On Wed, 7 Nov 2007 21:12:45 -0500, "Eisboch"
wrote:

In this case I think you do. The spinning gyro is within the vacuum
enclosure which is, in turn, on a single axis gimble. The enclosure is used
to transfer the stabilizing force to the beams or stringers on the boat.

Yes, the patent application refers to a gimbal which is dynamically
positioned by an active servo mechanism.

"The drum rotor is mounted in a frame, which in turn is mounted on
gimbals so that the rotor can nutate under the control of the system's
servo system. The servo system's operation is managed by a control
system having input from the ship angular position and rate sensors."

That implies to me that they use the servos to reposition the spin
axis to maximize its effectiveness but I'm not sure.

One of the nice things about using a large gyro stabilizer is that the
system is effective even while anchored or drifting. The Naiad active
fin stabilizers that we have on the GB49 require the boat to be moving
forward at least 6 knots or so to be effective.

I have heard some interesting reports of a much simpler anti-roll
system using port and starboard water tanks connected with a tunnel
which provides a controlled rate of flow between tanks. The size of
the tanks, amount of water and the flow rate of the connecting tunnel
are all carefully calibrated to counteract the natural roll frequency
of the boat. Conceptually it is very simple, uses no power, has no
mechanical or electrical components and is reasonably inexpensive to
implement. One of the guys on the trawler mailing list has it on a 59
footer and is very pleased with it. As with the gyro, it works all
the time, even when the boat is not moving forward. I believe that
his system was designed by a professor at MIT but I could be wrong
about that.

I was thinking about buying a couple of cheap dock boxes, putting them
on the flybridge with some connecting pipes, and doing some
experimentation just for the heck of it. It would be a nice backup
for the Naiads and solve the rolling at anchor problem but the
flybridge cosmetic issue may turn out to be a show stopper. I've got
to figure out a way to hide those pipes or convince Mrs B that the
scientific method can be beautiful! :-)

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