IMPROVEMENTS IN COFFER-DAMS OR SECTIONAL DOCKS FOR INSPECTING AND REPAIRING THE SUBMARINE PORTIONS OF SHIPS AND LIKE STRUCTURES
Year: 1882

page_text: LETTERS PATENT to Charles James Fox of Birkenhead in the County of
Chester for an Invention of "IMPROVEMENTS IN COFFER-DAMS OR SECTIONAL
DOCKS FOR INSPECTING AND REPAIRING THE SUBMARINE PORTIONS OF
SHIPS AND LIKE STRUCTURES" Partly a communication from abroad by
Richard P. C. Sanderson of the City and State of New York United States
of America
PROVISIONAL SPECIFICATION left by the said Charles James Fox at the
Office of the Commissioners of Patents on the 28th January 1882.
CHARLES JAMES Fox, of Birkenhead, in the County of Chester IMPROVE-
MENTS IN COFFER DAMS OR SECTIONAL DOCKS FOR INSPECTING AND REPAIRING
THE SUBMARINE PORTIONS OF SHIPS AND LIKE STRUCTURES [Partly a com-
munication from abroad by Richard P. C. Sanderson of the City and State of
New York United States of America]
This Invention relates to the construction of coffer dams, sectional docks, caissons,
in such a manner that they are applicable for use for inspecting and repairing
submarine portions of ships and like structures.
In constructing a coffer dam according to this Invention I form & vessel in
section and size suitable for the structure to which it is to be applied. This vessel
may be open at one, or both ends and at the open end, or ends is provided with
hinged arms, or equivalent devices, which extend horizontally, diagonally, or
vertically from the vessel so as to form a joint between the vessel and the structure
to which it is applied. Outside these arms or equivalent devices I spread canvas,
or equivalent fabric in such a manner as to complete the joint. The pressure of
the water on the outside forcing the arms against the object which they are to
grasp, in manner similar to the closing of a dock gate. When the vessel is away
from the structure, or the structure is small enough to be contained in the vessel,
the arms of each side may close against each other, and a floating structure is
formed. The vessel may be constructed of iron, timber, or other suitable material
and may be cellular in its sides and bottom, or plain sided and single bottomed.
Paving G71

page_text: An example of a coffer dam constructed according to this Invention and suitable
for inspecting and getting at the submarine after end of screw steamships consists
of a vessel of cellular construction with a double bottom. The vessel inay be of
rectilinear upper section about two thirds of its depth converging from thence to
its base, one end (the after end) is closed and the front end is open. The sides
of the front end incline from the top of the vessel to the base thereof and to these
inclined sides there are hinged a system of bars, which may be attached together
by continuous loops of fabric, bellows fashion, or may be plain and the fabric
applied as a sheet when the vessel is in position. In applying this coffer dam to
the stern of say a screw steamer I sink the coffer dam and bring the bottom thereof
under the after portion of the keel of the steamer. I then by ropes, chains, or
equivalent devices secure the coffer dam in position. The upper portion of the
sides and end thereof being above water. I then bring the hinged arms at the open
end of the coffer dam to bear against the run or sides of the ship, and over tho
joints I draw sheets of canvas, or equivalent fabric. I then pump the water from
the coffer dam and the pressure of the water forces the hinged arms and canvas
covering against the run of the ship, forming a watertight joint and the coffer
dam can then be entered for examining, painting, or repairing the after portion of
the ship, or propeller.
To insure a more perfect joint between the hinged arms and the ship, the ends
of the hinged arms may be made flexible, or they may be provided with a fibrous
packing, such as brushwood, heather, coir yarn, or wire, whale bone, or the like.
To enable the action of the water pressure to immediately act and as it were close
the gates, or arms against the ships side before the pumping action is commenced I
propose to have sluices between the cellular portions of the coffer dam and the
inside thereof, the sudden opening of which will cause reduction in the water level
and thereby cause the external pressure to press the arms against the side of the
ship and form a joint so that the pumping can be effectually carried out..
In the further carrying out of this Invention the coffer dam may be constructed
of a framework, or ribs and an outer covering of cellular canvas bags, or plain
canvas sheets, such canvas being by preference waterproof with a lining of india
rubber. After being put in position this structure, which is provided with arms as
before described can be held in position by pumping air into the cellular casing,
or bags and the coffer dam can then be pumped out and entered.
In the further carrying out of this Invention the coffer dam may be composed
of bowed arms hinged to a back piece, which arms when in position grasp the
structure to which the coffer dam is applied, the covering of waterproof canvas
keeping the coffer dam watertight.
In the further carrying out of this Invention, between the structure to be
grasped and the ends of the arms, I introduce when necessary a pad formed of
canvas in combination with manilla hemp, coir, or other yarn or other fibrous
material, or thick india rubber may be substituted. Instead of the arms being
hinged to the coffer dam they may be connected together by canvas and placed so
as to form the joint after the coffer dam is in position, or they may be connected
to each other by cords, or chains and having been drawn into their place a sheet
of canvas, or india rubber and canvas, or india rubber alone may be drawn over
them in such a manner that the pressure of water on the outside will form a
sufficiently watertight joint for the purpose required.
In the further carrying out of this Invention, the coffer dam may be constructed
without the hinged arms, but having a V shaped opening at one end, and using a
sufficient thickness of brush making material, or suitable fibrous material placed
along the edges that the pressure of water outside would make all watertight with,
or without canvas.
In the further carrying out of this Invention, cork, or waterproof bags may be
used on the edge of the canvas sheeting to assist in keeping it in its place when
first applied. Chains perpendicularly tightened may also be used to take part of
the strain from the arms.

page_text: This Invention is mainly applicable for repairing ships and as from the
configuration of the coffer dam and the structure thereof it is kept in position by
the pressure of the water, without, it will be evident that it will be applicable for
use in tideways, or streams, as well as in still water, which is not the case with
coffer dams as ordinarily constructed.
This coffer dam may also be made so as to be easily carried on board a merchant
ship, or man of war, the bottom being made in one pieco flat and watertight with
uprights hinged or otherwise fastened thereto, so that when required for use they
can be opened out and stayed at intervals to keep them in position. Outside of
these there is placed a strong net, or bars so positioned as to prevent the watertight
covering which is afterwards applied from bulging, or getting too much strain
when the water is withdrawn from the interior.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles James Fox in the Great Seal Patent Office on the
27th July 1882.
CHARLES JAMES Fox, of Birkenhead, in the County of Chester "IMPROVE-
MENTS IN COFFER DAMS, OR SECTIONAL DOCKS FOR INSPECTING AND REPAIRING
THE SUBMARINE PORTIONS OF SHIPS AND LIKE STRUCTURES." Partly a com-
munication from abroad by Richard P. C. Sanderson, of the City and State of New
York, United States of America
This Invention relates to the construction of coffer dains, sectional docks,
caissons, in such a manner that they are applicable for use for inspecting and
repairing submarine portions of ships and like structures.
In constructing a coffer dam according to this Invention, I form a vessel in
section and size suitable for the structure to which it is to be applied. This
vessel may be open at one, or both ends, and at the open end, or ends is provided
with hinged arms or equivalent devices, which extend horizontally, diagonally, or
vertically from the vessel, so as to form a joint between the vessel and the structure
to which it is applied. Outside these arms, or equivalent devices I spread canvas,
or equivalent fabric in such a manner as to complete the joint. The pressure of
the water on the outside forcing the arms against the object, which they are to
grasp in manner similar to the closing of a dock gate. When the vessel is away
from the structure, or the structure is emall enough to be contained in the vessel,
the arms of each side may close against each other and a floating structure is
formed. The vessel may be constructed of iron, timber, or other suitable material
and may be cellular in its sides and bottom, or plain sided and single bottomed.
An example of a coffer dam constructed according to my Invention and suitable
for inspecting and getting at the submarine-after end of screw steam ships consists
of a vessel of cellular construction with a double bottom. The vessel may be--of
rectilinear upper section about two thirds of its depth converging from thence to
The sides of
its base, one end (the after end) is closed and the front end is open.
the front end incline from the top of the vessel to the base thereof and to the sides
there are hinged a system of bars which may be attached together by continuous
loops of fabric, bellows fashion, or the fabric may be plain and applied as a sheet
when the vessel is in position. In applying this coffer dam to the stern of say a
screw steamer, I sink the coffer dam and bring the bottom thereof under the after
portion of the keel of the steamer I then by ropes, chains, or equivalent devices
secure the coffer dam in position. The upper portion of the sides and end thereof
being above water. I then bring the hinged arms at the open end of the coffer
dam to bear against the run, or sides of the ship and over the joints I draw sheets
of canvas, or equivalent fabric. I then pump the water from the coffer dam and
the pressure of the water forces the hinged arms and canvas covering against the
run of the ship, forming a watertight joint and the coffer dain can then be entered
for examining painting, or repairing the after portion of the ship, or propeller.
To ensure a more perfect joint between the hinged arms and the ship, the ends
of the hinged arms may be made flexible, or they may be provided with a fibrous
packing, such as brushwood, heather, coir yarn, or wire, whalebone, or the like.
To enable the action of the water pressure to immediately act and as it were close
the gates, or arms against the ships side before the pumping action is commenced,
I propose to have sluices between the cellular portions of the coffer dam and the
inside thereof, the sudden opening of which will cause reduction in the water level
and thereby cause the external pressure to press the arms against the side of the
ship and form a joint so that the pumping can be effectually carried out.
In the further carrying out of this Invention the coffer dam may be constructed
of a framework, or ribs and an outer covering of cellular canvas bags, or plain
canvas sheets, such canvas being by preference waterproof with a lining of india
rubber. After being put in position this structure which is provided with arms

page_text: of the coffer dam may be prolonged as at D to form a guard for the arms B. The
bottom of the coffer dam A is prolonged, or carried out in front of the coffer dam
as atE and the bottom is provided with keel blocks F to receive and pass under
the keel of the ship. At the point a of the coffer dam A, and on each sido thereof,
I attach strong waterproof sheeting b as shown in detail at Figure 12. This
sheeting b extends from the sides of the coffer dam A so as to cover the whole
outside portion of the arms B and the sheeting at its outer edge is provided with a
fibrous packing, or pillow & which laps round the ends of the arms B and comes
between the ships side and the ends of the arms B so as to form a watertight
joint therewith. The pressure of the outside water when the coffer dam is pumped
out forces the arms B against the side of the ship and keeps the waterproof
sheeting against the arms B and thus the gate formed by the arms B is kept in
position against the ships side. The coffer dam A is by preference constructed of
iron and may be cellular as shown at Figures 1. 2. 3. The cellular, or pontoon
portion H is formed between the outer shell of the coffer dam and the inner shell h.
and serves to float the coffer dam into position and when in position for example
when applied to the stern of a ship and the arms B and waterproof sheating b
brought into position, by chain, or rope guides, the cellular portion may be used to
reduce the water level in the coffer dam by causing the water from the coffer dam
to enter the cellular portion through suitable sluice valves. This sudden reduction :
of the water level in the coffer dam will induce the water outside the coffer dam to
press the hingel arms B against the side of the ship and form a joint so that the
pumping out of the water in the coffer dam can be effectually accomplished.
In Figures 4. 5 and 6, the coffer dam A is shown constructed of a single iron
shell, the floating power being afforded by the pontoons H which are hinged and
stayed to the upper portion of the sides and ends of the coffer dam. The pontoons H
are so arranged that they-will-turn up so as to increase the depth of the coffer
dam. This will be understood upon reference to Figure 6 on one-side of which
the pontoon H is shown turned up and on the other side turned down. This
arrangements affords facility for utilizing the coffer dam for ships of different
draughts of water. The pontoons H are securely binged round the top of the
coffer dam and are also secured by strong stays, or guys c. The coffer dam is
formed of rounded section, the arms B being hinged to the front flange C of the
coffer dam which flange is securely stayed to the body of the coffer dam A. The
bottom E of the coffer damn is extended to come under the ships keel and the lower
arms B' may be broader and form part of the bottom E Outside the arms B there is
provided a waterproof sheeting with fibrous packing, which as previously described
renders the gate formed by the arms B watertight when in position against the
ships side.
In Figures 7 and 8 the coffer dam A is of cellular construction and suitable for
gaining access to the midship portion of the ship. The ends of the coffer dam are
provided with horizontal hinged arms at the sides and vertical hinged arms at the
bottom. The arms are arranged at both ends of the coffer dam (which are open)
and the vertically working hinged arms are provided with floats J which lift the
arms into position, the whole of the arms being covered with the waterproof
sheeting and a fibrous packing being used between the ends of the arms and the
shell of the ship.
In Figures 9 and 10 the coffer dam A is constructed of a series of articulated
plates, which form a band and are provided with the struts K which when in
position keep the plates from the ships side as shown at Figure 9, the ends of the
plates are provided with the hinged arms B and the whole of the structure is covered
with waterproof sheeting, fibrous packing being used between the ends of the arms
and the shell of the ship to effect a joint.
In Figure 11 the coffer dam A is constructed of the bowed arms B, which are
hinged together to a back piece as shown, a flat bottom, or shoe being provided
Waterproof sheeting covers the whole coffer dam and fibrous packing is used
between the ends of the arms and shell of the vessel..

page_text: In the further carrying out of my Invention instead of constructing the coffer
dam in the form of a plated vessel a simple cage, or framework having hinged
arms at the front may be used, the whole being covered with cellular canvas bags, or
waterproof sheeting. The coffer dam may also be made so as to be easily carried on
board a merchant ships, or man of war, the bottom being made in one piece flat and
watertight with uprights hinged, or otherwise fastened thereto, so that when
required for use, they can be opened out and stayed at intervals to keep them in
position. Outside of these there is placed a strong net, or bars so positioned as to
prevent the watertight covering which is afterwards applied from bulging, or
getting too much strain when the water is withdrawn from the interior.
This Invention is mainly applicable for repairing ships as from the configuration
of the coffer-dam and the structure thereof, it is kept in position by the pressure of
the water without, it will be evident that it will be applicable for use in tideways,
or streams as well as in still water.
Having now described this Invention and shown how the same can be carried
out into practical effect, I would have it understood that this Invention is not
limited to any particular shape, or configuration, or dimensions of the coffer-dam,
as the same are capable of various modifications, what I claim as secured to me by
Letters Patent as aforesaid is:-
First The combination with a coffer-dam adapted to receive the stem, or stern
of a ship, of an upright series of separately adjustable arms, or bars arranged at each
side of the coffer dam and adapted to have their ends brought against the sides of
the ship, substantially as herein described and shown in the Drawings hereto
annexed.
Second The combination with a coffer-dam A of two series of the independently
adjustable hinged arms, or bars substantially as herein described and shown at
Figures 7 and 8 of the Drawings hereto annexed.
Third The combination with a coffer dam adapted to receive the stem, or
stern of a ship of an upright series of separately adjustable arms, or bars arranged
at each side of the coffer-dam and adapted to have their ends brought against
the sides of a ship and a covering of canvas, rubber, or other material applied to
the outer sides of said arms, or bars and a packing of fibrous material applied
between the ends of said arms, or bars and the sides of the ship, substantially
as herein described and shown in the Drawings hereto annexed.
Fourth The combination with a coffer-dam, comprising watertight compartments
and provided at each side with an upright series of separately adjustable arms or
bars, of valves for allowing water to flow from the inside of the coffer-dam into
said compartments as and for the purpose specified.
Fifth The construction and arrangement of coffer-dam, as herein described and
as shown at Figures 1. 2 and 3 of the Drawings hereto annexed.
Sixth The construction and arrangement of coffer-dam as herein described and
as shown at Figures 4. 5 and 6 of the Drawings hereto annexed.
Seventh The construction and arrangement of coffer-dam, as herein described
and as shown at Figures 7 and 8 of the Drawings hereto annexed.
Eighth The construction and arrangement of coffer dam, as herein described and
as shown at Figures 9 and 10 of the Drawings hereto annexed.
Ninth The construction and arrangement of coffer dam as herein described and
as shown at Figure 11 of the Drawings hereto annexed.
In witness whereof, I the said Charles James Fox have hereunto set my
hand and seal this Twenty first day of July in the year of our Lord One
thousand eight hundred and eighty two