Bowcone and Maxsurf... again

Discussion in 'Software' started by Grant Nelson, May 24, 2008.

  1. Grant Nelson
    Joined: Feb 2005
    Posts: 210
    Likes: 12, Points: 0, Legacy Rep: 163
    Location: Netherlands

    Grant Nelson Senior Member

    I am still waiting for that bowcone tutorial (see post from 2006) ;-)

    Seriously, I still struggle with this (but have not tied since last time).
    The scenario is generally that I have hull with more than 2 degrees of flexibility, and usually a couple of control points have come together and are compacted at the lower forward edge of the surface (where the bottom of the bow cone will be). From there the surface opens up in V, with one or more rows before reaching the top. I can not figure out how to do this with consistent minimum number of steps.
    I would appreciate an example of how to do it using a conic form, but also another 'rounded' shape in case I don't want a perfect circle bow in plan view (but tangent to the hull, with a smooth rounding at the foward end)...
  2. bhnautika
    Joined: Feb 2006
    Posts: 830
    Likes: 50, Points: 38, Legacy Rep: 571
    Location: australia

    bhnautika Senior Member

    Grant is this the way you want to do bow cone, one is with conic the other is with nurbs and playing around with the weighting of the internal control point.The conic surface tends to start the curve at the joint, were as the nurbs allow some control over the surface at the intersection.

    Attached Files:

  3. CTMD
    Joined: Dec 2007
    Posts: 198
    Likes: 9, Points: 0, Legacy Rep: 117
    Location: Melbourne, Aus

    CTMD Naval Architect

    Grant the sytem is the same whether you want to use conical or nurb surfaces.

    1. Create the cone surface with three columns of control points and the same number of rows and flexibilty as the topside surface.

    2. Create the profile you are after using the fwd most column of control points

    3. Set the middle row of control points parallel to the stem line

    4. Bond the aft most column to the hull edge using "approximate tangency" make sure you sellect the control point on the hull surface first so maxsurf doesn't move that surface.

    5. using the align to vector command set each of the middle column control points parallel to the last two corresponding control points on the hull surface. The height and longituinal location of each of these control points should be the same as the one in its row on the stem. ie. when viewed in profile the two points should appear in the same location.

    Note. You've mentioned that you have compacted some control points, be very carefull doing this if you intend on developing the surfaces as it can cause issues.
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.