the difference. A flake is used differently than a pour over because a flake sets you up to land relatively flat on the downstream side of it. A pour over has a vertical backside followed by a hole and taken square on will result in a plunging bow and a raft that is set up vertically before landing.

Photo: Matt & Jaci on Federal Falls, Pauley Creek, California

We can use some flakes to our advantage, typically to clear a hole. Look for smooth flakes ramping downward that are the width of your boat and have at least several inches of water flowing over the top. In order to understand a little more about how a flake could be a useful river feature instead of just a hazard, we need to think about holes, also called hydraulics or reversals, and how they affect a raft. Holes are caused where the downstream current is diverted over or around a rock, ledge, or outcropping of some sort and the void left behind the rock is then backfilled aggressively with water moving upstream to fill in the low pressure area. The primary distinction between a hole and an eddy is that an eddy is usually a friendly place to be where water is recirculating on a horizontal plane. Holes are unfriendly places where water is recirculating on a vertical plane. Even small holes can be retentive. Downstream current in a hole is going to the bottom of the river before exiting the feature and upstream surface current is feeding back into that cycle. This creates a hazard for a boat; we can recirculate, surf or flip if we don’t clear the reversing portion of the hole by getting far enough downstream into the water that flushes.

There are different approaches to clearing a hole based on the feature, your craft, the style of river or creek, and your personal tolerance for adventure and mystery moves. Riding a flake is one way we can clear a hole because it both puts you further downstream and keeps the bow up. Sometimes there is a soft spot in the reversal behind the flake as well. Most rapids won’t include must –hit holes until you’re doing class IV or V, so start practicing hitting these features on class II to get a feel for how they affect your boat.

Photo: A must -hit hole. In a raft, aim for the furthest downstream point off the giant flake.

Flakes can be used to our advantage primarily when there is a wide or unavoidable hole that the flake provides an off ramp through. Landing a drop without plunging underwater will help us maintain control of the inflatable. Sometimes a mid - drop flake is just the ticket to ramp out the entrance and help the raft skip over the top of the whitewater, avoiding the bow plunging underwater and the raft bathtubbing out.

In oar rafts, especially gear boats, choosing the least vertical path and landing in the part of the hydraulic with the least retentive power is important because we don’t have a lot of control over keeping the bow up. A small empty boat or R2 will be able to control the bow more effectively. More on boof strokes later, but basically a mid – drop flake can be considered an auto boof, a maneuver adopted from hardshell kayaking. A gear boat can take the auto boof line, just look out for depth and know how deep you are sitting with all that beer, I mean overnight gear. At some point, a big flake with an almost vertical drop should be considered an independent feature called a boof or a drop. Stay tuned for future articles, boofing is up next!

Photo: Can you identify the most retentive part of the hole? Would you take the green tongue on the right or the boof on the left?

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