[Public-list] Longitudinal Center of Gravity

Meinhold, Michael J MICHAEL.J.MEINHOLD at saic.com
Tue Sep 27 05:36:24 PDT 2005


John
   The indicated longitudinal center of bouyancy (LCB) is where the bouyancy
force will act if the boat is loaded and balanced to sit at her design
waterline (4' 3") and design trim. In this condition the center of gravity
(CG) will be directly above or below the CB, the longitudinal center of
gravity (LCG) will be the same as the LCB.  It's difficult to directly
obtain the LCG - it's easier to use the measured trim and sinkage combined
with the lines plan to find the LCB as she floats and the LCG is there. This
is all you need to consider to know where to place the straps.

The Vertical Center of Gravity (VCG or KG if measured from the keel) can't
be obtained from the hull form only - you have to do an "Inclining
Experiment", moving weights transversely, measuring the heel, and combining
that with the hydrostatics.  It's probably save to assume its about at the
waterline.

Mike


-----Original Message-----
From: public-list-bounces at alberg30.org
[mailto:public-list-bounces at alberg30.org]
Sent: Monday, September 26, 2005 8:03 PM
To: Alberg 30 Public List -- open to all
Subject: Re: [Public-list] Longitudinal Center of Gravity


Mike,
I looked at the lines plan on Roger's site and I think the 16' 1"
measurement is the Lateral Center of Buoyancy. I'm looking for the
Longitudinal Center of Gravity. There are two Centers of Gravity
measurements the Verticle Center of Gravity and the Longitudinal Center of
Gravity. The centers of gravity are what I am interested in to make the
calculations to design the hoist  to lift the boat out of the water. Jack
probably determined what these centers of gravity measurements were. Do you
think you  can get these?
Thanks,
John
  ----- Original Message ----- 
  From: Roger L Kingsland<mailto:rkingsland101 at ksba.com> 
  To: Alberg 30 Public List -- open to all<mailto:public-list at alberg30.org> 
  Sent: Monday, September 26, 2005 3:36 PM
  Subject: Re: [Public-list] (no subject)


  John,

  I have them posted on this site;
 
http://home.att.net/~jinnii/roger/perfect/pi_designs.html<http://home.attnet
/~jinnii/roger/perfect/pi_designs.html>

  Roger

  Roger Kingsland
  Chief Boat Boy, Rubber/Scraper and Check Writer
  Alberg 30 #148, PERFECT intentions
  N40-33.92, W79-51.25

  "You don't have to think outside of the box, but it doesn't hurt to peek
  over the edge once in a while."
  Leonardo Da Vinci (or somebody like that)

  ----- Original Message ----- 
  From: "JOHN GRAVES" <jg1111 at msn.com<mailto:jg1111 at msn.com>>
  To: "Alberg 30 Public List -- open to all"
<public-list at alberg30.org<mailto:public-list at alberg30.org>>
  Sent: Monday, September 26, 2005 3:17 PM
  Subject: Re: [Public-list] (no subject)


  > Mike,
  > Hey, great. Is there any way I could get a copy?
  > John
  >   ----- Original Message ----- 
  >   From: Meinhold, Michael
J<mailto:MICHAEL.J.MEINHOLD at saic.com<mailto:MICHAEL.J.MEINHOLD at saic.com>>
  >   To: Alberg 30 Public List -- open to
  all<mailto:public-list at alberg30.org<mailto:public-list at alberg30.org>>
  >   Sent: Monday, September 26, 2005 3:15 PM
  >   Subject: RE: [Public-list] (no subject)
  >
  >
  >   No problem- I have the lines plan that Jack made and the outboard
  profile
  >   from Whitby on the wall in my office - a constant distraction.
  >   Mike
  >
  >   -----Original Message-----
  >   From:
 
public-list-bounces at alberg30.org<mailto:public-list-bounces at alberg30.org<mai
lto:public-list-bounces at alberg30.org<mailto:public-list-bounces at alberg30.org
>>
  >   [mailto:public-list-bounces at alberg30.org]On Behalf Of JOHN GRAVES
  >   Sent: Monday, September 26, 2005 3:12 PM
  >   To: Alberg 30 Public List -- open to all
  >   Subject: Re: [Public-list] (no subject)
  >
  >
  >   Mike,
  >   Thanks for the quick reply. I am trying to design a boat lift so I can
  put
  >   my Alberg 30 up on the bluff and I am making some calculations to
figure
  out
  >   the most economical design.
  >   Thanks,
  >   John
  >     ----- Original Message ----- 
  >     From: Meinhold, Michael
 
J<mailto:MICHAEL.J.MEINHOLD at saic.com<mailto:MICHAEL.J.MEINHOLD at saic.com<mail
to:MICHAEL.J.MEINHOLD at saic.com<mailto:MICHAEL.J.MEINHOLD at saic.com>>>
  >     To: Alberg 30 Public List -- open to
 
all<mailto:public-list at alberg30.org<mailto:public-list at alberg30.org<mailto:p
ublic-list at alberg30.org<mailto:public-list at alberg30.org>>>
  >     Sent: Monday, September 26, 2005 3:07 PM
  >     Subject: RE: [Public-list] (no subject)
  >
  >
  >
  >     I have 16 feet 1 inch aft of the forwardmost portion of the stem -
the
  >   bow.
  >     This is from a hydrostatic analysis by a former Alberg owner (an a
  >   neighbor
  >     of mine) Jack Hornor.
  >
  >     Mike
  >     Rinn Duin #272
  >
  >     -----Original Message-----
  >     From:
  >
 
public-list-bounces at alberg30.org<mailto:public-list-bounces at alberg30.org<mai
<mailto:public-list-bounces at alberg30.org<mailto:public-list-bounces at alberg30
.org<mai>
 
lto:public-list-bounces at alberg30.org<mailto:public-list-bounces at alberg30.org
<mailto:public-list-bounces at alberg30.org>
  >>
  >     [mailto:public-list-bounces at alberg30.org]
  >     Sent: Monday, September 26, 2005 2:44 PM
  >     To:
 
Public-list at alberg30.org<mailto:Public-list at alberg30.org<mailto:Public-list<
mailto:Public-list at alberg30.org<mailto:Public-list at alberg30.org<mailto:Publi
c-list>@
 
alberg30.org<mailto:Public-list at alberg30.org<mailto:Public-list at alberg30.org
>>>
  >     Subject: [Public-list] (no subject)
  >
  >
  >     Does anyone know exactly where the longitudinal center of gravity is
  >   located
  >     on an Alberg 30?
  >     Thanks,
  >     John Graves
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