Capsize Screening

Date: January 12, 1999
From: Robert G. Chamberlain

Does anyone know what the range of positive stability is for the E32? According to the capsize screening formula, the E32 is below 2.0 but I'm curious if anyone has info from the designer or something from the IMS.

Date: January 14, 1999
From: Kevin D. Coon

I'm not familiar with the righting formula that you mention, but don't worry about it too much. There is no practical difference between most conservatively designed boats of similar proportion. One can keep himself awake at night worrying about minute mathmatical differences and still get run over by a freighter. Sail what ya got.

Date: January 14, 1999
From: Carl Hibbard

I find zip on the stability factor for anyboat under IMS. I am assuming that he is referencing the formula that is in the Coast Guard basic boating course. I guess at this point one would wonder why he is worrying. If you use the formula you find that the more people (weight) the better. So I would assume that as heavy as our boats are.....From many tales it is known that you can have water over the combing and provided the hull isn't flooded that they will right themselves.....If there is anything from a designer I wouldn't know. The outfit out of Denver that purchased Endeavour still has all of the drawings and engineering (if any) stats...The present Endeavour Yacht Corp. (catamarans) purchased just the name.

Date: January 15, 1999
From: John Bartoszek

Do you have a contact (phone #, email, or address) for the outfit that has the old Endeavour info?

Date: August 25, 1999
From: Ric Seymour

CAPSIZE FACTOR = Displacement of the vessel divided by 64, then take the cube root of that number and divide into the beam of the vessel.

So an Endeavour 32 (76-82) with a 10' beam and a displacement of 11,700 would have a capsize factor of 1.76

Date: August 28, 1999
From: Paul Uhl

Does anyone happen to know the range of positive stability in degrees for the E32? I should point out however that I agree with Kevin's earlier post. This would only be a consideration for me if I was intent on extended offshore cruising, something I don't believe the E32 was intended to do. Just curious though.

Needless to say the calculation for this is complicated and is generally done by computer, analyzing the boats lines (IMS and IOR can do this), deck house, etc. However, in "Desirable and Undesirable Characteristics of Offshore Yachts", they discuss all the factors that contribute to the range of positive stability and have developed a 'simple capsize screening formula' which Ric has described above. They go on to say that:

But just because a boat passes the screening formula doesn't mean that it should be thought of as an offshore boat. Several other factors that are of equal importance are:

Waves usually knock a boat down or invert it and wave motion usually rights it. The above book goes on to note that according to their calculations "a boat with a range of positive stability of 140 degrees or more that was rolled by a violent wave should come back upright promptly. . . .at 120 degrees, the time is around 2 minutes, and at 100 degrees it is around 5 minutes."

Obviously I could go on for a long time on this as many factors need to be considered. If you really want to understand it fully, I recommend that you buy the book. ©1987, W.W. Norton (ISBN: 0-393-03311-2)

Date: November 10, 1999
From: Paul Uhl

If you want to get all the specifics on you boat, check out Dr. Carl Adlers' Sailing Calculator. You can even compare one boats data against another.