456 NICEOLLS'S SEAMANSHIP AND NAUTICAL KNOWLEDGE

liners fit hard against the inner sight edges and level up the space between
the outer strake of shell plating and the fore-and-aft flanges of the frame
and boundary angles as indicated in Figure 44 where A represents an
outer strake, B the bulkhead liner, C the frame bar, D the boundary
angle, E and E the double row of rivets, and F the bulkhead plating.

d

*B

Fig. 44.
Watertight Longitudinal Bulkheads are made equal in strength
and have stifieners equal to those fitted to transverse bulkheads of the
same depth. Midship longitudinal bulkheads when fitted in lieu of
hold pillars, as in Caledonian Monarch, are stopped at the ends of
hatchways.
A Deep Tank to take water or cargo is fitted in many ships abaft
the engine space, and when a second one is fitted it is usually placed
just forward of the boiler space, as this arrangement puts the ship down
in the water on nearly an even keel. Deep fore peak and after peak
tanks for water ballast serve as trimming tanks in addition to increasing
the displacement of the ship when filled.
The construction of a deep tank consists simply of placing a watertight
transverse bulkhead at each end of the compartment, but the locality
must be increased in strength to withstand the internal pressure of
water. The transverse bulkhead in addition to the vertical stiffeners
is further strengthened by horizontal stifieners the ends of which
are bracketed to stringers.
A centre line division, not watertight, is fitted to take the place of
midship pillars and to act as a wash plate. It is connected to the deck
and to the double bottom by double angles and strengthened by closely
spaced vertical stiffeners -bracketed at top and bottom to beams and
floors respectively. Wash plates are also fitted in peak tanks.
Deck beams are fitted at every frame in the way of deep tanks,
the beam knees and side frames being made larger than elsewhere*