On Wed, 07 Nov 2007 20:11:58 -0500, Wayne.B
wrote:

On Thu, 08 Nov 2007 00:39:04 GMT, Short Wave Sportfishing
wrote:

I'm still confused about how it actually stops the mass of the boat
from moving in only one direction.

Probably the best way to get an intuitive grasp is to go out and buy a
toy gyro. Get it spinning and hold on to it by each end while you try
to turn it 90 degrees to its spin axis. It will try to fight back,
same effect that you sometimes get with a high powered electric drill.

I couldn't even begin to describe it mathematically but the reason it
resists is because of angular momentum. It wants to continue spinning
in the same direction, and it takes force to change it. That is why a
gyro will balance on one end while spinning, or suspend itself
horizontally if held on one end by a string. On a boat all you have
to do is securely fasten each end of the spin axis, and the whole hull
structure becomes an extension of the gyro itself, which will
consequently resist any force perpendicular to the spin plane.

I finally figured it out - it was the fixed axis thing that was
bugging me. I was always under the impression that gyros do represent
a fixed axis.