# What are bonjean and hydrostatic curves??

Discussion in 'Software' started by souravsandesh, Feb 12, 2015.

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### souravsandeshJunior Member

Hello,

I just want to know what exactly are "BONJEAN AND HYDROSTATIC CURVES" (definitions)......

and also what are they used for...I mean for suppose we have bonjean and hydrostatic curves with us..how to read them and what exactly can we CONCLUDE from them....(please explain me with examples..I mean with sample bonjean and hydrostatic curves)

please help me...I have an interview coming up....might as well get this as a question....please

regards

SANDESH

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### gonzoSenior Member

Bonjean curve: a curve formed by plotting transverse sectional areas measured up to each waterline against a vertical axis representing the waterline; thus the horizontal distance measured from the curve to the vertical axis gives the area of the section from the baseline to that particular waterline; usually sets of curves are obtained for each section; these curves facilitate immersed volume to be obtained for waterlines that are not parallel to baseline

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### NavalSArtichokeSenior Member

Well, I hope your upcoming interview is not for a position as a naval architect.

Bonjean curves are simply plots of the section areas versus draft for different stations in the hull of a vessel.

Hydrostatic curves are compilations in graphical form of various quantities of a vessel's hull. Like the Bonjean curves, these quantities are plotted versus the draft of the vessel. Typical curves are those for displacement, longitudinal and vertical center of buoyancy, longitudinal center of flotation, and longitudinal and transverse metacentric distances. Other quantities can be plotted, like the form coefficients (block, prismatic, and midship), or wetted surface area.

Most of this information is covered in basic texts on naval architecture.

If you are interviewing for a position as a mate on a vessel, there are texts which are available which explain how to use this information to safely manage and operate a vessel. What you are asking is much too broad to cover in the format of a message board like boatdesign.net.

Good Luck with your interview!

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### TANSLSenior Member

Let me explain some things so that there is no confusion and that souravsandesh has full information when asked:
The curve of areas described by Gonzo is one, among other, of Bonjean curves that can be drawn for each frame.
Bonjean values for each frame, no Bonjean curves, are used to calculate all parameters of the hull. Not only the submerged volume but also everything else, center of buoyancy, wet surface, area of the waterline ..... Not only when the water plane is not parallel to the baseline itself but also when it is parallel to the baseline.
These curves do not facilitate the calculations but make them possible. Without them, before the existence of programs that deal with 3D models, it was not possible to calculate the hydrostatic values.

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### gonzoSenior Member

To facilitate means to make possible. They are synonyms.

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### TANSLSenior Member

Facilitate and possible are not synonyms. You can not facilitate what is not possible.
But what can you tell us about everything else?

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### TANSLSenior Member

And what does it matter, Gonzo?
Explain the relationship Bonjean curves with hydrostatic curves, which is what souravsandesh is interested.

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### TANSLSenior Member

Because I was interested to see how you repeated your error.
What about Bonjean curves vs hydrostatics curves????

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### TANSLSenior Member

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### gonzoSenior Member

What about them? NavalSArtichoke explained it well.

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### TANSLSenior Member

What have you understood from NavalSArtichoke?.
I´ll ask you again : "Explain the relationship Bonjean curves with hydrostatic curves". What excuse are you going to wear now not to answer?

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### TANSLSenior Member

Not a very intelligent answer using my mistake for not answering. What excuse will you find now ?.
I´ll ask you again : "Explain the relationship Bonjean curves with hydrostatic curves".
(Sorry for any possible grammatical error, please explain if you are able to.)
If souravsandesh answer what you said in your post # 2, will be very difficult to get the job and would be very sad to lose his oportiunidad by talking a nonsense.
We should not say anything here without knowingly, because we can hurt those who ask us.
One thing is to make a mistake and quite another to say vague, meaningless, with appearance of technical reasoning.

Last edited: Feb 19, 2015

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### jehardimanSenior Member

Gonzo and Tansl... STOP IT...There are half a hundred ways to do anything. This is not getting anywhere.

FWIW, I like a complete set of Bonjeans...but that was what we did BPC. As I have always implied, a computer is no better or on worse than what was done before, but do not confuse precision for accuracy. With GHS and other programs I'm not sure how people interact with data to 0.xxxxx...but I view it with suspicion.

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