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Old 12-07-2007
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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.

To comment on two points in Notoway's post, "Most quoted AVS are provided by the manufacturer and. looking at typical modern designs that are light and wide, one wonders at their accuracy." One of the great things about modern design software is that it is much easier to accurately model LPS and get a reasonably accurate LPS for a boat while it is being designed. Of course manufacturers of boats can tilt the numbers a bit by assuming full tanks and empty lockers and the like.

For what it is worth when this technology has been applied to 1960's era keel/CB boats they generally have LPS angles well under 120 degrees, often down around 110 or so. Although narrow, they carried a larger percentage of their beam to the ends of the boat, and had lower freeboard both fators that results in a smaller limits of positive stability.

As seen in the US Sailing estimate of stability, displacement itself has a comparatively small impact on angle of vanishing stability, and because heavy boats of the 1960's tend to have comparatively high vertical center of gravities, their weight works against them in dynamic resistance to capsize as well.


Last edited by Jeff_H; 12-10-2007 at 10:59 PM. Reason: Correction.....
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