[alberg30] White Squall

[Joseph Palmer]

From: "Joseph Palmer" <jopalmer at classicsailboat.com>

 The Cruising Club of America came up with a simple formula to determine a
boats blue water capabilities. Its called the Capsize Screening Ratio and it
compares beam with displacement.
The formula is the max beam divided by the cubed root of the displacement in
cubic feet. The displacement in cubic feet for a boat can be found by
dividing the dispalcement in pounds by 64.
A boat is considered blue water acceptable if its calculated number is 2.0
or less.
Formulas like this and many others were featured in an artical written by
Ted Brewer in the August issue of Good Old Boat.
You can find them at
http://www.goodoldboat.com
--
Joseph Palmer
Classic Sailboat
Customer Service
1800-486-7245
jopalmer at classicsailboat.com
http://www.classicsailboat.com/

----------
>From: "Chester & Jan Koop" <cjk at tir.com>
>To: <alberg30 at onelist.com>
>Subject: Re: [alberg30] White Squall
>Date: Wed, Sep 15, 1999, 11:43 PM
>

> From: "Chester & Jan Koop" <cjk at tir.com>
>
>>From my experience, you probably had a "heeling experience" of around 55
> degrees.  Generally speaking, I don't believe wind alone will result in an
> Alberg doing a 360 degree roll. However high winds and squalls could cause a
> knock down of 75-90 degrees, particularly in a broach under spinnaker.  From
> what I have read on heavy weather sailing roll-overs are generally result
> from a combination of high winds and big waves.  Yves Gelinas, who
> single-handed an A 30 around the world in 1985-1986 experienced one knock
> down of 90 degrees+ and one of 360 degrees, both in the South Pacific
> (Roaring 40s).  The roll-over resulted in being dismasted, however the boat
> (and Yves) survived.
>
> As a result of the 1978 Fastnet Race, where a significant number of boats
> capsized/sank  and 13 or so lives were lost, considerable research was
> directed at deterring what design factors impacted a yacht's ability to
> recover from sever knock downs and roll overs.  Out of this research came a
> number of findings including a formula/calculation for determining a boat's
> "inverse stability co-efficient."  While I can't remember the formula or all
> the factors impacting the calculation (beam/length ratio, cockpit volume,
> displacement/length ratio, etc.), boats with a co-efficient of 2 or less had
> the ability to avoid achieving inverse stability and safely recover from a
> roll over.  The rule of thumb is boats with a co-efficient of 2 or less
> should be consider, all other factors being equal, blue water capable.
> Albergs 30 have an inverse stability co-efficient of around 1.9
>
> As the co-efficient rose above 2, it became more likely that the boat would
> achieve "inverse stability" (i.e. the ability to remain up-side down ).
> Generally narrow beamed boats had lower co-efficients than broad beamed
> boats, with catamarans and trimarans having the highest.  I would suspect
> that all these new cutting edge "aircraft carrier" type race boats (i.e. BOC
> boats etc.) have a very high co-efficient.
>
> If you want more info on this subject, read Fastnet Force 10.
>
> Chet Koop
> Tangaroa  #445
>
>
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