ARTIFICIAL REEF FOR RECREATIONAL DIVING

Abstract

Artificial reef for recreational diving (1) comprising a base (2) of a slab of reinforced concrete and a vertically extending superstructure (3) made of concrete of inert lightweight materials that is ejected onto a structural frame comprising a plurality of stem members (32) around a trunk (31) implanted into the base and plastic grid items (12) suspended thereupon in a predetermined manner so as to form, following concrete ejection, a reef having a form and aesthetics corresponding to that of a natural reef, comprising blind crevices (9) and through holes (7) leading to chambers (8) and smaller or larger cavities (10, 11), constituting microhabitats and refuges for targeted benthic and benthopelagic organisms. The reef (1) is founded onto the seabed with one or more beams (30) introduced into holes (4) that pass perpendicularly through the base (2) and extend vertically along the superstructure (3). Artificial reefs (1) are organized in groups (20) defining an artificial oasis for recreational diving within a planned section (ABCD) of the seabed.

Claims

1. Artificial reef for recreational diving (1) comprising a base (2) and a substantially vertically extending superstructure (3) having the general form of an upstanding elongate monolith seated thereupon, characterized in that the base (2) is made of a slab of reinforced concrete and the superstructure (3) is made with a structural frame having an exterior and an interior structural complexity predetermined in accordance with a preselected design pattern, said structural frame comprising a plurality of stem members (32) of predetermined structure extending all around a trunk member (31) implanted into the base (2) and a plurality of plastic grid items (12) suspended onto said stem members (32) all around said trunk member (31) in a predetermined manner that corresponds to said preselected design pattern, said structural frame of the superstructure (3) being thereafter coated with concrete ejected thereupon in one or more successive stages, whereby a plurality of blind crevices (9), through holes (7) leading to chambers (8) inside the reef and exterior holes of smaller or larger dimensions that define small cavities (10) and larger cavities (11) respectively are being formed functionally dependent on the predetermined design pattern of said structural frame of stem members (32) around said trunk (31) and of said plastic grid items (12) mounted thereupon, wherein said blind crevices (9), through holes (7) leading to chambers (8) and small and large cavities (10, 11) constitute microhabitats and refuges for targeted benthic and benthopelagic species, which live permanently or find a long term or temporary shelter within said microhabitats selecting them according to their size.

2. Artificial reef for recreational diving (1) according to claim 1, characterized in that the superstructure (3) is made of concrete comprising inert lightweight materials and in combination with its multiplex structure with numerous voids formed therein in the form of holes leading to small cavities (10) and large cavities (11), through holes (7) and blind crevices (9), chambers (8), etc., said superstructure (3) acquires a comparatively lower specific weight with respect to the base (2) thereby effecting a downward displacement of the center of gravity of the artificial reef (1) towards said base (2) and providing stability at the location of installation thereof onto the seabed.

3. Artificial reef for recreational diving (1) according to claim 1, characterized in that the base (2) comprises at least one through hole (4) that passes perpendicularly through the base (2) and extends vertically along a part or the entire height of the superstructure (3), said hole (4) being adapted to receive a beam or tube (30) previously mounted into the seabed (16) for effecting foundation of the artificial reef.

4. Artificial reef for recreational diving (1) according to claim 3, characterized in that said at least one through hole (4) terminates with an enlarged end at the bottom of the base (2), said enlarged end being configured in the shape of an open ended truncated cone (5) that facilitates insertion therein of said previously mounted foundation beam or tube (30).

5. Artificial reef for recreational diving (1) according to claim 3, characterized in that it comprises two or more through holes (4) adapted to receive two or more foundation beams or tubes (30), said through holes (4) passing perpendicularly through the base (2) and extending vertically along a part or the entire height of the superstructure (3) being transversally interconnected with a horizontally extending bar (17) within the base (2).

6. Artificial reef for recreational diving (1) according to claim 1, characterized in that a fastening device of the artificial reef (1) is employed in providing a handy launching of the artificial reef (1) onto the seabed (16), said base (2) being provided with a pair of through parallel holes (6) extending from one point on the circumference of the base (2) to a directly opposing point, symmetrically on either side of the center of the base (2), said fastening device comprising ropes or straps being adapted to pass through said through parallel holes (6) to suspend the reef during movement and launching thereof onto the seabed (16).

7. Artificial reef for recreational diving (1) according to claim 1, characterized in that the exterior and interior structural complexity of the structural frame pertaining to each preselected design pattern of the superstructure (3) that forms the basis for organizing distinct production lines of artificial reef units (1), each production line featuring identically configured and identically located through holes (7), blind crevices (9), open interior chambers (8), exterior holes leading to smaller and larger cavities (10) and (11), etc., is predetermined according to the number and the size of benthic and benthopelagic targeted organisms that could potentially choose the artificial reef (1) for their permanent or temporary settlement.

8. An underwater artificial oasis for recreational diving comprising a plurality of the artificial reefs for recreational diving (1) of claim 1, said artificial reefs (1) organized in groups (20) bounded in close proximity within a planned section (ABCD) of the seabed that defines the limits of a protected area, a plurality of elementary artificial reefs (21) being arranged along a diving trail (22) within the artificial oasis to lead the way from one group of artificial reefs (20) to the next, said elementary artificial reefs (21) being employed in identifying the course along diving trails (22), surface floaters (23) being provided for the anchorage of vessels carrying visiting divers at the starting point (24) and picking them up at the point of termination (25) of the diving trails (22) and surface buoys (26) being provided at the corners of the contour of the planned section (ABCD).

9. An underwater artificial oasis for recreational diving according to claim 8, characterized in that the artificial reef units (1) making up each particular group of artificial reefs (20) have a distinct identical structural complexity with a specific number of artificial reef units (1) in said particular group and a specific type and dimensions of the exterior and interior structural features of each artificial reef unit including the exterior holes leading to smaller and larger cavities (10) and (11), the through holes (7), the blind crevices (9), the open interior chambers (8), etc., said structural features defining attractiveness of said artificial reef units (1) of said particular group of artificial reefs (20) for settlement of specifically targeted benthic and benthopelagic organisms, compatible with said exterior and interior structural features of said artificial reef units (1) in the particular group (20), whereby successive installation of groups of artificial reefs (20) with artificial reef units (1) having varying distinct structural complexity along the diving trail (22) of the artificial oasis ensures diversification of the distribution of marine biodiversity.

10. An underwater artificial oasis for recreational diving according to claim 8, characterized in that it comprises elements simulating natural or man-made sculptures (27) along the diving trails (22) being provided within the planned section (ABCD).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention will be best understood by those skilled in the art by reference to the accompanying drawings which present illustrative preferred embodiments thereof.

[0020] FIG. 1 shows a diagrammatic view of an artificial reef for recreational diving mounted onto the seabed.

[0021] FIG. 2 shows a general perspective vertical view (a) and side view (b) of an artificial reef unit provided with a vertically oriented foundation hole in the base thereof and a pair of through holes for ropes or straps being adapted to pass through these holes to suspend the reef during launching thereof onto the seabed.

[0022] FIG. 3 shows an exemplary view illustrating the structural complexity of an artificial reef unit of the invention.

[0023] FIGS. 4a-4c show the sequential stages in accordance with a preferred method of construction of the superstructure of an artificial reef for recreational diving of the invention wherein a special scaffold is being employed for the suspension of the plastic grid items used in the construction of the superstructure of the unit.

[0024] FIG. 5 is a vertically oriented sectional view of an artificial reef unit for recreational diving presenting the foundation thereof with a pair of foundation beams onto the seabed.

[0025] FIG. 6 is an illustrative example of a composite artificial reef comprising two vertically oriented artificial monoliths with a horizontally oriented artificial boulder on top thereof.

[0026] FIG. 7 shows an illustrative arrangement of a variety of artificial reefs for recreational diving within a protected site for recreational diving (oasis).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0027] The invention will be hereinafter described by reference to the illustrative embodiments presented in the accompanying drawings. It should be noted that these embodiments are provided for illustrative purposes only to serve in adequately disclosing the invention and do not limit the scope of protection thereof.

[0028] An artificial reef 1 for recreational diving of the invention comprises a base 2 constructed with a slab of reinforced concrete and a vertically extending superstructure 3 having the general configuration of an upright elongate monolith of high structural complexity, such superstructure 3 being constructed with concrete, preferably with a special concrete comprising inert lightweight materials that is being sprayed in one or more successive stages to cover a structural frame composed of a trunk 31 implanted into the base, a cluster of stems 32 and plastic grid items 12 suspended onto the complex of stems 32. The structural frame of the superstructure 3 has a predetermined structure of the aforementioned cluster of stems 32 suitable for implementing a predetermined plan of suspension of the plastic grid items 12 thereupon, so that, following the aforementioned ejection of concrete, a predetermined wall configuration of the superstructure 3 is being created, such walls providing a desired, predetermined arrangement of microhabitats and refuges of the artificial reef. It is herein noted that due to the multiplex structure and the numerous empty spaces formed in between these walls in the form of holes, crevices, chambers, etc. the superstructure 3 is rendered with a comparatively lower specific weight as compared to that of the base.

[0029] The embodiment of the artificial reef unit of the invention illustratively shown in FIG. 3 comprises through holes 7 leading to chambers 8 inside the reef, blind crevices 9 and external orifices of smaller or larger dimensions that define smaller cavities 10 and larger main cavities 11 respectively.

[0030] The various lines of production of artificial reefs for recreational diving produce artificial reef units characterized by generally identical dimensions and shape with an identical structural complexity for each preselected design pattern in the exterior and interior thereof. By way of example, the artificial reef units of each production line follow an identical configuration and manufacturing standard in relation to the overall number, type, shape and location of the individual interior or exterior morphological structures, e.g. of the smaller and larger exterior apertures or cavities 10 and 11 or of the through holes 7 or blind crevices 9 or of the interior open chambers 8, etc.

[0031] The design of the varying lines of production of artificial reef units and the final selection of the structural characteristics of each series exclusively depends on the number and size of benthic and benthopelagic target organisms that could potentially choose to settle, either permanently or temporarily within the reefs of the invention. By way of example the provision of a certain number of major exterior holes forming cavities 10, 11 can provide the habitat for particularly targeted fish species of the family of Serranidae (e.g. groupers) and the corresponding construction of through holes 7 or of blind crevices 9 with or without configurations of interior chambers 8 is a preferred refuge of various species of the family of Sparidae (e.g. White seabream, Common two-banded seabream, etc.).

[0032] In areas of the seabed where there prevail profoundly intense hydrodynamic phenomena, additional measures are adopted for maintaining each reef unit fixedly mounted in the original location of installation thereof. In this respect one or more slots are provided in the form of cylindrical or alternatively shaped holes extending vertically upwardly into a portion or the entire superstructure of the reef perpendicularly oriented to the base. These holes are provided with a specially tapered opening, illustratively in the form of a truncated cone, in the lower part thereof allowing, during the launching of the artificial reef onto the seabed, a handy introduction therein of appropriately sized and shaped foundation tubes or beams fixedly mounted vertically within the seabed. The number of the aforementioned holes and of the corresponding foundation tubes or beams to be employed depends on the intensity of hydrodynamic phenomena, the overall height and the vertically oriented surface area of each reef unit exposed to the sea bottom currents. Similar methods of implantation of foundation pipes within sedimentary bottoms are known e.g. as disclosed by Dounas in EP0897034.

[0033] As illustrated in FIG. 2, the base 2 of the reef comprises a through hole 4 that is perpendicularly oriented with respect to the base 2 and extends vertically upwardly along a portion or the entire height of the superstructure 3, such through hole 4 being adapted to be used in the foundation of the artificial reef onto the seabed. The foundation is implemented by the introduction of a rigid foundation beam or tube into the through hole 4 and thereafter with fixedly mounting the same perpendicularly into the substrate of the seabed. According to a second preferred embodiment of the invention the bottom end of the hole 4 at the bottom of the base 2 is tapered and takes the form of a truncated cone with a broadened opening 5 adapted to facilitate the entry of the foundation tube or beam that has previously been fixedly mounted onto the surface of the seabed and extends perpendicularly oriented therefrom.

[0034] As shown in FIG. 5, the foundation might be implemented with a pair of foundation beams or tubes 30 extending vertically upwardly, throughout the superstructure 3, whilst being fixedly mounted into the seabed 16 in the location of installation of the artificial reef unit. According to this embodiment of the invention, the foundation tubes 30 perpendicularly oriented onto the base 2 are rigidly connected therein by means of a horizontally extending bar 17.

[0035] With a scope of handily launching the reef onto the seabed, in accordance with a preferred embodiment of the invention, the base 2 is provided with a pair of through holes 6, which extend from a point on the circumference of the base to the directly opposite point thereof, said holes 6 being oriented in parallel directions, preferably symmetrically on either side of the central vertically oriented hole 4, wherein these holes 6 are adapted to receive ropes or straps employed to fasten the artificial reef unit and enable movement and final settlement thereof onto the seabed.

[0036] FIGS. 4a-4c present successive stages in the manufacturing process of the superstructure 3 of the reef, wherein a trunk 31 is being implanted into the base 2 and a plurality of stems 32 originating from and around the trunk 31 is provided, such stems 32 thereby forming a predetermined design pattern whereupon a plurality of plastic grid items 12 will be suspended to form the structural frame of the superstructure 3. As shown in FIG. 4b, the abovementioned assembly of the base 2 and of the structural frame of the superstructure 3 is surrounded by a scaffold 13 that is employed in performing the gradual assembly and secure mounting of the plastic grid items 12 onto the stems 32 with a scope of appropriately implementing the predetermined design pattern prior and during the ejection of concrete in the process of forming the superstructure 3.

[0037] In order to securely fix the plastic grid items 12 at the predetermined positions that would render, following concrete ejection, the formation of appropriately configured walls of the artificial reef which would provide the microhabitats and refuges of targeted benthic and benthopelagic species, ropes 14 are provided, these ropes 14 being fixedly mounted onto the base 2 and appropriately suspended along the scaffold 13 by means of ropes 15 for securely supporting the superstructure 3 during the various phases of setting the plastic grid items 12 in position and of subsequently covering the same with concrete being ejected thereupon.

[0038] Whilst FIG. 4a shows the naked incomplete structural frame of the superstructure 3 with the complex of stem members 32 around the trunk 31, FIG. 4b shows an intermediate stage in the process of construction of the structural frame wherein the structural frame is being completed with a plurality of plastic grid items 12 suspended thereupon and in FIG. 4c one distinguishes a layer of concrete that has been ejected onto the structural frame of the superstructure 3 by means of a concrete ejecting machine to generate the desired microhabitats of the artificial reef 1 proposed in the present invention.

[0039] The stability of the artificial reefs in the locus of final installation thereof is ensured in the first instance with the displacement of their center of gravity towards the area of their mounting onto the seabed, such displacement being achieved with the employment of a slab of reinforced concrete in the construction of the base 2 on the one hand and of a special concrete comprising inert lightweight materials in the construction of the superstructure 3 on the other hand, whereby the multiplex structure and the numerous empty spaces formed in between the walls of the superstructure in the form of cavities 10, 11, holes 7, crevices 9, chambers 8, etc. render the superstructure with a comparatively lower specific weight as compared to that of the base. This differential in the specific weight of the base 2 and the superstructure 3 in each artificial reef unit 1 increases its stability in conditions of prevalence of weak or even moderate hydrodynamic phenomena (waves, bottom currents) through increasing their resistance (drag force) to prevailing currents and allows safe maintenance of their original upright mounting position onto the seabed.

[0040] The artificial reef 1 of the invention may be used as a singular item founded onto predetermined locations of the seabed. According to a preferred embodiment of the invention a plurality of groups comprising a plurality of artificial reef units 1 that have been constructed in accordance with a single design pattern or preferably in accordance with a variety of design patterns, the latter attracting a yet greater interest of divers, are installed onto the seabed at predetermined short distances from each other, thereby creating an underwater artificial oasis for recreational diving. The artificial reef units making up each group may be specialized in terms of the structural complexity thereof and in this respect they may be characterized by a specific number, type and dimensions of their exterior and interior structural features, e.g. holes 7, cavities 10, 11, crevices 9, chambers 8, etc., thereby enabling habitation of specifically targeted species of benthic and benthopelagic organisms in each particular group of artificial reefs. The hereinabove discrete groups of reefs provide a desired diversification of the distribution of marine biodiversity along the diving trails, thereby correspondingly increasing their attractiveness for visiting divers.

[0041] FIG. 7 displays an illustrative arrangement for an underwater artificial oasis for recreational diving, such arrangement comprising a plurality of artificial reef units 1 organized in groups 20 bounded within an appropriately planned section (ABCD) of the seabed that defines the limits of the protected area assigned for this artificial underwater oasis for recreational diving. According to a preferred embodiment of the invention, an appropriate plurality of elementary artificial reefs 21 is being arranged along the diving trail 22 to lead the way from one group of artificial reefs 20 to the next, such elementary artificial reefs 21 thereby identifying the course along a diving trail within the planned section (ABCD) of the seabed.

[0042] In order to ensure safe touring within the oasis for recreational diving, it is deemed appropriate to provide surface floaters 23 for the anchorage of vessels carrying visiting divers at the starting point 24 and picking them up at the end 25 of each diving trail 22 as it is specified by the dotted line connecting the starting point 24 and the point of termination 25. Appropriate surface buoys 26 are provided at the corners of the contour of the planned section (ABCD), such buoys 26 marking the outer limits of the oases thereby preventing the entrance of vessels within the protected interior areas of the oases and averting potential accidents.

[0043] Other selected simulations of natural or man-made sculptures might be located along the diving trails. By way of example, the artificial reef composition 27 is employed as illustrated in FIG. 6, wherein this reef composition 27 simulates a natural sculpture composed of two vertically oriented boulders 18 and a third horizontally oriented portion 19 on top thereof. The abovementioned artistic compositions 27 may be structurally similar to the artificial reef 1 of the invention and they may be provided with similar configurations on their exterior, e.g. crevices 9 and cavities 10.