can anyone suggest, how to calculate volume of forepeak tank

Discussion in 'Boat Design' started by appusree888, Dec 18, 2014.

  1. appusree888
    Joined: Jul 2014
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    appusree888 Sreenath

    can anyone suggest, how to calculate volume of forepeak tank as it is triangle in shape. 1/2 BxH or Lx Bx H can we use any of this equation
     
  2. doug9694
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    doug9694 Small Engine Mechanic

    Calculate tank size

    There will be a double triangle. One looking down from the top, another from the side. So the volume will be only 1/4 what it would be if rectangular. Providing there is no flat on the bottom. equation would be 1/4 HxLxW.
    You may want to consider a bladder tank.
     
  3. appusree888
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    appusree888 Sreenath

    thanks douge. But which value we will take as width..is it the width at aft end of forepeak tank
     
  4. doug9694
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    doug9694 Small Engine Mechanic

    re-1: Calculate tank size

    Yes, it would be the widest "aft" dimension.
     
  5. appusree888
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    appusree888 Sreenath

    but we cannot take this equation.because the forepeak tank shape is a tetrahedron shape so the equation may change
     
  6. doug9694
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    doug9694 Small Engine Mechanic

    re-2: Calculate tank size

    A tetrahedron is a four sided solid pyramid. Is that what you have? The pyramids in
    Egypt are not tetrahedrons because they have 5 sides.

    http://en.wikipedia.org/wiki/Tetrahedron#Formulas_for_a_regular_tetrahedron
    Volume

    The volume of a tetrahedron is given by the pyramid volume formula:

    V =1\3 x A x h

    where A is the area of the base and h the height from the base to the apex. This applies for each of the four choices of the base, so the distances from the apexes to the opposite faces are inversely proportional to the areas of these faces.

    If your tank or the space is a different shape then I need the dimensions.
     
    Last edited: Dec 18, 2014
  7. doug9694
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    doug9694 Small Engine Mechanic

    re-2: Calculate tank size

    I messed some where and sent a duplicate. So just delete this.
     
    Last edited: Dec 18, 2014
  8. appusree888
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    appusree888 Sreenath

    acube / 6 x root two is the equation for tetrahedron and it have only four side ..L x B x H / is the equation for pyramid and have five side so both are different.so which one we will accept

    And area of collision bulkhead surface is 4.49 side shell surface is 7.65 and deck surface area is 10.29
     
  9. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    You can draw several sections of the tank and integrated by the method of Simpson, trapezoids, ...
     
  10. appusree888
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    appusree888 Sreenath

    Thank you tansl
     
  11. appusree888
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    appusree888 Sreenath

    can you suggest which frame we can take as lcg where we can take tcg in this particular shape of No.6 F.O. Tank
     

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  12. TANSL
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    TANSL Senior Member

    Similarly to calculate the volume, integrating the areas of the sections, you can integrate values which are each sectional area multiplied by its distance from a certain point. The ratio of the value of the integral and the total tank volume will give the position of its center of gravity relative to the chosen point.
     
  13. appusree888
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    appusree888 Sreenath

    Can you explain it as simple...i didnt understand that.its my fault not yours. and i think it will be 29th frame when we taking it from profile view.right?
     
  14. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Now, to calculate the volume, you calculate the areas of several sections and, for example with Simpson's method, you calculate the total volume.
    To calculate the center of gravity, rather than the area of each section, you have to calculate the value of the area multiplied by its distance to, eg the AP. These values (areas moments), integrated with Simpson, will give a certain value, divided by the total tank's volume, will result in the distance of the tank's cog to the AP. If instead the distance to the AP you take the center line distance or the distance to the base line, you'll get the coordinate of the cog in relation to these planes.
    Sorry, I can not explain better. Maybe someone with more mastery of the language than me could explain it more clearly.
     

  15. Rabah
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    Rabah Senior Member

    Hi appusree 888,
    Whether have you a computer model in 3D, on what program and whether location of a forepeak bulkhead is fixed?
     
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