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


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