# Calculation

Discussion in 'Stability' started by naupigos_gr, May 7, 2010.

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### naupigos_grJunior Member

Hello, I have a pre-design project for my university.
I have to calculate main dimensions and coefficients of an LNG tanker with capacity of 145.000 cu.m., and speed 20 knots.
I found a list of similar vessels but i got lack of parameters in many vessels, such as Displacement.
Without the parameter of Displacement i can not design a curve through Regression analysis.
I tried many different web sites, like vesseltracker..
Is there any practical way, to calculate Displacement?

thanks john b.

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### jehardimanSenior Member

Why not do it the old fashioned way....Lay out the cargo holds, add an engine room, and then draw a hull around it. If this is for a school design project, you should have been taught all the tools and concepts you need.

Come on, this is not a time to copy, this is a time to have fun with design and self expression because there is no "correct" answer. You only need to show that you understand the concepts of design trade-off.

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### naupigos_grJunior Member

yea, okay...
but working with 19 vessels or more it is hard to draw 19 different plans
thanks anyway...

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### JRMacGregorJunior Member

Typical block coefficient for that size of LNGC is 0.67 to 0.72. That works for speeds in range 18.5 to 20.5 knots.

With the CB and the main dimensions you can work out the displacements of your hulls.

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### hoytedowCarbon Based Life Form

Why don't you start with the size and number of holding tanks needed, then design the ship around that?

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### conceptiaNaval Architect

naupigos,

Please refer to Practical ship design by Watson.. It gives you empirical formulas to fix your main dimensions. Remember one thing, your final displacement will have a reasonable change with the priliminary, so be conservative on primary fixing of displacement. You can also refer PNA, and Ship design for efficiency and economy by Schneekluth.

All the best for your project.

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### ejimNot Really Junior Member

Your question is how to calculate displacement, right?
here the formula : L x B x T x Cb x (density of water)

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### Grant NelsonSenior Member

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### daiquiriEngineering and Design

\$1130 is the minimum registration fee on that site? Geeee!

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### conceptiaNaval Architect

nelson, ship register dont provide free trial as of now. I did try for that 2 months back, but they told cannot give a free trial.

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