Improvements in and relating to Trawl-nets.
Year: 1898

page_text: Date of Application, 18th Nov., 1898
Complete Specification Left, 14th Sept., 1899-Accepted, 18th Nov., 1899
PROVISIONAL SPECIFICATION.
Improvements in and relating to Trawl-nets.
I, JAMES WILLIAM PEARSON, of 17, Elm Grove, Cricklewood, in the County of
Middlesex, Minister of the Presbyterian Church of England, do hereby declare
the nature of this invention to be as follows:-
My invention relates to trawl-ncts of the kind or class wherein the net is
extended or held open, during its motion through the water, by the action of the
water on otter-boards secured to the sides or wings of the net.
An important feature of my said invention is the provision of suitable means
whereby the angle which the otter-boards make with the direction of motion will
be automatically varied in accordance with the resistance offered by the net to
being drawn through the water, so that the said otter-boards will always operate
in the most efficient manner to keep the net distended without subjecting either
the net, boards or warp to undue stresses.
For this purpose, the said boards are each provided with one or more forwardly-
extending pivoted arms to which the tow-ropes or warps are attached
and also with rearwardly-extending arms or brackets to which the
head and ground lines are secured at the wings of the net; the
point or points of attachment of the pivoted arms to which the tow-
ropes or warps are secured, being in the forward or outer half or part of the
boards, whilst the point or points of attachment of the arms or brackets to
which the net is secured, are in the rear or inner half or part of the boards. By
these means, when the resistance offered by the net to motion through the water
is small, the pivoted arms to which the tow-ropes or warps are secured, or both
sets of arms, will be pulled by the net towards the board and the board thus in-
clined at a smaller angle to the direction of motion so as to exert a small but
sufficient distending force on the net; but when the resistance offered by the net
increases, the said arms will be pulled by the towing warps away from the boards
and the distending force exerted by the latter increased in proportion to the
resistance.
Another advantage obtained by this form of construction is that the rear ends
of the boards extend within the mouth of the net and thus a stream of water is
projected into the net which acts very efficiently to raise the upper part or bosom
thereof and keep the mouth open to its full extent.
My said invention, moreover, comprises other improvements hereinafter men-
tioned.
In carrying my said invention into practice according to one method, in order
to make the self-adjusting action as great as possible, I pivot both sets of arms
to the otter-board, and arrange the arms for the tow-ropes or warps so as to
pass through slots in the said boards from the rear to the front side thereof, the
pivots being mounted on the rear side; whilst the arms for the attachment of the
head and ground lines of the net, are pivoted at the front of the boards and extend
to the rear side thereof through slots. The said arms are preferably made double,

page_text: one at or near the top and one at or near the bottom of the board; and the ends
of each pair are united by chains or other suitable means, and the two pairs are
coupled together by a connecting chain or the like extending through a central
slot or aperture in the board. This connecting chain assists in the self-adjusting
action of the board by causing the two arms or sets of arms to move simultaneously
towards and away from the board. By this arrangement also I provide a flexible
connection between the wings of the net and the board, thus affording more free-
dom of movement of the board while ensuring that the pull upon the net shall
be in a line extending from the middle of the wing of the net to the point of
attachment of the warp. If desired, the front arms may be pivoted to the front
of the board and the rear arms to the rear of the board, thus obviating the neces-
sity for the slots for the said arms to pass through.
According to another method I rigidly attach to the rear of the board a bracket
to which the head line and ground lines of the net are attached, the front or tow-
rope arm or arms being pivotally mounted on the board as in the arrangement
first mentioned.
If desired, I make the attachments of the pivots adjustable on the board, for
example, by providing the eyes or sockets of the hinge-joints or pivots with screw-
threaded tangs each adapted to be inserted in one or other of a series of holes
in the board and to be secured in position by a screw-nut. When employing rigid
armis or brackets at the rear of the boards, I preferably make them in the form
of two frames hinged or pivoted to each other at one of their ends and having
their other or outer ends hinged or pivoted to eyes adjustably secured to the
boards. In this manner a triangular structure or bracket is obtained which is
both rigid and easily adjustable.
My improvements can be applied to self-righting otter-boards mounted on
balancing spheres, such as are described in the specification of former Letters
l'atent granted to William John Wood and myself and dated 29th November 1897,
No. 28123, or to other otter-boards.
I sometimes connect the towing-ropes or warps to the balancing spheres by
means of a bolt passing entirely through the axis of each of the said spheres and
secured in position by nuts or other suitable means.
I find it advantageous to make the balancing spheres with a groove or recess
extending through the top thereof to receive the otter-board, and with a pipe or
tube extending through the sphere beneath the said groove or recess to receive the
bolt for the attachment of the warp. And I prefer to make the said spheres
water-tight.
I, JAMES WILLIAM PEARSON, of 17, Elm Grove, Cricklewood, London, Minister
of the Presbyterian Church of England, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described 4
and ascertained in and by the following statement : ·
-
This invention relates to trawl-nets of the kind or class which are kept dis-
tended or held open, during their motion through the water, by the action of the
water on otter-boards secured to the sides or wings of the net.
Heretofore the head-rope and ground-rope of the net have been attached to the 5

page_text: rear edge of the otter-boards, and the towing-warps have been attached by chains
or brackets to the said boards at fixed points, the position of these fixed points
of attachment being shifted, while the net is out of the water, when it is desired
to change the sheer or inclination of the otter-boards to the direction of motion.
This arrangement possessed the disadvantages that the otter-boards were not free
to adjust themselves to the most favourable position and an undue strain was
thrown upon them by reason of the wings of the net being attached to the rear
edge of the boards.
Now the main object of my present invention is to provide for the automatic
variation in the inclination of the otter-boards by the variation of the resistance
which the net offers to being dragged through the water, whilst ensuring the
keeping of the said boards in an upright position while being drawn through the
water, and their return to an upright position by a pull on the towing-warps
should they fall when they come to rest.
To this end my improved trawl-net is chiefly characterized in that the head-rope
and ground-rope of the net, instead of being attached to the edge of the otter-"
boards, are connected to the towing-warps through the medium of chains or links
and urins which extend through the otter-boards respectively and the said head-
rope and ground-rope and the towing-warps are coupled to the otter-boards
through suitable connections which permit variations in the inclination of the
said boards, in accordance with variations in the resistance offered by the net
to being drawn through the water, so that the said otter-boards will always
operate in the most efficient manner to keep the net distended without subjecting
either the net, boards or warp to undue stresses.
The said invention, moreover, comprises other improvements hereinafter
described.
In the accompanying drawings
Figure 1 is an inside view, and
Figure 2 a plan, partly in horizontal section on the line A-B, Figure 1,
showing one wing of a net having my improvements applied thereto.
Figure 3 is an inside view, partly in vertical section, and
Figure 4a horizontal section, illustrating details of construction.
Figure 5 is an inside view, and
Figure 6 a plan, partly in horizontal section on the line C-D, Figure ō, illus-
trating a modification of my said invention.
Figure is a similar view to Figure 5, and
Figures 7 and 7b are transverse sections on the lines A-B¹ and C'—D³ respec-
tively, illustrating a further modification of my invention.
Figure 8 is an inside view,
Figure 9 a plan, and
Figure 10 a transverse section illustrating a further modification of my in-
vention.
Figure 11 is a plan view illustrating a detail of construction.
Like letters indicate corresponding parts throughout the drawings.
The net a, instead of being attached to the rear edge of each otter-board b, is
attached to rearwardly-extending arms e, which are pivoted at d to the board b
and are either left free to swing about their pivot as shown in Figures 1 and 2,
or are held at any desired angle or inclination to the board by a link or links e
as shown in Figures 5 and 6, the upper and lower arms a being respectively con-
nected to the head-rope f and ground-rope g of the net a. The tow-ropes or
warps h are each coupled by chains j to other arms k pivoted at to the board b
and free to swing about their pivot.
In the arrangement shown in Figures 1 and 2, the head-rope f and ground-
rope are coupled to the towing-warp h by a chain m which is connected to the
said arms and by means of the chains j and n respectively, the connecting
chain m extending through a slot in the board b. If desired, however, the head-

page_text: a
rope and ground-rope g may be coupled to the towing-warp h by a link or links
extending through the slot p, and the said chain m or the said links may be
pivoted at or near the centre of the said slot.
By these means, when the resistance offered by the net to motion through the
water is small, the pivoted arms c, & will be swung about their pivots so that the
board will only be slightly inclined to the direction of motion and will exert just
sufficient distending force on the net to keep the same open; but when the resist-
ance offered by the net increases, the said arms will be swung in the reverse
direction about their pivots and the distending force exerted by the boards will
be increased in proportion to the resistance. By this arrangement also I provide
a flexible connection between the wings of the net and the board, thus affording
more freedom of movement of the board while ensuring that the force pulling upon
the net shall be exerted in a line extending from the middle of the wing of the
net through the board to the point of attachment of the towing-warp, but shall
act independently of the board.
Another advantage obtained by this form of construction is that the rear ends
of the boards extend within the mouth of the net and thus a stream of water is
projected into the net which acts very efficiently to raise the upper part or bosom
thereof and keep the mouth open to its full extent.
To make the self-adjusting action as great as practicable, I prefer to arrange
the arms c and so that they extend through slots q in the board b, the pivot & of
the arms being at the rear side of the board and the said arms extending from
the rear to the front side thereof, whilst the arms c have their pivots d at the
front of the board and extend to the rear side thereof. I am thus enabled to make
the said arms of greater length than would otherwise be practicable. If desired,
however, the front arma may be pivoted to the front of the board and the rear
arms to the rear of the board, thus obviating the necessity for the slots for the
said arms to pass through.
The eye-bolts in which the arms c, k are pivoted, are preferably adapted to
be inserted and secured in one.or other of a series of holes s in the board b so that
the self-adjusting action of the gear can be regulated as desired.
The board b shown in Figures 1 and 2 is mounted on a balancing sphere so
that it will be self-righting. But when the board is used without such sphere as
shown, for example, in Figures 5 and 6, it will, by reason of the improved arrange-
ment above described, be kept in an upright position while the net is being towed
through the water, and, should it fall when it comes to rest, will be returned to
its upright position by the next pull upon the towing-warp.
In Figures 1 to 4, I have shown an arrangement in which the lower arm c is
connected by an extension of the ground-rope g to an arm which is pivotally
secured to a bolt z fixed in the sphere t, and is capable of moving in a segmental
recess win the sphere t so as to accommodate itself to the swinging motion of the
said arms c.
In the modification of my invention illustrated in Figures 5 and 6, the link e
to which the arms are pivotally connected, is also pivotally connected to the
pivot pin of the arms. By this means, since the eye-bolts r are adjustable,
the angle or inclination to the board at which the arms c are held can be varied
as desired.
Instead of providing the board with a sphere t, as shown in Figures 1 to 4,
it can be formed as shown in Figure 7. This form is very advantageous for use
with small boats although it may be used with steam-trawlers and large boats.
In this arrangement, the lower edge of the board b is made curved and is provided
with a shoe having flanges on each side, adapted to be bolted to the said
board. An additional shoe y, having a rounded under surface and provided with
perforated flanges, is bolted at y' to the board band shoe and serves as the running
surface. The shoe y is thus detachable and can be replaced by others of different
weight as required for balancing the board, or to enable it to be renewed when
worn. If desired, this shoe y, together with the shoes, may be made with internal

page_text: cavities to receive weights. Or the shoes x and y can be made in one solid
piece.
It will be seen that the board and shoes x, y here form part of a medium slice
or section of a balancing sphere such as is described in the specification of former
Letters Patent granted to William John Wood and myself and dated 29th
November 1897, No. 28123; it is however much cheaper and lighter and is thus
very advantageous for use with small boats.
In the arrangement shown in Figures 8 to 11, the sphere t is made hollow and
in two parts secured together by bolts, Figures 8 and 10. By these means I am
enabled to readily remove the weight 2 and replace it by a lighter of
heavier one, and also renew the lower section forming the running surface, when
worn or damaged. A pipe or tube is also provided extending through the aphere
to receive the bolt v.
In this arrangement additional shackles 2 are placed at equal distances apart
from the rear end of the board to the centre. To one of these shackles the head-
line is "bent" or attached in order to obtain more efficient drafting of the net,
and to balance the movement of the board, so that it will not lift on its shoulder
and allow the ground-rope to travel over and miss the fish. The reason of this
action is that the square (ie., the bosom or upper wall) of the net possesses a
larger number of meshes than any other portion and consequently drafts a larger
quantity of water than any other portion. This draft has a tendency to lift the
tail end of the board from the ground and causes the shoulder to plough into the
sea bed.
Some nets possess more square than others, (that is to say, the upper wall
extends further forward), and, by providing the fisherman with movable shackles.
attached at fixed points, he can ensure the balance of his gear and thus reduce his
coal consumption as the front corner of his board will not plough into the sea bed.
My improvements can be applied to self-righting otter-boards mounted on
balancing spheres, such as are described in the specification of said former Letters
Patent, No. 28123, or to other otter-boards.
It is evident that the construction of my improved trawl-gear can be further
modified if desired, whilst still retaining the principle of my invention, viz:—
The connection of the head-rope and ground-rope of the net to tow-ropes or warps
by chains or links and the coupling of these ropes or warps to the hoards by arms
pivoted or otherwise secured to the boards and either free to swing about their
pivots or held at any desired angle or inclination to the board.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:
-
1. A trawl-net which is kept distended, whilst in motion, by the action of the
water on otter-boards, and wherein the inclination of the otter-boards to the
direction of motion can vary with the resistance to dragging of the net, sub-
stantially as described.
2. A trawl-net such as is herein before described, wherein the head-rope and
ground-rope and the towing warps are connected through the medium of chains
or links and arms extending through the otter-boards and being coupled to the
said otter-boards by arms which are either pivotally or rigidly secured to tho
said hoards, substantially, as and for the purposes, hereinbefore described.
3. A trawl-net wherein the head-rope and ground-rope are attached to arms
pivoted to the front of the otter-board and extending rearwardly through slots
therein, and these arms are connected by chains to the towing-warp which is
also connected by chains to arms pivoted to the back of the board and extending
through slots therein, substantially as described.
4. The modification of my invention wherein the ground-rope is passed through
an eye on the lower rearwardly-extending pivoted arm and is coupled to an arm
pivoted in a balancing sphere on which the otter-board is mounted substantially

page_text: as described with reference to Figure 3 of the accompanying drawing, for the
purposes specified.
5. The modification of my invention wherein the arms to which the head-rope
and ground-rope are attached, are secured to the back of the otter-board and are
coupled by a link to the pivot-pin of the forwardly-extending arms, substan-
tially as hereinbefore described with reference to Figures 5 and 6 of the accom-
panying drawings.
6. The combination, with an otter-board, of a balancing-sphere, a bolt passing
through the said sphere and having one or more arms pivotally connected to the
said sphere, substantially as, and for the purposes, hereinbefore described.
7. The improved otter-board constructed substantially as described with refer-
nce to Figure 7 or to Figures 8 to 11 of the drawing and operating as and
for the purposes specified.
D-14
1900
D. YOUNG & Co.,
11 and 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.