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Anatomy of a Lake
Unmasking Mr. Hyde
By Tamia Nelson
tamia@paddling.net
July 1, 2003
Few paddlers need to be reminded that
whitewater is dangerous. Rapids, particularly difficult (Class III+)
rapids, simply look mean. Rushing water smashes into rocks, creating
whirlpool eddies. Fast chutes end abruptly in serried ranks of towering
standing waves. Froth and foam are everywhere. On shore, the very ground
vibrates beneath your feet, and you have to shout to make yourself heard
above the crash of falling water. Only members in good standing of the
What-Me-Worry? Club can ignore such obvious warnings.
Lakes are different, though. On a calm, sunny, summer day, when the only
sound is the gentle whisper of wavelets against a sandy beach, it's hard to
believe that a lake can ever be a dangerous place, even for the least
skillful novice.
This, of course, is nonsense. Paddlers drown in lakes every year. Some
are probably drunk. Others are certainly incompetent. (Make enough mistakes
and even a farm pond can be a death trap. Ask
Farwell.) But a few just run out of luck, caught by one of nature's
capricious mood swings. One minute they're paddling on Golden Pond. All is
serene. Then, in a flash, the wind rises and the waves hump up, tossing
their boat around with as much giddy violence as any whitewater rapid.
Suddenly, without even knowing that they were auditioning for the part,
they've got a starring role in the The Howl of the
Weather. Their placid afternoon paddle has become a fight for life.
Every year a few unlucky souls lose the battle.
You'd never guess the latent violence of a slumbering lake from the
language we paddlers use, though. We dissect even the easiest rapids into
their component parts, rate each individual hazard, then figure a total and
assign a classification, and we do all this with the grim satisfaction of
an insurance-company statistician computing a new mortality table. But to
many paddlers, all lakes are just, well, flat. Flatwater. (Unless, that is,
they're "quiet water.") Beaver pond or Great Lake, it makes no difference:
both are flatwater. No more and no less. And who can imagine coming to
grief on anything flat?
The truth is very different. Lakes yes, even the smallest ponds
have Jekyll and Hyde personalities. I'm sure you remember how Robert
Louis Stevenson's respectable Dr. Jekyll became the murderous Mr. Hyde, to
the dismay of all his trusting friends. Well, lakes are like that, too. The
mirror-like calm of a summer lake is an inviting prospect for any paddler.
But once the breeze picks up, waves will begin to form, and if the breeze
grows into a gale, those waves can get very big indeed. The paddler
unfortunate enough to get caught napping by a summer
squall will have a lively time ahead of him.
When all aloud the wind doth blow.
Wind is to lakes what
the mysterious drug was to Dr. Jekyll, the instrument of their
transformation. Lakes vary in numberless ways size, shape, and
depth, to name only a few of the more obvious but all lakes have one
thing in common: once the wind starts to whistle, they all become basins
aslosh with waves. And that's only the beginning of the story. Let's take a
closer look. We'll start with a map of Lac la
Vieille.
Lac la Vieille
First things first. Rivers are always going someplace, but their waves
usually stay put. That's why they're called "standing waves." Lakes, on the
other hand, are just hanging out. They're not going anywhere. Their waves
are, though. Wind-driven waves are ceaselessly on the move, scudding ahead
of the breeze that gave them life. They grow bigger as they go, too. This
has important implications for canoeists and kayakers.
Return with me now to Lac la Vieille. A breeze has just begun to blow
from west to east. Since winds are always named for the direction
from which they blow, this is a westerly breeze. (Confused? Turn
around till you have the wind full on your face. What direction are you
facing? West, right? Then it's a westerly breeze.) We might as well
enjoy the ride. So we'll begin at the western end of la Vieille and let the
wind push us along as it sweeps down the lake.
OK. We've just put our boat in the water. The leaves near the tops of
the aspen are all a-tremble. Even some of the branches are dancing. But
when we look at the lake, what do we see? Little ripples. Wavelets. And
that's all. Ready? Let's go! Fun, isn't it? The wind's at our backs, for
once!
* * *
Hmm. We've been paddling for about half an hour, and things are
changing. It's not the wind. The breeze is steady. It's still coming from
the west, and it hasn't gotten any stronger. But the ripples that we
noticed when we started out have grown into waves rollers, really.
Feel how the canoe lifts with the passage of each crest and then settles
down into the following trough? The crests are only about a foot high, but
they're certainly not ripples any more, are they? What's going on here?
Nothing. Or rather, nothing out of the ordinary. We're just seeing the
effect of fetch on wave height. The longer the wind can push on the
water, the bigger the waves get. When we started out at the western end of
the lake, the wind didn't have much of a purchase. Now, however, it's got
almost two miles of running room, with no intervening obstructions. This
distance over open water is what sailors call "fetch," and it helps explain
why the surf's up almost all the time on the Pacific coast of North
America. A wind can pile up an impressive mound of water when it blows
across a big ocean.
Lac la Vieille isn't the Pacific, of course, and I don't think we're
likely to find ourselves riding the crest of a 40-foot breaker. But even a
two-foot wave can look pretty big from the seat of a canoe. And we've still
got a couple of miles to go. The wind's not dying down. Maybe it's time to
think about
Seeking Shelter from the Storm.
No, not right away. But suppose the wind strengthens a bit when we've
paddled another mile. And suppose these rollers grow another couple of
feet? A sheltered spot might look very welcome then, don't you agree?
What sort of shelter are we looking for? Simple. Anything that breaks
the force of the wind. An island. A bay. A rocky point or headland. Once
you've put a barrier between yourself and the wind once you're in
the lee of an island, for example the waves will diminish. You can
rest, bail, check your map. It's a bit like parking in an eddy
on a river, except that you're looking for shelter from the wind rather
than the current.
"In the lee of an island." Did this make you scratch your head? I'm not
surprised. It's a familiar phrase among sailors, but I don't often hear
canoeists and kayakers using it. That's understandable. Sailors are always
watching the wind. It's their engine, after all. At any given time, their
world is divided into two halves: a windward half and a leeward half. The
half of the world that lies in the direction of the wind, the half that
sweeps round before them, from one shoulder to the other, when the wind is
blowing square in their face that half is the windward half. Anything
going on out there is said to be happening to windward. The other half of
their world is said to lie to leeward (usually pronounced "loo-ard"). So
the lee of an island is simply the side sheltered from the wind.
Of course, leeward and windward aren't fixed and unchanging. They're not
like compass directions. If you don't count the slow, drunken wandering of
the earth's magnetic poles, north is north and south is south, no matter
what. But windward can become leeward as quickly as the wind can shift
round.
You've been warned. Today, however, the wind is westerly, and it's not
shifting. We've left our put-in miles to windward, and we're heading down
the lake toward the lee shore at the eastern end. "Lee shore"? It's a
phrase calculated to raise the blood pressure of any sailor. Here's why.
You can't sail into the eye of the wind. So a lee shore is a trap. Many
sailing ships have ended their days on one, pinned by the implacable force
of an unrelenting wind, then driven aground and broken up by the
hammer-blows of successive breakers. It's no wonder that sailors are
happiest when they have miles of open water under their lee, and the
nearest lee shore is well over the horizon.
We're paddling today, though, not sailing. Still, it's worth taking a
minute or two to consider what a lee shore can mean to canoeists and
kayakers. The little ripples that we left behind us at the start are now
good-sized waves. As we approach the eastern end of the lake and the water
gets shallower, these waves will start to bunch up. Then they'll get
steeper. Sooner or later, they'll begin to break. And we'll be in the
middle of it all, on a lee shore if we keep paddling before the
wind, that is. Maybe we'd better start looking for shelter in the lee of
the island, eh? First, though, let's take a minute to decide whether
we're
Out of Our Depth.
Most novice paddlers feel safest in shallow water, and it makes sense
not to stray too far from shore, particularly when your boat is an open
canoe. But shallow water isn't always safe water. Breaking waves are
dangerous waves, and waves begin to break when they "feel the bottom." This
usually starts happening when the depth of the water under a wave is only a
little more than the wave's peak-to-trough height. So if you're in the
middle of some good-sized waves, you don't necessarily want to run for
shallow water. Not until you've prepared yourself for a surf landing, at
any rate.
This also explains why shallow lakes have bad reputations. Farwell can
remember seeing every member of a party of very competent sea
kayakers they had just come back from Labrador, no less dump
in a sudden squall on Middle Saranac Lake. Breaking waves in mid-lake
caught the kayakers by surprise. One after the other, they went in. They
looked, he says, like a family of diving ducks. Fortunately, they all had
good rolls, and they came back up almost as quickly as they'd gone under.
Farwell watched the whole show from the seat of his pack canoe, nestled
close to the sheltered weather shore of the lake. He's very glad he didn't
get out of his depth that day, and that he'd taken time to
Map Things Out.
My little sketch map doesn't show the land's contours, but your
topographic map will. Study it whenever you plan to cross open water.
Consider all the likely wind directions. Look for sheltered lees (and
dangerous lee shores) under all conditions. Make your best guess as to the
effect of local topography on wind force and direction, too. A lake
surrounded by marshy lowlands is more exposed to the wind's sweep than one
that's ringed by forested hills. On the other hand, hills and valleys can
channel winds, magnifying or redirecting gusts. In really mountainous
country, watch out for downdrafts and back eddies near the bases of cliffs.
And keep your eye on the clock. If there's no front moving through, big
lakes are often calmest in the early morning hours. Later in the day, as
the sun heats things up, local convection starts driving a stiffening
breeze, and the wind continues to grow in force till evening. The upshot?
When you don't anticipate a frontal passage, plan any long open-water
crossings for the shoulders of the day.
Whatever the time of day, however,
Think Safety.
Stack the odds in your favor by following these simple guidelines:
- Wear your PFD always. Yes, it's summer. But death
doesn't take a holiday. And your life jacket won't do you any good if it's
stashed in your pack or tied around a thwart when you capsize, will it?
- Practice, practice, practice. The best way to learn how to
paddle in waves is to do it. Once you've mastered the elements of boat
control, get together with a few experienced paddlers. Pick a summer day
when the water's warm and a moderate (15-20 mph) breeze is blowing. Then
practice paddling with the wind coming from every point: ahead, astern, and
on the beam. Take oncoming waves at a slight angle, giving your boat a
chance to rise to the swell. Search for sheltered lees behind islands and
points. Then try a few surf landings on a lee shore. (Two- to three-foot
waves are plenty big enough to begin with. If you value your head, you
might want to wear a helmet, too.) Once you've had your fill of surfing,
why not paddle a little way offshore and try a few dump-and-recovery
drills? Just be certain your lunch is in a waterproof pack!
- Keep your eye on the sky.
Listen to the forecast, by
all means, but cultivate a weather eye, too. Weather
happens, whether or not you're ready for it.
- And on the other guy. Sometimes the greatest danger comes
from other boaters. If you'll be paddling in traffic, learn the Rules of the
Road and always observe the Gross Tonnage
Rule.
- Be prepared. Dress for
the water temperature, not the air temperature. Fit flotation to
your boat. Carry spare paddles, as well as a bailer (or bilge pump) and
sponge, and don't forget to secure your bow and stern lines. If you're
ready to graduate to really big water, learn something about sea
anchors (also called drogues or drift socks), and decide whether or not to
carry one in your boat. Match your boat
to conditions, too. Some boats pack canoes and low-volume kayaks,
for example have no business on big lakes.
- Keep in touch. It won't do you any good to travel with a
party if you get separated. Groups should keep together at all times on
open water. The slowest paddler sets the pace.
- Stay alert. If you're exhausted, you should be taking a nap
on shore, not paddling. The transit time from dead tired to just plain dead
can be surprisingly short.
- Paddle smart. Hug the weather shore if you don't like the
look of the sky. And when you can, hop from lee to lee to avoid the full
force of the wind. On the water, the shortest distance between two points
is seldom a straight line.
- When in doubt, doubt. Call it Fletcher's Rule. Know your
limits, and listen to your inner voice. If it's whispering No, no,
no, it's time to call it a day, no matter what your pride says. Come
back another time.
Lakes are delightful places to paddle, and summer is when they're at
their best. They're no place for the feckless or unwary, though. Mr. Hyde
is always waiting for a chance to show his teeth. Don't let him put the
bite on you!
The Howl of the Weather
Copyright © 2003 by Verloren Hoop Productions. All rights
reserved.
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