Kayaking power

Peter (prathman@comcast.net) writes:

 > If you just want average power generated then you could use some of the
 > test and model data from Sea Kayaker magazine in their kayak test
 > reports that shows the drag force of each boat model at various speeds.
 > Combine this with measured speeds of paddlers in races and it should
 > give an idea of the effective paddling power.

That's design estimates taken from some boat design program.


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 >> Stay informed about: Kayaking power 

Might be worth looking at the reaction forces on the boat - ie/
footrests/seat, as these would be relatively easy to measure, and with
a bit of meathematical modelling could probably give you a fair amount
of information about paddle force & direction.
 >> Stay informed about: Kayaking power 

"Kieran" <kc_news.RemoveThis@sonic.net> wrote in message
news:j1tUd.66306$8a6.13749@trndny09...
 > Bob Arledge wrote:
  >> Why not put a strain gauge on the paddle shaft just below the paddler's
  >> hand. This would give you the moment at that point, so the force would be
  >> the moment divided by the distance between the strain gauge and the
  >> centroid of the paddle blade.
 >
 > That's the general idea, but because the paddling motion is 3-d, it's not
 > very easy to determine power just from the strain in the paddle shaft.
 > You need to know instantaneous velocity (direction and magnitude) at every
 > moment. In a fixed-pivot environment like rowing, you can just put a
 > potentiometer on the oar-lock. But the kayak/canoe paddle has no fixed
 > pivot point. So, I imagine that a virtual pivot point would have to be
 > derived via 3-d kinematic video analysis.
 >
 > I haven't yet sat down and done a free-body of the system, but in my head,
 > it seems like it's going to be an indeterminant system... not fun.
 >

Actually, it should be quite managable, seeing as how the paddle is a line.
You only need two points to track all the motions of the paddle shaft, and
two more on the sides of the blade to track the feather. Everything else
follows.

Seems like someone out there must have some sort of pressure plate: two
sheets of material with a lor of sensor points between. Put one on the blade
and get a readout of the water pressure against all points of the blade at
all times. If all you are interested in is the resultant force, put a
potentiometer on the bow and brace it against a wall.

--riverman
(I love trying to sound like I know what I'm talking about)<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Kayaking power 

riverman <nospam RemoveThis @sorry.com> writes
 >"Kieran" <kc_news RemoveThis @sonic.net> wrote
  >> Bob Arledge wrote:
   >>> Why not put a strain gauge on the paddle shaft just below the paddler's
   >>> hand. This would give you the moment at that point, so the force would be
   >>> the moment divided by the distance between the strain gauge and the
   >>> centroid of the paddle blade.
  >>
  >> That's the general idea, but because the paddling motion is 3-d, it's not
  >> very easy to determine power just from the strain in the paddle shaft.
  >> You need to know instantaneous velocity (direction and magnitude) at every
  >> moment. In a fixed-pivot environment like rowing, you can just put a
  >> potentiometer on the oar-lock. But the kayak/canoe paddle has no fixed
  >> pivot point. So, I imagine that a virtual pivot point would have to be
  >> derived via 3-d kinematic video analysis.
  >>
  >> I haven't yet sat down and done a free-body of the system, but in my head,
  >> it seems like it's going to be an indeterminant system... not fun.
  >>
 >
 >Actually, it should be quite managable, seeing as how the paddle is a line.
 >You only need two points to track all the motions of the paddle shaft, and
 >two more on the sides of the blade to track the feather. Everything else
 >follows.
 >
 >Seems like someone out there must have some sort of pressure plate: two
 >sheets of material with a lor of sensor points between. Put one on the blade
 >and get a readout of the water pressure against all points of the blade at
 >all times. If all you are interested in is the resultant force, put a
 >potentiometer on the bow and brace it against a wall.
 >

Since it is more the reduction in pressure on the convex back of the
paddle which moves the boat than the increase on concave face, you'll
need a sensing surface on both faces. Even then you'll measure pressure
but not shear (frictional) forces.

Might be better to measure the forces at the paddle neck directly by
means of strain-gauge rosettes. Then there's angle of shaft, direction
& velocity of blade motion & (variable) location of centre of pressure
to consider.

Sounds a nice easy problem, only slightly more difficult than the one
about life, the Universe & everything. Have fun, Keiran!

Cheers -
Carl

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"Carl Douglas" <Carl RemoveThis @carldouglas.co.uk> wrote in message
news:ssaNZ4BsM1ICFwlc@rowing-cdrs.demon.co.uk...
 > Since it is more the reduction in pressure on the convex back of the
 > paddle which moves the boat than the increase on concave face...

Huh?

Isn't it the force of the paddler's butt, feet, or whatever other
parts are in contact with the boat that propel it?

Wolfgang<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Kayaking power 

On 27-Feb-2005, "riverman" <nospam RemoveThis @sorry.com> wrote:

 > Actually, it should be quite managable, seeing as how the paddle is a line.
 > You only need two points to track all the motions of the paddle shaft, and
 > two more on the sides of the blade to track the feather. Everything else
 > follows.

You need three points in total to measure all the motions of the paddle.
If you have two on the shaft and one off the shaft (say, normal to the
mid-point) you can determine what's going on.

I thought about this and figure that measuring the motion of these
points is more trouble than it's worth. I'd be inclined to try the
following:

A six-degree-of-freedom accelerometer system (all in a box costs a
few hundred US$) attached to the paddle shaft. This will measure
all accelerations of the paddle in every direction. A six-channel
A-D converter actually costs more than the accelerometer.

A computer that integrates the above data from a starting point
(say, a paddle "saddle" as a zero-reference point on the deck
in front of the paddler). This can be used to determine the
position and orientation of the paddle at every point in the
experiment. Can be done in real time or after the fact.

A seat mounted on a three-support frame. This would be statically
determinate and will allow all paddler forces to be measured
directly from strain guages in the seat supports. The "seat"
would in fact be a frame that includes foot support, since
foot forces can be a considerable component of the paddler's
actions. The problem with this may be reinforcing the kayak
to allow all forces to be transmitted thru only three points
to the hull. You'd have to also design the seat frame to
have very little friction for certain degrees of freedom
at each support in order to have it determinate.

The geometry of the seat relative to the paddle starting point
can be measured accurately and then all paddle positions are
known in time. Forces at the three seat supports can then be
resolved into the forces exerted by the paddle.

Mike<!-- ~MESSAGE_AFTER~ -->
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"Michael Daly" <michaelDaly DeleteThis @foo.bar> wrote in message
news:r66dneRM18D-GL7fRVn-sA@magma.ca...
 > On 27-Feb-2005, "riverman" <nospam DeleteThis @sorry.com> wrote:
 >
  > > Actually, it should be quite managable, seeing as how the paddle
is a line.
  > > You only need two points to track all the motions of the paddle
shaft, and
  > > two more on the sides of the blade to track the feather.
Everything else
  > > follows.
 >
 > You need three points in total to measure all the motions of the
paddle.
 > If you have two on the shaft and one off the shaft (say, normal to
the
 > mid-point) you can determine what's going on.
 >
 > I thought about this and figure that measuring the motion of these
 > points is more trouble than it's worth. I'd be inclined to try the
 > following:
 >
 > A six-degree-of-freedom accelerometer system (all in a box costs a
 > few hundred US$) attached to the paddle shaft. This will measure
 > all accelerations of the paddle in every direction. A six-channel
 > A-D converter actually costs more than the accelerometer.
 >
 > A computer that integrates the above data from a starting point
 > (say, a paddle "saddle" as a zero-reference point on the deck
 > in front of the paddler). This can be used to determine the
 > position and orientation of the paddle at every point in the
 > experiment. Can be done in real time or after the fact.
 >
 > A seat mounted on a three-support frame. This would be statically
 > determinate and will allow all paddler forces to be measured
 > directly from strain guages in the seat supports. The "seat"
 > would in fact be a frame that includes foot support, since
 > foot forces can be a considerable component of the paddler's
 > actions. The problem with this may be reinforcing the kayak
 > to allow all forces to be transmitted thru only three points
 > to the hull. You'd have to also design the seat frame to
 > have very little friction for certain degrees of freedom
 > at each support in order to have it determinate.
 >
 > The geometry of the seat relative to the paddle starting point
 > can be measured accurately and then all paddle positions are
 > known in time. Forces at the three seat supports can then be
 > resolved into the forces exerted by the paddle.

All of this sounds terribly complicated to me. Why not just tether
the stern of the boat to the measuring device of choice anchored to a
dock?

Wolfgang<!-- ~MESSAGE_AFTER~ -->
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Ook hier aanwezig, Michiel?

M.C.D. Roos wrote:

 > Kieran wrote:
 >
  >> I might be taking on a project where we try to determine the power
  >> (force and velocity) developed by a kayaker while paddling. I'm
  >> wondering if anyone out there knows of any research that's been done
  >> like this. I know that it is a fairly common thing for rowing crews
  >> to be "instrumented" with strain guages on the oars, and
  >> potentiometers on the oarlocks, to get force/time curves for on-water
  >> rowing. So, I'm wondering if anyone is aware of this sort of study
  >> having been done on kayaking or canoeing.
 >
 >
 > For swimming, one method I know of consists of a line with floats
 > attached to it in a pool. The swimmer then pushes his hands against the
 > floats with each stroke and the power for each stroke is then measured
 > in the floats IIRC. There ought to be a better description of this on
 > the web. Another method might be to just drag a kayak with a line
 > accross the water at paddling speed and measure the force needed to do
 > this, but I suspect you want some more detailed measurements. Maybe you
 > can combine this with a videocamera.
 >
 > greetings,
 > Michiel
 >

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On 28-Feb-2005, "Wolfgang" <wolfgang.DeleteThis@mcw.edu> wrote:

 > All of this sounds terribly complicated to me. Why not just tether
 > the stern of the boat to the measuring device of choice anchored to a
 > dock?

Good idea - unless of course you want to measure something useful.

Mike<!-- ~MESSAGE_AFTER~ -->
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"Michael Daly" <michaelDaly.TakeThisOut@foo.bar> wrote in message
news:TJmdnf520f6kdLnfRVn-oQ@magma.ca...
 > On 28-Feb-2005, "Wolfgang" <wolfgang.TakeThisOut@mcw.edu> wrote:
 >
  >> All of this sounds terribly complicated to me. Why not just tether
  >> the stern of the boat to the measuring device of choice anchored to a
  >> dock?
 >
 > Good idea - unless of course you want to measure something useful.

Refresh my memory. What is it you wish to measure?

Wolfgang<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Kayaking power 

Kieran wrote:
 > Wolfgang wrote:
  > > "Michael Daly" <michaelDaly.DeleteThis@foo.bar> wrote in message
  > > news:TJmdnf520f6kdLnfRVn-oQ@magma.ca...
  > >
   > >>On 28-Feb-2005, "Wolfgang" <wolfgang.DeleteThis@mcw.edu> wrote:
   > >>
   > >>
   > >>>All of this sounds terribly complicated to me. Why not just
tether
   > >>>the stern of the boat to the measuring device of choice anchored
to a
   > >>>dock?
   > >>
   > >>Good idea - unless of course you want to measure something useful.
  > >
  > >
  > > Refresh my memory. What is it you wish to measure?
  > >
  > > Wolfgang
  > >
  > >
 > Force on the paddle shaft, at the handgrip.

Makes me think of a big torque wrench. Do you get any deflection of the
paddle shaft while paddling? Use a smaller shaft until you do, Take
video, or measure the deflection of the needle! Then in the lab,
measure the force needed to duplicate the deflection. You should then
have an idea of what the possible force exerted on the shaft would be
for a particular paddler.

The potential force would be based on as wolfgang points out the
effectiveness of the engine mount, the paddlers seat and feet, the
grip, and other loss of efficiency factors that could be isolated for
significance. TnT<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Kayaking power 

Wolfgang wrote:
 > "Michael Daly" <michaelDaly DeleteThis @foo.bar> wrote in message
 > news:TJmdnf520f6kdLnfRVn-oQ@magma.ca...
 >
  >>On 28-Feb-2005, "Wolfgang" <wolfgang DeleteThis @mcw.edu> wrote:
  >>
  >>
   >>>All of this sounds terribly complicated to me. Why not just tether
   >>>the stern of the boat to the measuring device of choice anchored to a
   >>>dock?
  >>
  >>Good idea - unless of course you want to measure something useful.
 >
 >
 > Refresh my memory. What is it you wish to measure?
 >
 > Wolfgang
 >
 >
Force on the paddle shaft, at the handgrip.<!-- ~MESSAGE_AFTER~ -->
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"Kieran" <kc_news.RemoveThis@sonic.net> wrote in message
news:_R9Vd.73792$g16.11180@trndny08...
 > Wolfgang wrote:
  >> "Michael Daly" <michaelDaly.RemoveThis@foo.bar> wrote in message
  >> news:TJmdnf520f6kdLnfRVn-oQ@magma.ca...
  >>
   >>>On 28-Feb-2005, "Wolfgang" <wolfgang.RemoveThis@mcw.edu> wrote:
   >>>
   >>>
   >>>>All of this sounds terribly complicated to me. Why not just tether
   >>>>the stern of the boat to the measuring device of choice anchored to a
   >>>>dock?
   >>>
   >>>Good idea - unless of course you want to measure something useful.
  >>
  >>
  >> Refresh my memory. What is it you wish to measure?
  >>
  >> Wolfgang
 > Force on the paddle shaft, at the handgrip.

Extrapolate. Look at the tables. Call the company. Do the math.

Wolfgang
who is no rocket scientist.<!-- ~MESSAGE_AFTER~ -->
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