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Whitewater
Kayaking
by
Stephen Marshak
Perhaps, 7000 year ago, kayaksboats with a sealed top, tapered
at each endbecame the principal means by which fishermen navigated
the icy waters along the coast of what is now Alaska. If a kayak
started to capsize, the kayaker executed a maneuver popularly called
the "Eskimo roll": with carefully time sweeps of a double-ended
paddle, she pivoted the boat through 360 (since their tops are sealed,
kayaks can’t fill with water) until it once again became upright.
Kayaking as a sport first developed just before World War I, and
by the 1930s it had become popular worldwide. Sport kayakers fall
into two groups: touring kayakers, who cruise long distances along
coasts or down quiet rivers, and whitewater kayakers, who join rafters
in challenging the rush of gravity in the rapids of a fast-moving
stream. Whitewater kayaking requires not only skill and strength,
but also profound knowledge or a river. Kayakers spend hours studying
a challenging reach of a stream, looking for a path that steer clear
of deadly boulders or falls.
Just as geologists use geology jargon to refer to parts of a river,
kayakers use their own jargon when describing rapids. For example,
riffles are small rapids above a shallow gravel bar; an eddy is a
protected stretch in which water circles lazily; a cushion is the
bulge or water that builds up over a submerged obstacle; a ledge
is a row of boulders across which a small waterfall develops; a chute
is a narrow channel between obstacles; and a hole is the depression
on the downstream side of a boulder into which water plunges and
overturns.
Depending on the violence of the flow, the size of holes, the vertical
drop across ledges, and the difficulty in finding chutes, whitewater
kayakers classify rapids from class I (easiest) to class V (virtually
impossible to navigate). The classification depends on the size of
the obstacles relative to the depth of the stream, the overall stream
gradient, and the discharge. As basic strategy, river runner aim
for chutes, try to avoid going over the top of a cushion (they prefer
to slide off the side), and steer clear of holes. They aim for eddies
whenever they need a rest.
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