ABS (bottom hull girder section modulus)

In ABS rules for vessel under 90 meter part 3 (construction),
Bottom Shell Plating subsection
ther is a term called (bottom hull girder section modulus) SMa what is that?
i know the hull girder section modulus, but what is meant by bottom?
is this mean the section modulus to the bottom?
the image shows the equation

 

SMa is the Actual section modulus of the Hull girder at the bottom level (Actual Moment of Intertia of the hull section about the neutral Axis / Distance of neutral axis from the bottom).

SMr is the Minimum Section modulus required as per Rule.

 

thanks PNACS you are a helpful man

 

hai pnacs, i need your help please.

How to calculate the actual Section modulus hull girder?what is the formula? is it same with the with the required section modulus formula?(i'm using ABS rule)..i have the SMr,but i dont know how to get the SMa..tq..please reply ASAP sir..TQ

 

jimianbu

If you know how to calculate the section modulus of a simple girder, then you should know how to calculate it for the hull girder. If you are using a simple computer program to calculate your modulus and are now stuck, then you need to do a basic course of structures. As a one line reply will not help you.

 

TQ Ad Hoc

I see. TQ senior member Ad Hoc. I'm reall sorry, I still new in this ship design yet i have to learn more at my campus. By the way, do u know any software that can calculate section modulus for a ship other than manual calculation?TQ.

 

jimianbu

If you are currently studying naval architecture, then I am sure you will very soon cover how to calculate modulus of any section, including a ships girder. Please do not start using software so early in your career. If you do you will not understand the theory and philosophy and how, when and where to use. Doing it by manual hand calculations first makes you understand and appreciate all the questions you currently have.

You will also find that doing a hull girder calculation by hand is actually very quick and easy, once you understand the structural theory.

Good luck, just be patient, you'll get there in the end...

 

TQ again.

That's a very good and brilliant advice sir. I will try my best to make it happen. by the way. can i get you contact info? i mean your emails,yahoo messenger,skype or anything that i can easily connect with u in the future. Are u working at japan sir?which company?sorry if i'm asking too much. i was just hoping to get to know each other better. TQ again sir.

 

jimianbu

Please feel free to contact me, should you need any further advise, just send me a private mail using this website

 

I see. TQ sir. right now i'm doing the scantling for deck cargo barge using ABS rule. there is still no structure drawings. just a plain GA. so, i still not sure how to start the scantling process.

 

Jimimianbu

Are you currently a student and this is project for your degree?..or are you working in a shipyard and studying part-time?

 

Yes. i'm still study. but my lesson for the ship structure is not coming yet. (next year). I'm working part time at a marine consultancy company...

 

I'm still study sir. but the lesson for ship structure is not coming yet.(next year). i'm working part time at a marine consultancy company.

 

OK, i understand now. So, first question, if you are in a consultancy, why not ask the person in charge, over seeing your work? I assume them to be a competent naval architect whom could advise as much as I can?

 

My superior went to Singapore for a couple of weeks, there's no one competent than him in the office. He only left me and his secretary. Haha. that's the story sir. I cannot afford to wait for him until he return...