HELP with ISO scantling

[fede]

Hi guys, I need a clarification on a couple of dimensions regarding the ISO standard.
I’m working on the scantlings of a 9 mt (30 ft) powerboat.
When talking of bulkheads (watertight) or transverse stiffners taking place of non watertight structural bulkheads, what are exactly the “l” and “s” dimensions?
“l” is also reffered to as “lu” unsupported lenght of stiffner.
The sections I’m referring to are 9.1.1 and 9.1.2 and 7.2.1 and 7.2.2 (section 9 deals with modulus and second moment of area,section 7.2 describes stiffners dimensions) .
Attached a jpeg with a sketch of the hull and bulkheads of the boat I’m working on,longitudinal stiffners included in the upper section,please if possible sketch “l” and “s” dimensions regarding the Bulkhead on my drawing to make it idiot proof.
Please help since I’m stuck!

[Cian Groves]

Hi Fede,
In the preliminary copy of the ISO standards you can find definition of 's', 'l' & 'lu' in section 7 figures 10 & 13. Basically 's' being spacing between frames, 'l' being largest unsupported length of panel & 'lu' being length of frame.

Hope that helps,
Cian

[fede]

Hi Cian,thanks a lot, "s" is clear,l is clear, Lu is not so clear,with lenght of bulkhead what measure do I have to take? the height of the bulkhead keel to centre of deck? if you could sketch it on my jpeg (paint would be more than enough!) it will be great!
Thanks again!

[fede]

Ok..."s" and "l" was clear, since I met the 2 formulas for minimum section modulus and minimum required second moment of inertia...a "b" measurment now appears.
My bulkhead will be made of sandwich, so I will have to check against these two formulas,in the case of a bulkhead, what are "l" and "b" ????
Height and beam (not necessarily in this order...) ????
In this case the panel under consideration is the bulkhead itself?

[Cian Groves]

Hi Fede,
In regards to 'l' & 'b' for your bulkhead they will be used to calculated the plating thickness, have a look at Figure 9 & 10a. 'l' being the large dimension of panel between 2 closet stiffeners & 'b' being short dimension of panel between 2 closet stiffeners. In regards to 's' & 'lu' for your bulkhead they will be used to calculated the stiffeners size.

Hope this helps.
Cian