# thickness calculation

Discussion in 'Metal Boat Building' started by naupigos_gr, Dec 10, 2011.

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### naupigos_grJunior Member

How I can calculate thickness (t) of my plates in case i know the maximum bending stress?

I also have a chart with components of a the midship section( girders, deck plating etc etc) with dimensions, levers, 1st and 2nd moments of area, for each component. But everything is bonded with "t".
My given maximum bending stress given is 160 MN/m2
160 x 10^6 N/m2.

thanks and best regards

John

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### Olavnaval architect

Maybe I got you wrong, but the bending stress you talk about (longitudinal strength) is just one of several areas of strength/scantling calculation that need to be performed. Think of loads normal to the plate surfaces due to static and dynamic (= slamming) water pressure, deck load etc.

I suggest you make yourself familiar with the scantling rules of a classification society (personally, I'm quite comfortable with Germanischer Lloyd, but any other class will do as well) which allow you to calculate plate thicknesses according to your inner structure (i.e. section spacing etc.), type and intended use of the vessel, material properties and so on.

To satisfy the longitudinal strength requirements those rules will demand a minimum main section modulus, so you have to check if your design meets this demand and increase plate thickness (usually of the uppermost deck) or use larger longitudinal stiffeners if necessary.

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