Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE
Subsurface Shellfish Farm
FIELD OF INVENTION
This invention relates to the field of shellfish farming and in particular to
subsurface
mussel farming.
BACKGROUND
Shellfish such as mussels have been farmed in the Marlborough Sounds in New
Zealand
for some years. A typical mussel farm includes a number of floats connected by
two
backbone ropes. Each backbone rope runs along one side of a line of floats and
is
connected to them. Mussel growing ropes are hung from the backbone ropes and
extend
below the waterline.
In open seas or adverse weather conditions backbone and growing ropes too near
the
surface can be subjected to significant amounts of wave action. This can place
undue
stress on the backbone ropes and mussel growing ropes, leading to undue damage
to the
farm and even loss of mussels if the growing lines break free.
OBJECT OF THE INVENTION
It is an object of a preferred embodiment of the invention to go at least some
way towards
addressing the above. However, it should be appreciated that the invention has
more
general application and so any objects or advantages applicable to a preferred
embodiment should not be seen as a limitation on the scope of the claims
expressed
broadly. The object of the invention per se is simply to provide the public
with a useful
choice.
DEFINITIONS
The term "comprising", if and when used in this document, should be
interpreted non-
exclusively. For example, if used in relation to a combination of features or
steps it should
not be taken as precluding the option of further unspecified features or
steps.
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SUMMARY OF THE INVENTION
A shellfish farm comprising:
= a plurality of floats at or near water level;
= a backbone thread;
= shock absorbing threads extending between the floats and the backbone
thread;
and
= at least one shellfish thread extending from the backbone thread with
shellfish
attached.
Optionally there are at least two backbone threads similarly arranged.
Optionally at least two shock absorbing threads extend between each float and
the
backbone threads.
Optionally each shock absorbing thread is elastic.
Optionally each shock absorbing thread connects to a respective float by way
of a collet
secured around the shock absorbing thread and a collar secured around the
collet,
wherein the collar is nested in an aperture extending through the float.
Optionally each shock absorbing thread is connected to a/the backbone thread
by way of
a hook.
Optionally each shock absorbing thread is connected to a hook by way of a
collet secured
around the shock absorbing thread and a collar extending around said collet,
wherein the
combination of these is secured in a recess of the hook.
IMAGES
Some preferred embodiments of the invention will be further described with
reference to
the accompanying images in which:
Figure 1 illustrates a marine subsurface mussel farm;
Figure 2 is a cross-sectional view showing detail through a float
within the farm;
Figure 3 is a cross-sectional view a mode of connecting the float to
a shock
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absorbing thread;
Figure 4 is a side view of a hook forming part of the farm; and
Figures 5A-D are isometric views of an alternative hook and the manner it is
connected
to a shock absorbing thread; and
Figure 6 is an isometric view of various parts of the farm.
DETAILED DESCRIPTION
Referring to figure 1, a marine subsurface mussel farm has a number of floats
1 at or near
the waterline, each connected to a pair of submerged backbone ropes 2 via
elastic (eg
cords 3 and hooks 4. The cords 3 may be substantially formed from rubber, for
example
as a single strand or from multiple strands. A number of submerged mussel
growing
ropes 5 are suspended from the backbone ropes 2 and trail deeper down into the
water.
The growing ropes 5 have growing or mature mussels attached.
The length of the elastic cords 3 is such that, in calm conditions, the
growing ropes 5 start
at a predetermined distance below the waterline. In preferred embodiments, the
only
connection between the floats 1 and the growing ropes 5 comes via the elastic
cords 3
and the backbone ropes 2. In alternative embodiments, the floats 1 may be
connected
together by a suitable line. One or more anchors (not shown) may be used to
anchor the
farm to the seabed.
Each float 1 is substantially in the form of a capsule having a cylindrical
centre with
hemispherical parts either side. The floats 1 may be hollow or filled with
foam or some
other suitable material for buoyancy. In further embodiments the floats 1 may
be any
other suitable shape.
Referring to figure 2, each end 6 of each float 1 is profiled to enable easy
connection of a
respective one of the elastic cords 3. More specifically, at each end a first
vertical
aperture 7 runs top to bottom and has a broader central opening 8. The opening
allows a
shock absorbing cord to be correctly housed within the aperture. The aperture
7 also has
a shoulder 9 immediately below the central opening 8.
Figure 3 shows the float's profiled end 6 when connected to one of the cords
3.
Because the cord is elastic it can be stretched, and when this occurs it
constricts or has at
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least a region of lessor diameter. As shown, the cord 3 has been stretched in
this way to
fit a collet 10 of a lessor diameter than the region of cord it engages. As
also shown, a
collar 11 has been fitted around the collet 10 to assist with a secure
connection to the cord
3. More specifically, the collar 11 sits snugly in the recess 9. Because the
collar 11 is
wider than the parts of the aperture 7 below the recess it resists downward
pulling on the
cord 3 so that the cord is securely held. To help keep the collet 10 engaged
with the
collar 11 and for more accurate placement, a lower laterally protruding rim of
the collar
extends inwardly into a narrowed part of the collet, as illustrated at 12.
As will be evident from figure 3, the outer diameter of the collet 10 is less
than that of most
of the aperture 7 (ie the parts above and below the central opening 8 and the
recess 9).
This enables the cord 3 with the collet 10 attached to slide through the
aperture 7 when
being fitted. The collar 11 is fitted to the collet 10 when these parts are in
the larger
central opening 8 (ie there is plenty of room there to enable this). When that
has occurred
the collar/collet/cord combination is lowered until the collar 11 sits in the
recess 9 in the
manner described above. The cord 3 will therefore remain connected to the
float 1 until
the collar 11 is removed by reversing the process.
In alternative embodiments the cord 3 may simply be knotted at both ends of
the aperture
7 to prevent it from pulling free of the float 1. However the mode of
attachment described
above is preferred.
Each elastic cord 3 prevents or at least reduces shock forces on the floats 1
from being
transmitted to the backbone ropes 2 and from there down to the shellfish
growing ropes 5
and shellfish. This means that in rough seas where the floats 1 may be
experiencing a lot
of movement, significantly less movement is transmitted to the shellfish. More
specifically,
when the floats 1 are moving in rough seas the cords 3 stretch and absorb
force
transmitted by the floats 1 so that the backbone ropes 2 (and shellfish ropes
5) are less
subject to movement than would otherwise be the case. The cords 3 therefore
serve as
shock absorbers.
The backbone ropes 2 are preferably made of polypropylene, but any suitable
alternative
material may be used. In some less preferred embodiments the backbone ropes
may be
substituted by alternative forms of thread, for example a rod.
Referring to figures 1 and 4, each hook 4 is used to connect a shock absorbing
cord 3 to a
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backbone rope 2. The hook 4 has an aperture 13, tab-like guides 14 and a front
groove
15. In each case an elastic cord 3 is threaded through the aperture 13 and
held by friction
between a pair of the guides 14. The hook 4 is then hooked around a backbone
rope 2
and the end of the cord 3 pushed into and frictionally held in the groove 15.
In this
manner the cord 3 loops around the backbone rope 2. Preferably the groove 15
is in the
shape of an open channel where the opening is wide enough to admit the cord 3
(eg when
constricted by stretching) and narrow enough to retain the cord (eg by
friction) when the
stretching force is relaxed.
Figures 5A-D showsan alternative hook4a when in use with the shock absorbing
cord 3
for fastening to a backbone rope 2. As shown the cord 3 is inserted into an
aperture 16 in
the top of the hook. A collet 10a and collar lla are used to retain the cord 3
in the
aperture 16 in a similar way to that described for the float 1. Therefore the
cord 3 is
secured against forces that would otherwise tend to pull it out of the hook
4a. The
aperture 16 may include a shoulder-like fastening recess for the collar lla
(eg similar to
the recess 9 above, for similar engagement).
The hook's collet 10a may be applied to the cord 3 before or after the cord is
inserted into
the hook's aperture 16. More particularly, after the cord 3 has been inserted
into the
aperture 15, the collar lla is attached to the collet 10a and the cord 3 then
pulled back up
through the top of the hook to move the collet 10a and collar lla into
position.
Referring further to figures 5A-D, the hook 4a has two lower apertures 17, 18
in its curve.
After the cord 3 has been passed through the aperture 16 at the top of the
hook and the
collet 10a and collar lla are in place, the cord is passed through the
aperture 17 and then
back through the aperture 18. A backbone rope 2 is then inserted into the hook
4a as
shown at figure 4C.
The hook 4a includes a lower groove 19 into which the backbone rope 2 is
nested. The
groove 19 is an optional way of keeping the backbone rope 2 in the desired
position with
respect to the elastic cord 3.
When the backbone rope 2 has been positioned in the hook the elastic cord 3 is
pressed
into front groove 20 in a tight friction fit. In alternative embodiments, the
front groove 20
may be substituted by an aperture and another collet and collar combination in
the
manner described above.
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Referring to figure 6, an elastic cord 3 is shown when 3 attached to a hook 4a
at one end
and to a collet 21 and collar 22 at the other end. A backbone rope 2 is shown
passing
through the hook 4a.
While the invention has been described with relation to mussel farming it has
broader
application. I may for example be used with appropriate other forms of
shellfish.
While some preferred aspects of the invention have been described by way of
example it
should be appreciated that modifications and improvements can occur without
departing
from the scope of the following claims.
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