Improvements in Paddle Wheels for vessels
Year: 1886

page_text: I, ALFRED TOWNSEND ELFORD, of 920 Folsom Street, City and County of San
Francisco, State of California, United States of America, Engineer, 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 Improvements in Paddle Wheels for steam vessels and
consists in a certain device by which all beating and splashing is avoided and a
constant and equal pressure is given upon the water and the full force expended by
the wheel upon the water is utilized for the propulsion of the boat at whatever
speed the same may be running-It is also calculated to avoid the agitation of the
water which is so objectionable in the navigation of narrow channels where the
embankment is liable to injury-It will be fully understood by reference to the
accompanying drawing and the letters marked thereon.
Fig. 1 is a perspective elevation showing the general construction of the wheel.
Fig. 2 is a plan view showing a vessel hull and the two side wheels.
Fig. 3 is a plan view showing a diagram of the paddle before twisting to adapt
it to the periphery so that at each point it shall stand perpendicular to the axis.
Fig. 4 is a cross sectional view showing the form of the paddle.
Fig. 5 is a side elevation of a vessel hull with my improved paddle-wheel
attached.
'
The following is the construction of the same I form the shaft and journals the:
same as those of the ordinary steamer wheels but I arrange the arms spirally so that
while each portion of the paddle stands perpendicular to the axis of the wheel, the
outer line or that portion of the paddle which extends to the periphery, crosses
the same at an angle of about forty-five degrees diagonally from side to side.
I form the paddles with rounded edges so as to give the outer edge the general
form, of a long round-bottomed boat hull twisted to conform to the periphery of
the wheel and is designed to cleave the water with the least possible friction. The
end of the paddle is formed to pass into water as the bow of a boat passes through
the water.
The sectional view shown in Fig. 4 represents the paddle cut transversely-The
object of rounding off the inner edge of the paddle-board is to prevent the same
from lifting water by allowing it to run off freely.
The following is the operation of my improved paddle-wheel -The paddles C
and D shown on the wheel A in figures 1 and 2, represent the angle at which they
are placed across the face of the wheel in order to give the best effect. It will be

page_text: seen that the wheels A and B shown in Fig. 2, being revolved in a forward
direction, the water is thrown in toward the hull of the vessel and backward (as
will be more fully explained).
In Fig. 1 which is a front elevation of the wheel A, the outer ends of the paddles
are designated by the letter a showing a thin sharp form like the bow of a boat
and as the wheel is revolved with a forward motion, the point a enters the water
first and the whole paddle is gradually passed through the water, the point b leaving
the same last, while the next paddle is entering at a.-Thus the pressure is at all
points kept about equal.
The force of the paddles against the water is applied in the same manner as the
force of the sail of a vessel is applied in propelling a vessel and whatever side
motion is given to the water is applied to the side of the vessel. Therefore the
best effect is had by placing my wheel nearer the stern of the vessel where the
wave line approaches the center or keel thus forcing the boat forward by the equal
pressure from both sides-The water heaped against the sides of the rear part of
the boat has a constant tendency to raise the rear end of the vessel, thus aiding in
the forward propulsion of the same. The action of the wheels in drawing in toward
the sides and stern of the vessel tends to neutralize the bow swell-Another effect
is seen in the fact that when the vessel has a rapid motion and the water cannot
be returned to the wave line of the boat by the specific gravity of the same, it
freely supplies the imperfection of the same or the want of adaptation of the wave
line and supplies an increased power at that point to aid the propulsion of the boat
at any practical speed which may be given to the vessel.
t.
Modifications of the construction of the paddles A and B will be requisite when
applied to the stern-wheel boat, or to that class of vessels known as double
enders.
The advantages of my improved wheel are realized in the navigation of shallow
waters, in the fact that the water is thrown towards the vessel instead of being
pawed away from it, as is the case when the common paddle wheel is employed.
When a vessel is barely floating clear of the ground, a little water drawn away
from the sides of the same by the wheels, lets it down hard upon the ground.-
While my wheels being employed, would heap the water against the side of the
hull and raise it entirely free so as to allow it to be moved along.
I do not confine myself to an exact form of paddle as it may be varied in form
without changing the principle of its operation-But 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
First. The paddle wheels A and B, having paddles set diagonally across the
face for the purpose of preventing the agitation of the water, constructed and
operated substantially as and for the purposes set forth.
Second. The paddles C, and D, sharpened at the ends, and rounded on the edges
for the purpose of avoiding friction in passing through the water, constructed and
operated substantially as and for the purposes set forth.
Third. The paddles C, and D, set diagonally across the face of the wheel to form
an extra bracing and give elasticity to the wheel.
Dated this 16th day of December 1885