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PostPosted: February 25th, 2004, 12:23 am 
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I noticed 7 or 8 degree bent shaft paddles seemingly have disappeared from the market. Bending Branches and Mitchell don't seem to offer them anymore.

Now since there are lots of advocates of both 14 degree bent shaft paddles, and straight paddles, it would seem logical that something halfway in between would also appeal to at least some people. This would be a compromise between ease of "control" and efficiency.

Like, with canoes, between white water playboats and dedicated flatwater cruisers, there are canoe models available for every possible blend of those specialties. Correspondingly, I'd expect a range of bent shaft paddles with different degrees of bend from 1 degree to whatever doesn't make sense. (I know there are 10's-15's.) Anyone have any idea what's behind this?

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PostPosted: February 25th, 2004, 7:59 am 
SGrant wrote:
I Anyone have any idea what's behind this?


Yes, $$$ :)


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PostPosted: February 25th, 2004, 10:40 am 
>This would be a compromise between ease of "control" and efficiency.

if only I could understand what is meant with ease of "control"
I could have an idea about this, but I just don't experience
any advantage when paddling with a bent-shaft of less than
14 degree.

Dirk Barends


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 Post subject: It's a compromise
PostPosted: February 25th, 2004, 12:13 pm 
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I think that the angle is going to be very dependent on body mechanics and I would suspect that each of us has a "perfect" angle that may or may not be 14 degrees. Zavs are 12 degrees. My guess is that between 0 and 12 degrees you end up with paddles that suit neither purpose well. Bent paddles are generally not preferred for whitewater and other canoeing desciplines that require precise boat placement and where having a dedicated powerface is not advantageous. The bend almost totally precludes an inwater recovery... it makes draws and prys, awkward, short and weak and far less predictable.

But bent's are preferred for paddling that maximizes the covering of distance. For this our compatriots in the racing end of our genre have determined that 12 is the best catch-all number for most body types at a very high cadence. Paddle manufacturers have determined that 14 is suitable for a slower recreational or tripping pace.

I just think that those paddles with angles in between offer none of the advantages that whitewater and freestyle paddlers want in a straight paddle, and offer less performance than the racers and touring folks want in a bent. Why build it if they won't buy it?

PK


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PostPosted: February 25th, 2004, 11:04 pm 
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I think I'm sorry I posed the question, and please be tolerant of my tone as the responses struck me as less than satisfactory.

Dirk,

By "control" I mean the use of the paddle for steering etc. Say, whitewater stuff as per pknoerr's response. If there's anything canoeists seem to agree on it's that a straight paddle is easier to use for steering than a bent one. I'd rather not explain why. I don't doubt there are extremely skilled paddlers who will claim they can steer as well with a bent shaft as a straight one. I'm not one of those people.

If a bend less than 14 degrees provides no advantage in propulsion over a straight paddle, I'd like to hear why that is so. We all know the theory behind the bend. To me, it makes sense that below and up to an optimum bend, the amount of bend provides a PROPORTION of that advantage. It makes no sense to me that below the optimum point, the physics suddenly are invalid and there is no advantage. "It's a matter of degree." Quantitative, not qualitative. And for those who agree a straight paddle makes steering easier, a shallow bend would make steering easier at the same time it loses propulsion efficiency. This type of relationship is sometimes called a compromise.

Other than straight shafts, what bends less than 14 degrees have you tried? How do you know they provided NO advantage? If 14 degrees seems perfect for you, is it possible a greater bend might be even better? I guess I should ask if you've tried anything beyond a 14 degree bend.


pknoerr,

No need to explain the pros and cons of straight and bent shafts. That was not my question.

To veify your position: straight shaft and 14 degree bent shafts have "their places" and no bend between 0 and 12 or 14 is of any value.

As we all know, much canoeing involves both moving and flat water. Most of the time, each of those will involve elements of the other, and therefore equipment and techniques that are "multi-purpose". A simple example is steering stroke elements that often are used to keep a canoe going in a straight line.

To apply your words about paddles, to canoes: "I just think that canoes designed for a combination of moving and flat water offer none of the advantages that whitewater and freestyle paddlers want in playboat, and offer less performance than the racers and touring folks want in a cruiser. Why build it if they won't buy it?"

So I'll reword my question: Why is every imaginable "compromise" in canoe purpose/design accepted and even demanded, while the paddles used in the same combination of cirucumstances as those canoes must be "optimized" to one extreme or the other? That is the question.

Another problem. You say 12 degrees has been found best for racing with a very high cadence. You then say 14 degrees has been found best for the recreational paddlers with a slower cadence than the racers. The use of a 14 degree bend for paddlers with a slower cadence seems logically incompatible with the use of a 12 degree bend for paddlers with a faster cadence in the light of the very slow cadence performed by most flatwater paddlers using straight paddles. I'm not trying to pick a fight or be argumentative, but the "progression" just doesn't make sense to me. So let's see. A cadence of 30spm is best with straight paddles, cadence of 40-60 suits 14degree bent shaft, and for some strange reason very high cadences go back a little to 12degree bent shaft. Makes sense, yes? And if indeed that makes sense to you, then why would there not be a cadence suited to a 7degree bend?


g.wotrock,

I appreciate someone understood my point. But my understanding of marketing stuff is that there is more money to be made from a wider selection of offerings. By the same reasoning, why not just offer just one whitewater canoe and one flatwater canoe? Yes, economies of scale come into it, but why couldn't paddle makers offer 7 degree bent shaft paddles for what it costs them to make plus a profit?


In the absense of any rational explanation, I'd answer my own question by saying that the validation of straight paddles and only bent shaft paddles of more than 10 degrees is another example of how securely canoeing is stuck in the comfort of dogma. Straight shaft or 14 degrees. Anything else is warped!

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PostPosted: February 26th, 2004, 8:24 am 
>I think I'm sorry I posed the question, and please be tolerant of my
>tone as the responses struck me as less than satisfactory.

Don't be sorry for the question, because it is a good one,
only I tried to express my 'apprehension' about the possible
'wrong' assumptions in this question.
I have the idea that some writer in the past tried to give a too
simplified explanation about the difference in use between a
bent-shaft paddle and a straight shaft paddle, and came up with this
'ease of control' statement, and than other people started to repeat
that. As so often happens with statements like 'longer is faster',
'rocker is slower'. that have some elements of truth in them,
but are not exactly right, and because of that create a lot of
misunderstandings.

For me there is nothing that I do in my touring canoe with a
bent-shaft, that might be better or easier for me with a straight
shaft. The only reason I use a straight paddle when paddling in
rapids with my touring canoe, is because my straight shaft paddle is
much stronger than my bent-shaft paddle, and because I had the
idea that a bent-shaft paddle was not an advantage for maneuvering
-- although I am doubting this more and more, because I find myself
switching to a straight shaft paddle less than I used to...?
Only in 'real' white water paddling, and especially with the stern
prie that we have discussed lately, I feel a real limitation
with a bent-shaft paddle. But since you seem to have the opposite
experience with that, this doesn't 'prove' much...

As for the reason why there is so much more diversity in boats than
in shaft angles, I think this might be because it is easier to switch to
another paddle than to a different canoe when paddling:
no need for compromises when it is so easy
to switch from a 14 to a none degree paddle.

Dirk Barends


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PostPosted: February 26th, 2004, 1:14 pm 
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During the 1980s and early 1990s there were alot of interesting paddles built. I've paddled 5 degrees, 7degrees, and 10 degrees 12 degrees and 14-15 degrees. I've paddled dedicated face stright shaft paddles too.

The issue comes down to having a dedicated power face on a paddle creates paddles that don't do things like reverse strokes, or compound back strokes, or revers sweeps well. Once you put a bend in the paddle it's not as reliable for an inwater recovery. They just feel wierd, the bladeflutters. This flutter occurs whether the bend is 5 degrees or 15 degrees. This is a characteristic that comes from because it's not easy to get a bent blade perfectly vertical while the paddle is transitioning through an arc as in any powered slice, or when it gets spun 180 degrees in a compound back stroke. These are strokes that whitewater paddlers use, and I use them every time I'm paddling. So if these strokes don't work well with a bent paddle why use a bent paddle.

On the other side... if you are going to cover distance why paddle with a 7 degree bent paddle if a 12-14 is more efficient. I have no idea why racers use 12s and the grand majority of rec paddles are 14. They just are... and the only difference between the two is cadence so that must be the reason.

So in conclusion... 12-14 degree bends are more efficient, and thos interested in paddling long distance can take advantage of by using a bent paddle. These people don't do many reverse strokes, or complex strokes like other paddlers may... so the efficiency makes up for the fact that bent paddles don't work well backwards. Then those that want a paddle that is more symmetrical as the paddle may be use in reverse strokes don't even want one degree of bend.

Thus my point is first that why would you own a paddle that doesn't do anything right... a 5 degree bent isn't less difficult to do a compound reverse stroke with than the 14 and it offers almost no effieciency gains. Thus since back in th 1980s and 1990s when these paddles were built, and great paddlers played around with this, they found that the optimal bend was 15 for most paddling, and nobody bought the 5s. 7s. and 10s. It's called supply meeting demand... No demand... no supply!

PK


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 Post subject: Gillespie Paddles
PostPosted: February 26th, 2004, 1:25 pm 
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www.gillespiepaddles.com

Gillespie is one of the companies that still builds 0, 5, and 7 degree bent paddles for steering. These are used for outrigger racing.

Almost all of the top marathon racers paddle Zavarels built at 12 degrees.

All the sprint paddles paddle with straights...

Differrent paddles for different reasons.

PK


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PostPosted: February 26th, 2004, 2:30 pm 
[
Quote:
quote]The issue comes down to having a dedicated power face on a paddle creates paddles that don't do things like reverse strokes, or compound back strokes, or revers sweeps well. Once you put a bend in the paddle it's not as reliable for an inwater recovery.


But virtually every playboater I know uses a curved blade which indicates if not a dedicated then certainly a preferred powerface. It would be draws, prys and rolling that would suffer the most with a bent-shaft in moving water, but, as with a curved blade, after some practice I suppose you could adapt to a 7 degree bend. Would it be worth it?... not for me! However I would agree 12-15 degrees is an efficient bend for most flatwater paddling styles.


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PostPosted: February 27th, 2004, 1:55 am 
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We're just repeating ourselves about whether the amount of bend has a progressive or absolute effect on propulsion efficiency or simplicity of steering movements. I can't explain my view any better than I have.

Similarly, we'll probably disagree fundamentally on whether stroke rate is partly determined by the amount of bend. I can't see any obvious reason why it would be, although certainly high stroke rates are associated with bent shafts and low stroke rates with straight paddles. But I know people who paddle slowly with bent shaft paddles, and dragon boaters have very high cadences with straight paddles.

It's also time someone pointed out that when the paddle enters the water, any force applied to it will also be pressing water down, and so will be wasting effort by raising the canoe. All else being equal, the more the bend, the more this happens. The argument favouring the efficiency of the bent shaft by having the blade more vertical during the power phase and end of the stroke, ignores the fact that the bend increases the (smaller) losses at the start of the stroke.

Thanks for the link to the Gillespie site. I don't agree with everything he says, but he certainly thinks for himself.

Somewhere on the ZRE site is a comment that the greater the bend, the more the workload during the stroke is transferred to the lower hand. An interesting claim or observation I haven't seen elsewhere.

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PostPosted: February 27th, 2004, 7:55 am 
quote="SGrant"]I noticed 7 or 8 degree bent shaft paddles seemingly have disappeared from the market. Bending Branches and Mitchell don't seem to offer them anymore.

Now since there are lots of advocates of both 14 degree bent shaft paddles, and straight paddles, it would seem logical that something halfway in between would also appeal to at least some people. This would be a compromise between ease of "control" and efficiency.

Anyone have any idea what's behind this?[/quote]

Demand. Not many folks want anything less than 14 degrees I would bet. I like 10 degrees for smaller creeks and milder white water to facilitate maneuvering. Some of the limited production manufacturers like Gillespie will make any angle you want for a nominal additional charge.

quote="Dirk-Barends"]>This would be a compromise between ease of "control" and efficiency.

if only I could understand what is meant with ease of "control"
I could have an idea about this, but I just don't experience
any advantage when paddling with a bent-shaft of less than
14 degree.

Dirk Barends[/quote]

Try a stern pry at speed. A bent shaft acts like a brake. Not desirable to me as I like to maintain my momentum. Another difference is in the draw. You present less blade surface area at the beginning of the draw stroke which grabs a lot less water.

Al


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PostPosted: February 27th, 2004, 8:05 am 
There's a lot to be said for original thinking and being curious about why something is or isn't,but regarding bent shafts on light weight paddles?, I have no problem watching how experts in the field do it and what they use to do it..and then adapting to my use.
True ,the application (racing) isn't exactly what we do mostly,but efficiency...speed ,at times,...and the ability to accelerate when you want to..all are a part of the pleasure of canoeing to most people I've met.
And who knows? you may get to paddle with one of these people who say that they are fastest,best paddler in the pond and presto! a friendly littlle contest is born!
Happy paddling!, however you choose to do it.


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PostPosted: February 27th, 2004, 9:11 am 
While it could indeed be that there is a relation between the amount
of bend and the stroke rate, I can think of several possible other
factors too. Problem is that there is so little 'scientific' study
and experimenting (as far as I know) about paddles and paddling,
that we just have to do for a large part with (our own) experiences
and logical reasoning. And I do agree with Paul's experiences with
straight and bent-shaft paddles, that are also shared with a lot of
other paddlers who paddle the same way as we do, I think. (And if we
are very wrong with our experiences, at least we are not alone:-)

Point is that with so little 'scientifical' back-up, I think it is
important not to assume things that might just not be really true.
For instance, I just don't think one 'raises the canoe' when making
a forward stroke. With a forward stroke you are pulling yourself
forward with your bottom hand (->arm) on the paddle, and you are
then also pulling yourself (always) downward in that same motion.
Possibly there might be little upward effect with the upper hand??
but that will not counteract the downward pulling effect enough
to create an uplifting effect of the canoe during any part of the
forward stroke.
Only with a bent-shaft paddle there might be a less
downward effect than with a straight shaft paddle --
and that is the best (technical) explanation I can come up
to explain the possible advantage of the bent-shaft paddle
over a straight shaft.
I do know that paddling theory is a very complicated matter.
I am glad my body does pretty well with the practical part
of it :-)

Dirk Barends


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PostPosted: February 28th, 2004, 12:23 am 
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It's true our discussions are limited (or necessitated?) by the lack of scientific research. But even science is contaminated by agendas. Someone once commented that today's scientific truth is tomorrow's ridiculous superstition.

Quote:
I just don't think one 'raises the canoe' when making a forward stroke. With a forward stroke you are pulling yourself forward with your bottom hand (->arm) on the paddle, and you are then also pulling yourself (always) downward in that same motion. Possibly there might be little upward effect with the upper hand?? but that will not counteract the downward pulling effect enough to create an uplifting effect of the canoe during any part of the forward stroke. Only with a bent-shaft paddle there might be a less downward effect than with a straight shaft paddle -- and that is the best (technical) explanation I can come up to explain the possible advantage of the bent-shaft paddle over a straight shaft.


I guess this depends on how someone starts their strokes. My comments below apply only if the paddler's lower hand is farther forward than their upper hand at the initiation of the stroke.

At the start of a paddle stroke, just after the blade tip touches the water, the blade is not vertical in the water. Any "forward" force applied to the paddle at this point, continuing until the power face of the blade reaches the vertical, will be depressing some water with respect to the water surface. You don't wait until the blade is vertical before applying forward power. This will have the effect of lifting the canoe. Whether it's obvious or not doesn't make this effect go away. At the very start of the stroke, the power face of a bent shaft paddle blade will be pointed more towards the lake bottom than a straight paddle, and so will make this effect worse. Exactly the same way the bent shaft is an advantage at the end of the stroke, where it lifts less water than a straight paddle. Which is what everyone looks at. But no one looks at what's going on at the start of the stroke.

I would assume canoe racers in classes where paddle configuration is not regulated, have done some pretty thorough testing. I'd also assume that given the specializaiton of their boats, steering wouldn't be an issue.

Presumably the idea is to end up with the blade vertical as it passes through the portion of the stroke where the most forward power is exerted the most easily. If the angle between the two hands relative to the water surface is 12 or 14 degrees at that point, then a bend of the same amount would optimize the forward propulsion by getting the blade vertical.

But unless you're using seats on tracks or something like that, the paddle blade is vertical in the water only momentarily during the stroke. When it's not vertical, (and most of the time it's not), any power being applied will, to some extent, lift or depress water. Whether the paddle is bent or not does not change this. Shorter strokes, which probably will correspond with a higher cadence, will minimize that loss by having the blade more vertical for a greater proportion of the stroke. As agreed, the advantage of the bent shaft is that it is vertical at the "sweet spot". No water is lifted or depressed at that moment, whereas with a straight shaft, some water is lifted at that point.

Correspondingly, with the bent shaft, before or after the sweet spot, not as much effort is being applied to the paddle, so less water is lifted or depressed. Going through the same range of motion with a straight paddle, there will be a point before the point of best application of forward power, where the blade is vertical (one hand directly above the other) and no water is being lifted or depressed. But at that point, the power in the stroke has not reached the maximum.

But that assumes something about how our muscles work that may not be true. Does the force applied to the paddle remain constant during the power phase, like a transistor that's either full on or full off? Or does it taper in and taper off, like a bell curve? If it's the former, then bent shaft paddles presumably woudn't offer any advantage. Any gain at the end of the stroke would have been lost at the start.

I want to look at this business of the blade being vertical, in the context of a pure forward stroke. Obviously that optimizes forward propulsion. If, when you got your blade vertical in the water, you moved both hands backwards with respect to the direction of travel, you'd prolong that optimum situation. But that involves bending the elbows a lot, especially the upper one, which most experts discourage as a recipe for tendonitis. Our bodies just don't work well that way.

Instead, what we do is pull back with the lower hand, keeping the upper arm relatively straight. This causes the upper hand to move down and back. You can simulate this sitting in your chair. As a result, the blade is vertical only for a moment. So then all this other stuff about lifting and depressing water and bent shafts comes into play.

As for flutter, I have noticed this, but I think it wouldn't qualify as a problem for most recreational flatwater paddlers. Probably we disagree here, but I think a greater bend would be more susceptible to flutter. I think it's also possible the power face of the bent paddle would be LESS likely to flutter than a straight paddle.

More serious is the inescapable fact that all else being equal, a bent shaft paddle isn't as strong. And the sharper the bend, the weaker it is. (I can see it already, someone will claim that in their opinion, all degrees of bend equally compromise shaft strength.)

I wonder if anyone's still reading this?

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PostPosted: February 28th, 2004, 8:43 am 
I have strong doubts about the "lifting the canoe" idea.
I prefer to look at the whole paddle motion and
not only what happens with the paddle blade in the water: try to
think about what forces are happening from the connection from your
paddleblade<->paddle shaft<->hands<->arms<->shoulder<->body<->
canoe, when making a forward stroke. These are a very complicated
combination of forward and downward pulling forces, and possibly
some pushing upward forces too, but not with the end result of
"lifting the canoe" effects, like perhaps possible
when poling a canoe.

>At the start of a paddle stroke, just after the blade tip touches
>the water, the blade is not vertical in the water.

Not vertical to the waterline, but so what?
(How) Is the waterline relevant in this respect?
I think that as long as the movement/direction of the blade is
perpendicular to the paddle blade, the paddle blade is working well
in creating a point of resistance that you use to pull yourself
forward (when you do the forward stroke, of course).
And I don't think it matters if this resistance comes from
depressing water. Also I doubt if the lifting water effect, if it
really exists, is the real negative problem here. I think it is more
coincidental with other effects, namely the fact that in the end of
the stroke the downwards pulling force is becoming much bigger than
the forward pulling force, visible by the arm of the lower hand that
is then more in a downward direction than a forward direction.

>But no one looks at what's going on at the start of the stroke.

I have, and I am convinced there are many others too.
And I have come to the conclusion that we just have been
making wrong assumptions about how paddle propulsion works
when looking at the paddle blade position only.
That this makes it more difficult to give a simple explanation
about the advantage of the bent-shaft paddle is inevitable,
but not a big problem for me. I can live with the fact that
there are a lot of complicated things in life, where I do not
have a solid explanation available.

Dirk Barends


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