Improvements in the Construction and Propulsion of Iron and Steel Ships.
Year: 1890

page_text: Date of Application, 10th July, 1890
Complete Specification Left, 10th Apr., 1891-Accepted, 23rd May, 1891
PROVISIONAL SPECIFICATION.
Improvements in the Construction and Propulsion of Iron and
Steel Ships.
I JAMES SIMPSON of 8ª Rumford Place Liverpool in the County of Lancaster
Manufacturer do hereby declare the nature of this invention to be as follows:-
It is well known that in the propulsion of steamships by means of screw propellors
a great deal of power is lost-it being estimated by competent authorities that only
about () one third of the power developed in the cylinders of the engines is
delivered by the screw in direct propulsion. A large amount of this loss is due to
the friction of the screw blades in passing through the water-besides that of the
shaft bearings-but there is also a very considerable loss owing to "slip." In addition
to this the resistance caused by the skin friction of the immersed portion of the
vessel has to be overcome as well as the augmented friction caused by the suction
of the screw.
This latter alone is estimated under certain circumstances to amount to 40 per cent.
of the total skin resistance.
It is manifest that if means can be devised whereby the power available for pro-
pulsion can be brought into more direct contact with the surrounding water so as to
get a better purchase on it than can be got by means of a screw the loss due to
slip" will be reduced and a still more important economy will be effected if a
method can also be devised either to do away with skin friction altogether or to
greatly diminish it.
66
My invention aims at accomplishing both these objects in a simple and efficient
manner where not only will a great economy be effected in marine propulsion,
but much higher speeds will be attainable than can be got by either screw or
paddle.
For this purpose I preferably construct the vessel with a double bottom as a
reservoir or distributor for the water or air used for propulsion placed over that
part of the immersed portion of the vessel where the propelling fluid, water or air
being preferred, is to be ejected-say for about to the length of the vessel from
the stern. The top of this double bottom rests on a number of fore and aft girders
which are substituted for flooring plates, not only for the purpose of giving free
passage to the propelling medium but also to compensate for the weakening of the
shell of the vessel by the cutting of orifices in it for ejecting the water or air
employed for propulsion. Where the size of the vessel is too small for a false
bottom a box keelson of sufficient size may be substituted. These orifices are as
low down in the water as possible extending quite across the flat of floor amidships
and towards the bow as far as the shape of the vessel will permit without coming too
near the surface of the water. They are placed at such distances apart that by the
time the ejected fluid reaches the orifice behind it, it shall have exhausted its energy
or speed to somewhere about or rather less than the speed of the vessel. These orifices
are designed to send a film of water or air a few inches in thickness (for moderate
sized vessels) along the submerged portion of the vessel at sufficient pressure and
of sufficient aggregate area as to propel the vessel at the intended speed. By
having a series of films discharged under sufficient pressure along the skin of the
vessel the numerous points of contact with the surrounding water will give a better
purchase than can be got by means of a screw-while the reaction of the water or
compressed air on the surrounding medium will neutralize the retarding action of
skin friction.
The orifices for ejecting the propelling fluid may be made by cutting the shell

page_text: of the vessel athwartship and bending the forward edge downward or the after edge
upward.
As the portion between the frames would be filled with cement-the risk of
osing power in the case of compressed air-by the abstraction of heat would be
minimised.
The pressure at which the water or air is delivered must be sufficient to over-
come the head of water due to the draft of the vessel and also to propel the vessel
at the required speed.
COMPLETE SPECIFICATION,
Improvements in the Construction and Propulsion of Iron and
Steel Ships.
I JAMES SIMPSON of 8ª Rumford Place Liverpool, in the County of Lancaster,
Alkali Manufacturer do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :-
It is well known that in the propulsion of steamships by means of screw pro-
pellors a great deal of power is lost-it being estimated by competent authorities
that only about one third of the power developed in the cylinders of the engines is
delivered by the screw in direct propulsion. A large amount of this loss is due to
the friction of the screw blades in passing through the water-besides that of the
shaft bearings-but there is also a very considerable loss owing to "slip." In
addition to this, the resistance caused by the skin friction of the immersed
portion of the vessel has to be overcome as well as the augmented friction caused
by the suction of the screw. This latter alone is estimated under certain circum-
stances to amount to 40 per cent. of the total skin resistance.
It is manifest that if means can be devised whereby the power available for pro-
pulsion can be brought into more direct contact with the surrounding water so as
to get a better purchase on it than can be got by means of a screw-the loss due to
"slip" will be reduced, and a still more important economy will be effected if a
method can also be devised either to do away with skin friction altogether or to
greatly diminish it.
My invention aims at accomplishing both these objects in a simple and efficient
manner whereby not only will a great economy be effected in marine propulsion,
but much higher speeds will be attainable than can be got by either screw or
paddle.
For this purpose I preferably construct the vessel with a double bottom as a
reservoir or distributor for the water, air, steam, or other fluid used for propulsion
placed over that part of the immersed portion of the vessel where the propelling
fluid is to be ejected-say for about one half to three fourths the length of the vessel
from the stem or bow. The top of this double bottom rests on a number of fore
and aft girders which are substituted for flooring plates not only for the purpose of
giving free passage to the propelling medium but also to compensate for the
weakening of the shell of the vessel by the cutting of the orifices in it for ejecting
the water, air, steam, or other fluid employed for propulsion. Where the size of
the vessel is too small for a false bottom, a box keelson or a series of box keelsons
of sufficient size may be substituted. These orifices are as low down in the water as
possible extending quite or almost-across the flat of floor amidships, and towards
the bow as far as the shape of the vessel will permit without coming too near the
surface of the water. They are placed at such distances apart that by the time

page_text: the ejected fluid-reaches the orifice behind it, it shall have exhausted its energy or
speed to somewhere about or rather less than the speed of the vessel. These
orifices are designed to send a film of water, air, steam, or other fluid of a few inches
in thickness (for moderate sized vessels) along the submerged portion of the vessel
at sufficient pressure and of sufficient aggregate area to propel the vessel at the
intended speed. By having a series of films discharged under sufficient pressure
along the skin of the vessel-the numerous points of contact with the surrounding
water will give a better "purchase" than can be got by means of a screw-while
the reaction of the water or compressed air, steam or other fluid on the surrounding
medium will neutralize the retarding action of skin friction.
The orifices for ejecting the propelling fluid may be made by cutting the shell
of the vessel thwartship and bending the forward edge downward-or the after edge
upward, preferably the latter.
As the portion between the frames would be filled with cement, the risk of
losing power in the case of compressed air by the abstraction of heat would be
minimised.
The pressure at which the propelling fluid is delivered must be sufficient to over-
come the head of water due to the draft of the vessel and also to propel the vessel
at the required speed.
In the term propelling fluid I include water, steam compressed air, a mixture of
compressed air and steam, as also the products of the combustion of a hydrocarbon
with air or with air and steam.
DESCRIPTION OF THE DRAWINGS.
Fig. 1. is a transverse section, Fig. 2 a longitudinal section and Fig. 3 a plan of a
vessel constructed in accordance with my invention. a shell of vessel made with a
double bottom bb', the double bottom is connected to fore and aft girders c, so that
the space between is divided into a number of ways for the flow of the propelling
fluid. d, d', orifices through which the propelling fluid is ejected. At d, the orifices
are made by bending the forward edge downward, at 7, by bending the after edge
upward. Any suitable engine for propelling fluid is used to force water, air or
other suitable fluid into the space between the double bottom and out of the
orifices.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
First. The method herein described for propelling ships by means of a series
of films of water air steam, or other fluid extending across the greater forward
portion of the submerged portion of the hull-at sufficient pressure to both propel the
vessel and to neutralize skin friction.
Second. The employment of a double bottom constructed as described for the
purpose of storing and distributing the propelling medium.
Third. The method described of constructing the orifices in the shell of the vessel
for ejecting the propelling medium.
Fourth. The employment of fore and aft girders in combination with the double
bottom to compensate for the weakening of the shell of the vessel as described.
Dated the 9th day of April 1891.
Per pro J. T. KING,
J. Johnson,
Agent.