An Improved Screw Propeller for Ships, Launches, Yachts, Barges, Wherrys, Tugboats, or other Vessel requiring its Use.
Year: 1887

page_text: Date of Application, 14th Mar., 1887.
Complete Left, 11th July, 1887.
Complete Accepted, 26th Aug:, 1887.
An Improved Screw Propeller for Ships, Launches, Yachts, Barges,
Wherrys, Tugboats, or other Vessel requiring its Use.
MICHAEL SCARTH Chemist etc. 4 Fern Avenue Southwick Sunderland and THOMAS
HENRY SCARTH Ship Draughtman 18 Ogle Terrace Southwick Sunderland do hereby
declare the nature of this invention to be as follows:-
An Improved Screw propeller consisting of six Blades or fans three large and
three smaller same breadth and fixed transversely across Boss the thickness of Blade
to be made according to circumstances required to be manufactured of any kind of
Metals or mixture of Metals or other composition or paper.

page_text: An improved Screw Propeller for Ships, Launches, Yachts, Barges,
Wherrys, Tug Boats, or other Vessel requiring its Use.
We MICHAEL SCARTH of 4 Fern Avenue in the Township of Southwick
Sunderland in the county of Durham Chemist &c. and THOMAS HENRY SCARTII
of 18 Ogle Terrace in the Township of Southwick aforesaid Ships draughtsman do
hereby declare the nature of this invention for Ax IMPROVED SCREW PROPELLER
FOR SHIPS LAUNCHES YACHTS BARGES WHERRYS TUG BOATS OR OTHER VESSELS
REQUIRING ITS USE and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statenient :-
Our improved screw-propeller is constructed with two sets of blades. The blades
forming one set being shorter than those forming the other set. The small blades are
fixed on the boss of the propeller between the large ones a large blade and a small
one being fixed alternately.
The number of blades in each set may consist of two or more.
The length of the small Blades, relatively to the large ones may vary according to
circumstances and the small blades may be either all the same length or of two or
more different lengths.
The breadth of the small blades may be either the same as or different from that of
the large blades. The small blades are fixed transversely across the boss simularly to
the large ones but the possition and the angle at which they are so fixed to the boss
may be varied from the position and angle of the large blades. The amount of pitch
accorded to the blades composing each set respectively may vary so that the pitch
of the small blades may be greater than that of the large ones, also the amount of
pitch accorded to the small blades severally may vary according to the respective
lengths or otherwise of the small blades.
The blades may be made to such sweep and thickness as by circumstances may be
required.
The propeller may be manufactured of any suitable kind of metal or mixture of
metals or alloy or of any suitable kind of composition.
In the accompanying sheet of Drawings Fig. 1 is a front elevation of a screw
propeller constructed according to our invention with three large and three blades,
Fig. 2 is a side elevation of a large and short blade and Fig. 3 is a side elevation of
Fig. 1. Similar letters of reference denote similar parts throughout the drawings.
A. B. C. are three large blades and D E F are three small blades placed alternately
between the blades A B C on the propeller boss H although three blades are shown it
will be understood as herein before explained, that we do not confine ourselves to such
particular number nor to the relative pitch or pitches and demensions of the blades as
set forth in the drawings, provided that in all cases large and small blades are arranged
alternatively round the central boss.
Our Invention may obviously be applied to existing screw propellers by affixing
suitably formed short blades between and alternatively with the existing long blades.
The main advantages which we obtain by the use of our improved screw propellers
are that more power will be gained by having a larger surface of inclined plain or

page_text: blade acting on the water that the small blades will take effect upon the water which
in case of an ordinary propeller passes the blades near the boss and is heaped up behind
the rudder above the level of the surrounding water and practically wasted thus giving
our propeller a grip upon the water; that vessels fitted with our improved propeller
will in consequence obtain increased speed, and can be started and stopped more
quickly and easily thus lessening the difficulty or danger attendant on entering or
quiting of harbours and Docks, or navigating narrow or Intricate channels that the
amount of vibration in the vessel will be greatly lessened particularly in the event of
a blade being broken off; and that these advantages will effect a saving in fuel time
and money and tend to the avoidance of collisions with their accompanying damage
to the vessels and frequently loss of life.
Having now particularly described and ascertained the nature of our of our said-
invention and in what manner the same is to be performed, we declare that what we
claim is;
(1.) A screw propeller constructed with large and short blades arranged alternately
round the central boss substantially as herein set forth.
(2.) A screw propeller constructed with large and short blades arranged alternatively
round the central boss in which the breadth of the short blades is equal to or greater
than the breadth of the large blades.
(3.) A screw propeller constructed constructed with large and short blades arranged
alternatively round the central boss in which the pitch of the short blades is equal to
or greater than the pitch of the large blades.
(4.) A Screw propeller constructed with large and short blades arranged alter-
natively round the central boss in which the short blades are arranged on the boss in a
position simular to that of the large blades or in a position or positions differing from
that of the large blades according to the variation or variations (if any) of the
breadth or length or amount of pitch or different breadths or length or amounts of
pitch of the small blades either among themselves or relatively to the large blades.
(5.) The combination with an ordinary screw propeller of short blades affixed to
the boss alternately with the ordinary long blades, substantially as herein set forth.
(6.) The improved screw propeller constructed substantially as herein described and
shown with reference to the accompanying drawings.
Dated this 9th day of July 1887.