Re: Is the Hills' flood possible?

I consulted my son, licensed as a sea captain, and summarize his take. He
notes that 4 mph is low for a river current. He has taken a boat upstream
with the wind, but it took a diesel. More importantly, vessels do not
stay bow or stern to the wind. They broach. This produces list, which is
aggravated by whatever slides to the low side.

Since the Ark, barring a miracle, would be beam-to the wind, I considered
a 5-foot draft, which leaves 40 feet to the wind, versus tipping the Ark
just enough so that all 45 feet would be exposed to the wind. I figured
this at about 11 1/3 degrees. With a cosine of 0.980 and the 12.5% larger
area, the pressure is about a tenth higher. Any greater list and the
bottom is exposed to the wind, increasing the torque. Oopsidaisy!
Dave

On Wed, 07 Jun 2006 00:08:21 -0400 philtill@aol.com writes:

Hi Glenn,

<snip>
The only minor thing I can point out in your critique is that the ark
would have less torque (not more) as it rolled over because the surface
area projected normal to the direction of the wind would decrease (not
increase) according to the cosine of the roll angle. Therefore, when it
rolls it will feel less torque and can return to upright or find an
equilibrium angle. Furthermore, wind speed in the boundary layer of our
planet increases according to the logarithm of height above the surface,
and so higher velocity winds are at higher altitudes and v.v. Thus, as
the ark rolls over, its top will no longer be subjected to the highest
velocity winds. That, too, causes the torque to be reduced, and quite
significantly! Finally, a good boat design will have a restoration
torque from the water so that it will naturally rock back. Your critique
of the center of mass might be correct, but I don't have the details to
look at it here in Canada.

God bless,
Phil Metzger
Received on Thu Jun 8 00:05:17 2006