IMPROVEMENTS IN TWIN- SCREW SHIPS OR VESSELS."
Year: 1882

page_text: LETTERS PATENT to Thomas Ridley Oswald, of the Town and County of
Southampton, Ship Builder, for an Invention of "IMPROVEMENTS IN TWIN-
SCREW SHIPS OR VESSELS."
PROVISIONAL SPECIFICATION left by the said Thomas Ridley Oswald at
the Office of the Commissioners of Patents on the 9th February 1882.
THOMAS RIDLEY OSWALD of the Town and County of Southampton, Ship
Builder. "IMPROVEMENTS IN TWLN SCREW, SHIPS OR VESSELS."
My Invention has for object improvements in twin screw ships or vessels and
relates more especially to twin screw ships or vessels of the kind described by me
in the Provisional Specification of my application for Letters Patent dated
24 October 1881 and numbered 4647,--but is applicable to twin screw ships and
vessels of other build or construction than the one above referred to.
In a twin screw ship or vessel I provide according to my present Invention
apertures or frames for the reception of the screws, so situated that the said screws
may revolve in the same vertical plane, or in planes one of which is more forward
than the other in relation to the ship. When I construct a twin screw ship or
vessel with two tails, I arrange these tails at any distance apart that I find
convenient, or suitable to the build of the vessel, and I cut away the dead wood of
each, as far forward as the point where they unite, in such a way that for a part
or the whole of the distance the said dead-wood does not extend or project below
the level of the screw boss.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas Ridley Oswald in the Great Seal Patent Office on
the 9th August 1882.
THOMAS RIDLEY OSWALD of the Town and County of Southampton, Ship
Builder. "IMPROVEMENTS IN TWIN SCREW SHIPS OR VESSELS."
My Invention has for object improvements in twin screw ships or vessels and
relates more especially to twin screw ships or vessels of the kind described by me
in the Provisional Specification of my application for Letters Patent dated
24 October 1881 and numbered 4647, but is applicable to twin screw ships and
vessels of other build or construction than the one above referred to.
In a twin screw ship or vessel I provide according to my present Invention
apertures or frames for the reception of the screws so situated that the said screws
may revolve in the same vertical plane or in planes one of which is more forward
than the other in relation to the ship. When I construct a twin screw ship or
vessel with two tails I arrange these tails at any distance apart that I find
convenient or suitable to the build of the vessel and I cut away the dead wood of
cach as far forward as the point where they unite in such a way that for a part or
the whole of the distance the said dead wood does not extend or project below the
level of the scrow boss.
Referring to the accompanying Sheet of Drawings, Fig. 1 represents in side
elevation a twin screw ship or vessel embodying my Invention.
Fig 2 is a part horizontal section-of-the-same in line a b_of_Fig 1.
Fig 3 is a stern or end view of the ship or vessel.
Fig 4 is a vertical transverse section in line c d of Fig 1.
A A¹ are two screws each rotating within a frame B: CC are two rudders each
pivotted to one of the frames B. These two frames are connected together by a
stay D (or otherwise), which serves to steady them. In the Drawing the two screws
are shown in the same vertical plane, and their shafts on the same horizontal plano,
but I sometimes find it convenient to place them in vertical planes one before the
other, in which case I modify one of the frames B accordingly, or I place one
frame further forward than the other. Thus either one aperture is longer than the
other to an extent equal to the distance that the one screw is to be before the other;
or else the one aperture is placed at such a distance behind or before the other
aperture. When I adopt this arrangement I can place the screw shafts nearer
together than as shewn in the Drawings, or if I keep them at the same distance
apart I can employ larger screws.
The Drawings shew a vessel with two tails joined together by a single upper
stern forming a continuation of the main body or bull of the boat. When I apply
my Invention to a boat or vessel of this description I cut away a part of the dead
wood of each tail E as in Fig 1 where they join with each other and with the keel
at the point F so that the screws work, as regards the lower halves of their
effective acting surfaces in solid water.
Having thus described the nature of the said Invention and the manner in
which it is to be performed I would have it understood that what I consider to be
novel and original and therefore claim as secured to me by the Letters Patent
hereinbefore first in part recited is :-
1. In a twin screw ship or vessel arranging the two screws in planes one
behind the other with respect to the ship or vessel substantially as described.
2. In a twin screw ship or vessel having two tails, forming oach tail in such
wise that the effective acting portion of each screw blade, in its lowest position,

page_text: shall project below the afterpart of the dead wood of the corresponding tail but
not below the keel line of the vessel substantially as described, forming what I
prefer to call "fish tails."
In witness whereof I the said Thomas Ridley Oswald have hereunto set my
hand and seal this Fifth day of August in the year of our Lord One
thousand eight hundred and eighty two.
(S) ASO LAW SYWORT