Sailing Vessels.
Year: 1887

page_text: Sailing Vessels.
I, GEORGE GATTON MELHUISH HARDINGHAM, of 191, Ficet Street, in the City of
London, Civil Engineer, do hereby declare the nature of this invention to be as
follows:-
A centre-board as commonly constructed and mounted consists of a plate, usually of
metal, approximately triangular in shape and pivotted near its apex or fore end; the
body of the plate working vertically through a longitudinal slot formed in the keel of
the vessel. The after end of the plate is attached at its upper edge to a chain or cord,
whereby the plate is raised and housed in a casing or lowered into the water beneath
the keel of the vessel.
A centre-board constructed and mounted according to my improved method is more
nearly of rectangular shape and is suspended from its upper edge by means of two
radius-bars pivoited at their forward extremities in the upper part of the centre-board-
casing. The radius-bars are preferably of the same length and thus work parallel
with one another as the board is moved. For raising the board, two chains or cords
are by preference employed, these being attached at different points in the upper edgo
of the board, and, as they work in unison, they may be connected to a single main
hauling line. Upon a centre-board mounted in the manner described being lowered,
it moves in a circular path, the radius-rods vibrating about their pivotted ends as they
turn from a horizontal to an approximately vertical position.
Amongst the advantages resulting from this improved method of mounting a centre-
board, it may be observed that when the board is in the lowered position, its lower
edge may be maintained parallel with the keel; and thus, for a given exposed area
and given draft of water, à greater area of plate and mass of metal are at the extreme
The
depth, as compared with a board pivotted at its fore end in the usual manner.
use of a pin through the keel or through the casing beneath the water line for the
plate to turn upon is also dispensed with. Moreover, if either or both the lifting
chains or cords give way, the plate remains suspended by the radius-bars and practically

page_text: retains its normal (lowered) position; whereas if a similar accident occurs with a
centre-board mounted in the usual manner, the plate hangs straight down beneath the
keel, and the vessel is not only liable to become unmanageable, but is exposed to
danger if in shallow waters. The handiness and weatherly qualities of a vessel pro-
vided with a centre-board fitted in the manner described are also improved by reason
of the facility afforded for varying to a certain extent the position of the centre of the
vessel's lateral resistance in relation to the centre of effort of the wind upon the sails.
The primary effect of hauling the plate is to move it through the approximately hori-
zontal portion of the circular path it traverses; the plate being thus shifted bodily aft
whilst only rising slightly. Under such conditions, the 'weather helm' or amount of
helm requisite to prevent the vessel coming 'head to wind' is reduced. Furthermore,
when the vessel is sailing off the wind' and the board is fully hauled and housed in
the casing, the weight of the plate is brought further aft in the vessel than when the
vessel is sailing 'on the wind' with the board lowered.
Although I have described the centre-board as mounted upon two radius-bars, it
will be obvious that the movements of the plate which take place under such conditions
or equivalent movements could be produced with the aid of other devices. For
example, the plate may be furnished with pins or rollers and carried in or upon curved
or inclined guides arranged within the casing. One radius-bar mounted as described
would suffice to control the movement of the plate; but the use of two such bars
affords security against disarrangement of the plate in the event of the lifting tackle
giving way. Chains or other flexible connections may be substituted for the radius-
bars.

page_text: COMPLETE SPECIFICATION.
Improvements in Mounting and Working Centre-boards for
Sailing Vessels.
I, GEORGE GATTON MELHUISH HARDINGHAM, of 191, Fleet Street, in the City of
London, Civil Engineer, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :-
A centre-board as commonly constructed and mounted consists of a plate, usually
of metal, approximately triangular in shape and pivoted near its apex or fore end;
the body of the plate working vertically through a longitudinal slot formed in the
keel of the vessel. The after end of the plate is attached at its upper edge to a chain
or cord, whereby the plate is raised and housed in a casing or lowered into the water
beneath the keel of the vessel.
A centre-board constructed and mounted according to my improved method is
represented in the accompanying drawings, whereof Figure 1 is a longitudinal section
through the casing, Figure 2 a transverse section, Figure 3 a side elevation, Figure 4
an end elevation and Figure 5 a plan view. Similar letters of reference are employed
to indicate corresponding parts, so far as they appear, in the several Figures. The
plate a, instead of being triangular, may be approximately rectangular in shape, or of
parallelogrammic form, as represented in the present illustration. It is suspended
from its upper edge by means of two radius-bars pivotted at their forward
extremities in the upper part of the casing c. The bars are preferably of the
same length and thus work parallel to one another as the plate is moved. For raising
the plate, two chains or cords d d are by preference employed; these being attached
or connected at different points d¹ in the upper edge of the plate; and as the
flexible connections d d work in unison, they may be connected to a single main
hauling line, or to a tackle as represented in Figures 3 and 5. Upon a centre-board
mounted in the manner described being lowered to assume the position indicated in
dotted lines (Figure 1), it moves in a circular path; the radius-rods bb vibrating
about their pivotted ends as they turn from a horizontal to an approximately vertical
attitude. The wire ropes or other flexible connections d d for raising the plate a are
respectively led over sheaves e e and round a pulley e'. This pulley is by preference
mounted in a bracket formed with a plate which serves as a stop for a buffer g
carried by the hauling line or lines d. The tackle may be single, double or treble
purchase, according to the weight of the plate.
Amongst the advantages resulting from this improved method of mounting a centre-
board, it will be observed that when the board or plate is in the lowered position, its
lower edge is or may be maintained parallel with the keel; and thus, for a given
exposed area and given draught of water, a greater area of plate and mass of metal
are at the extreme depth as compared with a board pivotted at its fore end in the usual
manner. The use of a pin through the keel or through the casing beneath the water-
line for the plate to turn upon is also dispensed with. Moreover, if either or both of

page_text: the lifting chains or cords give way, the plate remains suspended by the radius-bars
and practically retains its normal (lowered) position; whereas if a similar accident
occur with a centre-board mounted in the usual manner, the plate hangs straight down
beneath the keel, and the vessel is not only liable to become unmanageable, but is
exposed to danger if in shallow water. The handiness and weatherly qualities of a
vessel provided with a centre-board fitted in the manner described are also improved
by reason of the facility afforded for varying to a certain extent the position of the
centre of the vessel's lateral resistance in relation to the centre of effort of the wind
upon the sails. The primary effect of hauling the plate is to move it through the
approximately horizontal portion of the circular path it traverses, the plate being thus
shifted bodily aft whilst only rising slightly. Under such conditions, the 'weather
helin, or amount of helm requisite to prevent the vessel coming 'head to wind,' is
reduced. Furthermore, when the vessel is sailing off the wind' and the plate is fully
hauled and housed in the casing, the weight of the plate is brought further aft in the
vessel than when the vessel is sailing on the wind with the plate lowered. It will
also be perceived that, with the pendulous system of mounting, should the plate strike
the ground and be slightly lifted, the greater portion of the weight of the plate is still
carried by the radius-bars; whereas in the case of a triangular plate mounted upon
the pivotted system striking the ground, the greater portion of the weight of the
plate is borne by the ground, and the way of the vessel is checked to a greater
extent.
L
For
Although I have described the centre-board as mounted upon two radius-bars, it
will be obvious that the movements of the plate which take place under such conditions,
or equivalent movements, could be produced with the aid of other devices.
example, the plate may be furnished with pins or rollers and carried in or upon curved
or inclined guides arranged within the casing. One radius-bar, mounted as described,
would suffice to control the movement of the plate but the use of two such bars
affords security against disarrangement of the plate in the event of the lifting
tackle giving way. Chains or other flexible connections may be substituted for the
radius-bars.
.
:
Having thus particularly described and ascertained the nature of this invention and
in what manner the same is to be performed, I claim :
The improved method of mounting and working centre-boards for sailing vessels,
substantially as herein described.