CELLULAE DOUBLE BOTTOM

441

the strake of shell plating on which it rests The tank side bracket is
really a continuation of the interrupted floor.

The supplementary figure shows in plan the further connection of
the bracket to the cellular double bottom. H is the flange at the top
edge of the bracket Gis a "gusset" plate with its edge riveted to the
flanged edge of the margin plate C, with six rivets along its centre
up to the point of the gusset thus connecting it to the horizontal flange
of the angle at H. See also page 598

Lightening holes K are cut in the floor plates to reduce the weight
of material and to allow a free flow of water as well as access for cleaning
purposes between the cells of the compartment. Small drainage holes
are shown at the corners of the floors and a larger one in the tank side
bracket. Water can also pass through a drainage hole at the lower
corner of the bracket. It is in this space, called the bilges, where
drainage water, due mostly to condensation of moisture on the sides
of the ship, collects. The suction pipes leading from the various
compartments to the pumps in the engine-room are usually laid in the
bilges. Portable planks are secured along the top of the bilge space
so that the interior is accessible for cleaning. Access to the C D B,,
however, is only possible through manholes on the top of the inner
bottom plating which, of course, are covered with a door capable of
being screwed up watertight.

Fig 22 —Solid and Bracket Floors.

Figure 22 shows several cells of a C*D B. C is the centre plate
girder with angles at its top and bottom edges riveted to the flat plate
keel K) and centre plate of inner bottom N.