heeled waterline

DELFTship forum Hydrostatics and stability heeled waterline

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    • #35312
      Avataradriano natalini
      Participant

      question to Administrator

      Hi Marven
      I’m using DS free and have a question
      whether we can use “Rotate ” tool to check hydrostatic on heeled waterline.
      It appears to rotate from the base line only and not from the water line.
      Thanks for yr instructions
      Adriano

    • #35314
      AvatarMarven
      Keymaster

      You could try the following:

      • First mirror your model around the center plane so you have both sides of the geometry modeled
      • Then switch off the symmetry settings for all the layers you have just mirrored. This ensures the software doesn’t mirror these layers againg during the calculations.
      • Rotate the model around the longitudinal axis
      • Finally you can try to find the new draught by iterating between a minimum and maximum draught until your displacement matches the original design displacement
    • #35315
      Avataradriano natalini
      Participant

      Thanks Marven,
      I did that, I suppose to have placed the waterline at the right place again,
      but the problem is that when rotated, the hull is automatically splitted into two halves sothat no hydrostatics is calculated and shown?! I may have done something wrong?!
      I do not think I can get anyhow the new volume values of the fore and aft immerged bodies but at least the new total displacement?
      Thanks for any of yr comments
      Adriano

    • #35316
      AvatarMarven
      Keymaster

      but the problem is that when rotated, the hull is automatically splitted into two halves

      Hence the first two steps in my explanation above.
      That will overcome the problem

    • #35331
      Avataradriano natalini
      Participant

      Thanks Marven,
      I tried it again but no luck!
      I may do the mirroring incorrectly?!.
      If you’re kind enough, it will be appreciated, to explain what do I have to do when yuo say
      “mirror yr model around the center plane” I may not get it correctly!
      Definitely I will have anyway to buy the heeled hydrostatics extention soon or later
      for the proper tests.
      Thanks again
      Adriano

    • #35338
      Avataradriano natalini
      Participant

      Hi there,
      From Marven I was suggested to follow this sequence:

      -First mirror your model around the center plane so you have both sides of the geometry modeled
      -Then switch off the symmetry settings for all the layers you have just mirrored. This ensures the software doesn’t mirror these layers againg during the calculations.
      -Rotate the model around the longitudinal axis
      -Finally you can try to find the new draught by iterating between a minimum and maximum draught until your displacement matches the original design displacement

      Has anybody tried this? I tried but no luck!I get only the two hull halves apart and no hydrostatics!
      Appreciate any comments
      Adriano

    • #35339
      AvatarAlexia
      Participant

      some are shown moving the hull, whole with the mirrored side also on the same
      side of the centerline some others you can extrapolate them but at that point it doubles certain measures and the stability is way different, it sort of measures like a multyhull. Ok for waterlines flowlines volumes calculation…. depends on what do you need from the hydrostatics.

    • #35341
      Avataradriano natalini
      Participant

      well… I simply need to know the heeled total displacement and the curve of areas, apparently there is a way to manage this
      do you know the way?
      thanks

    • #35357
      AvatarAlexia
      Participant

      take off the “view both sides” mirror the hull so to make it whole e move everything on one side of the centerline so the centerline doesnt split it, the curve should show up, for the total displacement its probably double because the free version thinks there is another hull on the other side of the centerline, it treats it like a catamaran, but shouldnt be a problem because heeled or level the displacement of an hull its the same.
      Im trying to work out too some problems with asymmetric hulls so thats just what i noticed i dont guarantee you will have the results you need and havent checked which are the numbers that are right and the ones messed up by this way of doing things.

    • #35360
      Avataradriano natalini
      Participant

      Hi L:) utech
      Thanks I did my best and apparently I achieved that. The displ.value is obviousely double.
      Adriano

    • #35366
      AvatarPetri Clusius
      Participant

      Hi everybody. My first post. First of all, DS is a great piece of software!

      Marven, after iterating the correct depth, I would still have to iterate the correct trim, since my boat is a typical sailing yacht with wide aft sections. That is quite tedious job… Is there any other way to do this, for example, can one of the extensions in pro-version do this? After all, this is pretty plain number-crunching job that seems basically pretty trivial for the computer. Thanks!

      Pete

    • #35368
      AvatarMICHAEL KERR
      Participant

      The pro extension is Inclined Hydrostatics see Manual page 72, 15.5

    • #35369
      AvatarPetri Clusius
      Participant

      Mike, thank you! I must have been blind (or illiterate).

      Pete

    • #37527
      Avatarmustafa
      Participant

      Hi Marven,

      Maybe an old topic but if you are reading,

      I am trying to get hydrostatistics when heeled and i found this topic when searching the net. I understand that i have to make symmetry off when i try to do your suggestions, other whise i have two boats. But the symmetry button in the Layers–>Edit, is not working. It is checked and closed. I am using the latest version. Is there another way to uncheck the symmetry button?

    • #37528
      MaartenMaarten
      Keymaster

      Hi docmsakar,

      It depends on whether you are using the free or the pro version:

      The free version of DELFTship does only support asymmetrical layers that do not contribute the hydrostatic calculations. The professional version allows for asymmetrical layers provided that those layers are completely (physically) separated from any symmetrical layers in your model

      Hope this helps

    • #37529
      Avatargiorgio zuppin
      Participant

      More.. there is an alternative.
      I still use the free version and to obtain some calculation on heeling hulls, I make a non symmetric copy by ‘mirror’ etc.
      Then using it as a dummy on another file get some hydro data.
      To note that in that sampler I was testing the LCF position only!

      Sorry for low res. you can see that some hydrostatic datas are displayed, it depends on what are you looking for, otherwise is better and simpliest to rely on pro version.
      By, Jurgen.

    • #37535
      Avatarmustafa
      Participant

      Hi Marven,

      First sorry, because i didnt see your post and today i have posted to a new topic about heeling. It is a shame but i wrote that you didnt answer. Sorry again.
      After that i got the answer for closing the symmetric button. I had to close the hydrostatistics button first. But of course even i could see the heeled waterlines to a degree ( because the waterlines were limited to the originals in the vertical direction, and it didnt work to move the hull in the vertical direction to the positive values ), i couldnt get any information about the displacement or any other parameter.
      I think it is impossible with the free version.
      Tnx a lot..

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