Ships/Boats?

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Ships/Boats?

stonysmith
Random question: does anyone here know the formula(s) to generate the hull of a ship or boat?

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Re: Ships/Boats?

Kevin Crowley
I just started looking at a few equations and my brain started overheating.  I'm going back to NACA airfoils.


On Thu, May 22, 2014 at 8:52 PM, Stony Smith <[hidden email]> wrote:
Random question: does anyone here know the formula(s) to generate the hull of a ship or boat?

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Re: Ships/Boats?

drxenocide
The shape of hulls are so complicated that they aren't protected by patent - they are protected by copyright. It is the opinion of the federal government of the united states that a hull is not "designed" or "invented." It is a work of art that is protected for over 100 years.


On Thu, May 22, 2014 at 11:40 PM, Kevin Crowley <[hidden email]> wrote:
I just started looking at a few equations and my brain started overheating.  I'm going back to NACA airfoils.


On Thu, May 22, 2014 at 8:52 PM, Stony Smith <[hidden email]> wrote:
Random question: does anyone here know the formula(s) to generate the hull of a ship or boat?

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Re: Ships/Boats?

Alan Cox
On Fri, 23 May 2014 08:48:21 -0400
Ari Diacou <[hidden email]> wrote:

> The shape of hulls are so complicated that they aren't protected by patent
> - they are protected by copyright.

A lot of good representations of them can be produced by a mathematical
formula however, which nicely dodges the issue 8) or many of the
traditional designs which are out of even the USA's rather extreme
copyright nuttiness.

The thing to model though isn't the shape of the hull, at least for a
smaller traditional wooden boat. Model the spars and the internal
structure, the shape of the planking derives from that - it really is a
use of the "hull()" operator.

Alan
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jsc
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Re: Ships/Boats?

jsc
Only if the exterior shape has no concave areas, though. It is a *convex* hull operator. So, for example, a pointy keel would not do what you would expect.
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Re: Ships/Boats?

nophead
Also planking on spars will give a smooth curve but the hull operator will give straight lines between spars and a discontinuity in gradient at the spar.


On 24 May 2014 05:20, jsc <[hidden email]> wrote:
Only if the exterior shape has no concave areas, though. It is a *convex*
hull operator. So, for example, a pointy keel would not do what you would
expect.



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View this message in context: http://forum.openscad.org/Ships-Boats-tp8107p8133.html
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Re: Ships/Boats?

Alan Cox
In reply to this post by jsc
On Fri, 23 May 2014 21:20:57 -0700 (PDT)
jsc <[hidden email]> wrote:

> Only if the exterior shape has no concave areas, though. It is a *convex*
> hull operator. So, for example, a pointy keel would not do what you would
> expect.

I didn't mean to imply it was literally equivalent to hull(), just a
'hull' operator.
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Re: Ships/Boats?

FeetFirst.Bike
In reply to this post by jsc
I'm very new to OpenSCAD and the forum. I have been watching this topic in the hope that it might shed some light for me. All I have got out of it is that boat hulls are not simple.

I have a trike


and want to make a velomobile shell over it, like this one.


I created a very basic outline of my trike in OpenSCAD


and added started playing with different shapes to add to the shell.


Apart from the pieces of ball (code below) I will need to use pieces of cylinders and probably a few other shapes.

//shell front top
translate ([-200,0,400])    // position
scale ([2,1,1])                // stretch x
rotate([0, 0, -90])           // rotate z
qtr_ball(380);                  // 380 outside radius



module qtr_ball(out_rad){
 difference(){
  half_ball(out_rad);

  translate([-out_rad-1,-out_rad-1,(-out_rad-1)*2])
  cube ([(out_rad+1)*2,(out_rad+1)*2,(out_rad+1)*2]);
 }
}

module half_ball(out_rad){
 difference(){
  ball(out_rad);

  translate([-out_rad-1,0,-out_rad-1])
  cube ([(out_rad+1)*2,out_rad+1,(out_rad+1)*2]);
 }
}

module ball(out_rad){
 difference(){
  sphere(out_rad, $fn=200);
  sphere(out_rad-5, $fn=50);
 }
}


Peter
FeetFirst.Bike