Sample Incline Test using WB TANKS

Discussion in 'Stability' started by Dr34m3r, Nov 14, 2016.

  1. Dr34m3r
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    Dr34m3r Senior Member

    Anyone can give me a sample reference report of Incline test procedure / report which is conducted by using Water Ballast Tank or any Tank. (not done with solid weight block).

    Thanks in advance.
     
  2. Ike
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    Ike Senior Member

    Why would you use water ballast for an inclining? It will give you a false reading. For it to work the tank would have to be completely full. Other wise free surface effect will cause the center of gravity of the water to move outboard, causing the vessel to heel even farther. That's why solid weights are used. The CG of the weights doesn't change.
     
  3. Ad Hoc
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    Ad Hoc Naval Architect

    Water tanks are not recommend as Ike notes above. But it does not mean it cannot be done.

    I have inclined a 50m catamaran I designed, some 20years ago. We made water tanks out of aluminium with over fill outlets and the top of a shape that would promote any air to be scavenged out via the air outlet pipe. We carefully measured the total amount of water for each and noted on the side of each tank. As well as weighed via calibrated load cells to double check.

    As such we were able to satisfy the surveyor.

    Down side is, we only could get a small pump. The procedure took almost 10hours when in reality using solid ballast woudl have taken around 30mins to do!

    We couldn't use solid ballast as nowhere to put them without seriously damaging the boat...or having to use literally hundreds of small ones lifted by hand.
     
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  4. Ike
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    Ike Senior Member

    I recall an inclining we did of a a large ship at the shipyard where I worked in the 70's. we emptied all tanks (there were over 100) and opened every one to make sure there was nothing in them. However when we did the inclining the ship heeled a little way, and then suddenly heeled another degree or two. We had actually missed one tank that was about half full.
     
  5. Dr34m3r
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    Dr34m3r Senior Member

    For the project which i am taking about, it is not possible to use weight block for the inclining test. Class have also agreed to do with WB tanks. I am looking for a reference work mainly.
     
  6. TANSL
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    TANSL Senior Member

    If any of the WB Tanks, used for the experience, have free surfaces, it will be very difficult, if not impossible, to determine the angle of heel in each case. Ike has explained very well what happens. It is very difficult for the boat to reach the equilibrium position in each translation of weights, and that position of equilibrium is very difficult to determine.
    What kind of boat is it that does not allow the use of transferable weights?
     
  7. NavArc...
    Joined: Nov 2016
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    NavArc... Junior Member

    Dr34m3r,

    A while back I came across this document (you may have come across this yourself already). Not the inclining report you ask for but at least it contains some very basic guidance on the use of water ballast for inclining.

    https://rules.dnvgl.com/docs/pdf/DNV/cn/1990-02/99-V850.pdf
    (section 5.7.6)
     
  8. TANSL
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    TANSL Senior Member

    Here is a more detailed regulation, SOLAS, for the inclining test :
     

    Attached Files:


  9. Mermaid Co
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    Mermaid Co Junior Member

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