[MHml] Inclining experiment in air

[Peter Southwood]

Hi Evan,
A week ago I could have said the same.
Something new every day.
Cheers,
Peter

----- Original Message ----- 
From: "Diane Selkirk" <ceilydh at 3web.net>
To: "Informed discussion of multihull issues" <multihulls at steamradio.com>
Sent: Monday, December 11, 2006 9:49 AM
Subject: Re: [MHml] Inclining experiment in air


> Peter Southwood wrote:
>> Hi Evan,
>> Thanks for the reply,
>> In
>> ISO 12217-1:2002(E) Annex D: Determining the curve of righting moments.
>> Paragraph D.2.2 Vertical Centre of Gravity.
>> The vertical position of the centre of gravity (VCG) can be determined by
>> any of the following methods:
>> a)    an inclining experiment in water, the results being corrected to 
>> the
>> appropriate displacement condition,
>> b)    an inclining experiment in air using a known length of suspension 
>> and
>> moving weights transversely, the results being corrected to the 
>> appropriate
>> displacement condition
>> c)    calculation based on the calculated mass and centres of gravity of
>> individual components, raised by an addition of 5% of (Midships freeboard 
>> +
>> draft of canoe body)
>> Method a) shall not be used for boats with a metacentric height of over
>> 5.0m, since inclining experiments in water for such boats are liable to
>> significant inaccuracies.
>> unquote
>>
>> I must determine the VCG of  a power catamaran of about 14.5m and 15 
>> tonnes
>> with estimated KM of about 15m.
>> The boat is already partially fitted out and working out the VCG by
>> calculation is impracticable. It is hand layup balsa core and there are 
>> no
>> structural drawings available, so I seem to be stuck with method b). This 
>> is
>> going to be an interesting exercise in itself, as the area often has 
>> strong
>> winds, and the headroom in the building is not enough to lift it by 
>> crane.
>> Also I cant find a description of the procedure.
>>
>> Cheers,
>> Peter
>>
>>
>>
> Interesting problem.  I'll ask some of the guys at work on Monday and 
> report back.  Never done one in air or knew that it existed.
>
> Evan Gatehouse
>
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