Stabilisers - at anchor - how do they work?

[Gludy]

Re: Another system

Wow - there must be a performance penalty on weight alone? probably a displacment vessel I guess.

Seems to me that the simplest underway system is the wings but the Ferreti system sounds good for when at anchor as well. I understand it was tested in the USA and they came up backing up the 50% roll reduction fugure. So it really seems to work.

 

[duncan]

Re: 5th method

could work - but probably best saved for the thread on "stability when aground" that is due to appear Friday night....... /forums/images/graemlins/wink.gif

 

[Gludy]

Re: 5th method

In actual fact your right!!! But why wait until Friday so I have started one now!

 

[jfm]

Re: Another system

On reflection Kim, if the weight is big there will be a left-right movement of the boat as the weight is accelerated right-left. Action = reaction. So the boat might stay flat, but skit left and right as if some nutter is flicking the bow/stern thrusters left-right the whole time.... /forums/images/graemlins/confused.gif

 

[Tiger Rag]

Re: Another system

I do not know if they were the only builders to try such pendulum stabilisers but Moonen fitted a system to their yachts like the one you describe. It never caught on as the internal space needed was large and unless bearings rollers etc. were kept immaculate noise and vibration were a problem. Most Moonen owners either locked them off and forgot about them or removed them altogether.

 

[BrendanS]

Re: Satblisers - at anchor - how do they work?

Where have I said otherwise?

 

[Wiggo]

Re: Satblisers - at anchor - how do they work?

Don't have a gyro and drill to hand, so I'm doing the effect bit from memory here, so bear with me...

Boat rolls to port, gyro pushes the bows violently to one side, and the stern in the other direction?

Forget to switch off while underway, and a sharp turn rolls the boat on it's side. Or am I thinking of some other gyro effect here?

 

[whisper]

Re: Satblisers - at anchor - how do they work?

JKAY you seem to be sending replies to Brendan that have no bearing on what he last said. Somewhat confusing for all.
If you want to send a reply, or a further comment, make sure that you do it on the reply section for the post in question, as against the last post on the thread - if you see what I mean.

 

[BrendanS]

Re: Satblisers - at anchor - how do they work?

Depends on the spin axis of the Gyro. If it is vertical, so you can go round corners, tilting the spin axis (say roll to port) will cause a right angle force (precession) that will cause a fore aft direction, effect, so sya bows down, stern up. Often in gyro stablisation, you can counteract this, by inducing a mechanical effect to create a force in the direction you require. No idea how ferreti have set up their system (ie spin axis, and if any hydraulics etc are used to induce force on the gyro)

 

[kimhollamby]

Re: Another system

The one I saw was a track system, not a pendulum but now you come to mention it I might well have also seen the Moonen one on my travels. If owners have locked it off I'm not entirely surprised.

The concept seems scary to say the least - I never really saw it in anger but even the thought of it getting out of synch in a beam sea worried me, let alone aspects of noise and so on.

To answer other questions here, yes it was in the sub 30m size and displacement steel boats.

 

[Piers]

Re: Concrete lump

There's a large boat on the Hamble called Balandra, built by Berthon. Her stabiliser is a large lump of conctrete on rails athwartships, run by a donkey engine. As the boat begins to roll, the signals from the gyro control where the lump travels. How fast it moves is controled by the rate of precession.

Somehow, the thought of a large concrete lump being hurled around the bilge doesn't encourage me too much.

But Balandra is a beautiful vessel....