paddle flutter
pfiffner
vibration of the blade through the water. I recently purchased a
few canoe composite paddles that seem to flutter as i paddle. I
was thinking (hopefully better than my spelling) that this flutter
may be due to the stiffness of the paddle. When I use good old wood
paddles this problem does not occur. I have also noticed after many
miles of composite paddling my tendons are strained but using a
paddle that flexes this doesn't happen. Anyone have any thoughts on
paddle flutter? Could it be in my grip or stroke that causes this
problem. May your paddle never flutter. Tom
Chris Bell
>If someone out there has some explanation for why flutter
>occurs and maybe also, what I did to eliminate the flutter, I'd really
>like to see them post their explanation. Thanks.
>
And while they're at it, they can explain why everyone's first whitewater
kayak start out life incapable of holding a straight line, but within a couple
months tracks like a champ...
-- Chris
Dan21660
causes the flutter....see if the flutter deminshes if you don't pull so
hard... a slight adjust met will do it...and you'll enjoy the beneifits of
a lighter paddle.
Dan
John Gastineau
> For lack of better terminology I refer to paddle flutter as a
> vibration of the blade through the water. I recently purchased a
> few canoe composite paddles that seem to flutter as i paddle. I
> was thinking (hopefully better than my spelling) that this flutter
> may be due to the stiffness of the paddle. When I use good old wood
> paddles this problem does not occur. I have also noticed after many
> miles of composite paddling my tendons are strained but using a
> paddle that flexes this doesn't happen. Anyone have any thoughts on
> paddle flutter?
I too have noticed this phenomenon, but only in wood paddles. I have a
number of wood bent paddles for flatwater tripping. The ones that have a
smoothly shaped blade are very stable in the water. By that I mean the
blade surface makes a smooth transition from the paddle shaft to the blad
area. Other paddles are more like a flat sheet of wood bonded to one side
of a rod. Those paddles flutter badly.
I'd estimate that all these wood paddles are about the same flexibility.
The flutter is tiring, as it makes me grip the paddle that much harder.
JEG
--
John Gastineau "The indoor life is the next best
NCSU Physics thing to premature burial."
Raleigh, NC, USA Edward Abbey
gast...@ncsu.edu
Peter Schultz
I used to use a Perception kayak paddle. About a year ago I acquired
a graphite/kevlar shafted graphite/foam core bladed Schlegel. It is
a SWEET paddle. But, when I first used it I had a significant amount of
flutter. After spending about 15 hours working out with the paddle the
flutter slowly disappeared. I have no idea what I changed, but I simply
don't notice any more flutter. In borrowing a friend's graphite Mitchell
I also noticed flutter (this was back in my Perception paddle days).
So, the long and the short of it - hang in there with it a little while. It
might go away. If someone out there has some explanation for why flutter
occurs and maybe also, what I did to eliminate the flutter, I'd really
like to see them post their explanation. Thanks.
Pete Schultz
Penn State University
Serge Beland
I have been paddle with some different paddles and have found that the
flutter happens because:
- you pull too much on the shaft with one hand and push too much from the
other.
- the paddle doesn't have a dihedral (this is suppose to avoid the flutter
move, but i'm doubting)
I was surprise to read that wood paddle make avoid the fluttering move!
I am very interesting about hearing people who use wood paddle if this kind
of material allow to avoid the fluttering move because of the flexibility of
the wood?
Maybe paddle are too big in surface for everyone, maybe that's what cause the
fluttering? Or maybe the shaft is too long so the hands are far from the
paddle and the control?
I am planning to make wood paddle cover by a 4 ounces of fiberglass and
another by a 9 ounces of fiberglass both without dihedral (well a small one).
So after reading this thread i'm wondering if in the mean time, the
fluttering move will disseapears.
hardeman
>For lack of better terminology I refer to paddle flutter as a
>vibration of the blade through the water. I recently purchased a
>few canoe composite paddles that seem to flutter as i paddle. I
>was thinking (hopefully better than my spelling) that this flutter
>may be due to the stiffness of the paddle. When I use good old wood
>paddles this problem does not occur.
I read an article about paddle flutter. It only occurs on almost flat
paddle blades. Wooden blades usually have a thicker middle section that
separates the stream of water going to left and to the right side of the
paddle. When there is no good separation of the flow, you get a oneway
flow all over the paddle blade. This is an unstable situation that
reverses from one side to the other. The flutter you feel is the
result of this flowchange. If you tape a separator in the middle of the
blade you will see that the flutter has gone. It's something to think of
when buying a paddle.
--
M.R. Hardeman Ph.D.
pfiffner
paddled in my favorite spring fed creek. Since the ice shelfs made the
creek smaller, often I was in very shallow water ranging from a few
inches to a couple of feet. My question is since my paddle often hit bottom
would I be better using a longer or shorter paddle for my solo canoe?
Which paddle length would give me a more efficent stroke which would
require less energy used considering I'm often pushing mud with my
strokes.
Tom
Thomas H. Robey
-I read an article about paddle flutter. It only occurs on almost flat
-paddle blades. Wooden blades usually have a thicker middle section that
-separates the stream of water going to left and to the right side of the
-paddle.
One of the reasons for paddle flutter is the weight of the paddle. Paddle
flutter is caused by the water leaving the face of the blade through vortices
shed on the edges of the paddle between the high pressure on the face and the
low pressure on the backside. Because the shedding of vortices is a discrete
event instead of a continuous phenomenon, the blade will flutter as each
vortice is shed. A lighter paddle is not as stable because the momentum
energy (weight times velocity) is less and because the thickness of the blade
is usually less. A heavier paddle has more momentum and thus is less subject
to flutter. Just a little more weight can make a big difference. Thicker
paddles separate the high pressure and low pressure zones and thus the
vortices which releive this pressure difference are less powerful. The shape
of the faces can also affect this, but the relationship is more complicated.
Dihedral blades are subject to flutter, especially if the edges are thin. In
the forward stroke, the paddler will soon learn to compensate in the way
he/she holds the paddle. Flutter can also occur in bracing or sculling
motions which is not exactly the same as the flutter discussed above. In this
case dihedral blades are superior because the rib which often divides the high
pressure and low pressure zones is less pronounced.
William Houser
>For lack of better terminology I refer to paddle flutter as a
>vibration of the blade through the water. I recently purchased a
>few canoe composite paddles that seem to flutter as i paddle. I
>was thinking (hopefully better than my spelling) that this flutter
>may be due to the stiffness of the paddle. When I use good old wood
>miles of composite paddling my tendons are strained but using a
>paddle that flexes this doesn't happen. Anyone have any thoughts on
>problem. May your paddle never flutter. Tom
Paddle flutter is caused by the flow of water moving off the sides of
the paddle at uneven rates. the correction for this problem is often
found in blades with a di-hedral design, or edges swept back form the
middle rib of the blade. In kayak, this problem has (or had the
potential to) become much worse with the advent of WING blades. However,
in the absence of Di-hedral effect, the baldes are swept back, or
"trail" the shaft by a few degrees to gain stability. If you are having
a flutter problem, it can be corrected either by getting a blade with
greater "trail" , or by making technical correction, ie; make sure the
blade enters the water well ahead of your top hand, and let the blade
trail naturally.
In canoeing,
Jeff Houser
Tim Hewitt
Have you considered standing and using a pole? You are not limited to large
tripping canoes for this to be successful and enjoyable. While I have
significant experience standing in the canoe, if I can paddle it, I can
pole it :). Some canoes are more squirely than others, but if you have access
to a larger canoe for learning, you can easily move into a smaller canoe
when needed.
One of my poles has a special "ice end" on it that looks much like a peavy
or a pike pole. It's great for getting on and off the ice shelf as well
as propelling one down the narrow, ice choked streams at either end of the
season here in Maine.
Keep your paddle, er ah pole, wet!
-Tim
--
Tim Hewitt - President, Downeast Chapter
Wooden Canoe Heritage Association, Ltd
http://www.wcha.org
Mary Shaw
|> Today, January 14, we had a record high of 42 degrees in Madison, WI and I
|> paddled in my favorite spring fed creek. Since the ice shelfs made the
|> creek smaller, often I was in very shallow water ranging from a few
|> inches to a couple of feet. My question is since my paddle often hit bottom
|> would I be better using a longer or shorter paddle for my solo canoe?
|> Which paddle length would give me a more efficent stroke which would
|> require less energy used considering I'm often pushing mud with my
|> strokes.
|> Tom
This is ideal poling water, though you'll want a swamp pole if the mud is deep.
A poler just needs enough water to float the boat, since motion and control
come from pushing against the bottom.
Besides, if you encounter creek-wide ice, you can hop the canoe up on
the ice and pole across the ice to open water.
[Apropos another thread, on aluminum canoes -- the external kees of
a Grumman is helpful if you're ice poling :-)
Mary Shaw
mary...@cs.cmu.edu
Jimisnyder
Couldn't resist this thread. I've been making and designing paddles for
21 years and have looked into this problem. I think it is multi-faceted.
First the face has uneven loading and unloading. Slalom blades, for
instance, have that cute little corner that goes in first, which generates
twist on the shaft. As the wrist compensates a series of wobbles begins.
The popular Slasher design was made to balance this drag on paddles which
enter at angles as in K-1. The unnloading dissymmetries have already been
correctly discussed. Another factor is the turbulence generated by the
exact edge of the paddle. Thinner paddles generate more turbulence. This
is similar to cavitation but technically not the same. A final factor I
can note is that the major impact of the eddy hitting the back of the
blade about a third of the way through the stroke is an unavoidable
wobble. To learn more, watch the trail of bubbles coming off the paddle
tip as it travels. Are there 2 trails or 1. If the water doesn't flow
cleanly from the power face it is stalling and creating a puddle which is
effectively a buffer zone between the paddle and the water you are pulling
into. Dihedrals obviously dispell the puddle. I prefer my paddles small
and bland so I can boss them around and never have stall problems. I use
wood bi-facial di-hedrals around 203cm for cruising. I'm 5'10". I use
these paddles for ww only -flatwater usage has different performance
requirements- lightness among them. I think the "disappearing flutter" is
more like it became less bothersome. To deal with it you could reduce
your blade size. But definatly don't clinch down and fight it. Work
through it. Pay attention to the placement/course of the very tips of the
blade and don't let them waffle around. Just get the job done and don't
sweat the details. Get through your aquaintence faze as thousands of
others do. Keith Backlund says "A well made paddle will disappear in your
hands as you are using it." I wish John Winters would comment. I'm sure
it would be enlightening.
Still Strokin' Jim
Snyder
GrEp
>correctly discussed. Another factor is the turbulence generated by the
>exact edge of the paddle. Thinner paddles generate more turbulence. This
>is similar to cavitation but technically not the same. A final factor I
>can note is that the major impact of the eddy hitting the back of the
>blade about a third of the way through the stroke is an unavoidable
>wobble.
No expert on kayak paddles, but for marathon racing bent shafts, dihedral
on the back (non power) face of the blade seems to be the single biggest
factor in reducing flutter. Current carbon racing paddles have extremely
sharp edges and fairly flat power faces, but up to 3/4 inch of thickness
at the center distributed as dihedral on the back face. Early generation
carbon paddles had thin blades, but a ridge where the shaft was faired
into the blade and fluttered pretty badly.
Another factor is the equivalent of "center of gravity". In a bent shaft
(and many kayak paddles I've seen) a line through the shaft passes
significantly ahead of the center of effort for the blade. This
increases the stability with regard to flutter as well.
As for the "getting used to it", control of a paddle is a feedback
control loop with a complex adaptive mechanism (human) in the loop.
Flutter can easily result from the "gain" in the feedback loop being too
high. It's not hard to make a paddle which you believe doesn't flutter
do so intentionally, and doesn't take much effort to keep it fluttering
once you get it started!
Now...who's going to tell us about the details of how winged paddles
work?
Good thread,
Tom
GrEp
>would I be better using a longer or shorter paddle for my solo canoe?
>Which paddle length would give me a more efficent stroke which would
>require less energy used considering I'm often pushing mud with my
>strokes.
Yes. If a marathon race has a lot of shallow water a paddler might well
select a shorter paddle, preferably one with a somewhat wider blade (and
polycarbonate inserts in the tip!) Most of the time best progress in
shallow water can be made by increasing the stroke rate and effort and
not poling off the bottom. (This changes about the time you feel the
bottom start actually dragging or shortly before.) Getting this much of
the blade out of the water raises the upper hand to a very inefficient
height with regard to both stroke mechanics and circulation. Hence, your
intuition is just right...get a shorter paddle...probably only about 1-2
inches as you don't want it to be a pain when you hit those welcome deep
stretches where the boat picks up and runs again.
Also helps to trim a bit down at the bow. This helps keep the boat from
squatting at the stern as it rides the pressure wave reflected off the
bottom. With correct trim and effort it is possible to actually surf
that wave in water from about 12 inches to 8 inches...nothing much helps
from 3 feet to 1 foot...except patience, perseverence, and consideration
of the fact that you could be at work!!!
Tom
Shawn Burke
pfiffner <pfif...@waun.tdsnet.com> writes:
> I have also noticed after many
> miles of composite paddling my tendons are strained but using a
> paddle that flexes this doesn't happen.
Tom: If I use a carbon-fiber paddle for a few consecutive days of hard
paddling the tendons around my elbows start to complain. I also really
screwed up the tendons in my left elbow paddling whitewater last Spring
with a very stiff Werner paddle; my arm is only now feeling better, now
that the water is iced over and I can't paddle. Wood paddles generally
have more flex, and I've never had tendon pain after paddling with a
wood paddle.
I attribute my injury in part, however, to inadequate conditioning of
the muscles and tendons around the elbow at the start of last season,
plus inadequate stretching both before and after paddling. I won't
make the same mistake this year.
-- seb
P.S. I've had wooden straight-shaft paddles flutter (and they had
dihedral!), but generally this has occured (a) when I'm tired, and my
form goes to pot, and (b) when the water is turbulent.
______________________________________________________________________
bu...@bu.edu
WWW: http://eng.bu.edu/Photonics_Center/
GPS: 42 deg 20' 52.8" -71 deg 06' 06"
__O "There is nothing, absolutely nothing
\______\_|]_____/ Half so much worth doing
~~~~~~~~~~~~|~~~~~~~~~~~ As simply messing about in boats"
John William Kuthe
Thomas H. Robey <tro...@arc.unm.edu> wrote:
>
>-I read an article about paddle flutter. It only occurs on almost flat
>-paddle blades. Wooden blades usually have a thicker middle section that
>-separates the stream of water going to left and to the right side of the
>-paddle.
>
>One of the reasons for paddle flutter is the weight of the paddle. Paddle
Hmm, I suppose this may be why my new graphite kayak paddle flutters.
I never noticed any flutter when I had my old kayak paddle, but this
new one does flutter a bit. But, I think I can put up with it, for the
weight savings!
--
John Kuthe, aka jw...@cec.wustl.edu, St. Louis, Missouri |MWA Homepage: |
First Job of Government: Protect people from govermment.|http://walden.mo.net|
Second Job of Government: Protect people from each other.|/~akravetz/mwa.html |
It must *never* become the job of government to protect people from themselves!