# Simpson's formula

Discussion in 'Boat Design' started by Coen, Mar 3, 2005.

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### CoenJunior Member

Hi y'all

As I wrote before, we are designing an offshore support vessel. We thought we finished drawing the lines plan, but according to rhino there is quite a big difference between our calculated immersed volume and the immersed volume calculated by rhino. The frame surfaces are equal, which makes me think that we are doing something wrong in our calculation. I will give you the facts:

Lpp = 59,4 m

We have 12 ordinates, spaced 9 frames between. As the frame distance is 600 mm this leads to 5400 mm between the ordinates. The ordinate surfaces are as like this:

Ordinate Surface

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### DaveBSenior Member

might be a good idea to post the 3dm file and spreadsheet.... have you checked the direction of your surface normals? Is it a closed surface?

I'd be happy to use rhinomarine (phaser) to get a displacement if you send me the file...

Cheers,

Dave
(fireball682@hotmail.com)

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### yipsterdesigner

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### PalmerJunior Member

Simpson's requires an odd number of ordinates. IF you don't want to redefine them you could use the Trapezoidal rule instead. It's not quite as accurate as Simpsons but should be within a couple percent.

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The metric system is really easy!
-I still use my fingers

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### CoenJunior Member

Hey guys,

I'm am sorry to say, my thread was a mistake. While I was writing it I decided to go to the teacher and ask him

Accidently I probably pushed 'submit'. Thank you very much for your replies anyway.

When I have an answer I will let you know!

Tnx again,

Coen Meerbach

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### terhohalmeBEng Boat Technology

In Rhino, Phaser, check: Help-> Plug-ins-> Protheus Hydrostatics and Stability Plug-ins-> Checklist. It's all there. In the beginning I made many mistakes, which solved by these notes.

Terho

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