IMPROVEMENTS IN SHEATHING IRON VESSELS AND ARMOUR-PLATED SHIPS
Year: 1863

page_text: LETTERS PATENT to Robert Turnbull, of Portsmouth, in the County of
Hants, Shipbuilder, for the Invention of "IMPROVEMENTS IN SHEATHING
IRON VESSELS AND ARMOUR-PLATED SHIPS."
Sealed the 27th May 1864, and dated the 1st December 1863.
PROVISIONAL SPECIFICATION left by the said Robert Turnbull at the
Office of the Commissioners of Patents, with his Petition, on the 1st
December 1863.
I, ROBERT TURNBULL, of Portsmouth, in the County of Hants, Shipbuilder,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
SHEATHING IRON VESSELS AND ARMOUR-PLATED SHIPS," to be as follows:-
My Invention relates, first, to improvements in sheathing iron-clad vessels
of war. For this purpose, supposing the vessel to be a new wood ship and the
only iron externally the armour plates, I apply the plates in alternate longi-
tudinal rows of thick and thin plates, that is to say, if the armour plating of
the ship is to be four-and-a-half inches, I alternate a row of such plates, which
are usually about three feet wide, with a row of narrow plates, say about twelve
inches wide by about six inches thick; all these plates being bedded and
suitably fixed on a uniform surface, the thick plates projecting beyond the
thin ones to the extent of their extra thickness. Before fixing these thin plates
their edges to the extent of the extra thickness are undercut, or what is
termed a standing bevil is formed thereon, so that between two thick plates a

page_text: dovetail, so to speak, is formed. After fixing the plates I fill in and cover the
four-and-a-half inch plates with short pieces of wood, some three or four inches
thick, the ends being bevilled to fit into the bevils of the thick plates in which
they hold.
For the convenience of fitting and wedging up tight and removing if
necessary, I place these pieces of covering wood a little inclined to the
upright, and reverse the inclination at short intervals, the space between
the opposite inclinations being filled up by a wedged shaped or oppositely
inclined piece suited to the space. The four-and-a-half inch plates are
thus perfectly and securely covered with wood, the surface of which pro-
jects an inch and a half to two inches beyond the thick plates. These
plates are covered by a longitudinal planking some three or four inches
wider than the narrow plates, say fifteen or sixteen inches wide, the edges
of which planking are recessed in the timber dovetailed between the
narrow plates of a thickness when so let in to be flush with such timber
covering the thin plating; the whole would therefore present a level surface.
The longitudinal planks are secured at their edges to the dovetailed timber by
screws or other suitable fastenings which do not pass through the dovetailed
timber. The seams are formned suitable for caulking or otherwise rendering
them water-tight. The lower strake or row of iron would of course be 'a
thick one, and should be sunk below the surface of the ship's side a distance
equal to the longitudinal plank used to cover it, so that the whole will present
a uniform surface, which may be coppered precisely in the manner of an
ordinary wood ship, galvanic action being entirely prevented by the perfect
closing in and protection of the iron plates from the sea water. For the upper
plates and where the copper does not extend the dovetailed planking may
be thinned at its upper end to the thickness of the dovetail and so be flush
with the upper thick plate, which in that case would be exposed outside. I
prefer to dispose a thick plate at the level of the water line where its increased
strength would be of greater use.
In sheathing wood ships already armour plated I apply thickness pieces
dovetailed or undercut to represent the increased thickness of plates before
described, which being fixed to the armour plating may then be covered in in
manner similar to that before described; or instead of placing the thickness pieces
longitudinally they may be vertical or inclined; in either case I incline the
dovetailed filling pieces of timber to the direction of the pieces on which the
standing bevils or dovetails are formed, that is to say, they are not placed
directly transverse between the two (at right angles thereto) but a little
slanting, the slant being reversed at intervals, as before described. The thickness

page_text: pieces of plating fixed on as last herein-described need not be of the breadth
(12 inches) before mentioned, but in either case must be covered in by a
timber of suitable breadth fitted and held up as before described.
In building iron armour-plated vessels I either use thick and thin rows of
plates alternately, and sheath and cover the entire surface of the bottom as well
as the armour plates, as before described. Instead of using thick and thin
plates in the structure of the skin of the vessel the thickness dovetail piece for
holding on the wood sheathing may be bolted or otherwise fixed thereon at
intervals and in any direction that may be desirable. By means of this wood
sheathing I am enabled to copper sheath the bottoms and armour plating of
iron ships, and so protect them and prevent their bottoms fouling in as efficient
a manner as a copper wooden ship, at same time preventing all galvanic action
and destruction of the plates.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Robert Turnbull in the Great Seal Patent Office on the
1st June 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ROBERT
TURNBULL, of Portsmouth, in the County of Hants, Shipbuilder, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the First day of December, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-seventh year
of Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Robert Turnbull, Her special licence that I, the said Robert
Turnbull, my executors, administrators, and assigns, or such others as I, the
said Robert Turnbull, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times there-
after 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 "IMPROVE-
MENTS IN SHEATHING IRON VESSELS AND ARMOUR-PLATED SHIPS," upon the con-
dition (amongst others) that I, the said Robert Turnbull, my executors
or administrators, by an instrument in writing under my, or their, or one
of their hands and seals, 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

page_text: within six calendar months next and immediately after the date of the said
Letters Patent.
NOW KNOW YE, that I, the said Robert Turnbull, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the Sheet of Drawings hereunto annexed,
and to the letters and figures marked thereon (that is to say):-
war.
:—
My Invention relates, first, to improvements in sheathing iron-clad vessels of
For this purpose, supposing the vessel to be a new wooden ship, and
the only iron externally to be the armour plates, I apply these plates in alter-
nate longitudinal rows, of thick and thin plates, that is to say, if the armour
plating of the ship is to be four-and-a half inches, I alternate a row of such
plates, which are about three feet wide, with a row of narrow plates, say, about
twelve inches wide by about six inches thick; all these plates are bedded, and
suitably fixed on a uniform surface, the thick plates therefore project beyond
the thin ones to the extent of their extra thickness; before fixing these
plates their edges to the extent of the extra thickness are undercut, or have
what is termed a standing bevil formed thereon, so that between two thick
plates a dovetail (so to speak) is formed. After fixing the plates I fill in
and cover the four-and-a-half inch plates with short pieces of wood, some
three or four inches thick, the ends being bevilled to fit into the thick plates
in which they hold.
For the convenience of fitting and wedging up tight and removing them
if necessary, I place these pieces of covering wood a little inclined to the
upright, and reverse their inclinations at short intervals, the space between
the opposite inclination being filled up by a wedge-shaped or oppositely
inclined piece suited to the space. The four-and-a-half inch plates are thus
perfectly and securely covered with wood, the surface of which projects from
an inch-and-a-half to two inches beyond the thickness plates. These plates are
covered in by longitudinal planking, some three or four inches wider than the
narrow iron plates (say, fifteen or sixteen inches wide). The edges of this
planking are recessed into the timber dovetailed between the narrow plates,
and it is of a thickness when so let in to be flush with the thick timber
covering the thin plating. The whole therefore presents a level surface. The
longitudinal planks are secured at their edges to the dovetailed timber by
screws or other suitable fastenings, which do not pass through the dovetailed
timber. The seams are formed suitable for caulking or otherwise rendering
them water-tight. The lower strake or strip of iron would of course be a
thick one, and should be sunk below the surface of the ship's side a distance

page_text: equal to the longitudinal plank used to cover it, so that the whole will present
a uniform surface, which may be coppered precisely in the manner of an
ordinary wood ship, galvanic action being entirely prevented by the perfect
closing in and protection of the iron of the plates from the sea water. For
the upper plates and where the copper does not extend the dovetailed
planking may be thinned at its upper end to the thickness of the dovetail,
and so be flush with the upper thick plate, which in that case would be
exposed outside. I prefer to dispose a thick plate at the level of the water
line, where its increased strength would be of greatest use.
In sheathing wood ships already armour plated I apply longitudinal thick-
ness strips or pieces dovetailed or undercut to represent the increased thick-
ness of plate before described, which being fixed to the armour plating may
then be covered in in the manner similar to that before described, or instead
of placing the thickness pieces longitudinally they may be vertical or inclined.
In either case I incline the filling dovetailed pieces of timber to the direction
of the dovetailed recess formed by the standing bevils, that is to say, they
are not placed directly transverse between the two (at right angles thereto),
but a little slanting, the slant being reversed at intervals as before described.
The thickness pieces of plating fixed on as last herein' described need not
be of the breadth of twelve inches before mentioned, but in either case
must be covered in by a timber of suitable breadth, fitted and secured as
described.
In building armour-plated vessels I either use thick and thin rows of
plates alternately, or apply thickness strips as above mentioned, and sheath
and cover the entire surface of the bottom as well as the armour plates as
before described. Instead of using thick and thin plates in the structure of
the skin of an iron vessel, the thickness dovetailed pieces for holding on the
wood sheathing may be bolted or otherwise fixed thereon at intervals, and in
any direction that may be desired. By means of this wood sheathing I am
enabled to copper sheath the bottom and armour plating of iron ships, and so
protect them and prevent their bottoms fouling in as efficient a manner as
a coppered wooden ship, at same time preventing all galvanic action and
destruction of the plates thereby.

page_text: and fixed thereto in the ordinary or in any suitable manner, but by preference,
with this difference in the plating, that it is in alternate thick and thin strips.
A, A, is the wood framing and body of the ship which requires no
description; B, B, and C, C, are the armour plates, B. B, being the wide
plates of the thickness required to resist the shot, and C, C, the thicker plates
required for fixing the sheathing as described. I have not represented any
method of fixing these plates, which may be by through bolts as usual, and well
understood. Supposing the plates B to be about three feet wide, I have repre-
sented the narrow ones C as of twelve inches, but this may be more or less as
deemed most expedient; they are undercut on the edges to the extent they project
beyond plates B, as seen in the section Fig. 2, so that two of them present a
dovetailed recess in which the wood D, D, fits, which I cut at the ends to
the bevils required. By reason of the inclined position these pieces D, D,
occupy they are readily inserted between the bevils or dovetails by inclining
them at a still greater angle. I reverse the incline of these pieces at intervals,
as seen by introducing wedge-like pieces D', D2, omitting the dovetail or bevil
at the one end of the pieces D², D², meeting in the vertical line, which are easily
inserted or removed when the pieces D are all in position, and so provide for
the ready placing or removing of the whole. I make the pieces D, D, three-
and-a-half inches in thickness, and rebate the ends on the outside to the depth
of two inches, and of a breadth of about two inches, so that a channel is formed
for a longitudinal strip or strake E of two inches in thickness, and about
sixteen inches wide, more or less, which is fitted close down on plates C, C,
and flush with wood pieces D. The pieces D, D, being firmly wedged and
fixed in the dovetails, the pieces E are secured thereto by screws f, f, at each
edge, passing through E into D, D, but not through the latter; great care
must be taken that the holes prepared to receive the screws f, f, do not pass
through, in fact they should not pass more than half way through the pieces D.
The pieces E will secure the ends of pieces D³ that have no bevil, and retain
the whole firmly in place. The lower edge of the lower strake E below the
armour plating is rebated into the planking of the ship, and secured thereto
in manner as before described.
As it is unnecessary to continue the sheathing above a certain height, I thin
the ends of the upper row of pieces D and reduce them to the bevil in the
iron receiving them, as seen in the section Fig. 2. The planking D and E
being so prepared and fitted, I can caulk all the seams between the pieces
D, D, and between E and D in the ordinary manner of caulking a wooden
ship so as to render them perfectly water-tight. By these means I am enabled
to fix a sheathing of wood to iron surfaces without any of the fastenings passing

page_text: through the wood sheathing, and on this sheathing of wood I fix copper
sheathing H, H, in the ordinary manner of fixing copper sheathing to wooden
ships, which will require no further description. The copper sheathing is thus
perfectly insulated from the iron armour plating, therefore deterioration of
one metal or the other cannot take place from galvanic causes. The iron
plating may of course be carried lower down on the hull of the ship and the
wood sheathing higher up, and fitted and fixed in the same manner. From
the foregoing it will be readily understood that the wood and copper sheathing
can be easily removed for repair or otherwise if desired by first removing the
copper sheathing H, afterwards the longitudinal planks E, then the key
pieces D', D', and so releasing the whole of the wood sheathing. Instead of
the thickness dovetail pieces C being formed using thicker plates thickness
pieces C may be bolted or otherwise fixed on the armour plates as may be
necessary in ships already armour plated. The transverse section, Fig. 3,
represents dovetail pieces fixed on the armour plating of the ship and so to.
provide means for the holding of the wood sheathing; all else is the same as
before described, and will not require any further description. The armour-
plating instead of being on a wooden ship, as shown in the Drawings, may be
fixed on an iron framed ship or on the wood backing of an iron built ship, or
the iron armour plating may form a part of the framing and strength of the
ship, in all of which cases the external wood and copper sheaths may be applied
in manner above described.
Fig. 4 represents a side view and Fig. 5 a transverse vertical section of
part of a ship's side in which the wood and copper sheathing are applied to an
iron ship without armour plating, the scantling being slight as well known. In
sheathing ships of this kind, and more especially in ships already built, I rivet
the pieces that are to form the dovetail channels or recesses on to the skin
of the ship, and this I prefer to do in a diagonal direction as seen at I, I,
Fig. 4, in which case the filling pieces D, D, will be horizontal, but with the
ends inclined, and with the same facilities of fixing in the dovetails before
mentioned. The covering planks E are of course in a diagonal direction also,
and all fitted, fixed, and caulked as before described. In this example I have
dispensed with revèrsing the position of pieces D at intervals as before
mentioned, and dispose them all horizontally, the upper pieces D being kept in
position by a continuous fixed upper strake L. Instead of the diagonals of
dovetail pieces I, I, being reversed at intervals as in Fig. 4, they may be. all
in one direction, but so disposed as to add strength to the ship. The dovetail
thickness pieces I, I, may be fixed horizontally instead of diagonally as in the
case of the armour plated ships, and instead of being rivetted on outside they

page_text: may be thick projecting plates or ribs forming part of the skin of the ship. I
have shown the wood sheathing carried up to the gunwale, it may however
terminate at any suitable point, but must be carried down and cover the entire
of the bottom of the iron ship; this wood covering or sheathing is afterwards
coppered and affords the same facilities for coppering as an ordinary wood
ship. The framing of the ship I need not further describe, as not being
interfered with in any way or altered from the ordinary construction other than
as above mentioned. The wood I prefer to use for the sheathing is teak, but
other kinds of wood will answer the purpose.
Having described the nature of my Invention and the manner of performing
the same, I declare that what I claim as my Invention to be protected by the
herein-before in part recited Letters Patent, is,-
First, fitting and fixing a compound sheathing on the exterior of the
armour plating of ships, in manner and for the purposes herein-before
described.
Secondly, fitting and fixing a compound sheathing to the exterior of iron
ships, in manner and for the purposes herein-before described.
In witness whereof, I, the said Robert Turnbull, 'have hereunto set my
hand and seal, this Thirty-first day of May, in the year of our Lord
One thousand eight hundred and sixty-four.
ROBERT TURNBULL. (L.S.)