ship motion analysis

Discussion in 'Software' started by aiix, May 7, 2010.

  1. aiix
    Joined: Aug 2009
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    aiix New Member

    hye everybody..this is my second thread. now i am in progress with my final year project. it's about the motion prediction of trawler at sea. in order to do that, i need to determine the suitable formula to predict the behaviour of the trawler and using the MATLAB for analysis the motion. can anybody from here have ideas how to do that.for example the sequence that i should follow,the suitable method.(neglect the resistance)please help me. thank you :D
  2. Tim B
    Joined: Jan 2003
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    Tim B Senior Member

    I'm fed up with these requests.

    What are you in your final year of? It doesn't sound like you're on a Naval Arch course or you would have looked at a minimum of one approximation and a direct solution method for this already.

    Do you even have a static stability model yet?

    Which motions are you after? the full solution in six degrees of freedom? How are you going to determine coupling, damping, what wave options are you going to include? There are lots of good books about vessel dynamics around, and they all contain many formulae which may be suitable for your task.

    We are not in the business of telling people how to do final year projects.

    Tim B.
  3. LyndonJ
    Joined: May 2008
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    LyndonJ Senior Member

    You need the metacentric heights and the gyradius of rotation for both roll and pitch to do it by hand.
  4. conceptia
    Joined: Nov 2009
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    conceptia Naval Architect

    hey Tim we must not get fed up with these requests as the prime aim of this forum is knowledge sharing.
    Linear wave theory along with a wave spectrum(look for Pierson Moscovitsch spectrum) will be the better input i guess. Radius of gyration(6X6 matrix) is also another input. Your aim must be to calculate the main offset of the vessel, load and motion RAO of the vessel, wave drift forces, added mass, stiffness matrix. I had done a MathCAD software 2 years back for the same, but I lost it while rebooting the PC.
  5. frank2526244
    Joined: Dec 2009
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    frank2526244 Junior Member

    To predict the ship motion is not an easy task, it calls for strong relevant theory background. Current studies are most based on potential thoery which neglects the viscos effect of the fluid(water). Two major approach are optional, the 2D method and 3D method, and the later is much more popular. If you want to write codes to solve the problem on your own, one year is not enough wether you use MATLAB or other programming languages.

    You can refer to Wamit(or other hydrodynamic software eg. Hydrostar Aqwa) User Manual to get more information about the method.

    There are lots papers.

    Let me know if there's anything I can help you.
  6. aiix
    Joined: Aug 2009
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    aiix New Member

    in this case, i need to focus hydrodynamic. i need to culculate the hydrodynamic forces acting on the trawler first.
  7. Rohit D Rumade
    Joined: Jun 2010
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    Location: Chennai

    Rohit D Rumade New Member

    Hi Alix too in final year ...doing my project
    My project is in shallow water vessel response in an approach channel
    i hv estimated siltation & water depth changes in the approach channel & now going to study vessel response in shallow water to get minimum under keel clearance...I m going to use ANASYS AQWA 12.1 ..i hv generated my hull form using FREEship 3.1 & taken it in IGES format to put in AQWA for analysis
    AQWA inputs are water depth, mass , VCG, Radious of gyration abt X Y Z axis
    Wave climate/directs etc
    Plz let me know abt ur project progress
    Best Luck
  8. yipster
    Joined: Oct 2002
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    yipster designer

  9. ssaw005
    Joined: Jul 2010
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    Location: PERTH

    ssaw005 New Member

    We need to calculate RAO’s for multiple drafts in AQWA. Is there any way to run batch processing in AQWA?
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