Supporting structure for fish nets or the like

A supporting structure for a fish net or the like including a plurality of vertically extending supporting elements projecting, at least partially, above the water surface. Elongate connecting elements extending generally parallel to the water surface are releasably connected to the supporting elements to form a frame. A fish net is secured to the connecting elements, and is retained at a predetermined level relative to the water surface by inflatable members mounted upon the supporting elements. The connecting elements and supporting elements retain the inflatable members at fixed predetermined distances from each other.

BACKGROUND OF THE INVENTION 
The present invention relates to a supporting structure for fish nets or 
the like, of the kind disclosed in the preamble to claim 1, a fish net 
being defined for purpose of this specification as an open net for 
confining fish to a limited volume of water. 
In outdoor pisciculture, fish nets have been used for a long while, these 
being attached to a support structure floating on the water surface so 
that the greater portion of such a net is below the water surface while a 
portion of its mainly vertical walls are above the surface. 
The supporting structures used so far have often consisted of a number of 
air-filled petrol drums on which a wooded frame carrying a fish net has 
been attached, or by a number of bodies floating on the surface or 
attached to the sea or lake bottom, which support framed structures to 
which one or more fish nets are attached. These carrying structures, often 
manufactured by the pisciculturist himself, suffer however from a number 
of drawbacks. Among the drawback can be mentioned that the supporting 
structures have a short life, are heavy and voluminous, resulting in that 
they must be erected at the place where they are to be used, and they also 
have deficient attaching means for the nets, are easily broken up in an 
even comparatively minor rough sea. They contain a large number of details 
which makes erection time-consuming and cannot be taken apart, thus hardly 
being transportable from one place to another, which is necessary if they 
are to be used in water which freezes to ice during the winter. 
In later years, pisciculture has however been rationalized considerably, 
which has involved increased demands on the fish nets, on the structures 
carrying them and that these structures together with the fish nets 
supported by them can be generally used in any water at all where the 
environment is suitable for pisciculture. 
SUMMARY OF THE INVENTION 
The object of the present invention is therefore to provide a supporting 
structure which does not suffer from the above-mentioned drawbacks, is 
simple in construction, contains a small number of details available to a 
large extent in the open market, can easily be erected and dismantled, has 
long life, extremely stable even when exposed to difficult conditions such 
as a rough sea and severe wind, is easy to transport and has a 
construction allowing the easy replacement of torn or soiled nets. 
This object is fulfilled by the supporting structure having the 
distinguishing features disclosed in the characterizing portions of the 
patent claims.

DETAILED DESCRIPTION 
In FIG. 1, a fish net carried by a supporting structure according to the 
invention is designated 2. The fish net 2, consisting of a mainly 
rectangular bottom and four substantially vertical side walls integral 
therewith, is removably fastened to the supporting structure by means of 
eyelets or the like attached to the upper contours of the side walls. The 
supporting structure comprises four bodies in the form of buoys 4 floating 
on the water, the construction of which will be described more closely in 
conjunction with FIG. 3, there being a vertical tube 6 fastened in each 
buoy. On the upper end of each tube 6 there is pushed a scaffolding clamp 
8 and it is locked to the tube by means of a set screw 10. The clamp 8 is 
of the threeway type, with one hole for the tube 6 and two holes at right 
angles thereto and at right angles to each other for elongate connecting 
elements in the shape of tubes 14, locked to the clamp by means of set 
screws 12. 
When erecting the structure shown in FIGS. 1 and 1A, the vertical tubes 6 
fitted with their scaffolding clamps 8 are first fastened in the buoys 4, 
whereafter the long tubes 14 are inserted in the clamps 8 so that the 
tubes 14 also project rather a long way from the clamps 8 in a direction 
away from the net 2. Eyelets 2a attached to the corners of the net 2 are 
thereafter hooked into hooks 14a, and the upper contour of the net is tied 
onto the tube 14 by means of removable tapes or cords 16 which can be 
attached to the side walls of the net. Thereafter, the scaffolding clamp 8 
is moved in a direction away from the net 2 so that the portion of the 
tube 14 between the clamps increases in length, whereat the net is 
stretched out so that at least the cords 2b in the upper contour of the 
net and forming the upper corners thereof which are fastened between the 
hooks 14a are stretched, whereafter the set screws 12 are tightened. 
The frame formed by the tubes 14 and 6 constrained by the clamps 8 thus 
forms a stiff frame in all directions, and its dimensions cannot be 
altered without undoing the set screws 12, its stability being increased 
by the cords 2b in the upper corners of the net being tensioned between 
the hooks 14a. The tubes 14 and 6 and clamps 8 with screws 10 and 12 are 
standard details available in any well-stocked ironmonger's, and the 
length of the tubes can easily be adjusted to the dimensions of different 
fish nets 2 and their height above the water surface. More than four 
buoys, tubes etc. can naturally be used for each fish net, whereat it can 
be made larger, or a system of frames consisting for example of groups of 
four or six buoys, tubes etc. can be arranged for a plurality of fish 
nets. 
In FIG. 1 there is also shown a platform 18 in the form of a triangular 
slab which is attached in a suitable way to a plurality of tubes 20 fixed 
by means of suitable scaffolding clamps on two tubes 14 forming a corner. 
This platform 18 can be used as a collecting place for equipment or as a 
working platform for the person who feeds or otherwise works with the fish 
confined in the net 2. 
Another embodiment of the supporting structure according to the invention 
is shown in FIGS. 2 and 3. The number of buoys 4 here is six, but with 
simple modifications of the vertical tubes 22 fastened in the buoys this 
number can be increased or decreased according to requirement. The buoys 
4, the construction of which is best shown in FIG. 3, each consists of a 
plastic or rubber envelope forming a container and having a valve 4a 
through which air can be introduced or exhausted from the space inside the 
envelope. The vertical central axis of the container has a tubular portion 
4b so that a through-hole is formed in the container. When the container 
is empty, a vertical tube 22 (or 6) can be inserted in the tubular portion 
4b, but when the container is pumped up, the diameter of this tubular 
portion decreases causing it to clamp onto the tube 22 with large force. 
When it is desired to adjust the tube 22 in a vertical direction, air is 
let out of the container and the tube is moved to the desired position, 
whereafter the container is once again inflated. 
In each vertical tube 22 there are made two horizontal throughholes 22a 
(FIG. 3) forming an angle of about 120.degree. to each other. Horizontal 
tubes 24, the outer diameter of which is less than that of the tubes 22, 
are introduced into these holes and locked by means of set screws 28 on 
rings 26 slipped over the tubes 24 on either side of the tubes 22, the 
inner diameter of the rings 26 exceeding the outside diameter of the tubes 
24 by an insignificant amount. Hooks 24a are attached to the tubes 24, 
these hooks being identical with the hooks 14a in FIGS. 1 and 1a and 
constitute the attaching means for rings 26a or the like on the fish net 
26. 
Holes 22a' also been made in the portion of the vertical tubes 22 extending 
under the buoys 4, these holes being identical with the holes 22a above 
the buoys. In holes 22a' there can be inserted the tubes 24', which are 
identical with the tubes 24 above the buoys, and which have been locked by 
means of locking rings 26' identical with the rings 26 above the buoys. 
The tubes 24' fastened under the buoys 4 have the task of further 
strengthening the construction and carrying attaching means (the hooks 
24a') for the eyelets 26a' or the like at the bottom of the net. To adjust 
the distance between the tubes 24, 24' attached above and below the buoys 
4, to the depth of different nets 26, further holes 22b (only two are 
shown) have been made in the vertical tubes 22. Two of the vertical tubes 
22 are considerably longer than the remaining four, and in their upper 
ends they have each been provided with a hole 22c, in which a tube 29 of 
the same cross-sectional dimensions as that of the tubes 24 and 24' is 
attached by means of locking rings 26" of the same kind as used for 
locking the tubes 24 and 24' to the tubes 22. On this tube 29, which even 
further stabilizes the construction, there is attached a hook 34 
displaceable in the longitudinal direction of the tube 29, for hanging up 
a remotely controlled feed metering apparatus 30. Furthermore, a rope 32 
can be wound around the tube 29, the rope being attached centrally to the 
bottom of the net 26 for pulling vertically upward when removing fish from 
the net or cleaning it. The tube 29 can thereby serve as hanging means for 
the fish net or for one or more nets which are to be attached to the 
supporting structure instead of a broken or otherwise unusable net. For 
more easily filling the apparatus 30 and carrying out other work with the 
fish, a platform (not shown) similar to the platform 18 in FIG. 1 can be 
mounted at one of the corners in FIG. 2. 
The procedure for erecting the supporting structure according to FIGS. 2 
and 3 is similar to that described above in conjunction with FIGS. 1 and 
1A. Since the ropes in the corners of the net are also tensioned in the 
embodiment according to FIGS. 2 and 3, before the set screws 28, 28', 28" 
of the rings 26, 26', 26" are tightened, whereby the tubes 22 are urged 
towards the centre of the net, it will be understood that the rings 26, 
26', 26" arranged on the outside of the tubes 22, i.e. the rings remote 
from the net, are not necessary. However, they provide surety for the 
supporting structure not collapsing if the net 36 is ruptured or if the 
supporting structure is exposed to extremely large stresses. 
The greatest advantage with the supporting structure according to FIGS. 2 
and 3 over that in FIGS. 1 and 1A is that the horizontal tube 24, 24', 29 
are rotatable in the holes 22a, 22a', 22c, which allows the buoys 4 a 
motion e.g. due to waves, substantially independent of each other in a 
vertical direction, which considerably reduces breaking stresses in the 
supporting structure, while the structure remains stiff in the horizontal 
plane, i.e. it resists movements in the horizontal direction. This 
advantage will be most noticeable if four buoys 4 and only one supporting 
frame are used, the buoys forming the corners of a rectangle, since the 
angles between the tubes 24 and thereby between the holes 22a are 
right-angles. For example, a movement downward, by one of these four buoys 
causes associated tube 22 to force downwards the ends of adjacent two 
tubes 24 introduced therein, but since the tubes 24 are simultaneously 
turned in the holes 22a in the adjacent two tubes 22 the downwardly 
directed movement of said buoy is not propagated in its entirety to the 
buoys fastened to said last mentioned tubes 22. This circumvents breaking 
stresses in the supporting structure and makes the structure more 
accommodating to high seas. Another advantage is that the structure shown 
in FIGS. 2 and 3 can be more easily adjusted to nets having different 
depths, and that further tubes similar to the tubes 24 can be inserted in 
further holes similar to holes 22a, b and c situated at different angles 
relative to each other for building up further supporting structures for 
several nets. An example of such an addition is indicated by chain-dotted 
lines in FIG. 2. 
The supporting structure shown in FIGS. 1 and 1A, which can naturally be 
provided with a supporting frame on the underside of the buoys as well, 
made up in the same way as shown for the tubes 14 and clamp 8, has the big 
advantage over the supporting structure shown in FIGS. 2 and 3 that the 
diameters of all the tubes 6 and 14 identical. 
It should be understood that the invention is not limited to the 
embodiments described above and shown on the drawings. Thus, the number of 
buoys and tubes can be modified and adjusted to the size of the net and 
the environment in which the apparatus is intended to be used. 
Furthermore, one single supporting structure can be used for several nets, 
or a plurality of supporting structures can be built together into large 
systems where one or more buoys are common for several supporting 
structures and nets, it being possible just as well to replace at least 
one of the buoys with a portion of a quay or the like. 
The invention is therefore only restricted by what is disclosed in the 
appended claims.