Lightship weight

DELFTship forum Hydrostatics and stability Lightship weight

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    • #34737
      AvatarRemco van de Berkt
      Participant

      I am a student in the Netherlands and I use of the programme delftship.
      Now I am busy with stability, however there is no lightship weight standing atloadcase .

      for example, mild steel weights 7850 kg/m3 so it would be entered in the Density column as 7.850 , (lets say plywood weights 368 kg/m2 so it would be 0.368) , if your steel thickness is 10mm that would be entered in the Thickness column as 10.00 after you enter your density and thickness press Enter so its locked in, then go to Design Hydrostatics, you will see a list of all your Layers, they will include Layer Name, Area, Thickness, Weight and the 3 COGs, this will be automatically transfered to Load Cases under Lightship.

      I have followed the steps which stand on the forum what do do I wrongly?

    • #34738
      AvatarJesus Cruz
      Participant

      That data for the weight of the layers is just taken for the Design Hydrostatics Report, not for the loadcases, in any case the lightship weight have many ther items, such has the internal structure (girders, longitudinals, frames), equipments etc.

      From the design stand point you can take the weight of ships with similar characteristics (same length, beam and depth), that can be use as a “first appraoch” stand point.

      You can substitute the data when you have a more accurate calculations of the ship’s weight and CG.

    • #34739
      AvatarMICHAEL KERR
      Participant

      Remco,
      You have to manually enter them yourself in Loadcase Model under Lightship and as Cruzmayora said its only part of the Lightship weight. 😉

      Mike

    • #35372
      AvatarHauke Jessen
      Participant

      Sorry for digging out this old thread, but I have difficulties with the input of lightship weight and cog.

      I have a lightship weight estimate from a statistical method for a container vessel and want to enter it into the weight table at the bottom of the loadcase window but DelftShip won’t let me do that. I read the manual carefully and searched for relevant topics on this forum but had no success.

      No problems with other masses or tank fillings though.

      There must be something fundamentally wrong with what I do. I have attached a screenshot from DelftShip of where I tried to input my numbers.

      Thanks a lot in advance for any hints on this subject!

      Attachments:
    • #35373
      AvatarJesus Cruz
      Participant

      among the icons in the upper part of that screen there is an icon that says “edit the list with common weights”, click on it would allow you to edit the weigths for all the weight groups that are common, among those is the ligthship weight, you can edit all the weigths that you consider as part of the lightship weigth.

      Hope this helps

      Regrads

    • #35374
      AvatarHauke Jessen
      Participant

      Thanks for your quick reply, cruzmayora!

      After a bit of fiddling around with the checkboxes my lightship numbers finally appear in the list.

      Good to have such knowledgeable folk on the forum!

      Thanks again!

    • #35375
      AvatarJesus Cruz
      Participant

      any time

    • #35456
      AvatarBOUAZIZ
      Participant

      hello,
      i have the same problem but in the edition menu i cannot change any thing
      please help me !!!

    • #35457
      AvatarJesus Cruz
      Participant

      Which problem could you be more specific about the problem that you have?

      Hope i can help

    • #35458
      AvatarBOUAZIZ
      Participant

      thank you for your quick anwser.
      My problem is how to introduice the light ship weight in the edition menu ?

      So another question : i have a boat and i hope to draw it by using delftship because i want to evaluate his initial stability and to make some modification to increase his initial stability. Wich is the best means to reproduice this boat in delftship (make a photo,…)?

    • #35459
      AvatarJesus Cruz
      Participant

      Ok. I see

      First, for the ligthship, you have to go to the loadcase menu, cick the edit menu, a screen will appear with the image of the boat that you previously modelled, click the icon that say “Edit the list with common weights”, a “window” will appear with a label in the left upper corner that says “lightship”, that label can be scroll down and will appear all the elements that you define in weightlist (tanks extension), when the name of that element defined is shown in the screen you can add fix weigths to that element.

      For instance when the “lightship” label is shown, just push the insert button in your keyboard and a line will be added where you can put the name of the element that you want to add, either the lightship weigth or you can insert the ligthship weight element by element.

      Hope this helps

    • #35460
      AvatarJesus Cruz
      Participant

      And regarding modelling the boat, in the manual there is a chapter for importing files (.txt) formatt, i found really helpful this feature mostly in my earliest stages with the software, you will have to make some adjustments for getting better results but is a good way to start and you can allways keep the markers to compare with you final result.

      Hope this helps too.

      Good luck and if i can be of any help please do not hesitate to ask.

      😉

    • #35463
      AvatarBOUAZIZ
      Participant

      ok !! it is magic ! thank you very much for your precious help.

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