BULKHEADS

455

bottom plating &2. The brackets \ and &2 must extend one beam space
and one floor space adjacent to the bulkhead in order to get a rigid
connection and support.

The vertical stiffeners C above the watertight flat are ot lighter
section.

Fig 43 —Bulkhead.
Watertight connection round the margin of the bulkhead plating
is obtained by a boundary angle a which is riveted to the shell plating
and to the deck plating. The boundary angles are shown dotted in the
figure as they are on the reverse side of the plating, and at the upper
flat it will be noted that the boundary angle is fitted above and below
the deck plating. The edge of the bulkhead plating at the ship's side
fits in between the flanges of the frame and of the boundary angle
and these are riveted to the shell and to the deck plating although
sometimes only one angle may be fitted. The punching of these
rivet holes introduces a double row of perforations round the
whole girth of the ship thus introducing a source of weakness which
is not fully restored by filling the holes with rivets. The positions of the
transverse bulkheads in a ship fitted in this way may be located by
looking along her sides and observing where the double lines of rivets
appear.
The efficiency may, however, be regained by fitting broad liners
behind the frames connecting the bulkhead to the shell plating instead
of narrow ones the breadth of the frame flange only. These special