Hydrodynamical derivatives

Hi,

I’m doing my thesis about dynamical positioning of a small ship. Is there any database for hydrodynamical derivatives avaliable for displasment ships up to 10-20m lenght ? Is there a way to approximate them based on ship dimensiones and mass without programms (2D-3D strip theory) ?

Thank you. https://nox.tips/

As a hint, if you are going to be involved in programming; always check your spelling.
3 errors in your post although one of them may be kolloquial.
Smiley face emoji!

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I suggest visiting the Hydrodynamics and Aerodynamics Forum on Boatdesign.net:

https://www.boatdesign.net/forums/hydrodynamics-aerodynamics/

Some very senior researchers and professionals hang out there. They are not particularly kind to students who try to get their homework done without effort or who ask overly broad questions. So I would suggest first searching the forum for relevant posts (there’s a lot of stuff there) and then spending time to frame my question very carefully. Good luck.

Cheers,

Earl

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http://catb.org/~esr/faqs/smart-questions.html

Introduction

In the world of hackers, the kind of answers you get to your technical questions depends as much on the way you ask the questions as on the difficulty of developing the answer. This guide will teach you how to ask questions in a way more likely to get you a satisfactory answer.

Now that use of open source has become widespread, you can often get as good answers from other, more experienced users as from hackers. This is a Good Thing; users tend to be just a little bit more tolerant of the kind of failures newbies often have. Still, treating experienced users like hackers in the ways we recommend here will generally be the most effective way to get useful answers out of them, too.

The first thing to understand is that hackers actually like hard problems and good, thought-provoking questions about them. If we didn’t, we wouldn’t be here. If you give us an interesting question to chew on we’ll be grateful to you; good questions are a stimulus and a gift. Good questions help us develop our understanding, and often reveal problems we might not have noticed or thought about otherwise. Among hackers, “Good question!” is a strong and sincere compliment.

Despite this, hackers have a reputation for meeting simple questions with what looks like hostility or arrogance. It sometimes looks like we’re reflexively rude to newbies and the ignorant. But this isn’t really true.

What we are, unapologetically, is hostile to people who seem to be unwilling to think or to do their own homework before asking questions. People like that are time sinks — they take without giving back, and they waste time we could have spent on another question more interesting and another person more worthy of an answer. We call people like this “losers” (and for historical reasons we sometimes spell it “lusers”).

We realize that there are many people who just want to use the software we write, and who have no interest in learning technical details. For most people, a computer is merely a tool, a means to an end; they have more important things to do and lives to live. We acknowledge that, and don’t expect everyone to take an interest in the technical matters that fascinate us. Nevertheless, our style of answering questions is tuned for people who do take such an interest and are willing to be active participants in problem-solving. That’s not going to change. Nor should it; if it did, we would become less effective at the things we do best.

We’re (largely) volunteers. We take time out of busy lives to answer questions, and at times we’re overwhelmed with them. So we filter ruthlessly. In particular, we throw away questions from people who appear to be losers in order to spend our question-answering time more efficiently, on winners.

If you find this attitude obnoxious, condescending, or arrogant, check your assumptions. We’re not asking you to genuflect to us — in fact, most of us would love nothing more than to deal with you as an equal and welcome you into our culture, if you put in the effort required to make that possible. But it’s simply not efficient for us to try to help people who are not willing to help themselves. It’s OK to be ignorant; it’s not OK to play stupid.

So, while it isn’t necessary to already be technically competent to get attention from us, it is necessary to demonstrate the kind of attitude that leads to competence — alert, thoughtful, observant, willing to be an active partner in developing a solution. If you can’t live with this sort of discrimination, we suggest you pay somebody for a commercial support contract instead of asking hackers to personally donate help to you.

If you decide to come to us for help, you don’t want to be one of the losers. You don’t want to seem like one, either. The best way to get a rapid and responsive answer is to ask it like a person with smarts, confidence, and clues who just happens to need help on one particular problem.


Before You Ask

When You Ask

Choose your forum carefully

Stack Overflow

Web and IRC forums

As a second step, use project mailing lists

Use meaningful, specific subject headers

Make it easy to reply

Write in clear, grammatical, correctly-spelled language

Send questions in accessible, standard formats

Be precise and informative about your problem

Volume is not precision

Don’t rush to claim that you have found a bug

Grovelling is not a substitute for doing your homework

Describe the problem’s symptoms, not your guesses

Describe your problem’s symptoms in chronological order

Describe the goal, not the step

Don’t ask people to reply by private e-mail

Be explicit about your question

When asking about code

Don’t post homework questions

Prune pointless queries

Don’t flag your question as “Urgent”, even if it is for you

Courtesy never hurts, and sometimes helps

Follow up with a brief note on the solution

How To Interpret Answers

RTFM and STFW: How To Tell You’ve Seriously Screwed Up

If you don’t understand…

Dealing with rudeness

On Not Reacting Like A Loser

Questions Not To Ask

Good and Bad Questions

If You Can’t Get An Answer

How To Answer Questions in a Helpful Way

Related Resources

Acknowledgements

And of course;
Being a smart person; would you click on any of these links?
Even though, they seem to fulfill your every hope.
And. to be fair…

The hours of tow tank time (and dollars associated therewith) necessary for the development of the stability derivatives generally cause the people who do pay for the tests to guard that data quite secretively to prevent others from using it as a reasonable approximation for similar vessels (much like you are trying to do, albeit for academic pursuits).