IM- PROVEMENTS IN THE CONSTRUCTION OF STEAM AND SAILING SHIPS, YACHTS, AND BOATS
Year: 1871

page_text: LETTERS PATENT to James Macpherson, of the City and County of
Aberdeen, North Britain, Engineer, for the Invention of "IM-
PROVEMENTS IN THE CONSTRUCTION OF STEAM AND SAILING SHIPS, YACHTS,
AND BOATS."
Sealed the 19th December 1871, and dated the 12th August 1871.
PROVISIONAL SPECIFICATION left by the said James Macpherson
at the Office of the Commissioners of Patents, with his Petition,
on the 12th August 1871.
I, JAMES MACPHERSON, of the City and County of Aberdeen, North
Britain, do hereby declare the nature of the said Invention of "IMPROVE-
MENTS IN THE CONSTRUCTION OF STEAM AND SAILING SHIPS, YACHTS, AND BOATS,"
to be as follows, that is to say:
-
This Invention relates to improvements in the construction of ships
or vessels propelled either by steam or the action of the wind upon sails,
but may also be applied to yachts and boats, and is more especially
adapted for screw propulsion; it consists in forming the hull with two

page_text: keels extending its entire length, the keels converging together at the
bows, and diverging from each other at the stern, thus producing a
continuous hollow between the two keels, into the stern end of which
(in the case of ships, vessels, yachts, or boats being propelled by a screw
propeller) the screw is placed, so that it rotates in the space between
the two keels.
The effect of this arrangement is that whilst increased steadiness is
given to the ships, vessels, or boats so arranged, the efficiency of the
screw propeller is increased by reason of the two keels confining the
water set in motion between them, thus preventing the water from being
scattered in an angular direction to so great an extent as obtains under
existing arrangements of screw propulsion. Each of the keels is fitted
with a rudder, and the rudders may be connected together by linkwork
so as to work conjointly, or they may be actuated separately.
In the case of ships, vessels, yachts, or boats propelled by sails the
construction is the same as that herein-before set forth, excepting that
the screw propeller is dispensed with.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said James Macpherson in the Great Seal Patent
Office on the 12th February 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
MACPHERSON, of the City and County of Aberdeen, North Britain,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twelfth day of August, in the year
of our Lord One thousand eight hundred and seventy-one, in the
36th year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said James Macpherson, Her special license
that I, the said James Macpherson, my executors, administrators,
and assigns, or such others as I, the said James Macpherson, my
executors, administrators, or assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during the
term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS

page_text: IN THE CONSTRUCTION OF STEAM AND SAILING SHIPS, YACHTS, AND BOATS," upon
the condition (amongst others) that I, the said James Macpherson, by
an instrument in writing under my hand and seal, should particularly
describe and ascertain the nature of the said Invention, and in what
manner the same was to be performed; and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and
immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said James Macpherson, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement, reference being had to the accompanying
Drawings, and to the letters and figures marked thereon, that is to say :-
My said Invention relates to improvements in the construction of
ships or vessels propelled by steam, that is to say, either by a screw
propeller or paddle wheels, or by the action of the wind upon sails, but
it may also be applied to yachts and boats, it is, however, more especially
adapted for screw propulsion, and consists in forming the hull with two
keels extending its entire length, the keels converging together at the
bow and diverging from each other at the stern; but in the construction
of ferry boats, where it may be desirable to have both ends formed alike
and with a rudder or helm and screw propeller at each end in order
that the boat may by merely reversing the engines be driven with either
extremity foremost the two keels are placed parallel to each other; thus
a continuous hollow is produced between the two keels, into the stern
end of which (in the case of ships, vessels, yachts, or boats, being pro-
pelled by a screw propeller) the screw propeller is placed so that it
rotates in the space between the two keels at that part where the said
hollow or space is widest, and thus allows a propeller of greater diameter
to be employed than can with facility be used in vessels as hitherto
constructed. The effect of this arrangement is that whilst increased
steadiness is given to ships, vessels, yachts, or boats so arranged the
efficiency of the screw propeller is increased by reason of the two keels
confining the water set in motion between them, thus preventing the
water from being scattered in an angular direction to so great an extent
as obtains under existing arrangements of screw propulsion. The
opening between the keel at the bows being narrower than towards the
stern prevents more water from entering the hollow than can find an

page_text: easy course along the channel towards the stern, where the body of
water is supplemented from below in order to give a full supply to the
propeller, as at this point the discharge is always somewhat higher than
the surrounding level. Each of the keels may be fitted with a rudder,
and the rudders may be connected together by linkwork so as to work
conjointly, or they may be actuated separately, or in place of using twin
rudders a single rudder may be employed. In the case of ships, vessels,
yachts, or boats propelled by sails, the construction is the same as that
herein-before set forth, excepting that the screw propeller is dispensed
with, and an important result arising from constructing ships, vessels,
yachts, or boats in the manner herein before described is that greater
steadiness of the ships, vessels, or yachts is thereby obtained, as well as
fine water lines without an undue extension of length or the sacrifice of
cargo capacity. Another advantage accruing from this Invention is that
in the case of ships, vessels, yachts, or boats propelled by screw propellers,
the propeller being fully protected by the two keels is kept safe from
injury from loose floating materials, dock entrances, or walls, or the
banks of canals, whilst at the same time in the case of vessels constructed
for canal navigation, the two keels prevent damage to the banks by
confining between them the surge caused by the operation of the screw.
And in order that my said Invention may be properly understood, I
now proceed more particularly to set forth the system, mode, or manner
in or under which the same is or may be used or practically carried into
effect, that is to say,-
On the Sheet of Drawings hereunto appended, Figure 1 is a longi.
tu inal section of a ship or vessel represented as being propelled by
means of a screw propeller A; Figure 2 is an inverted plan thereof or
looking from the keels upwards; whilst Figure 3 is an elevation of the
stern end of the same.
On these several Figures the improvements which constitute this
Invention are illustrated, and they consist in constructing the hull of
the ship or vessel with two keels B, B, extending throughout its entire
length. The kecls B, B, converge together towards the bows C of the
ship or vessel and diverge from each other towards the stern D, as more
particularly seen in plan at Figure 2. Thus a continuous hollow space E
is produced in the bottom of the ship or vessel between the two keels
B, B, and at the stern end of this hollow space E, the screw propeller A

page_text: is situated as shewn so as to rotate between the two keels B, B. By
means of this arrangement increased steadiness in sailing is given to
ships or vessels and the efficiency of the screw A as a propeller is
increased by the two keels B, B, confining between them the water set
in motion by the action of the screw propeller A, thereby preventing the
water from being scattered in a direction angular to the vessel's course
to so great an extent as obtains under existing arrangements of ships or
vessels propelled by screws.
At the stern end the keels B, B, are or
may be tied together by means of a stay bar a, more particularly seen
at Figures 2 and 3, at the centre of which another bar or post b, Figures
1 and 2 is situated, the lower end of which is secured to the bar a, and
its upper extremity to the overhanging portion of the stern of the ship
or vessel as shewn at Figure 1. The helm or rudder F is secured to the
post b, and the pivot x, at its lower extremity on which it turns, rests on
the stay bar a, as shewn at Figures 1 and 3, or in lieu of this arrange-
ment each keel may be furnished with a rudder or helm as shewn at
F, F, on the stern end elevation Figure 4, and by the diagram plan
Figure 5. Under the arrangement shewn at Figures 4 and 5 the
rudders F at their upper ends are connected by links c, c, to opposite
extremities of a lever d, centred on a stud fixed to the deck of the vessel,
as shewn, by which means a parallel motion conjointly of the rudder is
obtained or the rudders F, F, may be actuated separately. It is to be
here understood that the improvements constituting this Invention are
equally applicable to ships or vessels built of wood, iron, or a com-
position of both, and to yachts or boats as well as to larger ships or
vessels, and in the case of ships, vessels, yachts, or boats propelled by
the action of the wind upon sails the construction is the same as that
herein-before described and illustrated upon the appended Sheet of
Drawings, excepting that the screw propeller is dispensed with. The
construction of ships, vessels, yachts, or boats is also the same in cases
where propulsion by paddle wheels is employed.
Having now described the nature of my said Invention, and the system,
mode, or manner in or under which the same is or may be used or
practically carried into effect, I would observe in conclusion that what
I consider novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent is,
the construction of ships, vessels, yachts, or boats with twin keels
which converge at the bows and diverge at the stern as herein-before

page_text: described and shewn upon the annexed Sheet of Drawings, or any mere
modification thereof.
In witness whereof, I, the said James Macpherson, have hereunto
set my hand and seal, this Third day of February One thousand
eight hundred and seventy-two.
JAMES MACPHERSON. (L.S.)