Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a device for the removal
of aquatic vegetation from the floor of a body of water
such as a lake, river or the like. More particularly, the
invention pertains to an aquatic harvester device
comprising a mesh-form, rigid, elongate body of generally
S-shaped cross~section, which has a raised forward face
with a smooth edge and a downwardly extending rearward face
carrying a plurality of spikes or teeth. The invention
also relates to a method of using the aquatic harvester
device.
Waterfront land owners and users often experience
difficulty in traversing by watercraft or the like
;~ relatively shallow waters adjacent the shore due to
proliferation of unwieldy aquatic plant and weed growth.
The satisfactory removal of such aquatic vegetation to
provide clearance for the free mobility of watercraft can
be a difficult and dangerous task.
Hitherto, various means for aquatic plant removal
have been attempted, all of which sufLer from significant
problems and/or disadvantages. For example, chemicals have
been successfully used to completely eliminate and/or
control agyatic plant growth. ~owever, due to society's
ever increasing environmental awareness, the use of
chemicals for this purpose has met with steadfast public
resistance. Various mechanical devices have also been used
with relatively limited success. For example, V-shaped
cutting devices (such as described in United States Patent
No. 2,702,975) comprising a pair of elongated knife members
which extend in a common plane to form a V-shaped
structure, cut the water plants at their stems leaving the
root systems intact. Such a device provides only a
temporary solution to the problem in that, by leaving the
root systems intact, the plants are able to recover in a
relatively short period of time. Accordingly, the use of
a V-shaped cutting de~ice necessitates the frequent
periodic reuse thereof in order to maintain the desired
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clearance. Furthermore, the exposed sharp blades of the ~
shaped cutting device represent a significant danger to the
operator, and human life in general, which has resulted in
substantial consumer resistance to its use.
Another aquatic plant removal device is described
in United States Patent No. 4,852,337 (Peterson) which
comprises a rake with an elongated transverse bar, a
structure for pulling the rake underwater, a plurality of
flexible and resilient teeth and a stress distributing
structure. Between the tine of each tooth is strung a
filament designed to engage underwater plants and pull the
plants from the bed by the roots. Although the teeth of
this device are resilient and bend in response to
underwater obstructions, the filament tends to become
snagged on rocks, or the like, and thereby to halt the
device, requiring it to be dislodged. Moreover, in
response to an obstruction, the filament can break
requiring the device to be removed from the water and
repaired before operation may continue.
United States Patent No. 3,057,139 (Lane et al.)
describes a basket-type device for collecting vegetation in
roll form. Distinct disadvantages of this device include
its bulkiness, the complexity of its design and the
requirement of a crane for operation.
Finally, United States Patent No. 2,961,817
(Mitchell) teaches a drag rake for cutting and raking
underwater plant growth which comprises a generally flat
metal blade having a sharpened cutting edge on the inside
profile with metal spikes protruding above and below the
blade and has, interspaced between the spikes, at least
four metal runners. Again, the question of operator safety
is at issue in light of the exposed blade and, moreover,
cutting as opposed to uprooting of the aquatic plants is
subject to rapid regrowth and consequently necessitates
periodic repeated raking throughout the summer season.
It is an object of the present invention to
provide a safe and efficient device for the removal of
aquatic vegetation on a relatively permanent basis from the
floor of a ~ody of water such as a lake, river, ocean or
the like.
It is a further object of the invention to provide
an improved and economical device for the removal of
underwater plant life which overcomes inherent
disadvantages of prior aquatic plant rem~Yal devices~
It is a still further object of the invention to
: provide a simple and convenient method for using the
aquatic harvester device.
Accordingly, the invention provides an aquatic
harvester device for the removal of vegetation from the
floor of a body of water comprising: a rigid, elongate body
which has a forward face terminating in first vegetation-
engaging means capable of assuming a raised position and a
downwardly extending rearward face carrying second
vegetation-engaging means; and means for permitting pulling
of the rigid body over an underwater floor while submerged
with said first vegetation-engaging means in the raised
position and said second vegetation-engaging means in
substantial contact with the underwater floor, whereby to
remove vegetation therPfrom.
The invention also provides a method o~ removing
aquatic vegetation from the floor of a body of water,
comprising the steps of: lowering the aquatic harvester
device to the floor of a body of water at a suitable
distance from shore, over which distance it is desired to
clear vegetation; pulling the harvester device while
submerged over the floor of the body of water towards the
shore, the first vegetation-engaging means of the forward
fa~e of the device engaging un~erwater vegetation while the
second vegetation-engaging means of the rearward face
uproot same, the uprooted plants being carried with the
harvester device the duration of operation; retrieving the
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harve.ster device from the body of water; and releasing the
collected veyetation from the harvester device.
In a preferred embodiment, the aquatic harvester
device comprises a mesh-~orm, rigid, elongate body of
generally S-shaped cross-section, which has a raised
forward face with a smooth edge and a downwardly extending
rearward face carrying a plurality of teeth: and means for
pulling the rigid body over the underwater floor while
submerged.
10The aquatic harvester device of the present
invention is designed to safely and efficiently remove
water vegetation (including water weeds and plants) from
the bed o~ a river, lake or other body of water in which
such vegetation grows.
15The S-shaped cross-section of the device is
integral to its harvesting action in that the smooth-edged
forward face engages the water vegetation causing the stems
thereof to bend onto the smooth contour of forward face of
the device. Approximately simultaneously, the teeth
disposed on the rearwaxd face of the device uproot the
water plants, effectively removing the plants ~rom the
~- water bed. The dislodged plants then fall into the trough
of the device, as defined by the forward half of the
inverted S-shaped cross-section, and are carried with the
- 25 device for the duration of operation. The cycle of
engaging and uprooting water plants repeats continuously
until the plant removal operation is completed.
-The open mesh-form of the rigid body allows the
device to ~low through water with relatively little
resistance~ This is of particular relevance when lowering
;1~ the harvester device to the floor of a body of water. The
op~n structure enables lowering of the device to be
performed accurately and without lateral surfing action
whi~h might occur with a solid structure. This can be
important in water depths over about 8 to 10 ~eet. It is
necessary that the device be of sufficient weight that it
readily sinks to the water floor and remains on the ~loor
when being pulled while in operation. Accordingly, the
aquatic harvester device of invention is preferably made of
a corrosion-resistant metal. Of particular preference is
treated iron such as painted or galvanized iron. However,
heavy-duty plastics, such as polyvinyl chloride (PVC) is
also suita~le as are other materials which provide
sufficient weight, rigidity and corrosion resisting
properties. If necessary, to achieve optimum weight for
operation, individual weights can be added to the body of
the device to increase the total weight thereo~.
The type of surface of the water floor is a factor
in the operable performance of the aquatic harvester
device. For example, a water floor comprising mostly sand
and without many significant surface obstructions will
allow the harvester to smoothly remove aquatic vegetation
in a uniform manner, whereas a rocky water floor with
substantial obstructions will obviously result in a more
uneven clearance o~ vegetation. However, it should be
emphasized that, due to the upwardly curved contour of the
- forward face, the device will simply ride over many
obstructions if present on the water floor~ The unique
design of the forward face results in a substantial
reduction in interruption of operation to dislodge the
device caught on obstructions as compared to conventional
devices of this type.
The device can be operated with reasonable ease
when the body is from about 2 to 8 feet in length,
~ preferably about 4 to 5 ~eet. A shorter body length is
; 30 particularly convenient when it is necessary to navigate
the device over a constricted area between multitudinous
obstructions on the water floor. Alternatively, two or
more of the harvester devices could be connected end-to-end
in order to achieve an effective body length such that
optimal operation may be obtained. For example, two 4 foot
~ devices could be connected end to end to effectively form
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an 8 foot device, allowing the number of nacessary repeated
operations to clear an area of vegetation to be reduced.
This can bs particularly advantageous when clearing large
areas of a water floor with few obstructions.
In an alternative embodiment of the device, at
least two skids are disposed in spaced relation on the
lower side of the device in order to hold the device in the
optimal disposition for operation with the forward face in
the raised position. The skids are designed to slide along
the water floor maintaining the device in the preferred
operable disposition while also enhancing ease of
operation.
In the accompanying drawings which illustrate
embodiments of the invention~
Figure 1 is an isometric view from above of a
- preferred form of aquatic harvester device according to an
embodiment of the invention;
Figure 2 is a perspective view from below of the
device depicted in Figure 1;
Figure 3 is an end view of the aquatic harvester
device shown in Fi~ure l; and
Figure 4 is an end view of the aquatic harvester
device of Figure 1 shown in operative position.
Referring now to the drawings, the preferred form
of the aquatic harvester device of the present invention
is shown in Figures 1 and 2. The device is defined by a
generally S-shaped profile 10, which shape provides
strength and rigidity to the device without the need for
additional rein~orcement. The body of the device is in
mesh-form 20 and is Pormed on its forward face with a
relatively smooth edge 30, while rearward face 40 carries
a plurality of spaced spikes or teeth 50 depending
therefrom. The spikes or teeth 50 are advantageously
spaced apart from each other by a distance of about 2 to 10
cm so as to optimize plant root removal ability. Two
metallic rings 60 are provided for pulling the aquatic
harvester through the water, one ring being disposed at
each end thereof. The rings also provide pivot means
useful when disengaging collected vegetation upon
completion of operation. The rings are connected to each
end of a rigid cross-bar 65 disposed transversely with
respect to the body of the device. Three V-shaped brackets
68 attached to the forward and rearward faces 30 and 40
secure the cross-bar 65 by a weld to the harvester device.
A rope, cable or the li~e can be looped through each of the
rings 60 and used to pull the device along the waterbed in
operation. As the ropes are placed under tension, the
pivotal effect upon the device tends to cause the teeth to
dig into the ground and effectively uproot water plants
therefrom. Depending on the situation, the pulling of the
rope or cable can be effected manually or by means of an
automated device such as a crank or tractor.
With reference to Figure 3, an end view of the
preferred form of the aquatic harvester device as depicted
in Figures 1 and 2 is shown. The forward half of the S-
shaped profile of the device 10 defines a rounded trough70. During operation, the leading edge 30 of the forward
face engages water plants in the stem mid- region causing
the plants to bend rearwardly over the smooth contour
thereof and into and across the trough 70. Approximately
simultaneously, the depending teeth 50 carried on the
rearward face 40 scrape across the water bed and
effectively pull at and uproot the water plants. The
dislodged plants, having fallen into and over the trough
70, ar~ carried with the aquatic harvester device for the
duration of operation. The cycle of water plant engagement
and uprooting repeats continuously until operation is
terminated.
Referring now to Figure 4, an end view of the
aquatic harvester device is shown in operative position.
Generally, while in operation, the device is disposed in a
specific optimum position, which position is of
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significance to the efficiency of plant removal action. In
the embodiment of Figure 4, when the harvester device is in
operation, the metal rings 60 are disposed at approximately
30 with respect to the water floor 100. In contrask, when
the device is at rest, the metal rings 60 are disposed at
approximately 60 to the horizontal as depicted in Figure
3. Furthermore, optimal operation o the aquatic harvester
device is found to occur when the ratio o~ the height A of
the forward vertical projection of the front edge 30 above
the water floor 100 to the horizontal length B of the
lateral horizontal projection is about 2:3. However, the
device is operable over the range of the above ratios of
from about 1:5 to 1.5:1. With reference to Figure 4, the
term "forward vertical projection" as used herein refers to
the height A from the forward edge 30 to the water floor
100. The term "bottom horizontal projection" refers to the
horizontal distance B from the teeth 50 to a point 130 on
the water floor vertically below the forward edge 30.
As shown in Figure 4, during operation the
harvester device travels along the water floor 100, the
~: smooth edge of the forward face 30 engaging water plants
-- 110 at their stem mid-portions causing the plants to bend
rearwardly onto and over the smooth-edged face 30 and into
~: the rounded trough 70. Meanwhile, the teeth 50 of the
rearward face 40 scrape across the water floor 100
effectively uprooting the engaged water plants 110, which
plants 110 once dislodged fall into the trough 70 and are
carried with the device for the duration of operation.
Throughout plant removal action, the disposition of the
- 30 device is preferably such that the above-discussed ratio of
~:i A to B is about 2:3. However, as mentioned, the device is
~ operable over a range of ratios A/B of from about 1:5 to
;~ 1.5:1.
The preferred method of using the device depicted
: 35 in Figures 1 to 4 comprises the steps of: lowering the
inventive device onto khe floor of a body of water at a
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suitable distance from shore, over which distance it is
desired to clear vegetation; pulling the harvester device
over the distance to be cleared, for instance by means of
a rope, cable or the like 120, looped through the metal
5 rings 60; retrieving the device from the body of water; and
releasing the collected vegetation by means of a reverse
flip and several complete turns of the device.
In practice, it has been found convenient to
transport the aquatic harvester device by watercraft, such
10 as an aluminium boat, to the point from shore from which it
is desired to commence clearance of vegetation. A single
operator can lift the device from the boat and lower it to
the waterfloor by means of a rope looped through the rings
disposed at each end of the device. From shore, by means
15 of the rope, a single operator can pull the harvester
device over the waterfloor; which pulling will initiate the
continuously repeated cycle of plant removal action of the
device as described above. Once the device has been pulled
the distance to be cleared ~usually to the shoreline) the
; 20 operator can retrieve the device from the water. On shore
the operator can disengage the aquatic vegetation collected
d and carried on the device by simply effecting a reverse
-~ flip and several complete turns of the device about its
- axis. The rings can be readily gripped to provide a pivot
25 means useful for this purpose. This manipulation of the
device causes the collected vegetation to become disengaged
~- and fall to the ground.
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