# ISO 12215-5 - Scantlings calculation

Discussion in 'Class Societies' started by ToMeK, Jan 9, 2017.

1. Joined: Nov 2006
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### ToMeKYoung naval architect

Hello everyone,

I am newbie naval architect new in composite boat structure design.

I am using Hullscant software to determine boat scantlings, but I am not sure I understand everything well. I have read all the rules and I understand formulas, but what I would like to learn more is

HOW TO DEFINE STRUCTURE TO GET BETTER RESULTS. WHICH STRUCTURE PROPERTY SHOULD BE MODIFIED TO MAKE STRUCTURE CAPABLE OF WITHSTANDING LOADS - something like panel and beam analysis guidelines (i.e. if shear factor is not passing, what should be modified)

I would be very thankfull if someone could suggest some literature or write few words on this topic.

Thank you very much,

Best,

Tomislav

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### TANSLSenior Member

If you have been able to read ISO 12215-5 to the end and have understood the formulas, let me show you my admiration because few technicians have been able to do that feat. If you continue on that path I have no doubt that you will become a good calculator of scantlings.
ISO 12215-5 is very difficult to read and almost impossible to understand because it gives no explanations of what it does or why it does. In many occasions you must have great experience in calculating scantlings to know, more or less, what you are doing and, therefore, know how to give the appropriate solution when there is a problem.
On the other hand, ISO 12215-5 has large gaps or inconsistencies. For example :
• there are no floors for ISO or, at least, does not specifically say how to calculate them.
• If you have a tank bulkhead, in a 0.8 m depth boat, you must apply a loading height of at least 2 m, which is totally absurd.
• the minimum thickness of the deck required by the standard is ridiculously small in small boats.
• the ideal structure depends on many things but you always have to calculate the scantlings of a boat thinking on the shipyard that will build it, in the human and material means that it possesses and in the customs of that shipyard. You can try to get the structure of minimum weight, structure of lower cost of materials or structure with lower cost of labor. Each of these criteria will lead to a structure with different elements, distributed in different ways and with different laminates schedule.
• When something does not comply, there are several solutions: changing the composition of the laminates or changing the spacing between reinforcements are the most common. For example, the same layers, otherwise distributed, can solve a problem.
If you need to consult anything else, out of the public domain, I will be happy to assist you in my email address.
Good luck with your work and encouragement.

Last edited: Jan 14, 2017
3. Joined: Nov 2006
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Location: Zagreb, Croatia, Europe

### ToMeKYoung naval architect

Today, after few weeks dealing with rules extensively I can completely agree with you. Although at first glance rules looked quite logical and understandable (at leaste pressures and coefficients part), now I can observe many disadvantages.

And of course, I have a new question I will send you e-mail as you suggested.

Many thanks once more.

Best,

Tomislav

4. Joined: Sep 2011
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### TANSLSenior Member

Hi Tomislav, I have sent you information via email. Have you got it?

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