Cellular Double Bottoms for Water Ballast.
Year: 1885

page_text: Cellular Double Bottoms for Water Ballast.
We HENRY WITHY and GEORGE WILLIAM SIVEWRIGHT both of West Hartlepool
in the County of Durham Ship Builders do hereby declare the nature of said
Invention to be as follows:-
Our Invention relates to the structural arrangement of longitudinal cellular
double bottoms for containing the water ballast of iron or steel ships.
Hitherto it has been the custom in constructing water ballast tanks on the
longitudinal cellular double bottomed principle to provide floors the full depth of
the tanks and spaced from 20" to 30" apart according to the size of the vessel that
is one for every angle frame of the ship with the intercostal keelsons at half the
distance from the centre line. The average thickness of iron employed in these
floors intercostal keelsons and tank top being about of an inch. Owing to this
close spacing of the floor plates the construction or repairing of these tanks is
costly and difficult the interior being difficult of access and the rivetting of the
tank top plates a laborious and costly operation.
The object of our Invention is to arrange these cellular double bottomed ballast
tanks in such a manner that plates may be employed in their construction of
greater thickness than usual in order that such increase of thickness may allow for
serious loss of strength caused by corrosion and the scouring action of water
contained in them as water ballast and to afford a more rigid support under the
engines and boilers and by making their interiors more accessible to facilitate their
construction or repairs especially with reference to rivetting the tank top floors
intercostals &°. The tanks being more accessible the rivetting can be easily done
by hydraulic power instead of by hand thus making a stronger job at less expense.
In carrying our Invention into effect instead of providing floors spaced at the
usual distance apart that is one for every angle frame of the ship we double the
distance between the said floor plates thus providing one for every alterate angle
frame of the ship and provide as usual an intercostal keelson at each side of the
ship placed between the tank side plate and the centre keelson. Half way
between each pair of solid floor plates and corresponding to every other angle
frame of the ship we provide what we term intermediate frames which take the
place of solid floor plates when placed in the ordinary manner. These intermediate
гъ

page_text: frames are of a bulb angle or Z section and are fitted with bracket pieces or knee
plates two of which are secured end wise to the centre plate or centre keelson and
may be called centre keelson knee plates two others being similarly secured one to
the tank side and may be called inner tank side knee plates and one or two others
may if necessary be fitted to each intercostal plate and may be called intercostal
knee plates, these knee 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 about 2' 6" to 3' 6" according to the size of the vessel
the lower edges of these knee plates are secured to the angle frame of the ship the
upper edges having angle irons attached to them both to give them rigidity and
to connect them to the plates forming the tank top. The reduction in the quantity
of material employed in the intermediate frame as compared to the solid floor
plate enables us to increase the floor plates intercostal plates and tank top from the
usual thickness of three eighth's of an inch to seven sixteenths or more according
to the size of the vessel.
J. HENRY JOHNSON,
Agent for the said Henry Withy and
George William Sivewright.

page_text: Improvements in the Structural Arrangements of Longitudinal
We HEN
Cellular Double Bottoms for Water Ballast.
IT and GEORGE WILLIAM SIVEWRIGHT both of West Hartlepool
in the County of Durham Ship Builders 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:-
Our Invention relates to the structural arrangement of longitudinal_cellular
double bottoms for containing the water ballast of iron or steel ships. Hitherto
it has been a custom in constructing water ballast tanks on the longitudinal
cellular double bottomed principle to provide floors the full depth of the tanks, and
spaced from twenty inches to thirty inches apart according to the size of the vessel,
that is one for every frame of the ship with the intercostal keelsons at half the
distance from the centre line.
The average thickness of the plate hitherto employed in the construction of the
floors, intercostal keelsons, and tank top, is about of an inch and owing to the
close spacing of the floor plates, the construction or repairing of these tanks is
costly and difficult, the interior being difficult of access and the rivetting of the
tank top a laborious and costly operation. The object of our Invention is to
arrange these cellular double bottoms ballast tanks in such a manner that their
interiors are more accessible to facilitate their construction or repairs, and the plates
employed in their construction may be of greater thickness than those usually
employed, such increase of thickness allowing for reduction of strength caused by
corrosion and the scouring action of water contained in them as water ballast, and
also affording a more rigid support under the engines and boilers.
And in order that our said Invention may be fully understood we will now
proceed particularly to describe the same and for that purpose shall refer to the
accompanying drawings in which like letters of reference are employed to indicate
corresponding parts in all the figures.
Figure 1 illustrates in plan part of a ships bottom constructed according to our
invention with the tank top removed. A is the centre keelson, B¹ B³ the intercostal
keelsons, CC the tank sides. Instead of providing floors spaced at the usual
distance apart that is one for every frame of the ship, we double the distance
between the said floor plates thus providing one for every alternate frame of the
ship, and provide intercostal keelsons B¹ B2 at each side of the ship placed between
the centre keelson A and the tank sides C¹ C. Half way between each pair of deep
floor plates and corresponding to every alternate frame of the ship we provide
what we term intermediate frames of " bulb-angle" "Z" or "channel" iron or
steel which take the place of deep floor plates arranged according to the usual mode
of construction, thus in figure 1 D D D³ are deep floor plates and E¹ E* E³ are
intermediate frames. Figures 2, 3 and 4 are drawn to a larger scale than figure 1.
Figure 2 illustrating in side elevation the deep floor plates D¹ D' D³ and Figures 3
and 4 illustrate also in side elevation the intermediate frames E¹ E' E' constructed
according to our invention. In Figure 2 A. represents the position of the centre
keelson B the intercostal keelson and C the tank side. F being a main frame of

page_text: the ship corresponding in position to one of the deep floor plates D¹ D* D³.
Figures 3 and 4 illustrate the construction of an intermediate frame in which knee
. or bracket plates are substituted for the deep floor plate, thus in Figure 3 G¹ is
what may be termed the centre keelson knee or bracket plate and G' the tank side
knee or bracket plate these knee or bracket plates are connected endwise to the
centre keelson and tank side respectively and extend towards the intercostal
keelson B and so far towards each other that no part of the tank top shall be
unsupported for a greater distance than from 2 feet 6 inches to 3 feet 6 inches
according to the size of the ship. In some cases in addition to the knee plates G
and G connected to the centre keelson and tank side as illustrated in figure 3 we
prefer to provide intercostal knee plates G³ G connected end wise to the intercostal
keelson B as illustrated in figure 4 and extending in either direction towards the
centre keelson knee plate G₁ and the tank side knee plate G³. The lower edges of
the knee plates or brackets G¹ G³ G³ G' are connected to the frames F of the ship
and their upper edges have angle irons attached to them both to give them rigidity
and to connect them to the plates forming the tank top.
The reduction in the quantity of material employed in an intermediate fraine as
compared with a deep floor plate enables us to increase the thickness of of an inch
to of an inch or more according to the size of the vessel without materially
adding to the weight.
Τσ
Having now particularly described and ascertained the nature of this Inven-
tion and in what manner the same is to be performed I declare that what.
I claim is :-
The improvements in the construction of longitudinal cellular bottoms for water
ballast substantially as herein before described.