Does displacement scale?

Discussion in 'Boat Design' started by stonedpirate, Apr 2, 2010.

  1. stonedpirate
    Joined: Nov 2009
    Posts: 384
    Likes: 3, Points: 0, Legacy Rep: 23
    Location: Australia

    stonedpirate Senior Member

    Hello,

    If i built a 10 foot boat that can carry 1000lbs, would a 1 foot scale model carry 100lbs?

    Thanks
     
    1 person likes this.
  2. kerosene
    Joined: Jul 2006
    Posts: 1,285
    Likes: 203, Points: 63, Legacy Rep: 358
    Location: finland

    kerosene Senior Member

    what do you think? just try to visualize it in your head...

    If you scaled it only along length but came same width and height it would...

    Area scales in power of 2 and volume in power of 3.

    in your example 1ft boat will displace 1lbs.
     
  3. stonedpirate
    Joined: Nov 2009
    Posts: 384
    Likes: 3, Points: 0, Legacy Rep: 23
    Location: Australia

    stonedpirate Senior Member

    of course :p

    Gee i'm dumb :)

    I was trying to imagine a tiny boat with 100lbs of lead in it :p

    Cheers
     
  4. pistnbroke
    Joined: Jan 2009
    Posts: 1,405
    Likes: 34, Points: 48, Legacy Rep: 404
    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    australian education system
     
  5. stonedpirate
    Joined: Nov 2009
    Posts: 384
    Likes: 3, Points: 0, Legacy Rep: 23
    Location: Australia

    stonedpirate Senior Member

    lol

    i'd say mary jane
     
  6. messabout
    Joined: Jan 2006
    Posts: 3,368
    Likes: 511, Points: 113, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    Pirate; To scale displacement take the scale ratio. In your example you reduced a 10 foot boat to 0ne foot. That is a 10 to one ratio. Raise the scale ratio to the third power. 10 x 10 x10 =1000 divide the displacement of the full sized boat by the scale ratio cubed...in this case you divided 1000 by 1000 and the quotient is one. Lets take a different case in which the the one thousand number does not occur twice. That is kind of confusing, so think of a ...16 foot rowing or sailing skiff. It might displace 360 pounds when occupied by one person. Let us build a model that is scaled to one and one half inches to the foot. That would be one eighth scale. so.....8 x 8x 8 = 512....divide....360/512 = 0.703 pounds. That is all the model could weigh in order to simulate the 16 footer. If you built the model to 3 inch to the foot scale then that would be a quarter scale or 4 to 1 model 4^3 = 64 .....360/64 = 5.625 pounds. The same rule applies when using the metric system of measurement.
     

  7. stonedpirate
    Joined: Nov 2009
    Posts: 384
    Likes: 3, Points: 0, Legacy Rep: 23
    Location: Australia

    stonedpirate Senior Member

    Thanks a lot Mess :)
     
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.