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post #13 of Old 12-11-2007 Thread Starter
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Originally Posted by Nottoway View Post
The angle of vanishing stability and capsize screening formals can be found at:

Originally Posted by Jeff_H View Post
That is an interesting formula seemingly pretty accurate. It came back with a LPS of 128 for my 10,500 lb- 38 ft boat, which is about right.
JeffH / Nottoway / Diva,

Thanks for your commentary -- I have found it to be very enlightening.

I tried fiddling with that US Sailing AVS formula, but got some results that didn't make a lot of sense to me. For instance, the AVS value I arrived at for our boat was negative!? Even when I convert this value to a positive figure, the value is far lower than the published LPS for our boat model.

I am now wondering if this AVS formula is quantifying a value that is actually different from the LPS? In other words, is the AVS value the point on the stability curve where the righting moment begins to decrease again, and the LPS is actually the point where the stability curve crosses the x-axis, i.e. the point after which the boat capsizes?

For illustrative/discussion purposes, here is the "Intact Stability Curve" for a common production boat, the Catalina 42:

The question rephrased: Are the Angle of Vanishing Stability and Limit of Positive Stability the same points on the stability curve? If the answer is no, then this might explain why many people are surprised to learn how low the AVS is for a given vessel (like the Bayfield in the other post that prompted this thread). Thoughts?

Last edited by JohnRPollard; 12-11-2007 at 10:42 AM. Reason: Added graphic
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