Re: Shorter Oars
- From: Marco <Marco.Bovo.A.H.C@xxxxxxxxx>
- Date: Thu, 2 Apr 2009 08:00:14 -0700 (PDT)
Hi Kit
It's amazing that everybody is talking about this but no one is
actually trying to replicate or to experiment with this.
I have been trying, with my limited resources, to test both oar shape
and different type of rigging to see which one is the most efficient.
Strangely this year I am focusing on oars length. Since it's really
hard to account for the variables I am trying to make as many pieces
as possible so I can reduce the amount of errors. So far it seems
that in my population (slow high school girls) the shorter length is
working to their advantage. I am now trying to find an optimal
inboard experimenting with different lengths in different boats (8+
and 4+).
I think we should start implementing a policy of numbers. Take your
crews down change one variable at the time and get results in your
hands and send them over.
The "I think" "higher rate" "lower rate" "faster" "slower" are terms
that mean nothing without a point of reference especially working in
an environment like water that behave so differently.
What are your thoughts?
Marco
On Apr 2, 6:12 am, kdav...@xxxxxxxxxx wrote:
On 31 Mar, 01:15, Carl Douglas <c...@xxxxxxxxxxxxxxxxx> wrote:
<SNIP>
One would do well to remember that the oar isn't really "moving
through" the water insomuch as it is being anchored at one position,
locking up against a fairly resistant medium (water), slipping a bit
due to the arc of the application of leverage and the properties of
the medium (water), then being removed to repeat the process. The
whirling "puddle" you create stays in relatively the same position.
It's the boat that moves past it. Hence my sculling coach ages ago
told me "don't row too long in the same spot." ;)
Couldn't agree more that the objective is not to move blade through
water but to move boat past blade.
However, I cannot agree with the notion that the blade is static, or
should be, in the water. If your catch angle is 40 degrees from the
boat's axis, then the tip of a scull's blade moves outwards through the
water, away from the boat, by a distance of over 70cm/28", & to
accomplish that it really is moving, tip first through the water, at an
initial 3 - 4m/sec.
In the first part of the stroke the blade moves a considerable distance
_forward_. In this process it generates hydrodynamic lift & does not
noticeably slip (indeed, the term "slip" has no meaning during this
phase of the stroke). Nor does it add much velocity or energy to the
water since its lengthwise motion means that it exerts a relatively
slight influence across a rather large mass of water. When the blade
nears the square with the boat it does stall, dwells in a fixed zone of
water & then it does slip, dragging water with it & thus creating the
puddle which contains most of the lost energy which contributed nothing
to moving the boat. As you approach the finish, the blade starts to
move inwards, with water now flowing increasingly from root to tip &
lift is re-established, raising propulsive efficiency once more.
The net result is that the blade tip leaves the water markedly further
forward in the direction the boat is moving than it entered. And that
despite the slip which occurs in the mid-stroke when the puddle is being
created
This is interesting.
A couple of months ago, I read a brief article by Andy Triggs Hodge
(GB4- stroke) about the technique exercises they did. One of their
coaches, Jonny Singfield, got them to do one exercise which Hodge
describes as putting the blade into the water at the catch then
holding it there for a "moment" (length unspecified) before taking the
stroke. This sounds alot like the advice Gordon Hamilton gave Charles
about waiting for the blades to come back to him before applying
pressure.
I had assumed that it was intended just to encourage patience and
relaxation at the catch. But thinking about the forward movement of
the blade through the water at the catch that you describe, I wonder
if allowing the water to flow briefly over an unloaded spoon creates
some lift _before_ load is applied, so that when it is applied, more
effort is effective. Catches which are loaded too quickly before some
lift has been generated (or even before the blade is fully immersed)
will result in greater slip and wasted effort.
I have tried the "catch and hold" method in our 4- (hold = c. 1/4 sec)
and (when done properly) I can attest to it improving the general feel
of the catch. Maybe this is why, or maybe I'm barking up the wrong
tree.
I have also tried it in a 1x with less success. With less momentum in
the boat, it seems to just mess up your catches.
Kit
.
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