# Motion sickness index

Discussion in 'Hydrodynamics and Aerodynamics' started by thanhtt2015, May 2, 2015.

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### thanhtt2015Junior Member

Hi every one!
First of all I would like to say hello to all of you.
I am looking for the topic "Estimate the motion sickness index (MSI) at the preliminary design stage", there are a lot of difficulties that I have to solve. Anyone can help me? I want to ask you that how to calculate MSI and how to apply this index for a real ship.
Looking forward to hearing any suggestions from you.

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### IkeSenior Member

do a search on The prediction of the Motion Sickness Incidence index. It is apdf file. I couldn't copy the link for it (don't know why) but a search brought it up easily.

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Welcome to the forum.

What difficulties are they?

The MSI is just a measure, a set of criteria, either the vessel's motion in a sea way is sea-kindly or it is not.

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### DCockeySenior Member

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### thanhtt2015Junior Member

Thank Ike, Ad Hoc and DCockey very much.
DCockey, I got this document; however, the problem is how to calculate the formular (1). As you can be seen from this formular, MSI can be determined if we know the error function (erf). What is the error function? I don't know, anyone can help me.

The other question is that what is the motion sickness dose value ?
In the formular (3), (4), (5) MSI can be calculated from MSDV.
And MSI can be also calculated by (7) if SMSI(we) can be determined. I have no idea for that.

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### DCockeySenior Member

Error Function, abbreviated "erf", is a mathematical function used in statistics and engineering. http://en.wikipedia.org/wiki/Error_function The Wikipedia article contains a number of approximations which can be used for calculations. Also many advanced math software libraries and packages include routines for calculating Error Function.

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Do you have RAO tank test data for your subject vessel?

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### thanhtt2015Junior Member

I have tried to find RAO without the test data from towing tank; however, there is no possible result till now.
I can show you my way in this research: from vertical acceleration, I can find MSI to know that how many percentage of people who get sea sickness. Then, in comparison with the ISO standard I can know the ship's dimensions are optimization or not.

Can you help me to have RAO without tank test data?

Looking forward to hearing from you!

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If you do not have tank test data, then the only other way is using strip theory. You can calculate it manually...very complex and time consuming..or, you can use dedicated seakeeping/motion software. If you use software, almost all of them are very limited and not comprehensive, not very accurate either. Since they also still need to be validated against tank test results too.

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### thanhtt2015Junior Member

I would like to ask you that can you help me to explain the formular (6) and (7) in the document "The prediction of the Motion Sickness Incidence index at the initial design stage".

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### thanhtt2015Junior Member

Ad Hoc, I know how difficult it is if I have no tank testing data. Now I am reading the Strip theory in order to find RAO to calculate the ship's spectrum. However, it is likely to be hard to understand these complicated formulars and fuctions. So can you have any suggestions for me, please?
I have to try my best to finish my case study before deadline. Oh my God, how hard to finish it, so disappointed.
Anyway, thank you so much, my dear

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It would help if you explain what is your case study and its objective.

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### thanhtt2015Junior Member

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### Leo LazauskasSenior Member

Or just type, for example, erf(1.2345) into your search window.

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### thanhtt2015Junior Member

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