Improvements in the Construction of Water Tight Partitions or Bulkheads for Ships' Coffer-dams or the like.
Year: 1889

page_text: Date of Application, 30th July, 1889-Accepted, 21st Sept., 1889
Improvements in the Construction of Water Tight Partitions or
Bulkheads for Ships' Coffer-dams or the like.
A communication from abroad by WALFRID THEODOR SYLVEN, a citizen of Sweden,
residing at Washington, in the District of Columbia, United States of America,
Gentleman.
1, WILLIAM PHILLIPS THOMPSON F.C.S., M.I.M.E. of the Agency for Foreign
Patent Solicitors, 6, Lord Street, Liverpool, and 6 Bank Street, Manchester, both in
the County of Lancaster, and 323 High Holborn in the County of Middlesex, Civil
Engineer, 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 :-
The object of the invention is to provide the hulls of ships or other vessels with
water tight partitions or bulkheads of such construction that the resistance at different
points shall be proportioned to the strain at such points.
The invention is particularly designed for use in the bulkheads separating water-
tight compartments in sea going vessels, and the desired object is accomplished by
arranging the stiffening ribs as herein described and shown.
Referring to the accompanying drawings: :―
Figure 1 shows in cross section a single deck vessel provided with the
improvement.
Figure 2 is a similar view showing the construction applied to a collision
bulkhead.
Figure is a longitudinal vertical section of a portion of a vessel having the
improvements applied in connection with a longitudinal or coal bunker bulkhead.
In Figure 1, A A is the deck, and S S stiffening ribs which, instead of being
equally spaced, are placed nearer together toward the middle of the bulkhead than
at the sides of the vessel. The spacing between the successive ribs increases gradually
in passing from the centre of the vessel toward the side.
In Figure 2 the ribs are arranged at increasing distances apart as the sides of the
vessel are approached.
In Figure 3 the distance between the successive ribs increases in passing forward
and also in passing rearward from the middle of the bulkhead. It is preferable to
use for stiffening ribs angle irons of any suitable form in cross section, but it is to be
understood that any other suitable material may be used. The bulkheads may be
constructed and arranged in other respects in the ordinary manner, and the ribs
secured to or against the bulkheads on one or both sides. The ribs are commonly
arranged as shown in the drawings, in lines converging toward their lower ends.
In other words, the spacing between the ribs increases with the distance above the
bottom of the vessel and also with the distance from the vertical centre line of the
bulkhead.
With this exception the advantages of the construction, both as to economy and
efficiency, will be readily understood. According to the well known laws of fluid
pressure the eccentricity of the pressure increases with the depth below the surface.
Hitherto in the construction of water-tight bulkheads the stiffening ribs have been
placed vertically, thus presenting an equal resistance at all depths, the result being a
waste of material. Under this construction the ribs approaching each other as the
depth increases, have individually a less surface to support, and, consequently, the
stability of the bulkhead is increased in proportion to the increasing water pressure
thereon.
When the bulkhead of a vessel is laid open to the sea, the strain due to the static
pressure or to the momentum of the moving water against the bulkhead will cause
the same to give way first at the middle, therefore the strengthening ribs should be

page_text: placed closer together at the middle than at the sides. On account of the static
pressure being greater at the bottom than at the top the stiffeners should also be
closer at the bottom than at the top. Such is the arrangement represented in the
drawings, the spacing of the ribs at the bottom of the vessel increasing as the sides
of the vessel are approached and the distance between the lower ends of any two
ribs being always less than the distance between their upper ends. In other words,
the stiffeners are so arranged that if continued downward they would cross the
vertical plane falling through the keel at different heights.
It will, of course, be understood that different relations between the depth and
breadth in vessels of different forms will necessitate some modification in the location
and arrangement of the ribs without, however, departing from the general mode of
arrangement laid down above.
Where it is necessary to pierce the bulkhead for doors, windows or other openings
the openings should be framed in and the ribs fastened to the frame.
The exact disposition of ribs herein shown is, of course, not essential to the
carrying out of the principle, the essence of the invention residing in the arrange-
ment of the ribs so as to everywhere present a resistance substantially proportional
to the pressure to be resisted.
It is obvious that the invention will apply equally well to the construction of the
walls of coffer-dams, caissons, etcetera, as to the bulkheads of vessels. In fact it is
applicable to any structure adapted to receive the pressure of liquids. Where extra
strength is required the middle ribs should be larger than the others.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. The bulkhead of a ship or like wall to resist fluid pressure and strengthening
ribs combined therewith in converging lines, substantially as set forth and shown.
2. As an improvement in the construction of ships and in combination with a
bulkhead, strengthening ribs applied to said bulkhead at successively increasing
distances apart as the ends of the bulkhead are approached.
3. In a ship, and in combination with a bulkhead, diagonal strengthening ribs
converging toward the bottom and placed closer together at the centre line of the
ship than at the sides.
Dated this 29th day of July 1889.
WM. P. THOMPSON & Co.,
Agents for the Applicant.