DNV loadpoint for Watertight Bulkheads

Does anyyone know where the loadpoint should be taken for a WT bulkhead. Is it a third of the way up the bulkhead or half way....A little confused

 

I seem to recall that for plates you must consider a point located 1/3 of its height, and for the profiles, a point at one third of its height, measured in both cases from the lowest point of element.
In any case, is to determine the loading height from the deck or from tank vents, as appropriate.
Attached picture is from ISO 12215.

 

The load point is simply the distance from the top of the WTB (or damaged waterline; which ever is greater) to the structural member.

So if you have a horizontal stiffener, that is easy, it is from the top to that stiffener. If vertical then it is usually 1/3 rd distance from the bottom, as the head. Same as those pic's from Tansl above. But note, that is for the pressure calculation, NOT the span when calculating the required modulus.