Jeff, Sailaway, or anyone else with an answer,
Why does the US Sailing Screening Stability Value (SSV) formula use hull draft rather than total draft (i.e., including keel) for purposes of calculating the AVS? It seems counterintuitive to me.
Also, where did you get that "hull draft" value for your own boats? Did you actually go out and physically take a measurement (keel span - total draft = hull draft)? Or are these values available in a database somewhere?
Great discussion. Thanks.
I see your point about maximum righting force. Certainly in the case of the Catalina 42 which is loosely an IOR hull form with a shallow keel depth, it would appear that maximum righting moment occurs near the point that the rail hits the water. This would seemingly be true for any boat where the center of gravity is near or above the waterline.
Not sure what you consider to be a "shallow keel depth", but the stability curve that I embedded above is for the standard draft Catalina 42, with a published draft of 6'8".