Hydrostatics & Calculations

[Shidoran]

Hi everyone,

I'm interested in learning the basics for hydrostatics (the stuff all the computers do these days) including basic theoretical calculations.

One of my first questions would be how to calculate the displacement of a vessel when you arent given the weight. There probably is a simple formula, but I don't know much.

If specifically, for an inclining experiment, you are given the draft, the density of water, the inclining weight, angle of inclination, LCG of weight and VCG of weight, how would you go about calculating the GM? I understand that to do so, you would need a formula along the lines of:

weight moved x distance moved / displacement x (tan of heel angle)

The first step would be to calculate the displacement, then it seems the rest of the formula values are given, so it becomes straightforward.

Also, can somebody walk me through manually calculating GZ's from a KN table and plotting a GZ curve for a particular loading condition?

Appreciate any help and input given. Just a side note, I'm not particularly looking for answers like "go and read this book" as people are usually more specific and easier to understand when they explain it. Not that I'm not reading any books though. I'm trying to :)

Kind Regards

[jmertens]

[quote:6d94194e87="Shidoran"]
Just a side note, I'm not particularly looking for answers like "go and read this book" as people are usually more specific and easier to understand when they explain it. Not that I'm not reading any books though. I'm trying to :)

Kind Regards[/quote:6d94194e87]

If I understand well, you expect one of us to explain in a brief message what takes 100 pages and 50 formulas in a book?
:wink:

I can't but let's see if somebody else volunteers.

OK, I'll give you a tip.
For displacement calculations, do a Google search with the words "Simpson rule".

[quote:6d94194e87]
Simpson's rule is a Newton-Cotes formula for approximating the integral of a function f using quadratic polynomials (i.e., parabolic arcs instead of the straight line segments used in the trapezoidal rule). Simpson's rule can be derived by integrating a third-order Lagrange interpolating polynomial fit to the function at three equally spaced points. In particular, let the function f be tabulated at points x_0, x_1, and x_2 equally spaced by distance h, and denote f_n==f(x_n). Then Simpson's rule states that
int_(x_0)^(x_2)f(x)dx = int_(x_0)^(x_0+2h)f(x)dx (1)
approx 1/3h(f_0+4f_1+f_2).[/quote:6d94194e87]

I did it and found what's above . . . I know some books about yacht design that explain it better.

[jericarla]

Simpson's rule is a Newton-Cotes formula for approximating the integral of a function f using quadratic polynomials (i.e., parabolic arcs instead of the straight line segments used in the trapezoidal rule). Simpson's rule can be derived by integrating a third-order Lagrange interpolating polynomial fit to the function at three equally spaced points. In particular, let the function f be tabulated at points x_0, x_1, and x_2 equally spaced by distance h, and denote f_n==f(x_n). Then Simpson's rule states that
int_(x_0)^(x_2)f(x)dx = int_(x_0)^(x_0+2h)f(x)dx (1)
approx 1/3h(f_0+4f_1+f_2).[/quote:6d94194e87]

i bet you cant say that in english