"Wayne.B" wrote in message
...
On Wed, 07 Nov 2007 20:26:53 -0500, HK wrote:

Try "inertial space." The angular momentum of the spinning rotor causes
the gyro to maintain its attitude even when its gimbal is tilted.

Yes, but if you are trying to stabilize a boat I don't think you use a
gimballed mount.

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.

Eisboch

On Thu, 08 Nov 2007 00:39:04 GMT, Short Wave Sportfishing penned the
following well considered thoughts to the readers of rec.boats:

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

http://en.wikipedia.org/wiki/Gyroscope

--

Grady-White Gulfstream, out of Oak Island, NC.

Homepage
http://pamandgene.idleplay.net/

Rec.boats at Lee Yeaton's Bayguide
http://www.thebayguide.com/rec.boats
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"Eisboch" wrote in message
...

"Short Wave Sportfishing" wrote in message
...

Interesting video.

I wonder how it affects bow-to-stern movement? It is a gyro - seems
to me that if it has that much of an effect on side-to-side roll, it
would have the same effect on bow-to-stern movement..

The gyro vacuum enclosure appears to be mechanically restricted to fore
and aft gimble movement, so I suspect it stabilizes on one axis only.

How the fore and aft movement translates to stabilizing beam to beam I
think has something to do with the principles of gyroscopic
progression, similar to helecopter controls of blade pitch.

But, I might be wrong.

Eisboch
Progression is what progressives do. Precession is what gyroscopes do.
Or try to do.

Del Cecchi wrote:
"Eisboch" wrote in message
...
"Short Wave Sportfishing" wrote in message
...
Interesting video.

I wonder how it affects bow-to-stern movement? It is a gyro - seems
to me that if it has that much of an effect on side-to-side roll, it
would have the same effect on bow-to-stern movement..
The gyro vacuum enclosure appears to be mechanically restricted to fore
and aft gimble movement, so I suspect it stabilizes on one axis only.

How the fore and aft movement translates to stabilizing beam to beam I
think has something to do with the principles of gyroscopic
progression, similar to helecopter controls of blade pitch.

But, I might be wrong.

Eisboch
Progression is what progressives do. Precession is what gyroscopes do.
Or try to do.




With the right gyro and a skyhook, you can precess yourself into another
dimension. :}

"Short Wave Sportfishing" wrote in message
...
On Wed, 07 Nov 2007 19:05:03 -0500, Wayne.B
wrote:

On Wed, 7 Nov 2007 17:08:34 -0500, "Eisboch"
wrote:

It seems to me the big "breakthrough" in this product is the vacuum
enclosure of the high speed gyro. I'd be interested in how they
handled the
issue I've described.

Good questions. They were talking about using signicant power to spin
it, something like 1.5 KW even though it's in a vacuum. That would
imply that it has a fair amount of friction and quite a bit of heat to
dissipate. It will generate a lot of side loading on the bearings as
it resists the boats rolling motion. Imagine the chaos on board if it
ever jumped loose from its cage!

When I was on the fire department, we responded to an injury call
where a building collapsed. I went direct to the scene and when I got
there, the whole saw mill had collapsed. After we got the workers
out, the Fire Marshall began looking and found what happened.

The fly wheel came loose from the 30 hp two lung jug engine and just
ripped the place apart. Max rpm on that thing was only 40 rpm. Of
course it weighed 900 pounds, but still... :)

This has all been tried before if my memory is correct. As I recall,
the problem with the older systems was that the gyro had to be quite
large, probably because they were running it at a lower speed.

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

Then again, I'm not the brightest guy on the face of the planet.

What ever happened to the "hybrid" vehicles of some years back that had
flywheels for energy storage? They were going to be used in buses etc,
complete with regenerative braking.

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! :-)

http://www.google.com/search?hl=en&q...&b tnG=Search

"Eisboch" wrote in message
...

"Short Wave Sportfishing" wrote in message
...
On Wed, 7 Nov 2007 16:41:36 -0500, "Eisboch"
wrote:


"Short Wave Sportfishing" wrote in message
...

Interesting video.

I wonder how it affects bow-to-stern movement? It is a gyro - seems
to me that if it has that much of an effect on side-to-side roll, it
would have the same effect on bow-to-stern movement..

The gyro vacuum enclosure appears to be mechanically restricted to fore
and
aft gimble movement, so I suspect it stabilizes on one axis only.

How the fore and aft movement translates to stabilizing beam to beam I
think
has something to do with the principles of gyroscopic progression,
similar
to helecopter controls of blade pitch.

But, I might be wrong.

I didn't think of that.

Good point.

Further on my boring analysis of this system ....

The manufacturer acknowledges that the system is similar to another
similar system, but claims it is superior due to the gryo being located
within a vacuum enclosure, thereby reducing the friction due to air. The
gyro can spin at a higher speed, therefore can be made smaller and uses
less power.

Fine.

But, having mucho years trying to make mechanical objects spin, move, etc.
in a vacuum environment, there is one potential issue that comes
immediately to mind.

In a vacuum there is no convective heat transfer to speak of, and very,
very little conductive heat transfer due to virtual point contact.
Bearings generate heat, particularly in high speed applications and if
that heat cannot be transfered away from the balls and races, the bearings
tend to self destruct. We used to use specially prepared aerospace
bearings designed for space flight in the systems we built ... and even
then often had problems with high speed applications.

It seems to me the big "breakthrough" in this product is the vacuum
enclosure of the high speed gyro. I'd be interested in how they handled
the issue I've described.

Eisboch
\

Maybe like diskdrives. No ball bearings. Fluid bearings.

On Wed, 07 Nov 2007 22:41:36 -0500, Wayne.B
wrote:


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! :-)

http://www.google.com/search?hl=en&q...&b tnG=Search

There's a fellow named "maddmike" who frequents the MacGregor
Poweresailor list. He has undertaken various expeditions in a 26X.
One of the many mods he has done to the boat is some type of outrigger
system. It includes shock absorbers.
He explains them a bit here. It's the second maddmike post.
http://macgregorsailors.com/phpBB/vi...sc&&sta rt=15

Some kind of deployable amas seem like a workable idea to reduce
rolling, especially at anchor. They would be lightweight, and their
buoyancy would have to fit the boat. Strength/weight of the arms
and how they are attached to the hull seem to be the biggest problems.
Not trivial problems at all when you consider the forces at play.
The tunneled water tank system you mentioned seems more elegant,
natural and stress free than amas.

--Vic

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.

On Wed, 7 Nov 2007 20:33:01 -0500, "Eisboch"
wrote:


"Short Wave Sportfishing" wrote in message
.. .


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

Study the little graphic they have of the gyro enclosure and how it is
mounted.

When the boat rocks, the spinning gyro imparts a force on the enclosure.
The enclosure, which is attached via telescoping arms to a beam or stinger
in the boat, is gimbaled to only move on one axis (fore and aft which is 90
degrees retarded from the boat's rocking movement (gyroscopic progression).

I think.

I've got it now - it was the fixed axis thing that I was confused on.