Inclining Test Using Double Bottom Tanks

Discussion in 'Stability' started by naserrishehri, Jul 28, 2013.

  1. TANSL
    Joined: Sep 2011
    Posts: 5,997
    Likes: 253, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    No, that's too bad raised. There can be no free surfaces.
    Free surfaces, not only produce a decrease in GM, you can calculate with your computer, but the ship will never reach its equilibrium position. Free surfaces greatly increase the roll of the ship.
     
  2. naserrishehri
    Joined: Jun 2006
    Posts: 163
    Likes: 0, Points: 16, Legacy Rep: 10
    Location: iran bushehr

    naserrishehri Senior Member

    you mean rolling cause moving pendulum?
     
  3. TANSL
    Joined: Sep 2011
    Posts: 5,997
    Likes: 253, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    When free surfaces, there is no way to stabilize the boat to take measurements. Any alteration due to wind or waves is increased.
    My advice is do not do the inclining test with these tanks.
     
  4. Vinassman
    Joined: Mar 2011
    Posts: 43
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Batam, Indonesia

    Vinassman Junior Member

    I agree that using tanks as inclining weights is not a good idea and will introduce problems such as free surface effects during the measurement but with large ships there is unfortunately no other practical solution.

    According to my experience, classification societies and/or flag states can agree to use such a method, as long as one can show that using conventional weights is not possible.
     

  5. TANSL
    Joined: Sep 2011
    Posts: 5,997
    Likes: 253, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    There are many aspects to consider before saying to do the inclining test of this form. Certainly not up to you or me to do it but that administration allows us to take over, in the way we want.
    From my point of view, there is a fundamental problem:
    - The enormous difficulty of obtaining the zero point for the deviations of the pendulum.
    - The dispersion of the measurements can be so great as to prevent to well know the inclination of the boat.
    Furthermore, the IMO code for stability before damage contemplates performing test using the ballast tanks, but the calculation imposes conditions which are not easy to meet, for example, to calculate the effect of the free surfaces considering actual heeling of the boat.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.