IMPROVEMENTS IN AND RELATING TO ELECTRICAL APPARATUS FOR THE PROPULSION OF BOATS
Year: 1882

page_text: LETTERS PATENT to Anthony Reckenzaun of Leytonstone, in the County of
Essex, Engineer, for an Invention of "IMPROVEMENTS IN AND RELATING TO
ELECTRICAL APPARATUS FOR THE PROPULSION OF BOATS"
•
(Void by reason of the Patentee having neglected to file a Specification in
pursuance of the conditions of the Letters Patent.)
PROVISIONAL SPECIFICATION left by the said Anthony Reckenzaun at the
Office of the Commissioners of Patents on the 6th October 1882.
ANTHONY RECKENZAUN, of Leytonstone, in the County of Essex, Engineer,
"IMPROVEMENTS
IN AND RELATING TO ELECTRICAL APPARATUS FOR THE
PROPULSION OF BOATS"
My invention relates to the utilization of electric energy for the propulsion of
boats, and comprises the employment of electric motors, generators, and secondary
batteries or accumulators, as hereinafter specified.
Experience has demonstrated that the most economical machines for transmitting
electrical energy are those which revolve at a velocity considerably greater than
that which is practicable for steam-engines. Steam-engines for screw-boats have
seldom been found advantageous when run at a higher velocity than 500
revolutions per minute as the vibration accompanying such velocity is generally
very inconvenient and sometimes dangerous. Moreover few attempts have been
made to construct propellors to work at such a high velocity as they will not when
so working act efficiently upon the water.
Experiments have shewn me that good results may be obtained with suitable
gearing to reduce the speed of the electro-motor to the usual speed of screw
propellors in the water, but nevertheless I prefer to avoid all gearing between the
screw-shaft and the motor, to economize space and expense, and diminish the wear
and the extra friction caused by such gearing. For this purpose I employ a
finely pitched screw with sharp edged blades, the leading edges of such blades being
cut off and curved to such an extent that the water is cut gradually without being

page_text: unduly stirred or agitated and the propellor shaft can be conveniently connected to
the shaft of the electro-motor. By this arrangement I obtain the advantage of
having all of these parts below the water line. Where the power of several
machines is required I place such machines in a line with the shafting and couple
them together; in the case of twin screws the machines will be placed side by side,
and in two rows, if more than one is necessary for each propellor.
It is well known that any dynamo-machine or electro-motor will have the
greatest efficiency when running at one particular speed, and that a slower speed
would involve a loss of power; therefore, in order that the armature of the electro-
motor may continue revolving at practically the same velocity whilst the speed of
the bont or vessel is diminished I employ the following means, that is to say, the
shaft of one motor or one set of motors is made hollow and extends through the
stern-post and carries a propellor at its rear or outer end, and tho shaft of the other
motor or motors in the same line works inside the said hollow shaft and this inner
shaft also carries a screw or propellor; the two screws may run in the same, or in
opposite directions; if the latter they will be made right and left handed. At any
time when it is desired that the speed of the vessel should be reduced I stop the
motion of one shaft whilst the other continues to make the same or nearly the same
number of revolutions. The vessel thus being driven by one screw only will run
at the desired diminished speed. This arrangement is obviously applicable to twin-
screw boats. When only one motor is used. I reduce the speed by shifting the
brushes on the commutator or by reducing the electro-motive force of the
generator, or by using reducing gearing, or by means of electrical resistance.
Any suitable dynamo or magneto electric machine may be used for utilizing the
electric energy. And I place the primary or secondary batteries or accumulators
in any convenient position in the vessel. And, in some instances, as at ferries or the
like, I obtain the electric energy from a dynamo-electric machine or from batteries
or other generators on the shore, by means of cables or conductors above or below
the water. The motors which I employ are provided with reversing gear.