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[Ron]

If I understand you correctly, you want the vessel to have a slow recovery.

To do this you need to add weight as high up in the vessel as possible. The weight has to be movable. You only have a small vessel so this will have a limited effect. However, put a brass tube across the width of the vessel, inside the vessel as high as you can reasonably get it. The tube should be as large as you can reasonably get it. Insert a steel ball bearing inside the tube so that it moves freely inside the tube. Seal the ends of the tube so the ball won't fall out. Install the assembly inside the vessel securely.

The slow recovery comes as a result of the ball moving to the low side of the vessel when it heels over. As the vessel comes up right, the ball moves to the center of the tube (center of the vessel) until the vessel starts to go the other way. This will give you the effect of weight and a slow recovery.
It is advisable to have the receiver and ESC in a water proof container in the event water gets into the hull. You vessel has a low freeboard and can be susceptible to taking on water.The vessel appears to be sitting exactly correct on the water.

[Capt Podge]

Sounds like it COULD work - won't be trying it on any of my models though, I'll just live with the non-scale water thanks.

Regards,

Ray.

[tigertiger]

The ball bearing method might work, but it might not react fast enough. Too slow to recover/heal back, before the water is in the opposite direction again. Or the boat may actually hold-hold-hold- flick over. Basically the model would be out of synchronisation with the water motion.


Having the weight higher up would in effect increase the roll, and the angular velocity/speed of the roll. It would not slow the recovery, just increase it's angle. The speed of the rotation would be faster. The speed of the recover (cycles per minute) would be the same.


The issue is not the boat speed of heal as it is the speed of the water/scale effect (as noted above).
If you want it to look better, film it in slow motion, some phones now have this feature.

[Brian60]

I remember similar being done back in the 70's, but in that instance the top inch or two of masts were cast in lead to add a counterweight high up.

[roycv]

Hi I am not sure if I have missed something? Is there previous conversation?  The first thread seems to be a question?
I have heard of similar ideas.

This involved the transverse tube but having some water and baffles in the tube.  This does iron out some of the extreme motion and gives a degree of stability.

Not disimilar to methods used  in high buildings in earthquake areas.  A friend of mine, a Chartered surveyor, produced a Meccano model (high building) that showed the principle and how effective it was.  Here a heavy weight up at the top of the building was out of phase with the movement from below.

On the water I think the steel ball needs some delay in movement to give any assistance to stability.  I can imagine it just moving to the lower positioned part of the tube and staying there.

regards Roy

[C-3PO]

To add a level of control to this concept you could use some tilt switches /sensor (gryo / rate of tilt) (possibly may need some additional sensing - Hall effect) and a weight in the hull that is moved using a servo (perhaps pivoted on a longish arm to increase movement relative to servo movement). A simple microprocessor could add some configurable intelligence as to how much, how fast and when the weight is moved.

This concept could also be used for:
-  helping some top heavy boats stay more upright as they turn - reading the rudder signal may help as well in knowing which way to swing the weight
-  trim adjustment automatically trimming the boat ballast to make the boat sit level.

C-3PO

[roycv]

AAAAH!  I see the element I have missed.  Helping top heavy models to turn, not general stability
 Not clear from the original posting though.
Roy

[C-3PO]

The original post seems to start half way through the thread..

The links below are mainly unrelated to this topic but give you an idea how quickly an Arduino can react to sensor information and do something clever with it :)

http://y2u.be/j4OmVLc_oDw

https://www.youtube.com/watch?v=y5Hmr-rR-yk

I think a weighted tray (fishing weights)  sliding from port to starboard may work well.

C-3PO

[NFMike]

I think the original idea could work, but it would probably greatly increase the chance of a  capsize.
I think it would also need to be refined a bit. I'd curve the tube down slightly so the ball starts back to the centre before the boat reaches vertical, and also partially fill it with, say, oil to damp the action a bit (and reduce the noise  ).

[Netleyned]

Old fishermen used to hoist an anchor up the mast to dampen rolling.
Square riggers used a barrel hoisted high.


Ned

[oldflyer2]

Ron, one thing I forgot to mention in my email ... when you put the ballast in your boat, if you split it up and get as much as you can in the extreme ends of the hull, instead of all in the center, it will help a bit.

Cheers

Tom

[roycv]

Hi, Ron is quite right.  When Joshua Slocum made his epic voyage, the first part of it was most uncomfortable.  He took advice and spread the stores at each end of his yacht.
It is like a dumbell it is much more difficult to oscillate than if the mass were in the centre.  The bumble bee has tiny blob loads kept oscillating and they act like a gyroscope.  This provides stability for an un-gainly object.

He had a much better end of his voyage.
regards Roy

[Ron]

Thanks fellas for your thoughts and I will place ballast fore and aft in my Carol Moran 18"model.

[Martin (Admin)]

This involved the transverse tube but having some water and baffles in the tube.  This does iron out some of the extreme motion and gives a degree of stability.

Yes, I remember that, in a very early edition of Marine Modelling Monthly?!

Not disimilar to methods used  in high buildings in earthquake areas.  A friend of mine, a Chartered surveyor, produced a Meccano model (high building) that showed the principle and how effective it was.  Here a heavy weight up at the top of the building was out of phase with the movement from below.

I saw that actually in use in a documentary - http://gizmodo.com/5019046/how-a-730-ton-ball-kept-the-second-tallest-building-from-falling-during-the-chinese-earthquake

[Plastic - RIP]

Why not forget about recovering from a roll and use a gyro & servo to use the mass to counteract the initial roll - or drive stabilisers to keep it flat & level?

Problem goes away and the ship appears to have more mass to cut through waves rather than bobbing around like a cork.

[NFMike]

Putting weight at each end of the boat will help control pitching (and yawing). It won't help roll (which is what the OP is about), unless it is also high up.

[oldiron]

Yes, I remember that, in a very early edition of Marine Modelling Monthly?!


I saw that actually in use in a documentary - http://gizmodo.com/5019046/how-a-730-ton-ball-kept-the-second-tallest-building-from-falling-during-the-chinese-earthquake

Martin

 that's probaly where I saw the article, Marine Modeling Monthly. I can't remember what issue it was. But it made sense, and I stuck it in the back of my mind. There is a youtube video on model boat stability that goes into this, but it is with a fixed weight rather than a movimng ball or water.

John

[hammer]

My first model a paddle steamer with a Cheddar steam plant. With 1.5 inch draft it was very unstable. When wind blew from the side it would stick the paddle box down on to the water & only come up when the wind changed. just to it repeat the on the other side.  My solution mount the batteries on a servo arm so they swing from side to side. I can now waggle the boat at will.  As I come from model air craft this is the aileron control, flying. R.G.Y. 

[oldiron]

This Yotube video will be of interest for those following this thread:

https://www.youtube.com/watch?v=T9xB964KDNA

John

[Capt Podge]

Thanks for the link John - interesting.

Regards,

Ray.

[Brian60]

So the old guys around the pond way back when were correct then, a lump of lead up the masts!

[Nemo]

If we are talking of yachts, any proper sailor knows that you 'keep the ends light' - it makes sense. Joshua got poor advice. The distribution of weight in a hull is dependent on the type of vessel and its  design there cannot be a simple rule here. As Plague has already said, pitching and rolling require different methods to assist recovery.