Predict flow lines along hull

Discussion in 'Hydrodynamics and Aerodynamics' started by Janne Enlund, Mar 28, 2015.

  1. Mr Efficiency
    Joined: Oct 2010
    Posts: 10,401
    Likes: 1,026, Points: 113, Legacy Rep: 702
    Location: Australia

    Mr Efficiency Senior Member

    Ok, interesting test, though a little "invasive" !
     
  2. appusree888
    Joined: Jul 2014
    Posts: 21
    Likes: 0, Points: 1, Legacy Rep: 10
    Location: Dubai

    appusree888 Sreenath

    Dear Brother.... Can anyone help me to find the Load line for flat barge having the length of 19.90m, Braedth as 10.00m and depth as 2.00m
     
  3. Leo Lazauskas
    Joined: Jan 2002
    Posts: 2,696
    Likes: 151, Points: 63, Legacy Rep: 2229
    Location: Adelaide, South Australia

    Leo Lazauskas Senior Member

    Best ask in another forum. This thread is about flow lines along a hull.
     
  4. HJS
    Joined: Nov 2008
    Posts: 372
    Likes: 69, Points: 28, Legacy Rep: 288
    Location: 59 45 51 N 019 02 15 E

    HJS Member

    Smear

    What kind of smear is the most suitable which is easy to remove after the experiment and do not discolor the hull?

    js
     
  5. Remmlinger
    Joined: Jan 2011
    Posts: 270
    Likes: 39, Points: 28, Legacy Rep: 172
    Location: Germany

    Remmlinger engineer

    I used artists' oil colour, e.g. Titanium white.
    It can be thinned with turpentine oil.
    After the test remove the paint with white spirit.
    Uli
     
  6. Janne Enlund
    Joined: Aug 2014
    Posts: 28
    Likes: 1, Points: 3, Legacy Rep: 10
    Location: Finland

    Janne Enlund Junior Member

    All in all I think that eyeballing, common sense and a little good luck is the preferred way to go whit my little ship. I was most interested if there where any rule of thumb when attaching bilge keels to a hull when taking flow lines in consideration. But when reading all posts I understand that the matter is to complex to solve in a simple way.
    The most important thing that I'm trying to accomplish is roll dampening, if the flow along the keels creates more or less turbulense is of less importance. My mighty 24' ship is anyway only topping 6 knots at full speed so the turbulence created will not have much impact anyway.
     
  7. TANSL
    Joined: Sep 2011
    Posts: 6,811
    Likes: 499, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    You can draw a bilge diagonal in the body lines plan. That will allow you to get the points for which it will pass a flat bar, your bilge keel.
     
  8. DCockey
    Joined: Oct 2009
    Posts: 5,025
    Likes: 514, Points: 113, Legacy Rep: 1485
    Location: Midcoast Maine

    DCockey Senior Member

    Does that apply to a fiberglass, "lapstrake", double-ended motorsailer without a parallel mid-body such as the Saga 24 which the original poster is interested in modifying?
     
  9. TANSL
    Joined: Sep 2011
    Posts: 6,811
    Likes: 499, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Why not ?. Having said that turbulence does not care, could you tell us why not ?. Surely you have a compelling reason but I am not able to guess.
     
  10. Janne Enlund
    Joined: Aug 2014
    Posts: 28
    Likes: 1, Points: 3, Legacy Rep: 10
    Location: Finland

    Janne Enlund Junior Member

    Of course I care about turbulence, but as the complexity to get the flow lines right is above my math skills I have to settel for something easier. Almost right is enough for me in this case and to mount them alog the hull following a slight curve will do the job just fine! It's at family boat after all, not a racer.
    The case would be a lot easier if there was existing drawings available, but when I asked Saga boats, their answer was that they only have the mould left.
     
  11. TANSL
    Joined: Sep 2011
    Posts: 6,811
    Likes: 499, Points: 93, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Janne Enlund, I understand you perfectly. You will not despise the turbulence but you don't want to take them into account given the complexity of determining water flow lines.
    The method which I propose has been used by many large ships, before the tank test or software with 3D models allow determining those lines. But if you have no body lines plan, you can not use it. Maybe you could draw 4 or 5 cross sections and, with that, I could give you some guidelines to draw the line.
     

  12. Janne Enlund
    Joined: Aug 2014
    Posts: 28
    Likes: 1, Points: 3, Legacy Rep: 10
    Location: Finland

    Janne Enlund Junior Member

    That would be much appreciated. I'll just have to wait until the snow has melted around the hull so I can make the measurements. Still winter in Finland...
     
Loading...
Similar Threads
  1. Surfer Naval Architect
    Replies:
    1
    Views:
    552
  2. laukejas
    Replies:
    13
    Views:
    2,653
  3. vaer
    Replies:
    13
    Views:
    3,160
  4. farjoe
    Replies:
    7
    Views:
    2,339
  5. Julien_C
    Replies:
    3
    Views:
    1,814
  6. KennyB
    Replies:
    0
    Views:
    1,900
  7. GeorgeMarEng
    Replies:
    13
    Views:
    3,913
  8. Leo Lazauskas
    Replies:
    51
    Views:
    13,932
  9. Leo Lazauskas
    Replies:
    17
    Views:
    4,938
  10. Luke Frisbee
    Replies:
    26
    Views:
    1,236
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.