I've been browsing in some physics books, two in particular. "Physics
Simplified" by Epstein and "Mad About Physics" by Potter and Jardonski (sp?).
The idea of both books is to pose puzzlers and then explain their answers. Both
have more than a handful of questions that apply to boating. One question
involves undertow that is created by a sharp turn in a river or stream. Another
concerns flow from a narrow channel into a wide channel and vice versa.

Suppose the turn is to the right. Then undertow is created near the left bank.
That is, water close to the bank moves downward, out to the center, back up to
the top, and then back to near the left bank, where it descends again. In the
case of channel width changes suppose the channel widens, then according to the
author, water will slow down as one enters the wide channel. The effect is that
when you enter a wide channel your body will move slightly forward as though you
are in a car and put on the brake.

In another instance a problem concerns a main channel, and a rock on the right,
which produces back flow. In other words the water flows clockwise around the
rock and back upstream. Finally, another problem, actually as part of the turn
question above, mentions that 1. water boiling up means water in that area is
rising, and 2. water whirling around means water is descending. Here is my
question. In general how does one use these ideas to his advantage when
paddling? For example, is there a paddling tactic that one should employ when
noting that one is about to enter slower moving water, and vice versa? As
another example, what tactic should be used when approaching boiling water?
Maybe these circumstances are handled by some general paddling strokes.

It just struck me that if these observations are right (the authors), then there
*might* be some way of handling them that is thought out and one could use to
there advantage instead of blindling paddling into the action.

Both of these books contain more problems and their solutions that are
applicable to paddling.
--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

"To a person carrying a hammer, everything looks
like a nail."--Old saying

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