Container Ship

Discussion in 'Boat Design' started by Ghost Boy, Jan 16, 2020.

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  1. Ghost Boy
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    Ghost Boy Junior Member

    I know the number of Container (Teu). How can I calculate DWT?
     
  2. TANSL
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    TANSL Senior Member

    It is enough to add the weights that the ship carries, and includes the cargo, the ship's own fuel, the provisions, the fresh water for human consumption, the ballast water, the crew and their belongings. Maybe there is something else but now it does not come to mind.
     
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  3. Ghost Boy
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    Ghost Boy Junior Member

    Sir, Have you any sample?
     
  4. TANSL
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    TANSL Senior Member

  5. Ad Hoc
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    Ad Hoc Naval Architect

    If you know the number of container, you can sue this graph to obtain the optimal BxD ratio:
    upload_2020-1-17_8-1-31.png

    That will then give you the 'midship' cross section.
    So that then roughly fixes you beam...no of unit (+structure allowance) and the number of units length wise.
    Add an allowance for fine entry fwd and aft for props...so no. of TEUs x 1.20 = Lwl.

    So now you have L x B, so using this graph:
    upload_2020-1-17_8-4-11.png

    You can use the LxBxD you have estimated...or use the moulded volume, knowing the volume of each TEU, to cross reference volume against the LxBxD.

    Hey presto
     
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  6. TANSL
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    TANSL Senior Member

  7. bajansailor
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    bajansailor Marine Surveyor

    A suggestion re deadweight - you can get approximate values for L, B and D from Ad Hoc's advice and useful diagrams above.
    And for deadweight, this is listed for container ships on Marinetraffic.
    Here is a typical example (currently berthed in our port at Bridgetown, Barbados). I like her name 'Sea Steamer'. :)

    https://www.marinetraffic.com/en/ais/details/ships/shipid:733240/mmsi:566840000/imo:9366158/vessel:SEA_STEAMER/

    Marinetraffic also gives you the L and B for each ship.
    So, you could compile a data base of container ships from Marinetraffic (there are an awful lot of them available here), and see how they correlate re Dwt, L and B?
    This approach might be a useful 'initial start'?
     
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  8. Ad Hoc
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    Ad Hoc Naval Architect

    Well kind of yes.
    Since as noted once he's established the basic form, LBD, depending upon how detailed he needs to do this, the quick easy option is to have a quick look at similar sized container ships, like in the link you provided, or any other similar source. Then look at their particulars, the principal ones being the speed and engine power/size.

    From that he can establish the basic DWT.
    Since only he can do this, as it is not a fancy one liner as some may wish to suggest, other than just showing their ignorance on how to establish the DWT.

    Because....where is the route, how far is it in good and bad weather what speed must they maintain what are the sea conditions like etc etc ??.... without this data, how does one know how much fuel to allow for, the joint major input to the DWT?
    You don't, only knowing the answers to the above .....but that is for the OP to establish once he's arrived at the LBD and 'typical' engine sizes used for the size of vessel he's going to use to carry his TEUs.

    Everything in design is iterative....
     
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  9. TANSL
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    TANSL Senior Member

    In the end, the OP has to look at similar ships to know the DWT of their ship. I propose, therefore, a much simpler method. Container ships are distinguished by the number of TEUs they can carry, which is how they are normally defined. Therefore, if the OP knows the number of TEUs on his ship, he only have to look at ships with a similar number of TEUs.
     
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  10. Ghost Boy
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    Ghost Boy Junior Member

    thanks a lot sir for your explanation. Sir, I have one request to you. Could you please tell me the books name of the graph you have uploaded as well as need a better copy of those graph.
     
  11. Ad Hoc
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    Ad Hoc Naval Architect

    It is the Classic paper written by DGM Waston & AW Gilifillan called - Some Ship Design Methods, published by RINA in 1976.
    This was essential reading material as a student.
     
  12. bajansailor
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    bajansailor Marine Surveyor

    it was a 'seminal work' more than 40 years ago (I also have a copy in my notes somewhere) - and I wouldn't be surprised if it is still regarded as essential reading for ship design classes today.
     
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  13. TANSL
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    TANSL Senior Member

    No doubt that was a fundamental paper 44 years ago but I wonder if at that time the design of container ships will not have improved. Is there nothing more up to date, equivalent to that?
     
  14. Ad Hoc
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    Ad Hoc Naval Architect

    I am not aware of the derivation of DWT changing in the past 44 years.
     

  15. TANSL
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    TANSL Senior Member

    Yes, that's what I thought. But there is no doubt that the design of these ships has changed and that, among other things, efforts have been made to reduce their DWT trying to improve their payload, for a given displacement at full load.
     
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