New Project Beam Trawler

Discussion in 'Boatbuilding' started by SixMadrid, Apr 5, 2013.

  1. rxcomposite
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    rxcomposite Senior Member

    Ok. At 0.50 ton/m3, it becomes a volume based design, meaning, I have to look at the volume of the whole ship. I need you to fix your total crew size as it is also volume based. Lots of space occupied for the weight.

    I will try another approach, narrowing the range of coefficients and Fn's. Maybe tonight. Have work to do today.
     
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  2. SixMadrid
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    SixMadrid Marine Engineer UPM (Mad)

    Sorry It is 8 people (18 people would be bigger), this data is based in similar ships
     
  3. SixMadrid
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    SixMadrid Marine Engineer UPM (Mad)

    Thank you any help will be useful! here, it is 4 a.m. I am going to sleep now!
     
  4. rxcomposite
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    rxcomposite Senior Member

    SixM,

    Here is the spreadsheet that will narrow down the ratios and coefficients. It is based on standard naval architecture formulae.

    Sheet 1 is a manual input. Suggest you play around varying input only one at a time. Start with the Cp first. Check in the upper rows if you are within range, then vary the draught, beam, length, one at a time. Once you get the hang of it, go to sheet 2.

    Sheet 2 contains error traps and might be difficult for you if you are not familiar with how the inputs interact. You will see only error messages. I have worked out the 36 meter length for you. It seems workable but you have a very narrow window. I am getting a Cb of 0.51. See if you can do better.

    Note that the end output is in wetted surface area. This is good to find the smallest area needed in terms of cost of build. In terms of operational cost, the WSA is not enough. A hull resistance evaluation is needed to find the least power needed by varying the L/D ratios and L/T ratios. I had posted something similar before in the Twin Hull analysis before but needs some tweaking.
     

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  5. SixMadrid
    Joined: Apr 2013
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    SixMadrid Marine Engineer UPM (Mad)

    Yeah finally all we agree, I am getting new measures with all the new info and new transformations and this my new data (it is not finished):

    - Loa (upper deck) = 40 m
    - Lwl = 32,7 m
    - Bwl = 7,8 m
    - H main deck = 4 m
    - Draft = 3,5 m
    - Block coefficient = 0,56

    Closer to a better results...

    When we decided the final data, I will update the main post and I will speak about the next step for anybody who want to help.

    thanks a lot!
     

  6. rxcomposite
    Joined: Jan 2005
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    rxcomposite Senior Member

    I was curious so I fiddled a little more. I increased the displacement and upped the Fn for an overdiven hull. I was able to get a Cb of 0.67 and Length of 36 meters at Fn 0.44 to 0.49

    The limits are guide only so it is not a hard and fast rule. Next, I will feed this into hull resistance analysis.
     

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