Least Square Method (linear) - Freeboards and drafts

Discussion in 'Education' started by Transom6.3, Sep 22, 2009.

  1. Transom6.3
    Joined: Sep 2009
    Posts: 3
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Ireland

    Transom6.3 New Member

    Hi Guys,

    I have seen the least square method (linear) in a number of inclining test reports when used to get the inclined waterline from a number of freeboards measurements and drafts.

    I have no idea what the formula/process is, does anybody know?

    I realise there will never be a perfect straight line through all the freeboard measurements so this method must average the differences out.

    Thanks for help.
     
  2. Ad Hoc
    Joined: Oct 2008
    Posts: 7,276
    Likes: 1,165, Points: 113, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    have you looked at the ISO code?
     
  3. Raggi_Thor
    Joined: Jan 2004
    Posts: 2,457
    Likes: 64, Points: 0, Legacy Rep: 711
    Location: Trondheim, NORWAY

    Raggi_Thor Nav.arch/Designer/Builder

    It's a lot of work to do this math manually.
    Say you have measured some heights (y1, y2, y3 etc) at some given locations (x1, x2, x3 etc), then find a straight line Y = ax + b (calculate the constants a and b) so that the sum of the squared differences between all your measurments and the calculated Y is minimized.
    Excel or OpenOffice does it for you.
     
  4. Transom6.3
    Joined: Sep 2009
    Posts: 3
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Ireland

    Transom6.3 New Member

    Thanks guys,
    I'll look into it and try and set up an excel spreadsheet.
    Does anybody have an excel template.
     
  5. Raggi_Thor
    Joined: Jan 2004
    Posts: 2,457
    Likes: 64, Points: 0, Legacy Rep: 711
    Location: Trondheim, NORWAY

    Raggi_Thor Nav.arch/Designer/Builder

  6. Raggi_Thor
    Joined: Jan 2004
    Posts: 2,457
    Likes: 64, Points: 0, Legacy Rep: 711
    Location: Trondheim, NORWAY

    Raggi_Thor Nav.arch/Designer/Builder

    Attached Files:


  7. Transom6.3
    Joined: Sep 2009
    Posts: 3
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Ireland

    Transom6.3 New Member

    Thanks alot Raggi,
    That's a big help.
     
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.