roo wrote:

I cant speak for Charlie directly but I think that he probably meant
"little more". Sounds like the blades were a bit more than a stick
flattened at each end? ;-) If they were "nothing more" wouldn't he
have described a stick flattened at each end that he conce tried to
paddle with.....

Sounds like a description of at least some Greenland paddles to me! ;-)

Explain the extended grip to me for use with these paddles, please.

Slide the paddle through your hand before turns (or rolls) so you're
holding it well away from the end that handles the action. This way the
paddle can be used as an outrigger as well as extending the sweep of the
blade considerably, so you get more turn and more stability in radical
(or at least radical for a long boat!) turns.
This is very, very handy with any sort of paddle in open water, I'd
imagine it would be rather less so in white water...

Extended grips aren't in any way limited to Greenland paddles, though
the high natural buoyancy coupled with long length and no real blade to
get in the way does make them especially suited.
I once saw a criticism of cranked paddles saying it prevented use of
extended grip, but that sounds like tosh to me: my main sea paddle is a
Lendal Mod Crank, and I use extended grip on most of my leaned turns in
the sea boat.

Pete.
--
Peter Clinch University of Dundee
Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

Jim Wallis wrote:
Inuit blades are a little more complex than Peter implies, but the
extreme styles do have blades that are probably no more than twice the
width of the shaft and most of the length of it.

My friend wot builds his own Baidarkas also makes trad paddles that
really are pretty much a flattened log, certainly nowhere near twice as
wide as the centre. And he uses them to great effect too! I should
have a pic of Alf in action doing a monster lean with one in a Baidarka;
if I can find it I'll put it on a page and post the address.

Pete.
--
Peter Clinch University of Dundee
Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

In article , roo
wrote:
Hi All

I did a quick archive search but found nothing too useful. If anyone
could point me in the right direction that would be great.....

I've been getting a lot of comments recently about the size of my
paddle blades. They've been ground down considerably since 1998 and
instead of a symmetric blade shape they are now very similar to a
shrunk kinetic shape.

(This is only because I use my paddles the same way round all the
time. They were any orientation paddles, but luckily I kept using
them the same way and avoided ending up with very expensive cocktail
sticks!)

So enlighten me to the pros and cons of different blade sizes.....

I assume it's a relative assessment, but...

Large blades provide more power, but give a higher chance of injury?

Small blades allow/require a higher stroke rate for equivalent large
blade propulsion?

Is the size irrelevant, because all that is required is enough
friction to plant the blade and pull yourself past the shaft?



Following the replies already posted: there are a few misconceptions and
incorrect assumptions:

Firstly, there is no such thing as a powerful paddle...

The term 'power' is very often misused and can lead to a great deal of
confusion.

Power = force x velocity.

Larger blades do not provide 'more power' - power is supplied by the
contracting muscles.

Most of the replies seem to rely on the assumption that the forwards paddling
stroke is a result of drag, ie the blade is immersed in the water and
pulled backwards. This is not the case (despite what might be believed or
taught), and would be an extremely inefficient means of propulsion in any
boat (canoe, kayak, rowing, sculling, paddle steamer or screw-propeller
craft).

There is a considerable degree of hydrodynamic lift (HDL) in the paddle
stroke (always has been), both at the immersion phase and the stroke phase.
The latter is the 'wing' effect /exploited/ by wing paddles. HDL is,
though the major propulsive force even for flat blades - and always has been
by top paddlers (as demonstrated by photographs and cine film dating back
over 50 years or so) ie the stroke with a wing paddle is not so different to
that with flat paddlers (for those with good technique...).

Whilst it appears that the blade remains stationary in the water during the
stroke, it is prescribing a complex 3-D path - downwards and sideways as
well as being rotated to some degree (like a propeller). All of these
movements can have very high lift coefficients and resist the backwards
slippage of the inefficient paddler.

A large blade will give less obvious slippage than a small blade (though the
total wasted energy due to slippage might be the same - a large volume of
water moved slowly or a small volume moved more quickly). Any slippage is
wasted energy, but more importantly, it means that the muscles cannot apply
force effectively during the stroke. The greater the slippage, the less
effective will be the stroke. It should be obvious that if pulling the blade
straight backwards causes slippage, then this is not an efficient means of
applying force to the blade and the truth is only masked by using the bigger
blade...

We have heard mention of vortices: Partly immerse a blade and pull it
backwards - a vortex is shed from each edge of the blade due to slippage.
This phenomenon is indicative of a blade operating using drag. Typically, a
wing blade or flat blade using hydrodynamic lift will shed just one vortex
(the other still being present but circulating around the blade, itself).
This wing action reduces slippage and is therefore more efficient.

In racing, it has long been known that smaller blades are better than larger
blades - for example Lendal Powermasters at 19.5cm were once called 'Ladies'
blades and no self-respecting man paddler would want to be seen using them.
When we changed the name to 'Standard', they became the norm and those trying
to use big blades (20.5cm) got left behind.

Once Wings became accepted, it was found that most paddlers (of both sexes)
could perform better with smaller blades. So much so that a very narrow
paddle was developed and used by a very strong German crew to win a Sprint
World Championships. This blade was accepted by some but considered 'crap'
by others... a quick analysis revealed that those who rejected it had the
worst techniques.

Smaller blades can result in a higher stroke speed (as opposed to stroke
rate which might also be affected), but this might take advantage of the
fact that the muscles are more efficient at higher rates of contraction (ie a
stroke rate of about 120-140pm, according to the research). Whilst this is
not applicable to touring canoeing it indicates that big blades = slower
stroke = reduced muscular efficiency. This has bee borne out by observations
that bigger blades result in more fatigue in eg the DW. Longer paddles and
bigger blades are not the way to go in marathon events.

There is no evidence that asymmetric blades (as opposed to square ends) are
more efficient, either - they were introduced in racing to replace the square
ended blades in the belief that the corner entering the water first was
somehow 'wrong'.

Regarding paddle weight: when we had very light weight paddles, they were not
well received and were quickly discarded. They were not suitable for
sprinting or marathon work. There are theories as to why this might be so,
but all the world's top sprint and marathon paddlers can't be wrong, can
they?

On a final point: I do not believe that paddle sizes are 'designed'. Much
of what is available is a result of 'me-too-ism' by the manufacturers in
order to capture a share of the market, and once moulds are made, they are
used. I have seen very little objective research done in order to arrive at
optimum paddle lengths / stiffness or blade areas. You get what is
produced with little deviation from what is the perceived 'norm'.

Many of our top paddlers (including World Champions) re-shape their blades
(ie reduce the area).

So, where does all this get us?

I would say: invest some time in learning to paddle 'correctly' so you can
take advantage of smaller blades.


Allan Bennett
Not a fan of absolute power


--

Interestingly if you compare Allan's post with mine you will find that
whatever may be implied in the first few paragraphs there is only one or
two areas in which our posts disagree.

Drag vs Lift:

I've never had the chance to study the path of a paddle through the
water, I assume probably incorrectly that most people messing around
with symmetric blades operate them in a mainly drag fashion - it appears
that Allan is in possession of data to the contrary which I certainly
can't argue with. Every bit of paddle motion that is not perpendicular
to the blade surface will produce lift (and drag), so a curved blade
will produce lift even if you do pull it in a straight line, which when
you really think about it - you can't. I wouldn't have thought initially
that the lift would be significant, but then I was forgetting that the
paddle is tilted in the Z direction no matter how vertically you try and
place it.

Asymmetry

As for asymmetric blades, I do feel they are more efficient, but maybe
not for the reasons you see quoted (which I often tell people for
simplicity) - the shape of a wingtip can have an incredible effect on
the way the vortices are shed but also on the stability of the wing, the
asymmetry will effectively reduce the aspect ratio which increases
stability which will in turn affect the rate at which you can apply
power. Reducing aspect ratio for stability is a trade off for lift but I
feel the stability is more useful. It also seems to affect the feel of
the bite and if anything encourages the blade to sweep out for
hydrodynamic lift when compared to a squarer tipped paddle. The above
does not constitute proof that asymmetry is better I do consider it
evidence though. It is a list of possible reasons why it feels better to
me - the chance to try 2 blades identical but for a cutaway is very rare
so I don't claim to have compared like for like.

What does all this mean for Roo?

Get out there and try some new paddles! If your river blades have had as
heavy use as mine (they have probably had more) they are probably
impracticably small now. But shape is more important than size, 2
paddles the same size but different shapes will have different
characteristics, will absorb different amounts of power and produce
different amounts of propulsion for a given power.

One other point - whilst a lot of paddle manufacturers do just copy what
is trendy, most of the better ones do use trial and error to determine
what they consider to be good shapes. I'm sure some are claiming to do
CFD to determine the shapes (madyaker?) but whether they have the
correct models for the paddle path (and thus water flow over the blade),
I couldn't say!

JIM

In article 0vtlqb.ijg.ln@Eskdale, Jim Wallis
wrote:
Interestingly if you compare Allan's post with mine you will find that
whatever may be implied in the first few paragraphs there is only one or
two areas in which our posts disagree.

There are. Whatever you may believe was implied :-)

Drag vs Lift:

I've never had the chance to study the path of a paddle through the
water, I assume probably incorrectly that most people messing around
with symmetric blades operate them in a mainly drag fashion

We will differ on that point, Jim. I don't believe that any paddler
*intends* to use drag or lift by choice, but from what I have observed the
major propulsive forces come from HDL. The same debate rages on a regular
basis in rowing where the lift forces are approx 9x greater than drag - in an
action where most people cannot conceptualise lift at all.

- it appears that Allan is in possession of data to the contrary which I
certainly can't argue with. Every bit of paddle motion that is not
perpendicular to the blade surface will produce lift (and drag), so a
curved blade will produce lift even if you do pull it in a straight line,
which when you really think about it - you can't.

....and in a normal paddle action, you don't.

I wouldn't have thought initially that the lift would be significant, but
then I was forgetting that the paddle is tilted in the Z direction no
matter how vertically you try and place it.

Asymmetry

As for asymmetric blades, I do feel they are more efficient, but maybe
not for the reasons you see quoted

Asymmetrics were introduced into racing (a bit before my time), because it
was believed the paddle would twist in the hands when one corner entered the
water first. They were therefore thought to be more efficient at the catch
phase and a benefit in reducing forearm fatigue and injuries.

There is no evidence that there is any benefit, either in improved
performance, comfort or anything else. They became a 'must have' as soon as
they were adopted by the best paddlers.

(which I often tell people for simplicity) - the shape of a wingtip can
have an incredible effect on the way the vortices are shed but also on the
stability of the wing, the asymmetry will effectively reduce the aspect
ratio which increases stability which will in turn affect the rate at
which you can apply power.

There night be something in that, especially in the first few strokes from
stationery - but once a lift-generating stroke is employed (ie most strokes),
those principles become less relevant.

Reducing aspect ratio for stability is a trade off for lift but I feel the
stability is more useful. It also seems to affect the feel of the bite and
if anything encourages the blade to sweep out for hydrodynamic lift when
compared to a squarer tipped paddle.

Again, we will differ on this point - the 'swing out' action is a consequence
of the blade )any blade) acting as a foil. It will adapt the angle of attack
and natural passage through the water according to the force applied - unless
the paddler attempts to control it for any reason.

It also exploits a more natural action, IMO - and, as I said - an action seen
in top paddlers before wing paddles were invented and HDL was considered.

The above does not constitute proof that asymmetry is better I do consider
it evidence though. It is a list of possible reasons why it feels better
to me - the chance to try 2 blades identical but for a cutaway is very
rare so I don't claim to have compared like for like.


....and a cut-off blade is not directly comparable, anyway, as it will have
reduces SA with the concomitant benefits that provides...

What does all this mean for Roo?

Get out there and try some new paddles! If your river blades have had as
heavy use as mine (they have probably had more) they are probably
impracticably small now. But shape is more important than size, 2
paddles the same size but different shapes will have different
characteristics, will absorb different amounts of power and produce
different amounts of propulsion for a given power.

One other point - whilst a lot of paddle manufacturers do just copy what
is trendy, most of the better ones do use trial and error to determine
what they consider to be good shapes.

sceptic mode

Yeah. Right.

\sceptic mode

I'm sure some are claiming to do CFD to determine the shapes (madyaker?)
but whether they have the correct models for the paddle path (and thus
water flow over the blade), I couldn't say!

Wing paddles were, we understand, designed at a UK university - as blades for
a water-pump (like a propeller)... which should give some clue as to how they
work and how they should be used.


Allan Bennett
Not a fan of trial and error - aka BCU Special Hearing Committee


--

Allan Bennett wrote:
In article 0vtlqb.ijg.ln@Eskdale, Jim Wallis
wrote:

There night be something in that, especially in the first few strokes from
stationery - but once a lift-generating stroke is employed (ie most strokes),
those principles become less relevant.

At least I don't feel quite so silly about getting assyms for surfing,
where "most strokes" (or at least the ones that really count) *are* the
first few from stationary!

One other point - whilst a lot of paddle manufacturers do just copy what
is trendy, most of the better ones do use trial and error to determine
what they consider to be good shapes.

sceptic mode

Yeah. Right.

\sceptic mode

They're quite possibly *trying*, but it's very difficult to get an
objective model of a paddler using the thing over a representative range
of conditions, especially away from the real top flight people as our
(probably much larger) personal idisosyncracies will, I'd think, have a
much bigger effect on what works best for us. I notice that amongst the
denizens of TSKC there's no real consensus of how big the effect of
changing blade size is (makes a big *perceived* difference to me, hardly
anything to others), whether cranks help (some wouldn't be without them,
some actively dislike them, I like them but am not really *that*
fussed), and so on.
People coming up with the Big New Thing may well be kidding themselves,
noticing an effect that has nothing directly to do with their idea, or
*really* having hit on something.

It's proving hard enough to understand things for the relatively
predictable world of sprint, it's no wonder it's much harder for
something with more of a mix of strokes on wildly different water
conditions.

Not a fan of trial and error

It's often the only way though :-( I don't think the folk who thought
of the Baidarka's construction had it all thought out in advance
according to known engineering principles on computer workstations...

Pete.
--
Peter Clinch University of Dundee
Tel 44 1382 660111 ext. 33637 Medical Physics, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

I've found blades that'r too small rip through the water without letting you
get proper drive ..... bit like a car having a slipping clutch - it does go
forward but wastes a load of power.

At the other end of the scale too big a blade just digs in and grips so
tight there's virtually no give at all except a tiny bit of spring in the
shaft. That sounds OK but it really loads your shoulders. I tried a set of
DB RVXs and found I got good accelaration but my shoulders took too much
hammer whilst the slightly smaller RVX accelerators were way nicer.

I can't see how there'd be a formula. Too many variables key ones including
your weight, size, strength and the quality of your joints.

Nidge

In article , Nidge
wrote:
I've found blades that'r too small rip through the water without letting
you get proper drive ..... bit like a car having a slipping clutch - it
does go forward but wastes a load of power.

At the other end of the scale too big a blade just digs in and grips so
tight there's virtually no give at all except a tiny bit of spring in the
shaft. That sounds OK but it really loads your shoulders. I tried a set
of DB RVXs and found I got good accelaration but my shoulders took too much
hammer whilst the slightly smaller RVX accelerators were way nicer.

I can't see how there'd be a formula. Too many variables key ones including
your weight, size, strength and the quality of your joints.


....and the biggest variable of all - technique.

I would suggest that, if a small blade slips, you are using drag and
development of a technique that incorporates hydrodynamic lift would be a
great benefit...

Having said all that, it is odd that most paddlers accept the 'one size fits
all' approach to blade size.

BTW, a similar discussion is taking place on the rowing ng.



Allan Bennett
Not a fan of cross posting

--

"Allan Bennett" wrote in message
...

snip 'learn how to paddle properly' stuff
followed by
snip comment about discussions on another newsgroup

Allan Bennett
Not a fan of cross posting

Yeah, yeah, we know all that, but is bad tempered posting is still OK?
gr
Mind you don't annoy the oiks again. Ah, happy days........

David
Not a fan of the oiks ;^)

In article , David Kemper
wrote:
"Allan Bennett" wrote in message
...

snip 'learn how to paddle properly' stuff
followed by
snip comment about discussions on another newsgroup

Allan Bennett
Not a fan of cross posting

Yeah, yeah, we know all that, but is bad tempered posting still OK?
gr

Just a simple misunderstanding... no change there, then :-)

Mind you don't annoy the oiks again. Ah, happy days........

David
Not a fan of the oiks ;^)

Too much Tolkien, methinks ;-)


Allan Bennett
Not a fan of breeding dinosaurs

--