# GL Rules: Section modulus of floors

Discussion in 'Class Societies' started by Arvy, Nov 20, 2007.

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### ArvySenior Member

Hi all,

As we all are asking questions about the GL rules at the moment, I have one too. Well actually 2. The first can simply be answered with yes or no: Is there some kind of book which explains the usage of the class rules in a more comprehensive way?

Second more technical question about floors: The GL rules give 2 formula for calculating the section modulus for the floors (in case of sailing yachts) one for the floors where the balast keel is and one for the other floors. Now my question is: one calculates the minimal section modulus for the floor, is this section modulus the sectionmodulus in the center of the floor (as it decreases when going to the side of the boat).

Grtz,
Arvy

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### Dutch PeterSenior Member

Second: read the rules!!! Section 8.2.3 gives you the answer. "the required section modules should still be present at a quarter beam from the centerline in case of a sharp deadrise". So the section the section modulus you calculate is on the centerline of the vessel.

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### lyqqmxmJunior Member

dear Peter

calculate the modulus which is right at the centerline or a quarter beam from the centerline

thank you

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### ArvySenior Member

Peter,

I have a roundbilge design, so hardly a sharp deadrise. But to be safe, I just use the section modulus from the center to a quarter beam to be at least the minimum.

Grtz,
Arvy

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