Location of GM Transvers

Discussion in 'Stability' started by amateur mariner, Mar 25, 2009.

  1. amateur mariner
    Joined: Feb 2009
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    amateur mariner Junior Member

    Hi,

    I want to ask two questions

    1 Is there any periodicity for Inclining experiment?

    2 What is the analysis if GM transvers is slightly starboard or port of center line?


    Cheers
     
  2. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    1. do you mean period as in roll period, or period as in time between having to perform an Inc. Expt?

    2. Is the TCG creating 0.0001 degrees list or 0.1, 1, 10 or 20 degrees???
     
  3. amateur mariner
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    amateur mariner Junior Member

    1. I mean periodicity of Incl. Expt.

    2. I want to know that if i get to know that my GM transverse is slightly stbd or port of centerline, what all affects it has?
     
  4. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    1. If the boat has changed from its "launched" as delivered state. If the mass has increased and/or move items around on board which affect the GM, then you need to re do it.
    2. You can only tell, once you have performed the calc's what the effect is, and then ascertain if it is a problem.
     
  5. amateur mariner
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    amateur mariner Junior Member

    I have come to know that my Transverse GM is Port?How can I say it is a problem or not?What I should do to come to a conclusion?
     
  6. DavidJ
    Joined: Jun 2004
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    DavidJ Senior Member

    Transverse GM, despite what it sounds like, is actually a vertical dimension and cannot by definition be to port. You are referring to TCG or "transverse centre of gravity" like Ad hoc said and it is only a problem if it produces a noticeable list. Many boats launch with a slight list. Is this boat still in design stages or is it on the water? If you are already using it and you can't notice the list then I would guess that it is not a problem.

    You will only need to do a new inclining experiment if like Ad Hoc said there has been major changes in weight or location of weight.
     
  7. DEboater
    Joined: Feb 2009
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    DEboater Naval Architect

    If you do the calculations and find out your TCG is not 0, and you think you may have transverse stability issues then you have to run through the appropriate stability criteria for your vessel to see if it has appropriate righting arm with statical stability curves. Use imo/CG/ABS/etc criteria.
     

  8. Guillermo
    Joined: Mar 2005
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    Guillermo Ingeniero Naval

    Depending on each country regulations, some fishing vessels, houseboats and other floating structures are to be checked for adequate stability at 5 to 10 years intervals.

    Cheers.
     
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