Reading the Water
"From Swerve of Shore to Bend of Bay"
Eddies Are Everywhere
By Tamia Nelson
November 18, 2003
Nothing lasts forever, does it? After a
pleasant interlude of unseasonably warm weather, a cold front swept across
the Adirondack foothills last week, tearing the last of the russet and gold
leaves from their branches. It was a wild day. As I hiked along a ridge
overlooking the Raquette River, the blustery wind made the loose drape of my
anorak billow and crack. It was all I could do to walk. Suddenly, a troupe
of chickadees scudded past me, hurtling pell-mell before the gusts. Only
their color distinguished them from the swirling, wind-driven leaves.
Keeping tight formation, they spun around and came up
into the lee of a thicket of jack pines. There they sheltered from the
wind, chattering tirelessly to each other as they foraged for food among the
I wasn't really surprised by their skillfully executed maneuver.
Canoeists and kayakers didn't invent eddy turns, after all, and air and
water are both fluids, with similar dynamic properties. The chickadees were
just doing what paddlers who feel the need of a breather often do: seeking
refuge in an eddy.
Eddies, it seems, are everywhere, and while few of us will be navigating
through the currents of the air anytime soon glider pilots, hot-air
balloonists, and windsurfers are the exception here it's good to get
into the habit of spotting eddies. They're certainly not confined to
whitewater rivers. In fact, you'll find them wherever a current meets an
obstruction. Some eddies are tiny. (Watch a water strider negotiate a
spring-fed rivulet to see just how small they can get.) On the other end of
the scale, you'll find eddies large enough to shelter a 500,000-ton Ultra
Large Crude Carrier. The eddies of most interest to paddlers lie between
these two extremes, of course. Let's take a closer look.
As any paddler who's dumped in a turbulent stream knows all too well,
riverbeds are not smooth, straight sluiceways. And every pothole or rock
leaves its impress on the current. The riverbank makes its presence felt,
too, particularly at bends, where the land forces the water to change
Come along and walk the right bank with me. (That's the river's
right, not yours or mine, and don't forget that the river likes to look
where it's going. It always faces downstream.) We'll go with the flow today,
starting upriver and following the run of the water.
Right across the river from us is a sweeper. You don't
want to find yourself just upstream of a sweeper, but each submerged
branch creates a weak eddy on its downstream side. Since the branches
ensnare much of what comes their way including luckless paddlers!
a substantial barrier may form over time, and the eddy will grow with
it. Such eddies can make useful staging points from which to rescue a
trapped paddler. They're no place for a novice boater, however.
Now look downriver. See the "slick" in the middle? Yep, it's that
curiously quiet area in midstream. It could be a boil a place where
water surges up from below and then oozes out in all directions. I don't
think it is, though. Watch the leaves being swept along on the river's
surface. Some of them drift into the slick near its foot. And what happens
then? They're carried upstream toward the head. Most make several circuits
before escaping to continue their downriver journey. Get the idea? Upstream
flow. Circular movement. Right! The slick is a weak eddy. You can bet that
there's a submerged bar or boulder just upriver. If the water level dropped
till the obstruction broke the surface, the eddy might well be more
powerful. It would certainly be more obvious.
When the river's in flood, however, the obstruction at the head of the
eddy will be buried so deep that the slick may disappear altogether. It'll
be "drowned out," in other words. It's a sort of paradox. Sometimes eddies
are stronger in low water than in flood. (But don't think that high water is
safe water. New and powerful eddies always appear when a river rises over
its banks, and dangers multiply. The dynamics of floodwater are best
appreciated from shore.)
Back on the riverbank, our walk has brought us to a bay. As the river
opens out, part of it doubles back on itself. See the leaves sailing round
and round? Another eddy. In effect, the riverbank acts as an obstruction.
Then, when the river is released from its constraining force, a new eddy is
Downstream of the bay, a rock spine juts out into the current. And below
it? Yet another eddy. Still further downriver, we come to
a "rock garden," a covey of boulders clustered together in midriver. Each
boulder has an eddy below it, and the eddies meld and overlap. The resulting
water music is a joyful symphony for experienced paddlers, but novice
boaters may have trouble finding the
beat. It's best to begin a paddling
apprenticeship by taking on eddies one at a time. A rock garden can give
a beginner more hard knocks than she can cope with.
Next, look across the river to the other bank. See any obvious signs of
an eddy? No? Neither do I. But it's a good bet that the shallow bay that we
can see is home to one. Call it a shore eddy. And I'll bet it would
be a good place to park your boat.
Our riverside walk is coming to an end. On the right bank, we find
another shore eddy. (What's the difference between a "shore eddy" and a "bay
eddy"? Scale and proportion. If it's a pretty good size, and if it's nearly
as deep as it is wide, it's a bay eddy. If it's not, it's a shore eddy.)
There's a long eddy below each bridge pier, too.
What lies ahead? The sea.
Rivers always run downhill, but the sea's nearshore currents change
direction with each tide. And the tides aren't constant. They vary from
place to place and time to time. The first rule of coastal navigation, then,
is "Know your tides." (Strictly speaking, "tides" are the sea's rise and
fall in response to the gravitational tug of the moon and sun. The resulting
currents are "tidal currents" and not "tides." But even professional
mariners sometimes nod, referring to the "set [i.e., direction] of the
tide." And so will I.)
To the experienced eye, the clues to the tide's direction aren't hard to
find. Unless the wind's blowing a gale or some lubberly skipper's left his
sails up, boats on single moorings swing with the tide, turning round so
their bows always face into the current. Buoys, too, are tugged by the tide.
They lean downcurrent, pointing the way toward the "set of the tide."
(Confused? I'm not surprised. While winds are named by the direction
from which they blow a north wind blows out the north
tidal currents are named according to the direction toward which they
flow. The tide is said to "set south" when it flows from north to south, for
example. Still confused? OK. Winds look back at where they've been. Tidal
currents, like rivers, look ahead to where they're going.)
Now it's time to take a closer look at an arm of the
sea. It's too far to walk, so what do you say to hitching a ride with a
passing hot-air balloon? Up, up, and away!
First, let's get our bearings. The open ocean is to the east, and the
tide is setting west into a deep bay. As the tidal current strikes the big
island, it forms a large eddy to the west. Large eddies also form west of
the promontories to the north and south, and behind the tip of the sand
spit. A small eddy will form downstream of each buoy, too. (The eddies below
buoys are not good places to park your kayak, by the way. The Coast
Guard and Harbor Patrol take a decidedly dim view of such practices.)
Farther west, a small river empties into the bay, and a delta has grown
up at its mouth. As the tide flows up the bay, eddies will form behind the
shoals and islands in the delta. But the picture will seldom be this
straightforward. The exact location of the eddies will depend on the
relative strengths of the tidal and river currents. You'll need local
knowledge if you want to do any exploring, and you'll want to be
particularly careful whenever the river is in spate or the tidal currents
are unusually strong. (As they might be, for example, if a storm surge
coincides with the flood tide.)
Today, however, the river's low and slow, and the tide's calling the
shots, forming a large, diffuse eddy complex to the nor'west. Later, as the
tide slackens, these eddies will weaken. Then, when the tide begins to ebb,
the tidal eddies will re-form to the east. Learn to anticipate these
changes, and you'll be able to "work the tides" to get where you're going.
It's one of the hallmarks of the expert waterman.
* * *
To less expert eyes, though, many eddies are invisible. But what if you
could see them clearly outlined? Well, sometimes you can. This was brought
home to me many years ago, on a late autumn day near North River on the
upper Hudson. High clouds veiled the sun, and the temperature hovered just
below the freezing point. The river was moving too fast for ice to form in
the main channel, but every eddy was starkly delineated by a frosty glaze,
gleaming alabaster in the watery light. The surface and shoreline were
dotted with these jewel-like plaques. I didn't have my camera, but no
matter. The image was burned into the emulsion of my mind.
Eddies are everywhere. You don't have to travel to the upper
Hudson to find them, and you don't need to be in your boat. Do you walk past
a neighborhood stream on weekends? Does your Saturday morning bicycle ride
follow a canal? Do you eat lunch in a park overlooking a river? Then take a
few moments to study the sinuous script of the current. Whenever you drive
along the seacoast or a riverbank, pull off the road from time to time and
watch the water's never-ending tale unfold. Make reading water a habit, and
pretty soon its secrets will be an open book. You only need to look.
Copyright © 2003 by Verloren Hoop Productions. All rights