Radial diagonals ?

Discussion in 'Boat Design' started by frank smith, Jun 16, 2011.

  1. frank smith
    Joined: Oct 2009
    Posts: 980
    Likes: 14, Points: 28, Legacy Rep: 185
    Location: usa

    frank smith Senior Member

    Daniel Z. Bombigher used the term radial diagonals in describing the lines of one of his designs . I have not heard this term before . Would someone please explain what this term means .

    Thanks , Frank
     
  2. tom28571
    Joined: Dec 2001
    Posts: 2,474
    Likes: 117, Points: 63, Legacy Rep: 1728
    Location: Oriental, NC

    tom28571 Senior Member

    I expect he meant the same thing as diagonals. They are radial about a longitudinal axis.
     
  3. ancient kayaker
    Joined: Aug 2006
    Posts: 3,497
    Likes: 147, Points: 0, Legacy Rep: 2291
    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

  4. frank smith
    Joined: Oct 2009
    Posts: 980
    Likes: 14, Points: 28, Legacy Rep: 185
    Location: usa

    frank smith Senior Member

    The question is about the term "radial diagonals " . It may have to do with the way in which the diagonals are arranged . I understand the conventional methods that are used for laying out diagonals, and the usage of diagonals . But have never heard the term " radial diagonals ".Maybe it is a French thing.

    I understand that diagonals are not used that much today with Cad design being so prevalent . But i use them all the time , and they give me a much better understanding of the form .
     
  5. frank smith
    Joined: Oct 2009
    Posts: 980
    Likes: 14, Points: 28, Legacy Rep: 185
    Location: usa

    frank smith Senior Member

    Well i went back and looked at some of Bombigher's line plans and can see what he is talking about.
     
  6. PAR
    Joined: Nov 2003
    Posts: 19,126
    Likes: 498, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I suspect what he's trying to say with radial diagonals is they fan out from a single point on the centerline. This isn't as effective as placing each to bisect the stations at close to a right angle as practical, which usually requires you to have multiple starting points from the diagonals.
     
  7. timothy22
    Joined: Feb 2008
    Posts: 95
    Likes: 6, Points: 0, Legacy Rep: 76
    Location: florida

    timothy22 Junior Member

    Bombigher's line drawing

    shows the diagonals emanating from two points in space, at max beam and, well, see for yourselves. The result is not unlike what we see on many older Murray Peterson designs among others. Bombigher just shows us the origin points. I think it may have been intended to help the lofter locate the diagonals on the floor.
     

    Attached Files:

    • dr2.jpg
      dr2.jpg
      File size:
      68 KB
      Views:
      1,404
    1 person likes this.
  8. Tad
    Joined: Mar 2002
    Posts: 2,321
    Likes: 214, Points: 73, Legacy Rep: 2281
    Location: Flattop Islands

    Tad Boat Designer

    In most of the larger lofting projects I've done those diagonal origins would be outside the building....not too practical but nice art.

    I usually use intersections of the lofting grid to locate diagonals....keep it simple and compact.

    In the design shown "Dream", I would rather see a diagonal run more vertically (body plan view) between the two lower diagonals shown. This will be a fair line from the bottom vee surface up through the reverse tuck along the garboard aft.
     
  9. ancient kayaker
    Joined: Aug 2006
    Posts: 3,497
    Likes: 147, Points: 0, Legacy Rep: 2291
    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

    Unless there is a structural member in the plan eof a diagonal I don't see how it can be of much use for lofting or building, although I did come across this -

    "Diagonals informed the shipbuilders of how to arrange the huge wooden components of the ship's ribs on the assembly platforms prior to the connection of the components and subsequent raising of the ribs into place.".

    It has also been suggested they help for fairing purposes, clarity, improved precision, a guide to planking curves, as an aid to the designer, or any time the regular orthogonal views fall short of displaying the designer's intent. Hmm - that one covers a lot of ground!

    Here's my theory: perhaps they act an aid in visualising the underwater shape of the hull when heeled. Which begs the question, is the use of diagonals unique to sailboat design?
     
  10. Tad
    Joined: Mar 2002
    Posts: 2,321
    Likes: 214, Points: 73, Legacy Rep: 2281
    Location: Flattop Islands

    Tad Boat Designer

    Long ago before the internet....before personal computers even......Lines drawings were made by hand, with a pencil on a piece of paper.......It was tedious work making all intersections in the exact same place in all three views of the drawing......so some quick and useful aids were invented......DIAGONALS!.......

    You can run in a diagonal after laying out only a couple of sections, this greatly speeds the fairing process.....note how I used them in the powerboat below to fair the forebody into an almost monohedron planing surface aft.....Also note how the diagonal is run through the tumblehome aft where no other lines occur.....

    3005.jpg
     

  11. Tad
    Joined: Mar 2002
    Posts: 2,321
    Likes: 214, Points: 73, Legacy Rep: 2281
    Location: Flattop Islands

    Tad Boat Designer

    Below is a more usual use of diagonals in a sailing hull....note how the lowest one is used to fair the fillet to the stub keel....the next one up runs upwards through the reverse tuck into the rudder.....also note the highest diagonal ends at the widest point on the transom and fairs the tumblehome into the topsides all the way forward.....

    signebodyplan.jpg
     
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.