David Hale wrote:
> Feesh! Your calculations treat the sausage surface as
> if the entire 1,357 sq inch surface of the cylinder
> (sausage) can be seen at one time. I know that you
> know better than that.
>
> I think the relevant figure is the two dimensional
> projection of the cylinder, which would be its
> diameter times height or 6 x 6 x 12 = 432. This would
> be the same no matter what angle it is viewed from, as
> long as you are in a plane that is perpendicular to
> the cylinder's axis.
>
> The viewable area of Andy's flag is 558, which is
> actually about 29% larger. But you have to be at
> exactly the right place to see that viewable area, so
> in nearly all cases the sausage will present a larger
> two dimensional projection than the flag.
>
> My geometry is rusty beyond belief, but I think the
> two dimensional projected sizes are what should be
> compared. I think I'm correct about this - please
> think it over. Of course if I'm wrong, I know this is
> really going to cost me! :D
I don't know if it's going to cost you, but here's my take on the subject.
Both of you should know that I would not let Andy claim his was bigger than
mine without considering how to weasel out of being bested. Since I
surrendered, you may assume I couldn't find a way. In my opinion, Andy's
correct for several reasons:
1. Bob's formula does not account for the fact that you can only see half
the sausage at one time, as you pointed out.
2. Bob also claimed you could only see the flag's surface from two
directions. At best, he should have said that you can only see the full
surface from two angles, but even that is not entirely correct. What you
both appear to have forgotten is that when signaling with his flag, Andy
waves it. When he does, it stands out from the staff, presenting most, if
not all of its surface to the person he's signaling to.
3. Everybody seems to have forgotten how and where the devices will be used.
We're talking in the water here . . . with waves. The display surface of my
sausage runs from the bottom to the top. A portion of the signaling surface
is almost always going to be concealed by waves. In 5 foot seas, much of my
sausage will be concealed much of the time, while all of Andy's flag will
still be visible all of the time.
Andy's flag is probably a bit better as a signaling device, but my sausage
also works pretty well. Further, my sausage does a lot that Andy's flag
can't. For example, my sausage does not have to be held to be effective.
It's highly visible even when laying over on the surface and almost as
effective with a weight suspended from it as it is being held upright. It's
an effective float if I need one (I attach all my hunting gear to it while
waiting for the boat to pick me up), lift bag when I need one (I've
recovered a few anchors with it) and DSMB if I want one (I rarely need one,
but once in a while . . .). Andy's flag is certainly better than the small
safety sausages most divers use, but I still like my bigger than Dallas
sausage better.
Lee
> --- Reef Fish <[log in to unmask]> wrote:
> >
> > Now consider a standard 6' long sausage with a 6"
> > diameter, as the
> > one Bjorn, Mike Wallace, Jeff, da Feeesh, and a few
> > other NEDfesters
> > have.
> >
> > The VIEWABLE surface area of this sausage, when
> > inflated, is the
> > circumference of the circle with a 6" diameter times
> > the length of
> > the sausage, which yields,
> >
> > (2 * pi * 3 ) * (6 * 12) or 1,357 sq.
> > inches
> >
> > which is the equivalent of 8,756 sq.cm, more than
> > TWICE the 3,600
> > sq.mm of viewable surface on Andy's flag.
> >
> > The sausage of course has the advantage that it has
> > the SAME viewable
> > surface from all directions, whereas the flag's
> > surface can be seen
> > only in exactly TWO of infinitely many directions.
> >
>
>
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