Improvements in the Structural Arrangements of Longitudinal Cellular Double Bottoms for Water Ballast in Ships.
Year: 1892

page_text: Date of Application, 1st Dec., 1892
Complete Specification Left, 5th June, 1893-Accepted, 29th July, 1893
PROVISIONAL SPECIFICATION.
Improvements in the Structural Arrangements of Longitudinal
Cellular Double Bottoms for Water Ballast in Ships.
I GEORGE WILLIAM SIVEWRIGHT of 5 Radcliffe Terrace Hartlepool in the
County of Durham Shipbuilder do hereby declare the nature of this invention to
be as follows:-
My invention relates to the structural arrangement of longitudinal_cellular
double bottoms for containing the water ballast of iron and steel ships. Hitherto
it has been the custom in constructing water ballast tanks on the longitudinal
cellular double bottom principle to provide floors the full depth of the tanks and
space them from 20 to 30 inches, apart according to size of vessel that is one for
every main angle frame of ship with intercostal keelson at half the distance from the
centre line and tank side. The average thickness of iron employed in these floors
intercostal keelsons and tank top being about three-eighths of an inch thick.
Owing to the close spacing of the floor plates the construction and also repairing
of these tanks is very costly and difficult, the interior being difficult of access and
the riveting of tank top plates and other portions of inside of tank a laborious and
costly operation. The object of my invention is to so arrange these cellular double
bottom water ballast tanks in such a manner that a combination of plates may be
employed in their construction of greater thickness than usual in order that such
increased thickness may allow for serious loss of strength caused by corrosion and
the scouring action of water contained in them as water ballast. By making their
interiors more accessible I facilitate their construction or repairs especially with
reference to the riveting of tank top floors and intercostals. The tanks being more
accessible the riveting can be easily done by hydraulic power instead of by hand
thus making a stronger job at less expense. In carrying out my invention into
effect instead of providing floor plates spaced at the usual distance apart that is
one for every main angle frame of ship I double the distance between the said floor
plates thus providing one for every alternate main angle frame of ship and provide
as usual an intercostal keelson at each side of ship placed between the tank side
plate and centre keelson. Halfway between each pair of solid floor plates and
corresponding to every other main angle frame of ship I provide what I term
intermediate frames which take the place of solid floor plates when placed in the
ordinary manner. These intermediate frames are of angle iron, bulb angle or of
zed section and are fitted with bracket plates two of which are secured end wise to
the centre keelson and may be called centre keelson bracket plates two others being
similarly secured to the tank sides and may be called inner tank side bracket
plates, and one or two others may if necessary be fitted to each intercostal plate
and may be called intercostal bracket plates these bracket plates extend towards
each other and are arranged of such dimensions that the tank top shall not be left
unsupported in any one part for a greater distance than from two to four feet
according to size of vessel the lower edges of these bracket plates are secured to
the angle frame of ship the upper edges having angle irons attached to them both
to give them rigidity and connect them to plates forming the tank top. The
reduction in the quantity of material employed in the intermediate frames as
compared to the solid floor plate enables me to increase the floor plates, inter-
costal plates, and tank top plates from the usual thickness of three-eighth's of an
inch to half an inch or more according to size of vessel, and also enables me to
increase the outer shell plating in way of cellular double bottom.
Dated this 20th day of Novembar 1809

page_text: COMPLETE SPECIFICATION.
Improvements in the Structural Arrangements of Longitudinal
Cellular Double Bottoms for Water Ballast in Ships.
I, GEORGE WILLIAM SIVEWRIGHT, of 5, Radcliffe Terrace, Hartlepool, in the
County of Durham, Shipbuilder, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
My invention relates to the structural arrangement of longitudinal cellular
double bottoms for containing the water ballast of iron and steel ships. Hitherto
it has been the custom in constructing water ballast tanks on the longitudinal
cellular double bottom principle to provide floors the full depth of the tanks and
space them to correspond with the main angle frames of the ship with the inter-
costal keelson at half the distance from the centre line to the tank side. Owing to
the close spacing of the floor plates when so arranged and to the large number of
rivets involved in their construction and fitting into position the construction and
repairing of the tanks is very costly and difficult, the interior being difficult of
access, and the rivetting of tank top plates and other portions of inside of tank a
laborious and costly operation. In order to overcome or mitigate the difficulty and
heavy expense involved in providing floors the full depth of the tanks at every
main angle frame and which for distinction I will terin solid floor plates, inter-
mediate frames have been provided of the modified construction described in the
Specification of the Letters Patent granted to Henry Withy and myself bearing
date of November the 3rd 1885 and numbered 13267 and placed to alternate with
the solid floor plates. This invention consists in further improvements in the
combination and arrangement of the several parts by which the advantages set
forth and claimed by me in the aforesaid Specification (and which consist mainly in
having the interiors more accessible to facilitate their construction, or repairs and
enabling the plates employed in their construction to be of greater thickness to
allow for reduction of strength by corrosion and the scouring action of the water)
are combined with a better, more equal and useful distribution of strength so as to
afford a rigidity and strength to resist strains equal to when all the floor plates are
the full depth of the tank whilst effecting a material reduction in the number of
rivets required amounting in some cases to 20,000 rivets in one ship.
Having described the nature of my improved structural arrangement of longi-
tudinal cellular double bottoms and its utility, I will now proceed to further
explain the same by reference to the drawing hereto annexed and the manner in
which my improvements are carried into practice.
Figure 1 is a cross elevation of the floor plate when provided the full depth of
the tank, that is, between the centre keelson and tank side.
Figures 2 and 3 are modifications of the floor plates the construction and use of
which constitute the essential features of my invention when arranged as inter-
mediate frames with the solid floor plates as hereinafter described.
Figure 4, is a fore and aft sectional view showing the spacing of the floor plates
transversely to bring them into line with the main angle frames of the ship, and
which spacing varies from 20" to 30" according to the size of the ship.
In the figures a, is the centre keelson, b, the intercostal keelson, and c the tank
side, and in, Figure 1 d, is the solid floor plate as hitherto used, and extending the
full depth of the tank from a to c for every alternate one of which I substitute the
intermediate frames having sectional floor plates el at centre keelson and e² at tank
side in Figure 2, and in Figure 3 in addition to the centre keelson and tank side
sectional floor plates el e³, the intercostal keelson sectional floor plates e³. In
carrying out my invention I arrange a solid floor plate as shown in Figure 1
to alternate with an intermediate frame as shown in Figure 2 or Figure 3, so that

page_text: referring to Figure 4 if A represents the solid floor plates, B represents the inter-
mediate frames. By extending the sectional floor plates el e² within such a distance
of the intercostal keelson b as in Figure 2 or within the like distance of the
sectional floor plates e extending therefrom as in Figure 3, and stiffening their
vertical edges ff whether by rivetting angle bars thereto or by flanging the said
vertical edges i combine in practice these several advantages viz. the quantity
of rivetting in the intermediate frames is materially less than would be required in
solid floor plates having angle bar connections extending from centre keelson to
tank side, and more especially is this the case if the vertical edges at fare
stiffened by flanging instead of by angle bars as shown the reduction in the
quantity of material employed in the intermediate frames as compared with the
solid floor plates enables me to increase the floor plates, intercostal plates and tank
top plates from the usual thickness of inch to inch or more according to the size
of the vessel and also enables me to increase the outer shell plate in way of
cellular double bottom: further the openings in every intermediate frame e make
the interior spaces between the floor plates much more accessible so that the
rivetting can be done by hydraulic power instead of by hand, thus making a
stronger job at less expense. Lastly by adjusting the distance between the vertical
edges of the sectional floor plates ee and the intercostal keelson or the intercostal
keelson section floor plates as the case may be, the tank top and shell plating
are not left unsupported along the line of the floor plate for a greater distance than
occurs between two adjoining floor plates and the full strength of the cellular
double bottom is maintained with a better arrangement of material.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
As a means for reducing the cost of manufacture and quantity of material
employed whilst maintaining the full and equal distribution of strength derived
from the floor plates, the improved structural arrangement of longitudinal cellular
double bottoms in which intermediate frames with sectional floor plates are used in
combination with solid floor plates substantially in the manner as hereinbefore
described with reference to the accompanying drawings.
Date is 2nd day
OL LUNC LONA
G. J. CLARKSON,
Chartered Patent Agent,
Stockton-on-Tees, Agent for the Applicant.
G. J. CLARKSON,
Chartered Patent Agent,
Stockton-on-Tees, Agent for the Applicant.