Understanding Holes

Understanding Holes

by Teresa Gryder

a Carolina Paddler Reprint

This article first appeared on the Lower Columbia Canoe Club website.

[Author’s Note: This is Part 1 of a series about holes in which we talk about what makes holes, and which ones are fun versus dangerous.  Part 2 is about surfing in holes, which is the skill that makes it possible to get out of a hole while still in your boat. Part 3 is about swimming in holes and rescuing swimmers from holes.]

PART 1: UNDERSTANDING HOLES

In whitewater boating, a hole is something to respect. We are taught to avoid them. We take sneak routes through rapids to stay away from them. If there is no alternative, we run them. You can usually punch a hole, or boof over the top of it. You can get pretty good at boating before you ever get stuck in one. But eventually it is bound to happen.

I learned about holes from paddling back east, where there are lots of bad holes. Woodall Shoals on the Chattooga River was picking off rookies after the 1972 release of the movie Deliverance. I was so scared of holes that it took me years to learn to punch them, much less play in them.

FLUVIOMORPHOLOGY

A hole is a water formation on a continuum between a breaking wave and an eddy. Add enough water to a hole, and it washes out to a wave. Take away water and the hole becomes an eddy. Add lots of water to a river full of boulders and you have what we call a “golf course.”

Things can get stuck in holes and not wash downstream. Some holes are stickier than others. The nature of a hole depends on the shape of the drop, the depth of the pool below it, and the speed and volume of the current. Water falling downstream over an obstacle will push downward until it hits the bottom, or its energy can dissipate into turbulence.

While the main current is pushing to the riverbottom, the surrounding water slides upstream toward the foot of the drop to fill in the depression. This is called the backwash, backroller, or tractor beam. Things that float (like boats) get pulled back up into the seam between the falling water and the backroller. Things that sink go with the downstream current which eventually boils to the surface some distance downstream from the drop. Where the current surfaces again is called the boil line.

SURFING HOLES

There is a gray area of features called holes that are actually breaking waves.  Breaking waves are fun to play in. If we flip over, we wash out. A breaking wave has a pile of whitewater where the wave is falling over on itself. This “pile” or “soup” is the best place to do cartwheels and other freestyle stunts. A big pile can stop you (hence the name “stopper”), fill you up, slap you around and flip you over.

A “turkey wave” is a one that crashes sporadically and might “gobble” you up. But if you flip, or if you are swimming, you will wash right through it. At worst it could hold you for a moment or two, and then spit you out. If a “hole” is really a big wave with a foam pile, you can probably bust right through it, and you might even try to surf it someday.

POUROVERS

A pourover is a narrow hole, formed by the water falling over a rock in the river.  Pourovers can be very sticky, even when small. People talk about smiling and frowning holes; pourovers can frown. Looking downstream at a frowning pourover, the edges of the hole curve upstream around the rock. This type of hole is harder to get out of because the edges are upstream and possibly higher than the middle of the hole.

Another kind of especially bad frowning hole is the horseshoe hole, which forms in a recessed spot in a ledge. A smiling hole, with its edges feeding downstream, is much easier to get out of. A good rule of thumb is that if you can SEE the pourover hole (while paddling downstream) you can probably punch it. Don’t run what you can’t see.

LEDGE HOLES AND LOW-HEAD DAMS

Some holes are treacherous. They may look benign, with a gentle drop into a quiet pool. Be suspicious any time a hole is river wide, or the river looks very flat downstream from a drop. Bad holes are often called keepers or hydraulics. Usually they are worse at high water. Look for the boil line, where the water comes to the surface below the drop. The farther it is from the seam to the boil line, the worse the hole is. If the current going back into the hole is strong, look out; it could recirculate you.

The worst keeper holes are often man made. Low-head dams are called “drowning machines” in swiftwater rescue because rescuers have been killed in them. They are likely to contain jugs, logs, shoes and other floating debris. There may be feeder eddies on both sides, and no current going downstream anywhere.  It is smart to portage dams and other bad holes.

NOT ALL HOLES ARE BAD

With all this said about bad holes, most holes are just friendly, maybe a little frisky, but generally not dangerous. They toy with you but an active paddler or swimmer will easily escape from most. Some are fun to jump into. If you’ve ever tried body surfing in the ocean, you have played in friendly wave-holes. When you are looking downstream and see a fast wave train that continues moving downstream, you know that the holes in that wave train are not of the keeper type.

If you are not completely clear about which holes are bad and why, experience will teach you. You can learn a lot from tossing sticks into a creek, and seeing what miniature holes do to miniature boats. You can learn even more from watching really good paddlers, like slalom racers, use holes to maneuver.  And you can learn from watching other’s mistakes, while you cautiously scout, portage, and set rope.

Upcoming articles on holes are about surfing and swimming–in self-rescue and rescue of others.

Teresa has been running rivers since the 1970’s and now lives in what she calls Whitewater Heaven (the Pacific Northwest). She has worked in the whitewater business for most of her life and loves the community that grows around the river. These days she mostly kayaks but has acquired a packraft and can occasionally be spotted in a canoe or raft.

Teresa is Safety Chair for the Lower Columbia Canoe Club. “Safety is a personal passion project for me.”

This article was originally posted on the Lower Columbia Canoe Club website.   We thank Teresa and the LCCC for allowing us to use this.