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THE DESIGN OFFICE
A = 10 ft. 6 in.
B = length of boiler.
C = 2 ft.
D = length of boiler.
E = 10 ft. 6 in.
F =-. length of cross bunker.
G = mean diameter -f- i ft. 9 in.
H = mean radius + 2 ft.
J = overall length of boiler room.
K = 2 ft. 6 in.
A BCD E F
Fig. 4.—Specimen Page of Data-book (2)
Special circumstances will always call for special arrangements, but a
few normal figures, worked to approximately in every case, very considerably
lightens the designer's task, and avoids, as far as possible, chances of large
and serious errors. With a system of book-keeping highly elaborated, such
as this, the main features of an arrangement design could be sketched on
the back of an envelope, and the shipbuilder enabled to make his arrange-
ments accordingly. Even where such a complete record is kept, it is still
advisable to go very closely into new designs and check results. Nothing
should be left to chance. The designer should know almost instinctively
what clearances to test and what scantlings are suitable.
Leading Particulars of Job.—An important work of the design
office is the preparation of a fully detailed sectional drawing, showing the
important dimensions and scantlings necessary to obtain the certificates of
some of the classification societies, which are frequently necessary before
the installation can be insured. Typical examples of these are the midship
section of a ship, main steam-pipe installations, and marine boiler design.
In the two latter cases, however, the working out of these arrangements
and scantlings is left to the detail office, the demarcation of what shall be
done in each office being a matter of internal arrangement. The classifica-
tion societies generally considered are the Board of Trade, Lloyd's Registry,
the British Corporation, and the Bureau Veritas. In structural work on land,
the span of bays for overhead cranes, the distance between columns, the
scantlings of columns, crane rails, the size of foundations, the thickness of