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thesecondwind 04-20-2010 06:15 PM

Bezier Curve Chine
I am interested and starting a forum on "Bezier Curve Design". It is a new method of construction for home builders. This method enables homebuilder's to construct true round bottom sailboats from aluminum.

messabout 04-21-2010 07:34 PM

Is this something similar to Jim Browns constant camber method?

sorenfdk 04-22-2010 05:16 AM


Originally Posted by messabout (Post 359748)
Is this something similar to Jim Browns constant camber method?

Bezier-curves are not a way of constructing boats; it is a way of drawing curves.
They were invented a long time ago by a Monsieur Bezier who worked as a cardesigner at Citroën (IIRC - maybe it was Peugeot) in France.
This way of drawing curves has been used in ship- and boatbuilding for many years.

daiquiri 04-22-2010 05:46 AM

It is not clear to me if you have a knowledge to share on this boatbuilding method, or you're in search of info about it?
A very quick search in Google returned this:
It appears to be basically another name for radius chine technique.

thesecondwind 04-22-2010 04:52 PM

Bezier curve chine
In response to messabout - the Bezier curve method applies to metal hulls. Jim Brown's constant camber method is a wood cold molded method. Perhaps similar in theory, but not application.

In response to sorenfdk - I am familiar with the history of Bezier curves. It is why I named my new method the "Bezier Curve Method". I applied Bezier curves to my design which results in true round metal hulls. This process allows persons of average skills the ability to construct a true round hull as easily as a double chine metal hull.

In response to daiquiri - Perhaps my original post was confusing, I am introducing the "Bezier Curve" method as an alternative to the radius chine or constant radius chine. The purpose of the post is to find out what builders and designers think about it.

I am familiar with the article you refer to, I wrote it. The Bezier curve method however, is not a radius chine technique at all.

I appreciate your replies and look forward to more feed back. Further information is available at

Dennis Schaffer

sorenfdk 04-22-2010 07:31 PM


Originally Posted by thesecondwind (Post 360011)
Perhaps my original post was confusing

No - it just wasn't very clear! Now I know what you are referring to, and it looks interesting.

Paul No Boat 04-22-2010 08:37 PM

I have just mastered bezier curves in photoshop and it's a fun way of designing ANYTHING but is maddening to get the hang of.

are bezier curves what we called "French curves" in the pre-digital age?
or "transitional curves" in highway and railroad where the radius starts out wide and tightens as you get farther into the curve?

liki 04-23-2010 01:11 AM

Start reading here:

conceptia 04-23-2010 04:42 AM

I just rewinded back to college notes of CAD. Wen we start learning the application of what we have studied then it is very interesting. I'm lovin' it.

LyndonJ 04-23-2010 08:00 AM

Looking at the site, it's intereresting.

Really it's a variable radius chine where the section shape orf the radius is curved by numerous bends. Nothing to do with Bezier curves at all, that bit is just creative marketing isn't it.

Effectively lots of mini-chines or flat panels created by straight line bending.

A few things spring to mind

Hard to do on thicker plate
Bending fractures alloy on a micro scale

Do the planes line up through into the next section? If not there will be a mess at the join

And particulalry since this would be applicable to thinner plate wouldn't it be easy and faster to roll the shape anyway rather than putting 30 accurate creases in each section of the radius chine ?

Joe Petrich 04-23-2010 10:29 AM

At first I was sceptical but after looking at the site the method looks reasonable.

The design process seems to indicate one particular software package was used. It would be good if this could be written to be compatible with other software.

I imagine there might be a bit of trial and error on braking the plates unless you have a method to mark the brake lines on the parts to be cut. Perhaps that is part of your method.

Paul No Boat 04-23-2010 10:40 AM

I use photoshop and a little bit of Illustrator to do some graphic design. Is any of that able to be imported into CAD? I would love to learn some autocad but just have not gotten around to it.

rugludallur 04-23-2010 12:40 PM

How about modern radius chine instead?
Unfortunately there don't seem to be many books written about metal boat building since CNC and CAD with splines/b-lines became commonplace.

Today you can buy a true round bottom boat kit for a very reasonable amount of money, the nice thing is that sections can be up to 2x6m which means there will be minimal welding and distortion.

On the other hand radius chine boat building has gotten simpler, kits can be delivered with radius plates pre-cut or at least the rolled plates can have the cuts painted on so all you need to do is cut out the sections.

In addition to this it's easier than ever to design boats with tilted radius sections where you can use the same radius rolled plates but tilt them slightly inwards towards the stern for a better form.

The biggest problem I see is that builders usually don't have presses or rollers and therefore are stuck with either ordering kits or sections rolled to a single radius.

This method does make it possible to buy a small press and form the sections yourself but the downside is that the sections are so small that the amount of welding is probably 3 times what it is for radius chine construction.

For anyone wanting to play with 3D design with splines I highly recommend downloading a trial of Rhino 3D.


dskira 04-25-2010 06:37 PM

Bezier curve
This is what Wikipedia has to say.


Bézier curve
From Wikipedia, the free encyclopedia

Cubic Bézier curveIn the mathematical field of numerical analysis, a Bézier curve is a parametric curve important in computer graphics and related fields. Generalizations of Bézier curves to higher dimensions are called Bézier surfaces, of which the Bézier triangle is a special case.

Bézier curves were widely publicized in 1962 by the French engineer Pierre Bézier, who used them to design automobile bodies. The curves were first developed in 1959 by Paul de Casteljau using de Casteljau's algorithm, a numerically stable method to evaluate Bézier curves.

In vector graphics, Bézier curves are an important tool used to model smooth curves that can be scaled indefinitely. "Paths," as they are commonly referred to in image manipulation programs[note 1] are combinations of linked Bézier curves. Paths are not bound by the limits of rasterized images and are intuitive to modify. Bézier curves are also used in animation as a tool to control motion.[

Bézier curves are also commonly used over the time domain, particularly in animation and interface design. Thus, a Bézier curve is often used to describe or control the velocity over time of an object moving from A to B. For example, an icon might "ease-in-out" or follow a "cubic Bézier" in moving from A to B, rather than simply moving at a fixed number of pixels per step. Indeed, when animators or interface designers discuss the "physics" or "feel" of an operation, they often are referring to the particular Bézier curve used to control the velocity over time of the move in

dskira 04-25-2010 06:43 PM

This is the animation

Can sombedy explain me why it make construction easy.
I don't see any relation between the two.


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