[Public-List] Incline test on an Alberg 30?

Sat May 8 16:06:23 PDT 2010

Anyone concerned about our boats' stability characteristics should have a
squint at C.J. Marchaj's book 'Seaworthyness, the Forgotten Factor'.   It is
a learned and uncompromising examination of trends in yacht design... While
the A30 is not named, her type is defined as an ideal.

While traditional or classic hull types may have lower resistance to heeling
initially, the combination of deep full keels and narrowish beams result in
very high LPS numbers.  LPS, Limit of Positive Stability, is the number that
counts.  The A30's LPS is somewhere around 170 degrees.  That means that you
have to roll us 170 degrees before the yacht stops trying to right herself.

Your average beamy, fin-keeled yacht, the type that clobbers us in light
airs and may even gloat about its 'stiffness' in 15 knots of wind, could
have an LPS between 80 and 110 degrees.  Those low numbers mean that over a
very wide swath of a circle (roll) they are as stable upside down as right
side up.  The extreme of this is a multi hull yacht, which has incredible
stability for the first 20 or 30 degrees of heel... And is then so stable
when capsized that in cannot be righted without outside help.

The A30 and its type are very good seaboats.  Provided you can keep the sea
out, in the Alberg 30 we have a boat that will continue to look after its
crew through extreme conditions.  (but I DO wish Mr. Hansen had followed Mr.
Albergs wishes and given us lighter fractional rigs and lead ballast..)

Gord #426 Surprise

On 08/05/10 6:39 PM, "JT" <speedbump at austin.rr.com> wrote:

> Dear John and Richard,
> 
> Agreed that these boats are indeed bulletproof! In fact, her excellent
> stability curve was one of the main reasons we bought an A30. I saw a
> lot of her wooden sisters on a recent trip to the Baltic...
> 
> I should've explained myself.
> 
> Baraka was a wreck when we found her in '06. After a hiatus, we're back
> to putting her to rights (so to speak)! We'll eventually take her
> offshore and are working with a rigger to ensure her replacement spars
> and standing rigging are properly sized for that job. While he can work
> from standard tables, he said the best way was to perform an incline
> test, as in Brion Toss's book "The Complete Rigger's Apprentice," p.
> 136: level the boat in the water, then line up several of your buddies
> along the toerail after noting their weights. Note the heel in degrees.
> (Hopefully, it's a handy 10 degrees.) By measuring the distance they are
> from the CL of the boat, and multiplying their aggregate weight by that
> distance, then multiplying again by 3 (if you got 10 degrees), you get
> the righting moment (RM) for the boat at 30 degrees of heel.
> 
> This morning, my partner-in-crime managed to perform this feat on an A30
> in Clear Lake, Texas. Our figure was 4,459 foot-pounds for 10% of heel.
> 
> Knowing that a lot of folks had undertaken complete restorations, I was
> wondering if anyone else had done this, and if so, whether their results
> were close to ours?
> 
> Regards,
> Jeff
> 
> John Birch wrote:
>> The Desirable & Undesirable Characteristics of Offshore Yachts has a
>> table which showed the A-30 had the second best rating second only to
>> the Ludders 44. The A-37 came in fourth out of something like 75 boats.
>> 
>> The Book was released after the disaster of the Fastnet Race and was
>> edited by John Rosmenyari (sp)
>> 
>> Albergs are damn fine boats.
>> 
>> Carl had some game
>> 
>> Best
>> 
>> John
>> 
>> 
>> ----- Original Message ----- From: "Richard Mair" <ramair49 at gmail.com>
>> To: "Alberg 30 Public List -- open to all"
>> <public-list at lists.alberg30.org>
>> Sent: Saturday, May 08, 2010 5:44 PM
>> Subject: Re: [Public-List] Incline test on an Alberg 30?
>> 
>> 
>>> No test but look at capehorn.com..go to the link the great voyage of
>>> Jean-de-sud..
>>> Tells how he was rolled in the southern ocean.We know they will come
>>> upright
>>> again
>>> Richard 609
>>> 
>>> On Sat, May 8, 2010 at 5:04 PM, JT <speedbump at austin.rr.com> wrote:
>>> 
>>>> Dear All,
>>>> 
>>>> I'm wondering if anyone has performed an incline test on an Alberg
>>>> 30 to
>>>> determine her righting moment? If so, could you please tell me what
>>>> your
>>>> results were?
>>>> 
>>>> Many thanks in advance!
>>>> 
>>>> Sincerely,
>>>> Jeff Twining
>>>> #58
>>>> 
>>>> 
>>>> -- 
>>>> -JT
>>>> South Austin, Texas, USA, North America, Western Hemisphere, Earth,
>>>> Solar
>>>> System, Milky Way, Local Group
>>>> 
>>>> Faith consists in believing what reason cannot...
>>>> In order to believe something, it is not enough that it should be
>>>> possible.
>>>> -Voltaire
>>>> 
>>>> 
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>> 
>> 
>> _______________________________________________
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>> 

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