For uniform application of these regulations, the depth
of penetration b should be determined using the following
guidelines:
The mean transverse distance b shall be measured
between the shell at the deepest subdivision load line and a vertical
plane tangent to, or common with, all or a part of the longitudinal
bulkhead but elsewhere outside thereof, and oriented so that this
mean transverse distance to the shell is a maximum, except that in
no case shall the maximum distance between this plane and the shell
exceed twice the least distance between the plane and the shell. When
the longitudinal bulkhead terminates below the deepest subdivision
load line, the vertical plane referred to above is assumed to extend
upwards to the deepest subdivision load line.
Figures A-7 and A-8 illustrate the application
of this definition:
Figure A-7 Damage penetration showing mean transverse distance
Figure A-8 Damage penetration showing mean transverse distance
A damage zone containing abrupt changes of breadth may also
be dealt with by subdividing into smaller zones, each having constant b-values.