Improved Ships or Vessels for Transporting Liquids in Bulk.
Year: 1892

page_text: Date of Application, 24th Nov., 1892-Accepted, 31st Dec., 1892
COMPLETE SPECIFICATION.
[Communicated from abroad by RICHARD BLÜMCKE, of Wilhelminenstrasse,
9, St. Pauli, Hamburg, Germany.]
Improved Ships or Vessels for Transporting Liquids in Bulk.
I, OLIVER IMRAY of No. 28 Southampton Buildings Chancery Lane, in the
County of London, Chartered Patent Agent, 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 :-
In transporting liquids in so called tank ships on the high seas, the difficulty arises
of properly ballasting the ships, when returning from the locality to which the liquid
has been conveyed, to the locality of production. The tank ships hitherto employed
for the import of oil from North America, are, for example, so constructed that the
space in the ship serving to receive the oil is divided by transverse bulk heads into
a suitable number of tanks. This existing construction is shewn at Figs. 1 and 2 of
the accompanying drawings. When the ship has to return in ballast, the oil is
replaced by water to obtain the requisite stability of the ship. But as the oil is
specifically lighter than water, the water ballast employed has to be less in
bulk than the oil; and even if the liquid. transported were of the sarac specific
gravity as water, it would be undesirable to use the same bulk as ballast, in
order not to obtain unnecessary immersion, and thus unnecessarily increase the cost
of propulsion.
Consequently only a certain number of the tanks are filled with the water ballast,
as shewn diagrammatically at Fig. 1, resulting in an unequal loading of the ship, the
load being concentrated at a comparatively small part in the middle of the length of
the ship, whereby the ship is subjected to injurious strains.
In order to obviate this disadvantage, it has latterly been proposed to divide the
tanks by horizontal partitions into upper and lower compartments, as shewn at
Figs. 3 and 4, so that the lower compartments of all the tanks could then be filled
with the water ballast, so as to distribute the load more or less equally over the
greater part of the length, as at Fig. 3. This arrangement however causes a further
disadvantage, namely that the centre of gravity of the vessel is thereby brought too
low down, causing the ship to float too rigidly in the water and rendering it liable
to injury in heavy seas.
The present invention consists in a peculiar arrangement of the tanks in such
ships, whereby the water ballast can be distributed over any desired length of the
ship while at the same time the centre of gravity of the entire structure is brought
exactly to the position required for giving the ship the necessary freedom of motion
in the water.
The invention consists, generally speaking, in limiting the space containing the
ballast in the transverse horizontal direction. This can be effected in the simplest
way as shewn diagrammatically at Figs. 5 to 11 by constructing the ship with two
or more longitudinal bulk heads L L, either with or without a central one, and so
arranged as to divide the tanks transversely into three, four or more compart-
ments, which are all filled with the liquid cargo, but of which only the middle
ones, or one or more on each side of the longitudinal middle line are filled up to the
deck with water ballast. By this means the centre of gravity a will remain at or
about the same height when the ship is in baliast as when loaded with cargo.
Moreover it is only necessary to make the distance apart of the longitudinal bulk
heads sufficiently limited to enable the ballast to be distributed to any required
extent over the length of the vessel. The said longitudinal bulk heads will also
materially increase the strength of the ship.
In some cases there may be provided a double bottom in the tanks; that is to say,

page_text: a horizontal floor P connecting the bulk heads at a certain distance above the bottom
of the ship, whereby the centre of gravity a will be maintained at the requisite high
level with a smaller volume of water ballast, and the watertight enclosure of the
liquid cargo will be better insured.
The longitudinal bulk heads L may be variously constructed and arranged for the
above purpose; thus they may be either flat, vertical and parallel to each other,
or they may be inclined to each other, or they may be curved or formed of
corrugated plates, being suitably stiffened in all directions to resist the lateral
pressure of the water ballast.
The double bottoms or horizontal floors P may also be either flat, curved or
corrugated.
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 :-
1. In tank ships or vessels for the transport of liquids in bulk, constructing any
required number of longitudinal bulk heads L arranged symmetrically relative to the
longitudinal centre line of the ship, in order to provide spaces for the water ballast
so arranged as to both maintain the centre of gravity (a) of the loaded ship at the
most suitable point, and to effect the distribution of the ballast over any desired
extent of the ships length, substantially as described.
2. In tank ships constructed as set forth in the preceding claim the provision
of floors or double bottoms P connecting the longitudinal bulk heads L, for the
purpose of bringing the centre of gravity of the loaded vessel into a suitable
position, and for insuring the watertight enclosure of the tanks containing the liquid
to be transported.
Dated this 18th day of November 1892.
ABEL & IMKAI,
Agents for the Applicant.