Improvements in the Screw Propulsion of Vessels.
Year: 1896

page_text: Date of Application, 24th July, 1896
Complete Specification Left, 26th April, 1897-Accepted, 3rd July, 1897
Improvements in the Screw Propulsion of Vessels.
I, JOHN FORMBY, of Formby Hall, Formby, Lancashire, Gentleman, do hereby declare
the nature of this invention to be as follows:-
My invention relates to the screw propulsion of vessels, and has for its objects to
provide propelling apparatus which shall offer the minimum resistance to the water
and so minimise the evil results of same upon the driving machinery, to better
distribute the weight in the ship, and to dispense with the long and heavy line of
shafting at present necessary, and to avoid the prominence and liability of any of the
vital parts to vulnerability or damage.
According to my invention I use electricity as the direct motive power, the
generating dynamos being driven by steam or other engines. I arrange the screworscrews
as the moving parts (either armatures or field magnets as the case may be) of electric
motors of magnetic, magneto- or dynamo-electric type, the fixed parts of such motors
(being the poles of the field magnets or the armatures as the case may be) as part of
the hull of the ship built into or fixed to the counter or keel thereof and following
more or less its lines, without any external hanging or pivotted or surrounding frame,
so as to be practically invisible and invulnerable.
Briefly the essential feature of my invention is the novel method of arranging the
hull of the ship to act as the fixed part, and the screw or screws to act as the moving
part of an electric motor, wherein the power is applied, not to the centre as heretofore,
but to the circumference of each screw whereat it has the greatest turning moment.
Obviously this broad principle. may be carried into effect in a variety of different
ways, of which will give some examples.
In some ways of carrying out my invention the outer end of each blade of the screw
is made or provided with a broad T head extending in circumferential directions for
any required distance past the edges of the blade and serving as either magnetic or
magneto-electric polepiece, and the blades of the screw may be wound with coils
suitably connected up and protected against the injurious effect of water; or according
to another method I may surround the blades with a broad "Gramme" armature
ring, the connections of the coils being made to suit the position of the field-magnet
poles. In either case this wholly or partly surrounding ring serves in great ineasure
as a check against centrifugal wash during rotation of the screw and tends to throw
the column of water directly astern whereby considerable gain in efficiency ensues
and the action or effect of a fly wheel or power accumulator counterbalancing added
friction is obtained. The fixed part of the motor is built (with suitable insulation)
permanently into an appropriate part of the hull of the ship adjacent to the moving
part or screw, and wound with coils when required. It is specially arranged so as to
avoid all prominence and lies in fact almost flush with the skin of the ship. The
screw shafts are or may be made hollow for carrying the connections between the
blade coils (if any) and the cominutators which may be arranged on their inner ends
or in other suitable manner, and with this arrangement I prefer to employ fluid
pressure thrust blocks of suitable type.
When the blades are wound with coils the motor may be for example magneto- or
dynamo-electric, double action, with reversing commutator and one two-poled fixed
field magnet of constant polarity, or magnetic and single action, the armatures being
simply parts of the mass of the vessel itself, the field magnets moving. With the

page_text: magnetic arrangement the blade coils may be connected as a multi-polar magnet
with reversing commutator, or there may be one coil on the shaft instead of several
on the blades, with simple make-and-break commutator, the blade heads being of one
polarity, and the inner end of the shaft of the other.
When a surrounding ring is used I prefer to employ one two-poled fixed field
magnet of constant polarity, the coils on the armature ring being connected to give
opposite magnetism in the ring conforming to centres of the field poles.
As an example of other ways by which the principle of ship and screw being the
fixed and moving parts respectively of an electric motor can be carried out, I may
mention the use and arrangement of coils on the screw shaft, either magnetic,
magneto- or dynaino-electric; or of a plain screw acting as a magnetic armature
attracted by field electro-magnets.
I would state that, while I anticipate that the best results inay be obtained by the
use of a magneto-electric (or separately excited) system connected on different circuits
inparallel arc, using currents of different tension and quantity for low resistance field
magnets and higher resistance armature coils, I do not confine myself to any specific
electrical arrangements or details of winding, connecting, commutation, and so on,
but will adopt those best suited to the individual circumstances. In every case the
electrical connections to the dynamos are arranged in the most effective and
convenient manners known to those skilled in the art to which this invention appertains.
The above described arrangements refer to four-bladed screws, but I do not limit
myself to these alone, as my invention may be readily adapted to screws having other
numbers of blades.
The system has many advantages. The long line of screw shafting with its weight
and other disadvantages is dispensed with, and the dynamos and their driving engines,
the coal bunkers, and so forth can be placed in the best weight-carrying part of the
ship and arranged in the most convenient way. The resistance to the work does not
come directly on the main engines as in the case of the actual motors being driven
by steam, but more electrical power can be generated when required without throwing
the extra driving resistance directly on the steam. There is no external moving
frame or ring surrounding the motor and hence no part liable to accident orderangement.
The system too will be very economical in a vessel in which, as in a ship of
war, there are many auxiliary engines, electric search lights, and so forth, for the
main engines would provide all the power necessary at any time, the auxiliary engines
being electric motors taking the supply from the main generator.
Dated this 4th day of July 1896.
J. C. CHAPMAN,
Agent.
Improvements in the Screw Propulsion
Vessels.
I, JOHN FORMBY, of Formby Hall, Formby, in the county of Lancashire, Gentleman,
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 :-
My invention relates to the screw propulsion of vessels, and has for its objects to
provide propelling apparatus which shall offer the minimum resistance to the water
and so minimise the evil results of same upon the driving machinery, to better
distribute the weight in the ship, and to dispense with the long and heavy line of
shafting at present necessary, and to avoid the prominence and liability of any of the
vital parts to vulnerability or damage.
The essential feature of my invention consists in arranging the hull of the ship
and the propelling screw or screws to act respectively as the fixed and moving parts

page_text: of an electric motor supplied with current from an electric generating plant installed
in any convenient part of the vessel or other source of electricity. It is immaterial
whether the moving part, viz: the screw, forms the armature or the field magnet of
the electric motor, the hull being always the other part, or whether the constructive
and operating principle of the electric motor be dynamo- or magneto-electric, or
simply electro-magnetic, the practical result being the same or equivalent, but I will
refer to certain examples of each class of motor.
The main generating dynamo-electric generators are driven by suitable engines,
and some of the electric current generated may be carried to the field magnets which
may be built or fixed into the counter, hull, or keel of the ship and following as accurately
as possible the lines thereof without any external hanging or pivotted or surrounding
frame, so as to be practically invisible and invulnerable. These inagnets are fixed in
close proximity to the peripheral line of travel or curve of the outer ends of the
propeller blades each of which is provided with a T head and which rotate in the
magnetic field; part of the current may be carried by cables passing through a
hollow shaft to coils on the screw which is arranged exactly in the usual way at the
end of a shaft projecting through sea bearings and suitably supported and not
enclosed in any casing or framing whatever. The screw constitutes the moving part
of the electric motor, or the motor may be electro-magnetic only, either the coils
being in the hull, the field poles of which attract the masses on the ends of the screw
blades, or the coils are only on the blades, being attracted to armature bosses
projecting slightly from the hull, and thus utilising the magnetic value of the masa
thereof; by either arrangement the power is applied not to the centre of the screw
as usual, but to the circumference whereat it has the greatest turning moment.
Obviously this broad principle may be carried into effect in different ways, but I will
describe in reference to the accompanying diagrams the preferred methods and
arrangements embodying the above defined principle of my invention.
Fig. 1 is a longitudinal sectional elevation of a ship, and Fig. 2 a sectional plan
thereof showing general arrangements of parts whereby my invention may be carried
into effect; Figs. 3 and 4 are respectively front and side elevations of a magneto- or
dynamo-electric arrangement offield magnet and screw armature with coils, and Fig. 5.
a section on line 1-2 of Fig. 4; Fig. 6 is an elevation illustrating a 3-poled field
magnet and screw arinature, without coils, the armature being magnetic only.
Referring to the general view of the bull, Figs. 1 and 2, B are steam boilers
driving engines C and generating dynamos D of any ordinary and suitable types, c, c,
are coal bunkers, S are propelling twin screws, and 8 8 their hollow shafts which are
carried in bearings and furnished with thrust blocks 81, fluid pressure or otherwise,
and sea bearings s', all arranged in usual way. F are the working poles of the field
magnetsf built into the counter as close as possible so as to be practically flush with
the lines of same on its outer side, E are commutators, L L are the main electric
cables from generator D to field magnet f suitably insulated and arranged. LLA
are cables passing from the generators D through the hollow revolving shafts a to the
screw blade coils if used. Now when current of sufficient electro-motive force is
applied to the magnets/f, the screws S S will be rotated.
Referring to the details of my invention shown in Figs. 3 to 6 wherein the same
letters of reference are used as above; in embodying the magneto or dynamo-electric
principle the screw is not completely surrounded with a "gramme ring" but
the outer end of each blade of the screw S is made or provided with a broad short
T head T extending in circumferential directions for a certain distance past the
edges of the blade as shown in the Figs. This head T serves as either a magnetic
or inagneto-electric pole-piece, and the blades of the screw in the latter case are
wound with coils t t as in Figs. 3 4 and 5, suitably connected up and protected
against the injurious effect of water by lagging or otherwise. In Figs. 3 and 4 one
2-poled fixed field magnet f is used, of constant polarity and the motor is of double
action (attraction and repulsion) so that two of the screw blades are always driving.
Opposite armature coils on the screw are connected and the commutator is reversing
for saine.

page_text: The motor may be electro-magnetic either by the field magnets built into the hull
attracting the mass of iron in the T heads, or the field magnets may be arranged on
the screw S drawing up to armature bosses on the hull, in this case the commutators
are ou the "make aud break" principle, the motor being single acting.
In the above cases these rapidly rotated T heads serve in some measure as a check
against centrifugal wash during rotation of the screw and tend to throw the column
of water directly astern whereby considerable gain in efficiency ensues, and the action
or effect of a fly wheel or power accumulator counterbalancing added friction is
obtained. The field magnet f, when it constitutes a fixed part of the electric motor,
is built as will be seen (with suitable insulation) permanently into an appropriate.
part of the hull of the ship as illustrated in the drawings adjacent to the moving
part or screw and wound with coils. It is specially arranged so as to avoid all
prominence, and lies in fact almost flush with the skin of the ship. When however
the field magnets are moving, plain armature bosses are fixed to the hull where these
poles would come and of similar formn. The screw shafts 8 are or may be made hollow
for carrying the connections L between the blade coils e (if any), and the commutators E
which are constructed in suitable manner and arranged on their inner ends or in
other suitable manner.
With the above arrangements the blade coils may be connected as a multi-polar
magnet with reversing commutator, or there may be oue coil on the shaft instead of
several on the blades with simple make-and-break cominutator, the blade heads heing
of one polarity and the inner end of the shaft of the other.
As an example of other ways by which the principle of ship and screw being the
fixed and moving parts respectively of an electric motor can be carried out, I may
mention the use and arrangement of coils on the screw shaft, either magnetic,
magneto- or dynamo-electric or of a plain screw with T-heads acting as a magnetic
armature attracted by field electro-magnets.
I would state that, while I anticipate that the best results may be obtained by the
use of a magneto-electric (or separately excited) system connected on different
circuits in parallel are for each screw, using currents of different tension and quantity
for low resistance field magnets and higher resistance armature coils, I do not confine
myself to any specific electrical arrangements or details of winding, connecting,
commutation, and so on, but will adopt those best suited to the individual circumstances.
In every case the electrical connections to the dynamos are arranged in the most
effective and convenient inanuers known to those skilled in the art to which this
invention appertains.
The above described arrangements refer to four-bladed screws, but I do not limit
myself to these alone, as my invention may be readily adapted to screws having
other numbers of blades.
The system has many advantages. The long line of screw shafting with its weight
and other disadvantages is dispensed with, and the dynamos and their driving engines,
the coal bunkers, and so forth can be placed in the best weight-carrying part of the
ship and arranged in the most convenient way. The resistance to the work does not
come directly on the main engines as in the case of the actual motors being driven
by steam, but more electrical power can be generated when required without throwing
the extra driving resistance directly on the steam. There is no external moving
frame or ring surrounding the motor, and hence no part liable to accident or
deangement. The system too will be very economical in a vessel in which, as in a ship of
war, there are many auxiliary engines, electric search lights, and so forth, for the
main engines would provide all the power necessary at any time, the auxiliary engines
being electric motors taking the supply from the main generator.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is
1. In the electric propulsion of vessels arranging the hull of the vessel and a
propelling screw or screws in such manner as to act respectively as the fixed and moving
parts of an electric motor operating substantially as herein set forth,

page_text: 2. In an electrically propelled vessel such as above referred to, the arrangement of
field magnet or magnets or armature bosses built into and practically flush with the
skin of the ship adjacent to the line of travel of the ends of the screw blades in
combination with a screw or screws mounted as described and having T heads to each
blade and with or without coils, the shafts, commutators, electric connections being
arranged substantially in the manner and for the purposes above described in reference
to the drawings.
3. The several arrangements of fixed field magnets and rotating screws with Theads
on each blade forming respectively the fixed and moving parts of an electric motor
constructed or adapted to operate substantially as described in reference to and shown
in the drawings.
Dated CHIS MOCH
1001
J. C. CHAPMAN,
70, Chancery Lane, London, W.C.,
Chartered Patent Agent, for the Applicant.