GZ Stix or stability curve
I am looking for a GZ, Stix or stability curve for a Swan 36. Can anyone give me directions to where I can find one?  Also a polar diagram if available.

Dear Saltyrope

There are two UK websites providing such stability information. For some reason the second one does not list Swan 36

http://www.ircrating.org/en/technical-a-certification/sssn-a-stix.html

http://www.rya.org.uk/KnowledgeBase/technical/Pages/stabilitydata.aspx

Kind regards

Lars

Here a stability curve. The very high Limit angle of positive stability should be noted, and it can also be pointed out that the ratio of positive/negative stability areas is 17, while for recent designs this value is between 2 and 3.

Kind regards

Lars

Just great, Lars!
following another thread, I wonder which is the stability curve of a Beneteau...
:-)
Daniel, 411-004

Dear Lars, very useful websites thank you. would it be possible to post the "Righting Moment" stability curve for the 47 as well? would like it for my files. thank you in advance.
Jayne Aorangi 47/047

IT WOULD BE INTERESTING TO COMPARE THE RIGHTING MOMENTS OF THE 411 1-19 AND 20-...

ALSO, THIS SITE IS A GREAT OPPORTUNITY TO COLLECT AND COMPARE INFORMATION ABOUT ALL THE S&S SWANS SUCH AS:
- RIGHTING MOMENTS
- POLAR DATA
- ENGINE REPLACEMENTS
ETC.

A PRESTO PIPPO 411/22

Jayne

Enclosed pls find the requested information. The lower curve is for the centerboard keel

Best regards

Lars

Thank you Professor for all this invaluable information.

I would be very interested by this curve for a 41, other very active members by the curve for a 411... may be we could access it on a data base instead of asking you?

Kind regards. Philippe.

Can anyone help me on how to read the stability curve as shown? I would like also to know if it would be possible to have the 48's one (thank Lars).

Sergio
48/042 Clarion of Skye

Sergio,
if you browse the two sites mentioned by Lars in a former post, you will find all the information you want.
Basically the curves show the righting tendency (vertical scale) of the boat as a function of the heeling angle (horizontal scale).
As the boat heels from the 0 degree position (the normal vertical position), the righting tendency increases till a maximum around 60 degrees and then it starts to decrease. It will still tend to righten herself but with less "power". With the mast touching the water, at 90 degrees, there is still a righting attitude but farther down, at about 130 degrees, the righting attitude becomes null and the boat will not tend to righten herself anymore.
After that point, the righting tendency becomes negative and the boat tends to go belly-up.

Daniel, 411-004

many thanks Daniel

Sergio

Sergio

The stability curve for Swan 48 is by coincidence very close to the Swan 47 centerboard curve, and you can well use that curve.

It can be pointed out here that measuring the stability accurately is the most difficult operation within yachting. The problem is the environment, if it is not dead calm and absolutely no wave action the results are affected. The measurement would ideally be made in an indoor basin where the water is given plenty of time to calm down after each movement.

Outdoors in practice there is some wind, and usually some waves from passing powerboats, or some swell from the ocean. Using accurate electronic devices it can be seen that boats in the water are moving quite a lot even when you would think they are absolutely stationary

Lars