IMPROVEMENTS IN MEANS OR APPARATUS FOR PREVENTING. THE CORROSION AND FOULING ' OF THE BOTTOMS OF IRON OR STEEL SHIPS AND ALSO APPLICABLE TO PROPELLERS"
Year: 1882

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LETTERS PATENT to James Ballantyne Hannay, of Glasgow, in the County of
Lanark, North Britain, Chemist, for an Invention of "IMPROVEMENTS IN
MEANS OR APPARATUS FOR PREVENTING. THE CORROSION AND
FOULING
' OF THE BOTTOMS OF IRON OR STEEL SHIPS AND ALSO APPLICABLE TO
PROPELLERS"
PROVISIONAL SPECIFICATION left by the said James Ballantyne Hannay
at the Office of the Commissioners of Patents on the 11th December 1882.
JAMES BALLANTYNE HANNAY, of Glasgow, in the County of Lanark, North
Britain, Chemist, "IMPROVEMENTS IN MEANS OR APPARATUS FOR PREVENTING
THE CORROSION AND FOULING OF THE BOTTOMS OF IRON OR STEEL SHIPS AND
ALSO APPLICABLE TO PROPELLERS".
.
7
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This Invention has for its object to prevent the corrosion and fouling of: iron or
steel ships, and the improvements are also applicable to propellers.
In carrying out the Invention the bottom of an iron or steel ship is kept clean or
uncoated with any paint of composition and it is rendered electro-negative. For
this purpose an electric current is made to pass from a galvanic battery or dynamo-
electric machine or other suitable source to one or more positive electrodes in
contact with the sea or external water thence through the water to the bottom of
the ship and finally through a suitable conductor or conductors back to the battery
or other source. Rods of carbon may be used for the positive electrodes, and they
are by preference made to project through stuffing boxes at the stern or any other
convenient part of the ship below water. The electrodes are connected by a
suitable conductor to the battery or source' of the electric current but are carefully
insulated where they pass through the skin of the ship. The bottom of: the ship
is connected by another suitable conductor or by two or more to the negative pole
or terminal of the battery or other electric source; and when a propeller is to be
similarly protected care is taken to connect its shaft by means of a metallic brush
or other suitable appliance with a conductor connected to the battery.or. electric
source. Any suitable electrode which is positive relatively to the iron or steel of
the ship or to the metal of the propeller may be used instead of a carbon electrode
and it may be held in the water in any convenient way.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said James Ballantyne Hannay in the Great Seal Patent Office on the
9th June 1883.
JAMES BALLANTYNE HANNAY, of Glasgow, in the County of Lanark, North
Britain, Chemist IMPROVEMENTS IN MEANS OR APPARATUS FOR PREVENTING
THE CORROSION AND FOULING OF THE BOTTOMS OF IRON OR STEEL SHIPS, AND
ALSO APPLICABLE TO PROPELLERS "
My said Invention has for its object to prevent the corrosion and fouling of iron
or steel ships; and my improvements are also applicable to propellers..
In carrying out my Invention the bottom of an iron or steel ship is kept clean
or uncoated with any paint or composition, and it is rendered electro-negative.
For this purpose an electric current is made to pass from a galvanic battery or
idynamo-electric machine, or other suitable source to one or more positive electrodes
in contact with the sea or external water, thence through the water to the bottom
of the ship, and finally through a suitable conductor or conductors back to the
battery or other source. Rods of carbon are by preference used for the positive
electrodes, and they are by preference made to project through stuffing boxes at
the stern or any other convenient part of the ship below water. The electrodes
are connected by a suitable conductor to the battery or source of the electric
current, but are carefully insulated where they pass through the skin of the, ship.
A sheath of rubber may be conveniently used to insulate and protect each electrode
where it passes through the stuffing box, the external projecting end of the
electrode being of course left uncovered. The bottom of the ship is connected by
another suitable conductor, or by two or more to the negative pole or terminal of
the battery or other electric source; and when a propeller is to be similarly
protected care is taken to connect its shaft by means of a metallic brush or other
suitable appliance with a conductor connected to the battery or electric source.
Any suitable electrode which can by the electric current be rendered electro-
positive to the iron or steel of the ship or to the metal of the propeller may be used
instead of a carbon electrode; and the electrode or electrodes may be held in the
water in any convenient way.
In practically applying my Invention the strength and quantity of electric
current required will vary in different cases, and will depend upon the nature or
quality of the iron or steel forming the ship's bottom, and upon various conditions
and circumstances. As a guide I may state that from actual trials I have calculated
that for a large steel ship having about. 18000 square feet of wetted surface one or
more galvanic batteries or dynamo-electric machines yielding an aggregate,current
of 1200 amperes of an electromotive force of 7. volt will secure the object in view.
For the same ship there should be two carbon electrodes consisting each of a round
rod 1 inches in diameter and made to project about inch. These two electrodes
may be placed one at each side of the stern of the ship; or there may be more than
two of the carbon electrodes and they may be placed at various parts of the ship's
'bottom,
T
Having thus particularly described my said Invention and the manner of
performing the same I have to state that I do not. restrict myself to the precise
details herein before described but that what I believe to be novel and original
and claim as the Invention secured to me by and in terms of the hereinbefore in
part recited Letters Patent is:-
1. Preventing the corrosion and fouling of the bottom of an iron or steel ship by
keeping it uncoated with paint or composition and rendering it electro-negative !

page_text: by means of an electric current applied substantially in the manner hereinbefore
described.
2. Preventing the corrosion of a propeller by applying an electric current so as
to render it electro-negative substantially in the manner hereinbefore described.
In Witness whereof I, the said James Ballantyne Hannay, have hereunto set
my hand and seal this seventh day of June in the year of our Lord One
thousand eight hundred and eighty-three.
Witness,
EDMUND HUNT.
Patent Agent
Glasgow.
JB HANNAY (L.S.)