New software: Sailing Hull Design Method

[Mario]

SHDM software is based on unique method that is in process of taking out a patent. The result of this programm is a hull that has satisfied the following conditions:
For diferent heeling of the hull (up to maximal programm heel) the hull will have:
A) Symmetrical water lines (under water plan
B) The same shape of the water lines (under water plane)
C) The same displacement volume

SHDM runs inside AutoCAD. A Demo on demand.

[BrettM]

Wow a program that designs spheres and cylinders....

[Mario]

No, that program really generates the hull of sailing boat

[Andrew Mason]

C) The same displacement volume

You are joking aren't you?

[BrettM]

Does it work for those older "variable displacement" type boats too?

[Mario]

Gentlemen,
I like to joke, but I do not know what is the problem here. Maybe is my first short describing of my SHDM software is not very clearly, but it works and all statements I wrote are true.
Of course now I will not give the fully explanation of the SHDM's aparat , but I can give the demo that runs inside AutoCAD. By the way, I sent two pictures on BoatDesign->Gallery->Sailboats-Monohull: 8m sail-boat and SHDM-Hull design. Last slide is not verynice, but you can see the main. These slides are done by SHDM.
My web site is not finished yet in english, but when it will be done I will inform you.

Mario Kus, mechanical engineer
e-mail: mario.kus@sk.htnet.hr

[Andrew Mason]

Ignoring forces such as dynamic lift from the hull or sail downforces, all boats maintain a constant displacement volume as they heel, this is a function of their weight and Archimedes' principle.

I agree that your hull shape has symmetrical waterlines at the heel angle shown, but they will clearly not be symetrical at other heel angles other than zero.

[Mario]

Mr. Mason,

Thank You for Your lecturing about Archimedes' principle and forces in sailing.

I mentioned
C) The same displacement volume
because it is one of the input conditions for developing the programm aparat.
If I did not mention that condition in this article, I am sure somebody ask me about that.

The hull generated by SHDM software has symmetrical waterlines at heel angle from zero up to the maximal programm heel angle. A designer determines this maximal programm heel angle at the start of the programm and it depends on how a designer see the sailing condition.
For example, in the slide SHDM-Hull design on BoatDesign->Gallery->Sailboats-Monohull, that hull has generated with 20 degrees of the maximal programm heel angle.

Of course, there is not only one rotation of the hull. The hull has to be rotated about all axis (X, Y and Z) to content above mentioned condition:
C) The same displacement volume

I have to say there are more than this input data in prgramm, that shaped the hull.

[Mario]

Software Kus-SHDM can be downloaded at www.kus.hr

[CGN]

Mario can you do the same but in Rhino?, i wonder if you can make use of the nurbs capabilities of rhino

[Mario]

It is a very logical question. In my opinion it is not problem to do that in softwares those use NURBS surfaces. When I started programming I was focused on the main idea of my program and in that time AutoCAD seems to me as a good solution.
I am not sure for conversion AutoCAD's Spline in Rhino, but I did some kind of program for AutoCAD to make a text file of the Kus-SHDM's hull for MaxSurf' Prefit.
I repeat, the main target of Kus-SHDM program is an idea of making the hull of sailing boat.
As I know neither of the other marine softwares do not use that method until now.

[Andrew Mason]

Mario

Your method look interesting, can it handle hull shapes with fairly hard bilges or does it require a fairly low Midship Area Coefficient? Also, does it handle hulls with long overhangs which are designed to increase their waterline length substantially when heeled?

[gonzo]

A well behaved boat changes shape as it heels. The CE of the sails moves outward with increased angles of heel. A symetrical hull produces a lot of weather helm.

[Mario]

Reply to Andrew Mason

As I mentioned in my first post my method use a specific mathematic model that is in process of taking out the patent. At present I could say that my method not use, as You say hard bilges . My method considers there are two surfaces of the sailing hull, an active and passive one. An active surface of the hull is surface that is in contact with water at any heeling angle.
In a manner it could be said that active surface of the hull have a shape that is similar to a specific shape. But if You trial Kus-SHDM program You could see that you have a pretty different shapes of the hull depending about input data.

Low Midship Area Coefficient is not required directly although it is involved in modified form in mathematic apparatus.

Happy Easter, Mario

[Mario]

Reply to Gonzo
As I know there is that theory, but also there is a theory that say the waterline and its shape respectively influences on the form resistance, and it would be the best if that waterlines is symetrical ones.
Of course the heeled hull produces weather helm but it not depends about the symetrical hull. I think it cannot be spoken in generally.

Happy Easter, Mario