CHAPTER XVII.

SHIP CONSTRUCTION.

A Ship is a Girder—A ship considered as a structural unit is a
girder, a box or beam girder, composed of many small girders braced,
supported and tied together so that the strength of the ship as a whole
is dependent upon the effectiveness of all her members, and she is no
stronger than her weakest component although some parts are more
vital to the floating structure than others. The science of shipbuilding
is directed to the designing and assembling of the several parts of the
vessel in a practical and economical manner so that the ship may
conform to the regulations laid down by the registration societies and
yet be as light in weight as possible consistent with strength, rigidity
and seaworthiness

Fig. 1.—A Girder.

Longitudinal Stresses.-—Figure 1 represents a narrow steel plate
standing on its edge, the ends resting on supports A and B. It is a
simple girder* If a heavy load C be suspended from its middle point,

Fig. 1

a

(Figure 2), the edges of the plate will be subjected to stresses, compression
on ite upper edge and tension on its lower edge, with a line of unchanged
strength or neutral axis, DE, between. Should the load be excessive tue
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