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

Web Page: home.earthlink.net/~mtnviews

W. Watson wrote:
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's all a matter of degrees and direction. If you're going with the
flow and you paddle into a wider area where the current slows, so do
you, but the difference in speed doesn't create any problems. The same
is true going from slow to fast water. It's not like you're getting
slammed around, just gradually accelerating or decelerating. It's
different if you're entering an eddy from a fast flowing current or
vice-versa, but that's not the question you posed.

As for boiling water, it depends on how much boiling is going on. In
water where the upwelling just makes a relatively flat "footprint", it's
no big deal. If you enter off-center, it will push you slightly toward
the outside of the boiling area, but that's pretty much all you'll feel.
Standing waves could be considered as large boiling water, but they
require an entirely different set of skills.

Hi W,

You ask "In general how does one use these ideas to his advantage when
paddling? The general answer is that you can take whitewater paddling
classes or paddle with experienced whitewater kayakers. You need
whitewater skills to safely paddle strong flows that exhibit these
characteristics.

In whitewater, these water flows occur regularly and often intensely.
The whitewater paddler has to know how to handle them. These flows, and
others, are the reason whitewater paddling is so much fun.

In sea water, these water flows do occur, but usually not as regularly
or as intensely. However, it is wise for the sea paddler to have
whitewater skills also.

I learned more about paddling in one year of whitewater than in my
previous 10 years of sea kayaking.

Al Kubeluis

W. Watson wrote:
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.

I try to reduce paddling effort any way I can. That includes reading the
wind and current and taking evasive action to avoid both when they are not
going my way, and taking advantge of any going in my direction.

--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
warning: non-FreeNet email must have "notspam" in subject or it's returned

In article et,
W. Watson wrote:
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.

I've certainly observed an effect like this at bends in a river. What happens
is that the river undercuts the bank on the outside of the bend, and piles up
loose material on the inside, creating a sandbar. You have to watch for downed
trees hanging off that outside bank! But there's also likely to be circulating
water just off the sandbar, as the main current passes by closer to the
outside of the bend. What can happen is that you come along at a good clip,
you see the bend ahead, and you say, "Might get pushed into the bank--might
hit strainers--stay well to the inside!" So you head to the inside of the bend,
you think staying out in the center far enough not to run into the sandbar.
But what happens is that the bow gets into the circulating water behind the
sandbar while the stern is still in the main current, being carried downstream.
The result is that the boat turns suddenly and unexpectedly. Usually it's just
an embarrassing thing, not dangerous, but it can be puzzling as you think
there's a smooth flow of water around the curve. The right course seems to be
to stay just in the downstream flow in the middle of the river, neither
getting swept to the outside nor getting turned by the different speeds of
flow.

John Purbrick wrote:

In article et,
W. Watson wrote:

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.


I've certainly observed an effect like this at bends in a river. What happens
is that the river undercuts the bank on the outside of the bend, and piles up
loose material on the inside, creating a sandbar. You have to watch for downed
trees hanging off that outside bank! But there's also likely to be circulating
water just off the sandbar, as the main current passes by closer to the
outside of the bend. What can happen is that you come along at a good clip,
you see the bend ahead, and you say, "Might get pushed into the bank--might
hit strainers--stay well to the inside!" So you head to the inside of the bend,
you think staying out in the center far enough not to run into the sandbar.
But what happens is that the bow gets into the circulating water behind the
sandbar while the stern is still in the main current, being carried downstream.
The result is that the boat turns suddenly and unexpectedly. Usually it's just
an embarrassing thing, not dangerous, but it can be puzzling as you think
there's a smooth flow of water around the curve. The right course seems to be
to stay just in the downstream flow in the middle of the river, neither
getting swept to the outside nor getting turned by the different speeds of
flow.

Interesting. That's fairly close to what I had in mind, although it's kind of
tough to explain it.

My question borders on suppose we are back 400 years ago and know almost nothing
about modern paddling techniques. Maybe I'm an indian (American) on a river in
the midwest. The tribe has noticed something about the way water flows. Perhaps
it's on a river the tribe has never seen before. How do I turn that into a
response while paddling?

Perhaps another way of thinking about this is to assume you are blindfolded and
paddling down the river, and you are with a companion. He says, "Small eddy dead
ahead." What do you do to prepare for it?

As another example, maybe more realistic, suppose you are given some sort of
waterflow map of a river that you have never been on. How do you prepare for it,
tactically or technique wise, without ever having been on it and only knowing
from the map of a written description what to expect?

I guess this gets down to how do you analyze water flow and your reaction to it
in order to navigate it?

--
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

Web Page: home.earthlink.net/~mtnviews

My question borders on suppose we are back 400 years ago and know almost
nothing
about modern paddling techniques. Maybe I'm an indian (American) on a river in
the midwest. The tribe has noticed something about the way water flows. Perhaps
it's on a river the tribe has never seen before. How do I turn that into a
response while paddling?

If you were an Indian not knowing "modern techniques" I'm sure you'd know
"ancient techniques" that were every bit as effective! The point is
"experience". You come to a bend in the river that you've never seen before,
and you have a good idea of how to handle it because if you haven't seen that
particular bend, you've seen plenty of other bends and they all had something
in common--what we'd call "physics".

Perhaps another way of thinking about this is to assume you are blindfolded and
paddling down the river, and you are with a companion. He says, "Small
eddy dead
ahead." What do you do to prepare for it?

As another example, maybe more realistic, suppose you are given some sort of
waterflow map of a river that you have never been on. How do you prepare
for it,
tactically or technique wise, without ever having been on it and only knowing
from the map of a written description what to expect?

Once again, experience is the key. Based on a verbal description or a map, you
know what to expect when you get there and how to deal with it. You could say
that you "speak the language" that allows you to turn the description into
a realistic plan of action. It would be just like a description of anything
that wasn't right there in front of you but you had a basic familiarity with
that kind of situation--you'd know what it was likely to be in reality.

In fact this kind of thing does come up in whitewater canoeing: you don't get
an intimate look at every drop before you go through, but someone may give
you a quick description ahead of time. "Head right just after you get round
the first bend, then watch for the main stream rejoining on the left. Then
there's a choice of gaps between the big rocks--just left of center is best
in this kind of water, and you can make a quick run there, or set over to it.
There'll be some big standing waves on the run-out, and you may pick up some
water. There's a nice big eddy on the left at the bottom and we'll meet there
and anyone who needs to empty their boat can do it there."

Stuff like that.

W. Watson wrote:

My question borders on suppose we are back 400 years ago and know almost
nothing about modern paddling techniques. Maybe I'm an indian (American)
on a river in the midwest. The tribe has noticed something about the way
water flows. Perhaps it's on a river the tribe has never seen before.
How do I turn that into a response while paddling?

Excuse the glib response, but you do it the same way those guys did,
many miles on the river.

Perhaps another way of thinking about this is to assume you are
blindfolded and paddling down the river, and you are with a companion.
He says, "Small eddy dead ahead." What do you do to prepare for it?

There's almost never an eddy dead ahead. Eddies are caused by
obstructions of one sort or another--rock, point, fallen tree, bank,
pourover--so that's what will be dead ahead. The way to prepare for an
eddy is to get a little speed up and paddle straight across the eddy
line, which means you have to be out away from the obstruction to get
the proper angle. Then heel the boat down current as you cross the
eddyline, which will probably be "upstream" from the point of view of a
guy on the bank. Failure to heel when needed is a major cause of wet
paddlers.

As another example, maybe more realistic, suppose you are given some
sort of waterflow map of a river that you have never been on. How do you
prepare for it, tactically or technique wise, without ever having been
on it and only knowing from the map of a written description what to
expect?

I've never seen a map such as you describe, but there are some
interesting graphics in the Masons' Path of the Paddle and Thrill of the
Paddle books that I think you would get a lot out of.

You don't have to be in a canoe to paractice this. Every time you're
close to moving water--river, creek, gutter, driveway--look closely at
how it moves and where the current accelerates, slows, and reverses.
Pretend you're in a 2" long boat and plot your course down the kerb to
the great Soo-Whur cataract.

I guess this gets down to how do you analyze water flow and your
reaction to it in order to navigate it?

Look where the most water is going and follow it. Let the current do as
much of the work as possible. Try to avoid waterfalls. Spend lots more
time in the boat.


--
Steve Cramer
Athens, GA

Follow yer charc.

-Richard, His Kanubic Travesty
--
================================================== ====================
Richard Hopley Winston-Salem, NC, USA
.. rhopley[at]earthlink[dot]net
.. Nothing really matters except Boats, Sex, and Rock'n'Roll
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================================================== ====================


W. Watson wrote:
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.

[snip]

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.

Oci-One Kanubi wrote:

Follow yer charc.

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.


Yep. The boat, the water & yourself become one. Not enough time to run a
sliderule & the motions are ugly.

Pete H

--
A person is free only in
the freedom of other persons.
W. Berry