AN IMPROVED METHOD OF AND MEANS FOR PROPELLING VESSELS
Year: 1882

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention
of "AN IMPROVED METHOD OF AND MEANS FOR PROPELLING VESSELS."
A communication from abroad by John B. Root, of Portchester, New York,
United States of America, Manufacturer.
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 21st February 1882.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "AN IMPROVED METHOD OF AND MEANS FOR
PROPELLING VESSELS." A communication from abroad by John B. Root, of
Portchester, New York, United States of America, Manufacturer.
The object of the present Invention is to reduce the great loss of power attending
the present inethod of applying screw-propellers to the sterns of vessels; also to
obviate the necessity for long screw-shafts and their liability to break; also to
provide means for applying the propelling power to vessels by two or more
independent engines, thus reducing the risk of disablement of vessels; and also to
provide for the application of power with less draught of water than is practicable
with the ordinary application of screws. The loss of power attending the
application of screw-propellers to the sterns of vessels as heretofore practised is
mainly due to, first, the suction upon the stern of the vessel caused by drawing the
water backward by the slip of the screw, which acts to retard the forward
movement of the vessel; and, second, the working of the screw in a current formed
by its own slip, whereby its efficiency is decreased in proportion to the velocity of
the water before it enters the screw.
The main feature of my Invention consists in a screw or equivalent device
arranged to move the water transversely to the line of movement of the vessel
and direct it against or away from inclined surfaces of the hull so as to drive the
vessel forward or backward.
The said Invention is illustrated in the accompanying Drawing, in which
Figure 1 is a side elevation of a vessel provided with my improvement, the
screws being entirely submerged at one end of the vessel, and only partially
submerged at the other end.
Figure 2 is a plan or top view of the same, and
Figures 3 and 4 illustrate an application of my improvements to the bow or
stern of a vessel.

page_text: In Figures 1 and 2, A and B represent two pairs of screws, the screws of each
pair being connected by their respective shafts or axis a and b extending across
the vessel and provided with cranks c and d to which the power is applied. The
pitch of the screws A and B upon the one side of the vessel is opposite or opposed
to their pitch upon the other side of the vessel, that is to say, their pitch is so
arranged that the screws acting upon one side of the vessel will throw or propel
the water in a different and opposite direction to that in which the screws acting
upon the opposite side of the vessel will throw it, and the water passed through
the screws will be moved or propelled transversely to the line of the movement of
the vessel.
If the screws B are revolved so as to throw the water passed through them away
from the vessel, the vessel will move to the right, as looked at in the Drawing, this
movement being caused by the diminution of the pressure of the water upon the
inclined surfaces S, S, of the hull adjacent to the screws B; if the screws B are
revolved in the opposite direction, so as to throw the water passed through them
against the inclined surfaces of the hull, the movement of the vessel will be to
the left, as looked at in the Drawing, this movement being caused by the
impingement of the water passed through the screws against the inclined surfaces
of the hull, thus increasing the pressure upon the inclined wedge-shaped portions S, S,
of the hull adjacent to the screws.
If both pairs of screws A and B work in unison so that one pair diminishes the
pressure against the inclined surfaces S¹, S', at the forward end of the hull, and
the other pair increases the pressure against the inclined surfaces at the after end,
the vessel will move forward with a speed due to the power applied.
Figures 3 and 4 show the manner of applying the same principle to the bottom
of a vessel at either the bow or storn, or both, with a screw or screws having
vertical axes, C representing the screw and e its shaft or axis, and S the inclined
propelling surface of the hull. In this application the movement of the water will
be substantially vertically transverse to the line of movement of the vessel,
that is to say, the water will be moved upward or downward instead of
horizontally transverse, as is the case when the shaft or axis is horizontal, as
shown in Figures 1 and 2.
In the application shown in Figures 1 and 2, wings or skegs f.f, may be
attached to the bull and extended laterally therefrom beneath the screws or wheels
for the purpose of turning the course of the water, which may be thrown downward,
and directing it against the inclined propelling surfaces, and thus prevent loss of
power. So in the application shown in Figures 3 and 4 wings or skegs g, g, may
be placed on each side of the screw or wheel to prevent the lateral escape of the
water and direct it against the inclined surface of the hull.
It is evident that the axes of the screws may be applied at any angle between
the vertical and horizontal positions shown in the Drawing, it being essential that
the pitch of the screws and their arrangement on their shafts be such as to move
the water transversely to the line of movement of the vessel, and that the
arrangement of the screws and the inclined surfaces of the hull be so related to
each other that the increase of pressure of the water shall be against the inclined
surfaces which converge towards the fore and aft line of the vessel at the end
opposite the direction in which she is moving, and the decrease of pressure of the
water shall be against the inclined surfaces which converge towards the fore and
aft line at the end of the vessel, which points in the direction of her movement.
From the above description it will be seen that the inclined surfaces of the hull
of the vessel when acted upon by the water thrown against or drawn away from
them by the transverse action of the screw or equivalent device, become the
the vessel
propelling surfaces or means by which, in conjunction with the screw,
is moved either forward or backward; the transverse action of the screw alone has
no tendency to move the vessel in either of the directions named.
Although I have only shown in the Drawing screws arranged upon shafts or
axes substantially at right angles to the line of movement of the vessel as the

page_text: preferable construction, I do not limit myself to such precise arrangement of the
shafts, as it is evident that the position of the shufts can be considerably varied
from that shewn, and substantially the same results produced, by varying the
angle of the propelling surfaces of the hull, or the pitch of the blades of the screw,
or both. Neither do I confine myself to the use of screws for throwing the water
against or drawing it away from the inclined propelling surfaces, as it is evident
that other equivalent devices may be used for this purpose, as for instance,
sculling blades or paddles so constructed and arranged as to throw the water
against or draw it away from such propelling surfaces.
It is evident without further explanation that in the arrangement above
described of propelling devices and inclined propelling surfaces the loss of power
referred to at the beginning of this Specification will be largely reduced, inasmuch
as any suction occasioned by drawing the water away from the inclined surfaces of
the hull, whether at the prow or stern thereof, will act as a propelling and not as
a retarding force; also, inasmuch as the action of the screws in this arrangement
is transverse to the line of movement of the vessel, the screws will constantly take
hold of comparatively still water, that is to say, water whose velocity towards the
screws is far less than in the case of screws acting on the line of movement of the
vessel, or in lines parallel thereto.
It is also evident that with the arrangement above described long screw-shafts
can be dispensed with, and that each scrow or pair of screws may be driven from
a separate engine. By partially submerging the screws, as shown at A in Figuro 1,
and giving them sufficient diameter, the friction of the blades in the water may be
in great part converted into propelling force; also the shaft may be brought abovo
the water line and made more accessible. This form of side screw is well adapted
to shoal water. It is important that the wedge-like ends of the hull should be of
such form as to best utilize the impact of the water. A hollow curve gradually
approaching the centre fore and aft lino of the vessel is the best, although straight
inclined surfaces will produce substantially the saine results; also the ends of the
hull should extend far enough beyond the screws to ensure the full effect upon the
hull of the inomentum of the water put in motion by the screws.
This method of screw propulsion is particularly adapted for application to
canal boats.
Having thus fully described the said Invention, as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim,-
The method of propelling vessels by means of the combination substantially as
described of a screw or its equivalent, arranged to move the water transversely to
the line of movement of the vessel, and an inclined propelling surface of the hull
for receiving the increase or decrease of pressure produced by such movement of
the water, such surface being inclined to or at an angle with the fore and aft line
or line of movement of the vessel, whereby the latter will be driven in ono
direction by throwing the water against such inclined surface, and in the opposito
direction by drawing it away from such inclined surface.
In witness whereof, I, the said William Robert Lake, havo hereunto set my
hand and seal, this Twenty first day of February, in the year of our
Lord One thousand eight hundred and eighty two.