MAXIMUM PERMISSIBLE VCG vs DISPLACEMENT GRAPH

Discussion in 'Stability' started by QUICKNAVAL, May 19, 2013.

  1. QUICKNAVAL
    Joined: May 2012
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Philippines

    QUICKNAVAL Junior Member

    Hello, Do anyone know about manual calculation of the values of this graph?
    Preferably for a pontoon.

    THANKS...
     
    Last edited: May 19, 2013
  2. TANSL
    Joined: Sep 2011
    Posts: 5,736
    Likes: 184, Points: 73, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    You have to calculate, for a range of displacements between the lightweight and full load, the higher value of VCG with the ship meets all stability criteria applicable to her.
    These calculations, made by hand, can last an eternity.
     
  3. QUICKNAVAL
    Joined: May 2012
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Philippines

    QUICKNAVAL Junior Member

    I got it....i have no choice,,,hehehe,,,but do the manual calculations,,,,because our company do not spend money for this new stability softwares.

    Thank you...
     
  4. TANSL
    Joined: Sep 2011
    Posts: 5,736
    Likes: 184, Points: 73, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    You can get a very good program that does all that for less than 6000 euros. That's less money than the amount of hours that you will be using. And always have the doubt if you were wrong in the calculations or not.
    If you send me a G.A., body plan, type of ship and weights of the boat, I will do for you limit KG calculations.
     
  5. QUICKNAVAL
    Joined: May 2012
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Philippines

    QUICKNAVAL Junior Member

    Please see attached General Arrangement Plan. I really appreciate your kindness.
     

    Attached Files:

    Last edited: May 19, 2013
  6. TANSL
    Joined: Sep 2011
    Posts: 5,736
    Likes: 184, Points: 73, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Have you an idea of ​​the lightship weight and her maximum displacement?. At least need to know the depth at full load.
     
  7. QUICKNAVAL
    Joined: May 2012
    Posts: 25
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Philippines

    QUICKNAVAL Junior Member

    lightweight = 1011.5 tonnes and max. displacement = 6011.5 tonnes
     
  8. Stephen Ditmore
    Joined: Jun 2001
    Posts: 1,388
    Likes: 44, Points: 58, Legacy Rep: 699
    Location: Smithtown, New York, USA

    Stephen Ditmore Senior Member

    Recommended reading:
    http://www.ntsb.gov/doclib/reports/2006/MAR0601.pdf
    Because pontoons are round overloading can cause diminishing stability.
    Reserve bouyancy diminishes when all displacement is effectively shifted to leeward hull.

    I'd like to see your graph from post #1. Can it be restored?
     
  9. Ad Hoc
    Joined: Oct 2008
    Posts: 6,129
    Likes: 364, Points: 83, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    Much cheaper than that!! Mine, currently costs £1250.

    This is the program I have been using since...1988:

    http://www.wumtia.soton.ac.uk/software/hst

    Does it all for me..and free unlimited service support too, can't beat that!
     
  10. TANSL
    Joined: Sep 2011
    Posts: 5,736
    Likes: 184, Points: 73, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Seems an interesting program and a very good price. Now if you need the hydrostatic module, plus the module "HST Loading" (maximum KG) plus the module "GoPlot", the final price is £3000 (about €3600) which is not as surprising. Damage stability module costs £1500, etc.. All this leads us to see that the price is not so surprisingly good (about €5400).
    Seems imo a rather outdated program (need to define negative volumes, very laborious tank definition, not nurbs, ..) but no doubt that would be taken into account before deciding to purchase a naval architecture program.
    Thanks for the information. The fact that AdHoc defend the program, to me, is a guarantee of quality.
     

  11. Ad Hoc
    Joined: Oct 2008
    Posts: 6,129
    Likes: 364, Points: 83, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    I don't have the HST Loading nor GoPlot. The HST and Damage module has the max KG in the software, and I use excel to plot my values.

    It is "dated" hull input can be tricky (since the program has been around since floppy disc drives), but very stable, no errors. It could be more "fancy" and flashy colours, but is more about numbers than graphics. As the website says, it is used by the UK's MCA to validate 3rd party software, they have that much confidence with it.
     
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.