

Mathematician solves rowing boat "wiggle" problem - ypavan
http://www.technologyreview.com/blog/arxiv/24437/

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sandrogerbini
> the serious problem of oscillating non-zero transverse moment in racing
> boats, otherwise known as wiggle.

Thank goodness for simplification of terminology.

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bmickler
I rowed in college, we experimented with different riggings (including
arrangement 'a' from the article) and found that, indeed, bucket-rigging and
others seemed to yield good times. There were other variables though, strength
of the current, wind, how intense our hangovers were... so it's hard to
attribute it to just the different arrangements. I will say that sitting in an
arrangement where the guy in front/behind has his oar on the same side as you
leaves very little room for error. If you don't get that oar up and out at the
finish you'll hit oars and crab for sure.

~~~
mhb
Why would the current matter? Assuming the boat and oars are all in it?

~~~
bmickler
The start and finish of the race are located at fixed points. If you're racing
on tidal rivers near the coast, where most of our regattas were, the current
varies widely throughout the day. Say it's a 5k head-race starting upstream
and coming down towards the sea. At high and low tide you're essentially
racing with no (or very little) current - much like a lake. When the tide is
coming in, you'd be racing against it and a 5k race can take 20 or more
minutes. If you're lucky and your race heat starts when the tide is going out,
that same race will take 15 or less minutes.

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evanjacobs
There are several considerations that a rowing coach must make when deciding
the rig of the boat as well as which rowers should occupy each seat.

These considerations may vary for each rower and include:

1\. arc length (i.e. the distance traveled by the blade of the oar)

2\. force curve (i.e. the amount of force applied during each part of the time
the oar is in the water)

3\. boat feel (it is a much different sensation rowing in the bow, middle and
stern of the boat and different rowers are "better" in different parts of the
boat)

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briancooley
I wonder if some of those rigs are more fragile than the others. Perhaps some
of them (rig (a) perhaps?) would wiggle more severely if the rowing forces
were uneven while others would be fairly robust to differences in force.

~~~
mike_organon
I wouldn't expect so, at least by the math. It looks is pretty simple. Number
the seats 1 to 8, then for each side sum the seat numbers. The standard rig
gives 16 and 20, but all 4 of these solutions are 18, 18.

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obsaysditto
"to show that the balance of forces in this rig as the oars are pulled through
the water"

If the oars are pulled through the water, the boat wouldn't move.

~~~
pwmanagerdied
What do you mean?

~~~
RiderOfGiraffes
I suspect his point is that the blades of the oars, when immersed in the
water, don't move (much) relative to the water. Approximating the blade as
stationary in the water, we can see that the boat moves because of a lever
effect. If the oars moved freely through the water there would be no thrust,
as would be the case when rowing in liquid helium.

However, given the context, it seems a singularly pointless nitpick.

~~~
celoyd
Especially considering that, in practice, oars move quite a lot through water.
It’s fluid, after all; rowing is not like ski-poling yourself along.

