490
DOCK ENGINEERING.
The eccentricitv is- — -4-= x., which is accordingly known. Make
MO]
-su]
and
W
IJ= T
6 Wæ.
W 6Wæ4
Join J U, and IJUBis the pressure diagram.
Similarly at G we have
Length betweens Perpendiculars 500 fdet.
----Length over all 519 feet . -----
Tl
Boiler Boom
^-SUO] 121-
:ÏUO) 9.4
$Engine Boom ’—
Fig. 481. — Distribution of Weight, s.s. “ Umbria and “ Etruria.
line indicates to scale
a- =-=—, where 15 is the length G B;
W GW^
and
W 6Wæ6
being, of course,^ Joining H V, we
have the pressure diagram GHV B for these
particular conditions.
In this way, we have found a series of points,
DFHJLNQ. Joined together, they form a
curve which may be termed the curve of maximum
pressures, since any ordinate, E F, G H, IJ, &c.,
is a measure of the intensity of pressure at the
outermost keel-block, corresponding to an over-
hang from that point.
With the limited space at disposai, it is not
possible to enter into a discussion of the modifi-
cations caused in the above equations by a depar-
ture from any of the conditions upon which they
are based. It must be stated that such modifi-
cations will often entail values largely exceeding
those given, but as they, too, are founded upon a
series of hypotheses, no practical advantage would
accrue from the very complicated investigation of
their influence. The point to be really emphasised
is the absolute necessity for a large margin of
safety.
The diagram (fig. 481) shows, in the case of
the Cunard s.s. “Etruria” and her sister ship the
“Umbria,” the relative distribution of weight
throughout the length of each vessel. The dotted
the intensity of pressure upon the keel-blocks.