Michael Hearn Anna Houpt wrote:

Just for the fun of it, Why does a racing scull go faster when the oars are
out of the water, and slower with the blasdes in the water? (no it is not
drag)... Mike

Because as the paddler slides toward the stern, the motion plus the
inertia of the oars drives the hull forward momentarily. It's really
somewhat illusory, as the rower is actually slowing down and the boat is
just moving relative to his/her body. It's more of a "windup" than
anything else.

"Jaakko" wrote in message
...

stuff deleted

A hint: watch your kayak´s bow. As long as it stays steady, you are doing
fine. If you paddle too fast for your ability or pull too long strokes,
your bow starts going either up and down or moving sideways. Then it is
time to slow down/shorten the pull.

Jaakko

o~
(____/____)
/

Since the bow of my kayak is curved rather strongly (I guess to allow it to
go over waves), I get a nice bow wave appearing once I get to about 4 mph.
As I go faster, the wave gets bigger. The bow does go up on the wave as I
go faster, but what I find most noticeable is the size of the wave. Lately,
I've been using that as the indicator of speed and every time the wave
starts going down from its "usual" height, I know I'm slacking off.

"Rick Donnelly" wrote in message
m...

...stuff deleted

Paul is onto the basic idea. Muscles fatigue for two reasons:
- overuse from repetitions at a high rate of speed
- overuse from few repetitions against force at low speeds

You can replicate these by doing the following:
- open and close your hand as fast as you can (no resistance)
- climb a steep hill (10 % + grade) on a bicycle

In both cases, you will fatigue within a couple of minutes. Depending upon
conditioning, you may be able to continue to climb the hill, but it is
unlikely that you can continue to open and close your hand after about 2
minutes. After climbing the hill, however, you will need more time to
recover from the cycling than you will from the hand exercise, so there is
a difference in the two types of fatigue (i.e. hard work against low
resistance tends to produce soreness, while fast repetitions do not).

Thus, there is an obvious mid-point of optimal performance before fatigue
sets in. Surprisingly, however, the physical studies suggest that this
optimal performance point results (for most) in a cadence that is too slow
(not a universal truth - I know a few distance cyclists who prefer a
cadence closer to 60, but most, like me, prefer a rate closer to 90).
Cyclists and paddlers will (tend to) find a cadence that is a tad faster
than that optimal performance point. The last study I read suggested that
this is because at the optimal performance point, the muscles fatigue from
both methods of overuse.

Paddlers can adjust cadence by shortening the shaft and narrowing the
paddle blade, with the short shaft having a more drastic effect (a fat
blade is similar to a high gear in that it increases resistance, and
weight, making each stroke a tad more difficult to do). In any case, the
right cadence is fully dependant upon the choice/comfort of the paddler.

Hope this helps (rather than muddies) understanding.

Rick


Rick, I once played the role of a "trained athlete" (all together now...
many moons ago) in which I and a "sedentary" individual were compared in
terms of physiologic responses to increases in exercise rate (this to a
class of med students doing a course on exercise physiology). We both rode
stationary bikes, and were hooked into an ECG machine, ventilator and gas
analyzer. The protocol was for us to both ride the bikes for five minute
intervals, first at no resistance, then at successively increasing
resistance levels. The machines measured the work output, the heart rate,
the amount of air being breathed in and out, and the gas composition (c02
and O2 ratios). While the levels at which I and the other individual
"topped out" were different, the physiologic responses were similar.

In essence, the exercise demonstrated that as the amount of work increases,
the body adapts by increasing heart rate (oxygen delivery), ventilation
volume (oxygen uptake and carbon dioxide exhaust), and oxygen consumption up
to a certain level (which, if I remember correctly was termed VO2max).
Energy consumption up to this point is purely aerobic. As the effort level
increases past this point, the muscles start producing energy anaerobically
(accumulating lactic acid as a by-product). Anaerobic work cannot be
carried out for long as the accumulation of lactic acid starts becoming very
painful, and the breathing pattern collapses into gasps.

If the work is spread out over a number of muscle groups, then the overall
work level is increased (up to the limit of maximum ability of the
heart/lungs to deliver the oxygen). How this applies to kayaking is to use
technique to balance the paddling workload over the maximum number of
muscles, so that no one group gets overloaded. So in essence, that is what
I am trying to figure out - how to achieve maximum output (without crossing
into the anaerobic territory) and which combination of techniques to use.

How this relates to your defining the two types of exercises (high
resistance & low cadence, vs. low resistance & high cadence), is that the
soreness caused by the high resistance exercise is due to lactic acid
accumulation. Recovery is also slower because the lactic acid is an
intermediate oxidation product, and must be oxidized to CO2 to be
eliminated, and the "oxygen debt" that is incurred while producing lactic
acid is then repaid during recovery. Increasing cadence (while reducing the
load) works to a certain point, but as the cadence increases more we get
into neuro-muscular control issues - it becomes harder and harder to
coordinate smooth muscle motion and the motions become more "ballistic",
until you cannot keep the motions coordinated and it all falls apart. The
sweet spot I'm looking for is where the cadence is high enough that the work
level is within the aerobic capacity of my system.

Now, do the maximal exercise long enough, and you run into another
limitation - that of your liver's ability to deliver glucose to the
bloodstream at a sufficient level to support both work generation and brain
function. Once your liver depletes its stores of glycogen, the blood sugar
level drops rapidly, and you get the infamous "bonk" where the athlete runs
out of energy and becomes sluggish and uncoordinated. I've had that happen
to me twice during my cycling phase - and it is not a pleasant experience.
Fortunately, I haven't yet reached that level in paddling.

Regards,

Paul

PG wrote:
"Jaakko" wrote in message
...

stuff deleted

A hint: watch your kayak´s bow. As long as it stays steady, you are doing
fine. If you paddle too fast for your ability or pull too long strokes,
your bow starts going either up and down or moving sideways. Then it is
time to slow down/shorten the pull.

Jaakko

o~
(____/____)
/


Since the bow of my kayak is curved rather strongly (I guess to allow it to
go over waves), I get a nice bow wave appearing once I get to about 4 mph.
As I go faster, the wave gets bigger. The bow does go up on the wave as I
go faster, but what I find most noticeable is the size of the wave. Lately,
I've been using that as the indicator of speed and every time the wave
starts going down from its "usual" height, I know I'm slacking off.

It also means that you're near the maximum hull speed for your boat and
that you're probably wasting energy trying to push past it. It's a very
inefficient way to paddle, as once you reach this point, the energy
requirements to increase your speed go up exponentially. Here's a link
to an explanation and a calculator:

http://www.cncphotoalbum.com/technic.../hullspeed.htm

There is some debate at to whether the formula is accurate for kayaks,
since racers routinely exceed the theoretical maximum speed for their
boats, but fundamental premise is still applicable.

It sounds like you need a higher performance boat that's better suited
to your paddling style. Worrying about the most efficient cadence is
rather pointless when you're throwing away massive amounts of energy due
to an inefficient boat. It's the functional equivalent of riding a bike
while towing a parachute. "Penny wise and pound foolish", so to speak.
The most efficient way to paddle your Squall is to slow down to below
the maximum hull speed where the wavemaking drag on the boat is
dramatically lower.

Don't get me wrong, the Squall is a fine boat for what it is, it's just
not what you want if you're serious about efficiency and going fast. You
should be looking at racing boats or "race-inspired" touring boats.

On Thu, 01 Sep 2005 10:31:25 GMT, Brian Nystrom wrote:
Worrying about the most efficient cadence is
rather pointless when you're throwing away massive amounts of energy due
to an inefficient boat.

That is true, but I applaud Paul's effort in trying to better his
forward stroke. Buying a better, faster boat is easy, perfecting the
forward stroke is not. And no matter what boat he gets, the issue of
forward stroke and cadence will still be there.

BTW, I really appreciate your input Brian, as well as Paul's
statements regarding muscle fatigue. You guys are great and Brian I
have enjoyed your posts in pnet as well. I mostly just read these
posts, but though I would comment this time.

Regarding maximum hull speed I have been thinking of an experiment. It
would be nice to tow a kayak at different speeds and measure the tow
line force. I would love to see the speed vs. force curve for a
variety of kayaks. The towing would have to be done is such a way
that the kayak in tow is not in the wake of the towing boat. It would
show how closely the maximum hull speed formula in Brians link applies
to kayaks. Does anybody know if this has ever been done?

Lou

"Brian Nystrom" wrote in message
news:1MARe.47543$j41.21902@trndny05...
PG wrote:
"Jaakko" wrote in message
...

stuff deleted

Since the bow of my kayak is curved rather strongly (I guess to allow it
to go over waves), I get a nice bow wave appearing once I get to about 4
mph. As I go faster, the wave gets bigger. The bow does go up on the
wave as I go faster, but what I find most noticeable is the size of the
wave. Lately, I've been using that as the indicator of speed and every
time the wave starts going down from its "usual" height, I know I'm
slacking off.

It also means that you're near the maximum hull speed for your boat and
that you're probably wasting energy trying to push past it. It's a very
inefficient way to paddle, as once you reach this point, the energy
requirements to increase your speed go up exponentially. Here's a link to
an explanation and a calculator:

http://www.cncphotoalbum.com/technic.../hullspeed.htm

There is some debate at to whether the formula is accurate for kayaks,
since racers routinely exceed the theoretical maximum speed for their
boats, but fundamental premise is still applicable.

It sounds like you need a higher performance boat that's better suited to
your paddling style. Worrying about the most efficient cadence is rather
pointless when you're throwing away massive amounts of energy due to an
inefficient boat. It's the functional equivalent of riding a bike while
towing a parachute. "Penny wise and pound foolish", so to speak. The most
efficient way to paddle your Squall is to slow down to below the maximum
hull speed where the wavemaking drag on the boat is dramatically lower.

Don't get me wrong, the Squall is a fine boat for what it is, it's just
not what you want if you're serious about efficiency and going fast. You
should be looking at racing boats or "race-inspired" touring boats.

Thank you Brian, for your comments and the link. According to the formula
the max hull speed for my boat is 5.31 knots or 6.1 mph. I've already
noticed that at 5 mph I'm pushing fairly hard, and trying to get above that
seemed like I was hitting a wall. I'll have to pay attention to the quarter
wave to see if it is there at the end of the boat when I am going my
fastest. But your point is taken - probably the optimal cruising speed for
me in the Squall is around 4.2-4.5 mph. I'm not sure that I've outgrown the
boat yet, as there are still a bunch of skills I need to acquire (rolling,
edging, getting a decent high brace...).

While I got your attention, there's another question that's been bothering
me. Somewhere I have read that a good paddler should be able to go backward
in a straight line almost as fast as going forward. When I try to do that,
I find that at slow speed I can maintain a straight line, but at higher
speeds there is a pronounced turn to the right, which I cannot compensate
for with sweep strokes. My rudder is always up so I can't blame it. I
thought perhaps I was doing an inadvertent edge, but doing a deliberate edge
in either direction still gave more or less the same result. Do you think
there is something assymetric in my technique, or is it inherent in the
boat?

Paul

"PG" wrote in
:



While I got your attention, there's another question that's been
bothering me. Somewhere I have read that a good paddler should be able
to go backward in a straight line almost as fast as going forward.
When I try to do that, I find that at slow speed I can maintain a
straight line, but at higher speeds there is a pronounced turn to the
right, which I cannot compensate for with sweep strokes. My rudder is
always up so I can't blame it. I thought perhaps I was doing an
inadvertent edge, but doing a deliberate edge in either direction
still gave more or less the same result. Do you think there is
something assymetric in my technique, or is it inherent in the boat?

It's probably not the boat. One of the skills you're tested on when taking
a BCU 3 star assessment is paddling backwards in a figure 8. It turns out
to be one of the skills that prevents a successful completion of the
assessment. After a day of training and assessment with 11 other people the
most common problem was being able to change directions once you started to
turn. First, if you *want* to turn you should edge the boat to the outside
of the turn. Once you've started to turn the boat will tend to continue to
turn in that direction, even if you edge in the opposite direction. The
trick is to bring the hull to a flat position, initiate the turn in the
opposite direction with a sweep stroke, then edge away from the direction
you want to go. Most likely there is something asymetric in your technique
that is causing the boat to start to turn right and once it starts it tends
to go that way.

I like using a reverse stroke when teaching beginners torso rotation.
Rotating the torso until the paddleshaft is nearly parallel with the boat,
then present the backface of the blade to the water for the catch, then
uncoil you body and repeat on the opposite side. Start slowly and gradually
put a little more into the stroke and you should be able to maintain a
straight course.

Mr. C wrote:
On Thu, 01 Sep 2005 10:31:25 GMT, Brian Nystrom wrote:

Worrying about the most efficient cadence is
rather pointless when you're throwing away massive amounts of energy due
to an inefficient boat.


That is true, but I applaud Paul's effort in trying to better his
forward stroke. Buying a better, faster boat is easy, perfecting the
forward stroke is not. And no matter what boat he gets, the issue of
forward stroke and cadence will still be there.

True. My point was that it's a matter of degrees. For a performance
oriented paddler, a more efficient boat will yield a much larger
improvement than fine-tuning one's cadence, but both are beneficial.

BTW, I really appreciate your input Brian, as well as Paul's
statements regarding muscle fatigue. You guys are great and Brian I
have enjoyed your posts in pnet as well. I mostly just read these
posts, but though I would comment this time.

Thank you for the kind words. I'm glad to be of help.

Regarding maximum hull speed I have been thinking of an experiment. It
would be nice to tow a kayak at different speeds and measure the tow
line force. I would love to see the speed vs. force curve for a
variety of kayaks. The towing would have to be done is such a way
that the kayak in tow is not in the wake of the towing boat. It would
show how closely the maximum hull speed formula in Brians link applies
to kayaks. Does anybody know if this has ever been done?

Sea Kayaker did some tow-tank testing several years ago. I have the back
issue somewhere, but I'm not sure what issue it's in. Perhaps you can
order a reprint of the article, as they do offer that service. The boats
used no longer exist, but it may make for interesting reading.

PG wrote:
Thank you Brian, for your comments and the link. According to the formula
the max hull speed for my boat is 5.31 knots or 6.1 mph. I've already
noticed that at 5 mph I'm pushing fairly hard, and trying to get above that
seemed like I was hitting a wall. I'll have to pay attention to the quarter
wave to see if it is there at the end of the boat when I am going my
fastest. But your point is taken - probably the optimal cruising speed for
me in the Squall is around 4.2-4.5 mph. I'm not sure that I've outgrown the
boat yet, as there are still a bunch of skills I need to acquire (rolling,
edging, getting a decent high brace...).

I don't mean to "dis" your boat, as it's a capable craft that's
certainly useful for learning in, not to mention day/weekend trips. I've
got one boat, a Pintail, that hits the wall at around the same speed.
It's a great boat in rough water, but it's a pig when it's flat and calm.

While I got your attention, there's another question that's been bothering
me. Somewhere I have read that a good paddler should be able to go backward
in a straight line almost as fast as going forward. When I try to do that,
I find that at slow speed I can maintain a straight line, but at higher
speeds there is a pronounced turn to the right, which I cannot compensate
for with sweep strokes. My rudder is always up so I can't blame it. I
thought perhaps I was doing an inadvertent edge, but doing a deliberate edge
in either direction still gave more or less the same result. Do you think
there is something assymetric in my technique, or is it inherent in the
boat?

It could be either, but the former is more likely. Paddling straight in
reverse can also be very boat dependent. Some boats are easily
controllable while being paddled backwards, others won't go straight for
any reason.

As with the forward stroke, it's normal to have some asymmetry in
technique and strength that can cause the boat to turn in one direction
or the other. It's also common for people to sit with one hip a bit
lower than the other, which can have a similar effect.

It IS possible that the boat is slightly "bent", but it's pretty unlikely.

On 1-Sep-2005, Mr. C wrote:

It would
show how closely the maximum hull speed formula in Brians link applies
to kayaks. Does anybody know if this has ever been done?

We know it doesn't apply strongly and it is not worth worrying about. First
of all, there's no such "maximum" speed. The hull speed given by Froude's
speed-length ratio of 1.34 is an somewhat arbitrary value that links the
waterline length to the wavelength of the bow wave. Unfortunately, a lot of
folks have interpreted it as a speed limit of some sort.

The page Brian linked to discusses the speed-length ratio in terms of sailboats.
In the case of a displacement sailboat, most designers know that you can't
realistically increase the speed over the so-called hull speed, so the design
of the sail rig is based on that. If you could carry a _lot_ more sail, you
could start pushing past the hull speed. However, that sail rig would cost a
lot (if a significant speed increase is wanted) and it would be a bitch to
handle in most conditions. Since the average sailor never sees his craft
exceed the hull speed with a typical sail rig, the speed-length rule of
thumb starts to look like an absolute law and it enters into the sailors'
legends.

Multihulls and other displacement craft show that the speed-length ratio is
not so much of a limit. Olympic class kayaks do it routinely:
http://www.kayakforum.com/cgi-sys/cgiwrap/guille/wiki.pl?Hull_Speed

The way to interpret the speed-length ratio or the hull speed is to
recognize that it represents a speed that takes a lot of work to achieve.
If you want to paddle fast all the time, then a longer waterline length
is one thing to look for. However, it isn't an absolute guide to the
behavior of a kayak. For example, based on the analyses of a bunch
of kayaks reviewed in Sea Kayak magazine, you can see the following

http://www.greatlakeskayaker.ca/loaVSlwl.htm

You can see that the resistance generally goes down with waterline length,
but there are some exceptions.

Mike