IMPROVEMENTS IN THE MODE OF APPLYING WATER-BALLAST TANKS TO SCREW STEAMERS
Year: 1881

page_text: LETTERS PATENT to Charles John Denham Christie, of Neptune Works, near
Newcastle-upon-Tyne, in the County of Northumberland, for an Invention
of "IMPROVEMENTS IN THE MODE OF APPLYING WATER-BALLAST TANKS TO
SCREW STEAMERS."
PROVISIONAL SPECIFICATION left by the said Charles John Denham
Christie at the Office of the Commissioners of Patents on the 3rd. August
1881.
CHARLES JOHN DENHAM CHRISTIE, of Neptune Works, near Newcastle upon
Tyne, in the County of Northumberland. "IMPROVEMENTS IN THE MODE OF
APPLYING WATER-BALLAST TANKS TO SCREW STEAMERS."
This Invention has for its object the applying of water-ballast tanks to screw
steamers in an improved manner, which whilst convenient and economical in con-
struction will increase the stability of deep ships by allowing cargo to be placed at
the lowest possible level in all the holds, a disposition which is not attainable with
some existing arrangements of water-ballast tanks.
In carrying out the Invention according to one modification a water-ballast tank
is constructed in the machinery compartment of the steamer as a double bottom in
the usual way.
From the machinery compartment to the stern a tank is con-
structed under the tunnel of the screw shaft, such tank being for the whole or
greater portion of its length made with vertical sides extending down to the skin
of the steamer, either in or near the same vertical planes as the sides of the tunnel.
At the part near the stern where the hull becomes narrow at the level of the tank,
the vertical sides of the tank may be made to merge into the sides of the hull, the
top being shaped to correspond.
In some cases water-ballast tanks in the fore and after peaks of the steamer
may be used in combination with those herein before described. A tank or tanks
may be fitted in the coal bunker or bunkers instead of or in addition to that in
the machinery compartment, and additional water-ballast tanks may, if desired,
be fitted in other parts of the steamer, but in certain cases, when the improved
combination of tanks herein before described is adopted, other tanks in the several
holds can be dispensed with.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles John Denham Christie in the Great Seal Patent Office on the
30th January 1882.
CHARLES JOHN DENHAM CHRISTIE, of Neptune Works, near Newcastle upon
Tyne, in the County of Northumberland. "IMPROVEMENTS IN THE MODE OF
APPLYING WATER-BALLAST TANKS TO SCREW-STEAMERS."
My said Invention has for its object the applying of water-ballast tanks to screw
steamers in an improved manner, which whilst convenient and economical in con-
struction will increase the stability of deep ships by allowing cargo to be placed at
the lowest possible level in all the holds, a disposition which is not attainable with
some existing arrangements of water-ballast tanks.
My Invention consists principally in constructing a tank, in the manner herein-
after described, under the tunnel of the screw shaft and extending from the
machinery compartment to the stern, such tank being for the whole or greater
portion of its length made with vertical sides extending down to the skin of the
steamer, either in or near the same vertical planes as the sides of the tunnel. At
the part near the stern where the hull becomes narrow at the level of the tank
the vertical sides of the tank may be made to merge into the sides of the hull, the
top being shaped to correspond.
And in order that my said Invention and the manner of performing the same
may be properly understood, I hereunto append a Sheet of explanatory Drawings
to be hereinafter referred to, and representing a portion of the hull of a screw
steamer as constructed with my improved water-ballast tank.
Figure 1, on the accompanying Sheet of Drawings, is a longitudinal vertical
section showing a portion of the lower part of the hull between the machinery
compartment and the stern; Figure 2 is a transverse vertical section as taken near
the stern; and Figure 3 is a transverse vertical section as taken near the machinery
compartment. In these Figures the same reference numerals are used to mark the
same or like parts wherever they are repeated.
"
In practically carrying out my Invention according to one modification a water-
ballast tank is constructed in the machinery compartment of the steamer as a
double bottom in the usual way. My improved water-ballast tank 4, 5, extends
-from-the-machinery-compartment-to-the-stern,-and-occupies._the_space_under_the_
tunnel 6 of the screw shaft, this tunnel being in fact built upon the tank., The
larger portion 4 of the tank forming the end of it near the machinery compart-
ment is of a rectangular form in cross section, being made with vertical side plates
which project down between the "floors or floor frames 7 to the bottom skin 8 of
the hull, and are attached to the frames and skin by means of angle iron.. Flat top
plates 9 are attached by means of angle iron to the vertical side plates, and also to
a central vertical longitudinal plate or kelson 10, the bottom of which rests on and
is attached to the floor frames 7. At suitable intervals the tank is strengthened
by internal cross plates 11 having openings through them and attached by means
of angle iron to the side and top plates and to the kelson or middle plate 10, the
structure forming a box kelson and contributing to the strength of that part of the
vessel. At the part of the hull where the internal space at the level of the tank
begins to beconie narrow, the vertical sides of the forward part 4 of the tank are
made to merge into the skin of the hull, and from that point to the stern the after
part 5 of the tank is shaped, as shown in the left-hand part of Figure 1, and in
Figure 2, the flat top plates 9 being connected to the skin plates of the hull by
more or less inclined plates 13.
In some cases water-ballast tanks in the fore and after peaks of the steamer
may be used in combination with those herein before described. A tank or tanks

page_text: may be fitted in the coal bunker or bunkers instead of or in addition to that in
the machinery compartment, and additional water-ballast tanks may, if desired,
be fitted in other parts of the steamer, but in certain cases, when the improved
combination of tanks hereinbefore described is adopted, other tanks in the several
holds can be dispensed with.
Having thus particularly described my said Invention and the manner of
performing the same, I have to state that I do not restrict myself to the precise
details herein described or delineated, but that what I believe to be novel and
original and claim as the Invention secured to me by and in terms of the herein-
before in part recited Letters Patent is,-
The applying of water-ballast tanks to screw steamers by constructing them
under the tunnels of the screw shafts, and substantially in the manner hereiņbefore
described.
In witness whereof, I, the said Charles John Denham Christie, have hereunto
set my hand and seal, this Twenty-seventh day of January, in the year of
our Lord One thousand eight hundred and eighty two.
CHARLES J. D. CHRISTIE. (L.S.)