Hullform software from Blue Peter Marine system

Discussion in 'Software' started by melvinwangac, Apr 9, 2014.

  1. melvinwangac
    Joined: Apr 2014
    Posts: 4
    Likes: 1, Points: 0, Legacy Rep: 22
    Location: uk

    melvinwangac New Member

    Hi, I would like to check if anyone that is provision in the software can provide me with an answer to whether the software can differentiate a same vessel type (same length, breath, depth and displacement) with and without a bulbous bow feature?

    This is because my results have indicated a lower resistance in the file without bulbous bow feature where it should be the opposite. It has confused me as to whether the software has the ability to analyse correctly.
     
  2. daiquiri
    Joined: May 2004
    Posts: 5,373
    Likes: 247, Points: 73, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    The manual of the software can be found here: http://alastor.daviel.org/hullform/manual_hullform.pdf

    The chapter about drag prediction starts at the page 75. Apparently, the only adopted method for drag prediction which might take the bulbous bow into account is the Holtrop-Mennen, but... check this line:
    hullform.gif

    So, basically, the software is not able to include the effects of the bulbous bow. Hence, it is possible that the program always calculates a higher drag with the bulbous bow simply because all it "sees" is a bigger wetted surface of the added bulb and hence more friction.

    Cheers
     
  3. TANSL
    Joined: Sep 2011
    Posts: 6,230
    Likes: 299, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Bulbous bow does not mean that total resistance to be lowered. The bulb, if appropriate, is well placed and depending on the type of ship, its displacement and its speed, may decrease, or not, the wave making resistance but what is certain is that it increases the frictional resistance.
     

  4. melvinwangac
    Joined: Apr 2014
    Posts: 4
    Likes: 1, Points: 0, Legacy Rep: 22
    Location: uk

    melvinwangac New Member

    hi daiquiri and TANSL, thank you for the information. It has indeed helped me alot in understanding the program especially with the manual of the software link provided. Thank you.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.