Proafile v5.0 | Updated: Jul 28, 2010

Contributions Proas

FreeShip Walap

Posted by on 10/06 at 05:28 PM
A contribution from Aquiles Luna that solves the problem of modeling asymmetrical hulls in software that only thinks symmetrically. Thanks!

I've found a way to force the freeware boat design softwareFreeship 2.6 to do proas, it may interest proafile readers.

The problem is that such programs assume that the port and starboard sides are mirror images of each other, so you can build a catamaran or a trimaran, but not a proa. Then I remembered that proas *are* symmetrical, only the axis of symmetry is turned 90 degrees.

The trick is simple: begin with the default design, and set the measures to say, 6 meters WIDE and 0.5 meter LONG. the hull will look weird at first, but once you move the control points around, it becomes pretty normal. Since the waterline doesn't have to continuous, you can extrude the akas forward and put the ama where freeship expects the bow.

One unexpected benefit of this approach is that since features in the forward-aft axis are not expected to be mirror images, you can design an asymmetrical hull profile, like those used in micronesian proas.

The hydrostatics and hydrodinamics calculations are useless, since they'll be done in the wrong direction, but I suppose this is a small price to pay.

I'm donating to proafile a walap design, but this is only an example of the technique. I have no idea if the akas and ama proportions are reasonable, chances are it won't sail without modifications.

If some reader gets inspired by my ideas and wants to inspire me back, this is my dream boat: a 6 meter, hard chined, stich-and-glue korkor.
--Aquiles Luna

Download Freeship (.fbm file) model




Comments

  • I need to play with Freeship more it looks like fun!

    Does anyone know how to add extra “parts” like amas, leeboards and rudders?

    Posted by flsail  on  10/12  at  01:27 PM
  • basically, you mark an edge and extrude it. This
    works on the gunwale, but to have akas going
    through the hull’s walls, you have to cut
    a hole there first.

    To make a hole, the easiest way is to make a
    square, none of it’s sides can be on the top
    edge. Then you mark the square’s face only,
    and delete it. The edges of the hole are now
    “extrudable”.

    If your aka is going throuh both sides of the
    hull, it’s best to cut a hole on each side,
    extrude both outwards and only afterwards
    add faces in between.

    The rudder wizard has problems with proas,
    (or I have problems with the wizard), but
    the micronesian way simply uses a steering
    oar anyway.

    Posted by  on  10/16  at  03:18 AM
  • looks good ,do not let the rudder saga worry you use the paddle .on my proa we used the quarter rudder works fine as there is always a little pressure on it ,go build it

    Posted by  on  10/16  at  09:32 AM

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