Question about stability(newbie)

[turbo2]

Bare with me guys, I am new to this. Alright, so I recently began reading about boat stability and have come across several products that help do so, namely gyroscopes. I am slowly understanding how they work; a change in angular momentum of the flywheel creates a torque which is coupled back into the ship to reduce roll moment.

I have a question though, would it be possible to stabilize a boat with JUST a spinning flywheel and no gimballing? I know that a fast spinning wheel will resist any change in its motion due to inertia. Can this concept be applied to this situation??

[rwatson]

Great idea turbo. Theoretically, the gyroscope would keep the boat perfectly level in waves, and in small waves this might work .

The trouble could come when bigger waves *have* to move the boat. A big wave could overcome the original horizontal axis, and then you would have a boat being kept at a 25 degree angle by the flywheel after the wave had passed.

Also, Flywheels exert their effort in full 360 degrees around them, so it would also be fighting the pitching motion of the boat, as well as the rolling motion. That would put incredible forces on the flywheel support structure when the boats bow was forced up by a wave, or the bow dived into a trough.

I think though that the concept could work in calm waters with a little chop, and a specially designed hull. For example, maybe a houseboat could be made stable from those annoying small wakes caused by nearby powerboats

Other dicussions have mentioned using a flywheel as a source of power storage - maybe the two effects could be utilised.

I look forward to hearing other discussions on the concept.

[TeddyDiver]

See Elements of Yacht Design by Skene fig 40 and 41 (pages 60&62) " The Sperry gyroscopic stabilizer". Very sophisticated gizmo and it really worked some 70 years ago
Also http://www.sperrymarine.northropgrum...perry-History/
and http://en.wikipedia.org/wiki/Anti_rolling_gyro
and som patents too http://www.freepatentsonline.com/1590778.html

[rwatson]

"Unlike hydrodynamic roll stabilising fins, the ship gyroscopic stabiliser can only produce a limited roll stabilising moment that may be exceeded as the wave height increases. Otherwise, it is not unusual for the manufacture to recommend that the unit not be used at sea in large waves."

That was a good guess then :-)

[turbo2]

so what will govern the stability of such a device? Since there is no gimballing-just a spinning flywheel and shaft fixed on supports, i am guessing there will be no output or "counter" torque.

Great input though. Keep it coming. Thanks

[TeddyDiver]

Originally Posted by turbo2

so what will govern the stability of such a device?

Spinning wheel...

[Ike]

Professional Boatbuilder Magazine had an excellent article on this in issue number 113, June/July 2008. Fortunately the digital version is online at http://www.proboat-digital.com/proboat/20080607/

What you need to do is look up gryroscopic precession http://en.wikipedia.org/wiki/Precession. Lots of other references. Google it.