[0001] The invention refers to an integrated system for the implantation of metal tubes
from the surface of the sea to marine sedimentary seabed. The system consists of a
mechanism with grabs, that can hold tightly the metal tube from its upper part aiming
at deploying it from the surface to the bottom in a vertical position. The support
vessel winch is used for the deployment. The grabs hold the metal tube through a watertight
seal to the lower part of a flexible water tube which is connected to top of the metal
tube. The other end of the flexible tube is connected to an autonomous water pump
on the working deck of the support vessel. By activating the pump, pressurised water
comes out from the lower end of the metal tube, washing out the sediment particles,
gradually creating a narrow hole that allows the lowering of the tube to the desired
depth. The final penetration depth is controlled by special shoes attached to the
main body of the mechanism which prevent further penetration of the metal tube when
they come in contact with the seabed. When the metal tube reaches the desired depth
into the sediment the operation of the pump is interrupted and a special tube release
on the grab holding mechanism is activated. Finally, the main body of the system with
the holding grabs and the shoes as well as the flexible tube are brought back to the
vessel's working deck in order to be reused for a new tube implantation.
[0002] The invention aims to protect fishing grounds and marine sensitive habitats from
the illegal use of towed fishing gears (bottom trawling). The adverse effects of trawling
activities upon the marine organisms and the biota have been well studied and documented
scientifically. According to recent decision of the European Union in the frame of
the Common Fisheries Policy (Council Regulation No 1626/94 of 27 June 1994) the use
of bottom trawls within the three nautical miles from the coast (or up to the 50 metres
contour depth) and also above sea grass meadows
(Posidonia oceanica beds) shall be prohibited (article 3). Unfortunately, the implementation of effective
controls is not always possible and as a result in many areas, vessels at sea are
not controlled throughout the fishing period. The use of illegal bottom trawling causes
a continuous and severe deterioration of valuable natural marine habitats as well
as overexploitation of marine living resources. In many Mediterranean countries, artificial
reefs known in the literature also as antitrawling reefs, are used as simple mechanical
obstacles to prevent illegal trawling in marine protected zones. Unfortunately, it
seems that the use of artificial reefs i.e. massive structures from concrete, for
the creation of protected marine zones presents a series of disadvantages. Considering
the proven enhancement and aggregating role of artificial reefs in the absence of
proper control measures on fishery operations, their deployment may have the effect
of concentrating fishery activity and consequently further exacerbating over-fishing.
Among other disadvantages the long term bureaucratic implications and high cost of
artificial reef construction, including potential requirements for removal are also
included.
[0003] The integrated system for the automatic implantation of metal tubes in soft bottom
substrates can offer a high level of protection to marine seagrass beds and nursery
grounds from illegal trawling. The method can be used as a cost effective alternative
to the deployment of antitrawling artificial reefs in areas where urgent action has
to be taken. Also, it is by far more economic, is reversible, allows the protection
of extensive areas, does not aggregate fish and does not affect passive fishing gears,
furthermore it is simple and does not require long term construction implications.
The metal tubes will be implanted in such a way that their major part will be buried
in the sediment and only the upper part of the tube will remain protruding above the
seabed. The distance between the metal tubes is in the order of tens to hundreds metres,
depending on the surface of the area that is preselected for protection. When a towed
fishing gear comes in contact with the metal tube there are two possibilities: either
the gear is stopped, or the ground rope of the trawl passes over the metal tube and
consequently the trawling net is seriously damaged. Another application of the invention
is the use of the implanted metal tubes as an alternative to conventional mooring
systems in marine and freshwater environments (e.g. concrete blocks, sandbags, embedding
anchors, etc.)
[0004] For the automatic implantation of the metal tubes, a working platform (e.g. vessel)
equipped with a hydraulic winch and a crane is needed. The main body of the implantation
system consists of a metal frame that supports a pair of grabs that could hold tightly
a metal tube (e..g. standard 6 metre long galvanised iron or steel tubes) from its
upper part aiming at deploying it from the surface to the bottom in a vertical position.
The vessel's winch wire connected to the system's metal frame and the crane will be
used for the metal tube deployment. The grabs hold the metal tube through a watertight
seal to the lower part of a flexible water tube which is connected to top of the metal
tube. The other end of the flexible water tube is connected with a water pump located
on the working deck. The holding mechanism of the grabs could be hydraulic, or simple
mechanic (e.g. return springs) or a mixed type. When the lower part of the metal tube
comes in contact with the seabed the water pump is activated and as a result pressurised
water comes out from the lower end of the metal tube, washing out the sediment particles
and thus gradually creating a narrow hole in the seabed. This procedure allows the
lowering of the metal tube to the desired depth controlled by special metal shoes
attached to the main metal frame of the system that prevent further tube penetration
when they come in contact with the seabed. The attachment of these shoes to the main
metal frame of the system can be regulated according to the desired penetration depth.
As a result the upper part of the implanted tube protrudes a predefined distance above
the seabed. Finally, the tube holding mechanism (hydraulic and/or mechanic) is decoupled
and as a result the system minus the tube can be brought back to the vessel's deck
in order to be reused for a new tube implantation.
[0005] In order for the reader to gain a complete understanding of the present invention,
example of one preferred embodiment follow, with reference to the accompanying figures:
[0006] Figure 1A shows a bird's-eye view of the system's main body with the two grabs (3
and 4) that are stably connected, the first (3,) to the main metal frame of the system
(1) and the second (4) to a metal plate that can reciprocate freely on cylindrical
guides (5), connected stably to the internal sides of the main metal frame (1). A
hydraulic piston (6) which is fed by an oil pump located on the support vessel, when
activated, moves the metal plate (2) and consequently the grab (4) that is stably
connected to it. Both grabs hold tightly the upper part of the metal tube (7) and
at the same time the lower part of a flexible water tube (8) which by having slightly
larger diameter surrounds as external casing the upper part of the metal tube. The
movement of the metal plate (2) towards the grab (3) creates the hold and seal on
both tubes (7, 8) and also compresses the two return spiral springs (9). The arrow
indicates the direction of the movement of the hydraulic piston (6).
[0007] In figure 1B the arrow shows the removal direction of the metal plate (2) towards
the side of the frame that bears the hydraulic piston (6). This removal is caused
by the expansion of the two springs (10) when the hydraulic piston (6) is deactivated.
The dynamic energy of the two springs move backwards the metal plate (2) and consequently
the grab (4), finally releasing both the metal and the flexible tubes (7, 8).
[0008] In figure 2 an enlarged elevated side view of one of the two shoes that are stably
attached to the external sides of the main metal frame of the system is shown. It
consists of the shoe pad (1), of which the lower surface comes in contact with the
seabed, a vertical arm (2) stably connected with the shoe pad and a horizontal arm
(3) that is semi-permanently connected with the vertical arm (2) and from the other
side is stably connected to the external side of the metal frame of the system (4).
[0009] In Figures 3A, 3B and 3C a diagrammatic presentation of three successive operational
phases of a tube implantation is given. In figure 3A a side view of the metal frame
(1) and the two shoes of the system (2) and also the metal tube (4), the flexible
water tube (5) and the oil supply tube (6) to the system's hydraulic piston are depicted.
The main metal frame is deployed by wire (3) from the winch of the supporting vessel.
As soon as the lower part of the metal tube comes in contact with the seabed (7),
a water pump located on the supporting vessel deck is activated and pressurised water
is pumped through the flexible tube (5) and the metal tube (4), washing out the sediment
gradually creating a narrow hole (8) that allows the lowering of the metal tube into
the seabed.
[0010] In figure 3B the major part of the metal tube is already burried into the seabed
and its further deployment is prevented by the two shoes of the system. The supply
of pressurised water is stopped and the narrow hole has started to be filled in with
sediment.
[0011] In figure 3C the supply of oil by the hydraulic pump has stopped, resulting in the
realease of the system from the tube. The metal tube remains implanted in the seabed
and the system including both the oil supply tube and the flexible water tube are
removed back onto the deck in order to be reused for a new implantation.
1. Integrated system for the automatic implantation of metal tubes from the surface of
the sea to marine sedimentary seabed comprising a metal frame that supports a hydraulic
piston, pressing grabs that can hold tightly a metal tube from its upper part aiming
at deploying it from the surface to the bottom in a vertical position, said grabs
holding also through a watertight seal the lower end of a flexible water tube connected
to a water pump supplying pressurised water through the flexible tube to the lower
end of the metal tube that washes out the sediment and gradually creates a narrow
hole that allows the lowering of the metal tube up to the desired penetration depth,
said metal frame also supporting external arms having at their lower ends footpads
which prevent further penetration of the metal tube when they come in contact with
the seabed, said hydraulic grab mechanism when is deactivated allowing the opening
of the grabs caused by expansion springs and finally allowing the release of the implanted
metal tube into the seabed and the bringing back to the sea surface of all the system's
components in order to be reused for a new tube implantation.
2. Integrated system in accordance with claim 1 wherein both grab closing and opening
mechanism is supported by hydraulic pistons.
3. Integrated system in accordance with claim 1 wherein both grab holding and opening
mechanism is supported by expansion springs.
