The Union of Naval Architects

61 members

Description

This group is intended as a collective of gh users who have a marine background.

Despite the name you do not have to be a Naval Architect to join. Whether you are a budding Optimist Sailor or Admiral of the Fleet please feel free to share and discuss any topics relevant to Grasshopper and the Maritime Industry.

Also acceptable "Off Topics" of conversation include "How will l'Hydroptere fair on her Transpacific Record attempt?" Or "Should Juan K have been appointed the VOR one design, or is he to arrogant to toe the line?".

However I would like to point out that the level of decorum should not descend to that of Sailing Anarchy and there will be no Fridays here! 

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Hydrostatics in grasshopper

by Simon Delvoye

May 20, 2014

As a new grasshopper user, I am trying to solve hydrostatic caculations...

I did some try with hoopsnake, and now with Anemone... I can reach the static equilibrium with the correct displacement, but when I try to work with two loops and change the trim angle AND the displacement, it doesnt work properly...

Does anyone has an idea?

The gh programm is here: StabTest.gh

Sorry if it is not done properly, I ve been using GH for a week only... 

Simon

  • up

    Fernando

    Very interesting post!! I made once an script on VBA for Rhino to calculate the hydrostatics... but I never have tried to calculate them on GH!!

    Nowadays I'm working more with blades for propellers than vessels, but I will follow this discussion!!

    May 20, 2014

    • up

      Fred Becquelin

      Here's what I think you should do :

      1 create a loop that aligns the center of gravity with the center of buoyancy. E parameter of this anemone would be (xCG - xCB)² < thrsld²

      2 create a  loop that sets the displacement at the desired value. You've done that but I would recommend moving the object rather than the water.

      now once you've done that, go back to the anemone tutorial and nest one in another.

      In that post in the hoopsnake group I talked about how to guess the amount of rotation from the usual longitudinal stability analysis (metacenter theory). It helps a HUGE deal with convergence so I really advise you to go there.

      Also, don't discourage yourself. with 7 days of gh it is not a trivial undertaking.

      2

      May 20, 2014

      • up

        Fred Becquelin

        Simon,

        I checked your file, seems you took the long way! I didn't even understand why 3 loops?

        Check out this file, seems to work ok here.

        1

        May 22, 2014