IMPROVEMENT IN SHIP BUILDING
Year: 1884

page_text: PROVISIONAL
DELICATION
I JAMES MITCHELL of 8 Bentinck Terrace Regents Park in the County of
Middlesex Gentleman do hereby declare the nature of the said invention for "AN
to be as follows:-
IMPROVEMENT IN SHIP BUILDING
"
My Invention relates to the construction of vessels of high speed on a new
principle whereby the depth relative to the length and breadth of beam, and the
lines of the hull are determined with mathematical precision According to this -
system the forward and after bodies are shaped and constructed precisely alike as
illustrated in the annexed drawings wherein figure 1 is a plan figure 2 an elevation
and figure 3 cross sections of the hull at different points.
The line A B (fig. 1) represents the length and O. D. the breadth of a vessel
having a beam of one tenth its length.
To obtain the proper relative depth upon C. D figure 3 I construct an equilateral
triangle CDE, CD being equal to the width C B in figure 1 and E marking the
place of the keel. The lines of the hull are obtained by describing ares AC B.
ADB for the topsides (or the water line) and by joining CA D A, C B D B by
the dotted lines in figure 1 which represent the planes wherein are situated the
points of junction of the straight sides with the semicircular bottom of the hull.
The centres from which the latter is struck are found by setting off from the line
of the keel and at certain points in the length of the vessel distances equal to half
the distances between the lines A COB and A D D B at corresponding points in
the length of the vessel, and drawing the lines a, b, b, c.
By this system the construction of the hull is simplified and the cost diminished.
The speed is very considerably increased by the adoption of lines offering the
least resistance to the motion of the vessel through the water. A scientific
distribution of strain is ensured thereby giving the hull an enormously increased
resistance to flexion.
If the maximum speed is not required the form of the hull may be modified
by making the hull parallel for a certain distance fore and aft of the midship
section C D.

page_text: "
I, JAMES MITCHELL of 8 Bentinck Terrace, Regents Park, in the County of
Middlesex, Gentleman, do hereby declare the nature of my invention for
AN
IMPROVEMENT IN SHIP-BUILDING" and in what manner the saine is to be
performed, to be particularly described and ascertained in and by the following
statement: -
My Invention relates to the construction of vessels of high speed (ocean
passenger steamers and torpedo boats especially) on a new principle whereby the
depth relatively to the breadth and the lines of the hull below water are determined
with mathematical precision.
According to this system of construction, the forward and after bodies, so far as
the parts under water are concerned, are made of equal length and in all other
respects precisely alike as is shown in the annexed drawings whereof figure 1 is the
sheer plan with athwart ship vertical half sections, figure 2 is the breadth plan and
figure 3 the body plan.
The line A B figure 2 represents the length on the upper deck and C, D the
extreme breadth of a vessel having a beam of one tenth the length.
To obtain the proper relative depth upon C, D, figures 1 and 3, which represents,
in vertical section, the extreme breadth amidship, I construct an equilateral
triangle C, D, E, whereof the apex E marks the top of the keel and the base C, D,
the underside of the upper deck.
The lines of the hull under water are obtained as follows:-By describing the
ares A, C, B, and A, D, B, figure 2, the configuration in horizontal section, of the
hull at the water line is marked out, the height from the keel (A B figure 1) of
the most suitable water line being obtained by setting off from E, at a distance
equal to half of C, D (the extreme breadth) the point F. The midship configuration
of the hull in vertical section, below the said water line, is semicircular, the
semicircle G, E, H which defines the same, being struck from the said point Fas
centre. The configuration of the forward and after bodies below the said water
line, as regards the frames, is also semicircular the semicircles diminishing in
proportion as they recede either way from amidships, and the centres wherefrom
are struck these semicircles are found by connecting by an are of the same radius
as A, C B, and A, D, B, figure 2, the point F (figure 1) with A on the one band
and with B on the other. The hull fore and aft is completed below water, by
drawing straight lines or nearly straight lines from the upper extremities of the
semicircular frames to the aforesaid water line see (A) to (G) figure 1.
The under water lines of the hull having been thus obtained, the freeboard can
be carried up on lines giving the due amount of tumble home amidship, the proper
form of stem and stern and the requisite sheer (see figure 3) and the athwartship
vertical half-sections a to h figure 1.
When the maximum of speed is not required or when sail propulsion has to be
provided for, the form may be modified by diminishing the length relatively to the
breadth and if necessary increasing the depth.
By this system of construction, some most important advantages are gained.
The adoption of the semicircular bottom, which offers the least amount of resistance
to the passage of the vessel through the water, ensures the maximum of speed with
a given amount of propulsive power, other things being equal.
Construction is likewise thereby simplified and cost diminished.

page_text: Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is :-
The construction of vessels upon the principles substantially as herein specified
and illustrated in the drawings.