Improvements in Screw Propellers.
Year: 1893

page_text: Date of Application, 21st Apr., 1893
Complete Specification Left, 22nd Jan., 1894-Accepted, 24th Feb. 1894
PROVISIONAL SPECIFICATION.
Improvements in Screw Propellers.
I, GAVIN CHAPMAN of The Athenæum Glasgow in the County of Lanark
Chemist do hereby declare the nature of this invention to be as follows:-
This invention has for its object improvements in screw propellers and under it
the blades of which any desired number may be employed may either be screwed
as usual or be composed of plain or flat plates. In either case they are of approxi-
mately triangular shape the narrower end being at the boss and they are set upon
the boss at or about an angle of 45 degrees to the longitudinal axis of the propeller
shaft.
The outer edge of each blade is or may be almost a straight line rounded at the
ends and the leading corner of each blade that is to say the part of the outer edge
which first enters the water when the vessel is going ahead is curved or bent astern
until it is in the same vertical plane as the forward end of the boss of the
propeller.
By this construction with an equal expenditure of power a considerable access of
speed is obtained.
Dated this 20th day of Anril 1893.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.
COMPLETE SPECIFICATION.
Improvements in Screw Propellers.
I, GAVIN CHAPMAN of The Athenæum, Glasgow in the County of Lanark,
Chemist, 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 :--
This invention has for its object improvements in screw propellers and under it
the blades, of which any desired number may be employed, may either be screwed
as usual or be composed of plain or flat plates.
As illustrated in front elevation at Figure 1 and in plan at Figure 2 of the
accompanying drawings the blades a are of approximately triangular shape the
narrower end b being at the boss c and they are set upon the boss at or about an
angle of 45 degrees to the longitudinal axis of the propeller shaft d.
The outer edge e of each blade is or may be almost a straight line rounded at the
ends and the leading corner fof each blade that is to say the part of the outer edge
which first enters the water when the vessel is going ahead is curved or bent astern
as shewn particularly at Figure 2 until it is in the same vertical plane as, or a plane
parallel to or approximately parallel to, the forward end of the boss of the propeller
that is to say until a tangent drawn from the edge of the curve falls in the same
vertical plane or a plane parallel to or approximately parallel to the forward end
of the propeller boss.
By this construction with an equal expenditure of power a considerable access of
speed is obtained.
Under a modification illustrated in front elevation by Figure 3 and in plan at
Figure 4 the blades instead of being of triangular are of rectangular form.

page_text: 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 :-
A screw propeller constructed substantially as described with reference to the
several figures upon the drawings hereunto annexed.
Dated this 19th day of January 1894.
CRUIKSHANK & FAIRWEATHER,
62, St. Vincent Street, Glasgow, Agents.