Improvements in Otter Boards of Trawling Nets.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in Otter Boards of Trawling Nets.
We, CHARLES LAURENCE, of 12, Albert Square, Ella Street, Mariner, and
FREDERICK WILLIAM FISHIER, of the Citadel, Engineer's Agent, both of Kingston-
upon-Hull, in the County of York, do hereby declare the nature of this invention
to be as follows:-
Our invention relates to the otter boards of trawling nets and has reference to
certain details of construction as hereinafter described by which the number of
chains required to take the towing warp is reduced and better results are obtained
in the efficiency and control of the otter board.
In carrying out our invention we furnish the otter board with two fin-like flaps
attached by hinged joints to opposite sides of the board which fin like flaps spread
out as the otter board encounters the resistance of the water and by their position
and action effect the improvements in otter boards which constitute the essential
features of our invention. For this purpose the fin like flaps are adapted to
spread out to a particular position in which they become automatically locked.
Otherwise they can be turned down flat with the board which facilitates the hand-
ling and stowing away of the boards when on deck. These flap-like fins are
hinged to opposite sides of the board preferably in corresponding positions the
line of contact or line of joint with the board being set to an angle converging
towards the sole or bottom line of the otter board in the direction in which the
board is towed the flap like fins also extend outwards at an angle relatively to
the board when locked in the spread out position which angle also converges to the
bottom line or ground level of the otter board. The advantages derived in practice
from this arrangement are that the pressure of the water acting upon the said fin
like flaps tends to keep the otter board down to the bed of the sea and in the
upright position the angle to which the flaps are set in either direction being
adjusted entirely with a view to these results. The automatic locking of the fin
like flaps at the right position may be effected by any suitable means and in a
variety of ways such as by a vertical pin housed in a slot provided in the otter
board so that connecting rods extending from the fin like flaps to which they are
pivotally attached are also pivotally attached to a block adapted to slide up and
down on the vertical pin. When this sliding block arrives at a certain position
a paul or catch comes into play and all further movement thereof is prevented,
the fin like flaps being then in the spread out position. The usual leading or
fore chains are dispensed with by this arrangement the after chains or connec-
tions thereto being passed through an eye bolt or ring fixed in the inner side flap
and which may be free to revolve in the outer or net end of the said inside flap.
The position of this chain hole is selected so that it is out of line with the pull or
strain on the towing warp excepting when the flap is fully extended the adjustment
being with a view to cause the pull on the towing warp to extend the flaps in the
manner required for the purposes of our invention.
Special advantages of the construction herein described are that the tendency

page_text: of the otter board when under tow is to maintain an erect position at the bottom
or ground level of the sea and the board is prevented from falling flat on either
side by the fin-like flaps attached thereto for this purpose folding flat with the
board when drawn on deck and further more the arrangement of the chains or con-
nections to which the towing warp is secured is simplified and the number of
chains reduced, and the tendency of the flaps to spread out is secured by the resis-
tance of the water aided by the pull of the towing warp. And the tendency of the
otter boards to spin round and twist the ropes together when being hauled up is
prevented.
Dated 19th June 1897.
Improvements in Otter Boards of Trawling Nets.
We, CHARLES LAURENCE, of 12, Albert Square, Ella Street, Mariner, and
FREDERICK WILLIAM FISHER, of the Citadel, Engineer's Agent, both of Kingston-
upon-Hull, in the County of York, 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:-
Our invention relates to the otter boards of trawling nets and has reference to
certain details of construction as hereinafter described, by which the number of
chains or slings required to take the towing warp is reduced and better results
are obtained in the efficiency and control of the otter board.
In carrying out our invention, we furnish the otter board with two fin like
flaps attached by hinged joints to opposite sides of the board, which fin like flaps
spread out as the otter board encounters the upward resistance of the
water when the towing warp is slack and by the strain of the tow-
ing warp when taut and thus by their position and action effect the
improvements in otter boards which constitute the essential features
of our invention. For this purpose the fin like flaps are adapted to spread out to
a particular position in which they become automatically locked in respect of
further outward movement. Otherwise they can be turned down flat with the
board, which facilitates the handling and stowing away of the boards when on
deck. These flap like fins are hinged to opposite sides of the board preferably in
corresponding positions, the line of contact or line of joint with the board being
set to an angle converging towards the sole or bottom line of the otter board in the
direction in which the board is towed; the flap-like fins also extend outwards at
an angle relatively to the board when locked or held in the spread out position
which angle also converges to the bottom line or ground level of the otter board.
An important advantage derived in practice from this arrangement is that the
pressure of the water acting upon the said fin like flaps tends to keep the otter
board down to the bed of the sea and in the upright position, the angle to which
the flaps are set in either direction being adjusted entirely with a view to this
result. Other advantages derived from or incidental to our invention will be
referred to hereafter.
To effect the purpose of our invention, we adopt the construction represented in
the accompanying drawing which illustrates the embodiment of our invention
in different forms, to which might be added others, without departing from the
scope of our invention. But the modifications shown are deemed sufficient to
explain the practical utilization of the invention,

page_text: In the drawing Fig. 1 is an inside or towing side view of an "otter" board
furnished with fin-like flaps constructed in accordance with our invention; Fig. 2
is an end view and Fig. 3 a plan view corresponding thereto.
Figs. 4 and 5 are similar views to Figs. 1 and 2, but showing certain modifica-
tions in some of the details.
Referring to Figs. 1 to 3 inclusive, a a are two fin-like flaps attached by hinged
joints 66 to opposite sides of the "otter" board c, which fin-like flaps are adapted
to spread out to a particular position in which they become automatically locked,
in respect of further outward movement. This controlling device of the fin-like
flaps at the right position may be effected by any suitable means and in a variety
of ways, such as by the sliding block housed in a slot e provided in the otter
board so that connecting rods f f extending from the fin-like flaps, to which they
are pivotally attached, are also pivotally attached to the block d adapted to slide
up and down in the said slot e. When the towing warp g is made taut, the sliding
block d arrives at a certain position in which all further movement thereof is pre-
vented, the fin-like flaps being then in the spread out position as shown in the
figures. The usual leading or fore chains are dispensed with by this arrangement,
the after chains h or connections thereto being passed through a hole i in the tow-
ing side flap. The position of this chain hole i is selected so that it is out of line
with the pull or strain on the towing warp g, excepting when the flap is fully
extended, the adjustment being with a view to cause the pull on the towing warp
to extend the flaps in the manner required for the purposes of our invention.
Referring to Figs. 4 and 5 the automatic locking device of the fin-like flaps a a
consists of a vertical pin j and sliding block k housed in a slot provided in the
66 otter "board so that connecting rods ff, extending from the fin-like flaps to
which they are pivotally attached, are also pivotally attached to opposite parts of
the block k, which is adapted to slide up and down the vertical pin j. In this
case the after chains h or connections thereto are secured to a ring or shackle /
by which they are linked to the towing side flap, and also to the towing warp so
that when the towing warp is taut, the flaps are extended to the position limited
by the connecting rods f, which may also be secured to the same ring or shackle.
It will be observed in Fig. 5 that the line of travel of the sliding block k is
athwart the line of pull of the towing warp, which conduces to unnecessary friction
and strain. We therefore prefer to set the travel of the sliding block, whether
in the form shown in Fig. 5 or in Fig. 1, to a more suitable line of travel that is
nearer in line with the line of pull of the towing warp as shown in Fig. 1.
The modification shown in Fig. 6 is similar to that shown in Fig. 1 in respect
of the sliding block d, and to Fig. 5 in respect to the mode of securing the back
chains connecting the rod flap and towing warp to a shackle or ring. But in order
to get the requisite pressure on the flaps and to keep the otter board down to the
sea bed on an even keel, the extent of surface available for such pressure must be
adjusted, and if found desirable the flap is partly open as shown in Fig. 6 instead
of being wholly covered as in Figs. 1 to 5 inclusive. Otherwise, the "otter" board
might have a tendency in some cases to tilt over towards its nose or fore end and
plough into the sea bed, whilst the tail end was tilted up.
In addition to the tendency of the otter boards when furnished with flaps such
as a to keep to the sea bed when towing, and to maintain an erect position, other
advantages derived from or incidental to the construction hereinbefore described
are that the flaps can be made rigid by automatically locking themselves against
all movement either in the spread out or closing direction and then the board is
prevented from falling over flat on either side. But we usually prefer to have the
Haps to lock against the outward movement only, being collapsible inwardly, and
thus folding flat with the hoard when drawn on deck. The tendency of the otter
boards to spin round and twist the ropes together when being hauled up is pre-
vented, and when lowered to the sea bed the upward resistance of the water to the
flaps tends to support the otter board in the erect position when sinking.
The arrangement of the flaps and connections being collapsible, damage to the

page_text: board or to the ship's side is prevented in case of collision and furthermore should
the board fall over flat on either side, as the pull of the towing warp opens out the
flaps that on the underside acts as a lifting lever set to a favourable angle.
Having now fully described our said invention and the manner of performing
the same, we would have it understood that we are aware that otter boards have
been devised and used with means to enable them to be towed at an angle to the
plane of the board, we therefore make no claim to such device or principle, but
only to the improvements as embodied and carried into practice in otter boards
constructed and fitted, as hereinbefore set forth and we declare that what we claim
is:-
1. In otter boards for trawling nets the use of fin like flaps such as a attached
to opposite sides of the board, and having their movements connected so that both
open and close together, substantially in the manner and for the purpose described
with reference to the accompanying drawing.
2. In otter boards for trawling nets the combination of parts consisting of flaps
such as a hinged to opposite sides of the board, connecting rods or their equivalent
such as f, connecting the said flaps to opposite parts of a sliding block housed in
the board, and towing chains h whether shackled to the towing warp only through
a hole in the flap, as illustrated in Figs. to 3, or shackled to the flaps and their
connecting rods as well, as illustrated in Figs. 4 to 6, all arranged and operating
substantially as and for the purpose as herein before described.
Dated this 10th day of March 1808
G. J .CLARKSON,
Chartered Patent Agent, Stockton-on-Tees and Hull,
Agent for the Applicants.
G. J .CLARKSON,
Chartered Patent Agent, Stockton-on-Tees and Hull,
Agent for the Applicants.