Calculate Inclination of pontoon

Discussion in 'Stability' started by Robert Wilkinson, Feb 11, 2018.

  1. Robert Wilkinson
    Joined: Jan 2018
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    Location: New Zealand

    Robert Wilkinson Junior Member

    I am trying to workout how to arrive at the answer for the following question.

    A rectangular pontoon is 12m long, 4.2m broad and 2.1m deep and it floats in fresh water. The pontoon has a displacement of 65 metric tons unloaded and the centre of gravity is 0.6m up from the bottom and 20 mm aside from the vertical centreline.
    Determine inclination of centreline when pontoon floats freely?
    If pontoon becomes partially floaded, find inclination of centreline when depth of water inside pontoon at centre is 200 mm?

    Answer from book is given as 58 minutes and 4 degrees, 40 minutes.

    For the first part I tried calculating it using GG' = inclination * (I/V) where inclination is in radians, I = second moment of inertia and V = volume displaced.
    I used GG'= 20mm, I = (12 * 4.3^3)/12 and V = 65m^3 and I got inclination = 60.32 minutes or just over a degree.
    I was just thinking that 20mm is probably the perpendicular distance from centreline, so when pontoon is inclined you will have to workout horizontal GG' somehow.

    I'd just like to hear some thoughts on this from anyone!
  2. upchurchmr
    Joined: Feb 2011
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    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Trying to get your homework done?
  3. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Forgive my way of expressing myself and, please, do not be offended. I want to help. Are you an amateur trying to learn more about naval architecture or are you a student of some branch related to naval architecture that tries to get someone to solve his problems? In the first case, I will be happy to help you. In the second case, the best advice I can give you is to study a bit.
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