U.S. Sailing Screening Value

[dale]

The February issue of Chesapeake Bay Magazine reviews a Dufor 38
Classic and says this boat has a "U.S. Sailing Screening Value of
2.09 (less than 2 desirable for offshore)" Also that the Dufor
has a "Certification CE Catagory A (Unlimited Ocean)". Anyone
familiar with these parameters and what the equivalent values for
the Morgan 38 might be ??

 

[balthazor]

See first or second archived bulletin board for discussion of limit of stability. Meassured 382s average about 125 degrees, I think, which is not great (compare an Alberg 37 at 139), but is considered off shore capable (120 degree minimum required by certain offshore races.)

 

[dale]

<div>I sent an e-mail to the Editor of CBM, who forwarded it to Tom Dove, the Author of the review. Tom responds "The Screening Value was devised by US Sailing (formerly USYRU) after the Fastnet disaster as a quick method of estimating ultimate stability in storm conditions. It is not as accurate as the more complex Range of Positive Stability calculation you can get from the organizationif your boat has an IMS certificate rating. They recommend a value of less than 2 for boats going off-shore for extended times."
Tom provides the method for calculating the Screening Value: first calculate the boat's displacement in cubic feey by diving her displacement in pounds by 64. (18000lbs/64=281.25 cu. ft.)
Find the cube root of that number (6.55185)
Divide that number into the beam in feet. (12/6.55185=1.83)Tom has a really interesting web page at http://home.bluecrab.org/~tdove/
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[svcatharsis]

<div>that is to say that the Displacement (lb) must be higher than 8 times the beam (ft)to the cubeisp(lb)&gt; 8 * [Beam(ft)]^3 ,or in metric unitsisp(Kg)&gt; 100 * [Beam (m)]^3 Regards,Mike
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