Abstract:
A modular unit intended for use as an artificial reef, marine habitat and/or sea wall which can be placed in stacked structures along the floor of an ocean, bay, or other body of water comprises a top wall, bottom wall, opposed side walls and opposed end walls which are interconnected to form a hollow interior. Each of the walls is formed with one or more openings whose position and size is designed to allow access of marine life into the interior of the units, permit the passage of sunlight therein, direct the flow of sea water into and through the units in a way which increases stability of the units when placed on the ocean floor, and permit alignment of the holes of one unit with those of another when stacked together.

Description:
FIELD OF THE INVENTION 
   This invention relates to an apparatus which functions as an artificial barrier reef, a marine habitat and/or a sea wall in a variety of underwater environments to foster the growth and reproduction of marine life and assist with preventing erosion of beaches. 
   BACKGROUND OF THE INVENTION 
   Numerous scientific studies have shown that the depletion of the world&#39;s coral reefs is occurring at an alarmingly fast rate. Coral bleaching, as well as man&#39;s activities on both the land and water, have led to a decline of as much as 75-90% of the coral reefs in the waters off certain areas in the State of Florida and some estimates indicate that as much as 30% of the entire world&#39;s coral reefs have been destroyed in recent years. In addition to providing a habitat for soft and hard corals, coral reefs provide protection from coastal and beach erosion and act as a “nursery” or estuary where a variety of fish and other marine life spawn, grow and live. The coral reefs are at the bottom of the world&#39;s food chain, and are thus critical to sustaining life on the planet. 
   Realizing the importance of maintaining and replenishing the planet&#39;s already damaged and destroyed coral reefs, many countries have been working to reverse this trend. In the United States, governmental agencies at both the state and federal level have established artificial reef programs to study and provide solutions to the problem of disappearing reefs. A number of designs have been proposed, but most suffer from one or more deficiencies including high cost, manufacturing difficulties, poor choice of materials. and instability in moderate to severe weather and current conditions. 
   For example, one popular method of creating artificial reefs has been the sinking of old vessels at selected locations on the floor of an ocean or other body of water. It has been found that a number of corals do not grow well on metal, and many species of fish will not reproduce near or inside of hollow metal structures due to their tendency to resonate ambient sound or amplify noise. 
   Another method of encouraging the growth of coral which has been utilized in the past is the sinking of vehicle tires, either individually or bundled by attaching them together with rope or metal bands. It has been found that during periods of strong tidal or current activity, particularly during storms and hurricanes, the tires in bundles become detached from one another. These detached tires, and any individual tires placed on the ocean floor, can be moved by the tide and current into contact with existing reefs thus killing the coral and other marine life they were intended to foster. 
   A number of designs for artificial reefs and sea walls have been suggested in the prior art as an alternative to sunken vessels, tires and other substrates. It is recognized that artificial reefs must include multiple surfaces for coral and other sea life to attach and grow, while providing limited resistance to the flow of water from tides and current. Artificial reefs must also allow sunlight to bathe areas where the coral attaches. Structures having a number of walls interconnected to form an interior wherein each wall is formed with one or more holes or openings which intersect the interior are disclosed, for example, in U.S. Pat. Nos. 3,548,600 to Stolk, Jr. et al, U.S. Pat. No. 5,024,796 to Iwasa, U.S. Pat. No. 5,080,526 to Waters, U.S. Pat. No. 3,386,250 to Katayama, U.S. Pat. No. 5,178,006 to Lowe, U.S. Pat. No. 4,711,598 to Shaaf et al., and U.S. Pat. No. 6,186,702 to Bartkowski. The openings in the walls of structures of this type allow the flow of water through their interiors which helps stabilize them on the floor of the body of water and allows fish and other marine life to swim through their interiors. Many of these patents disclose structures having tapered or angled side walls, which, in combination with the openings in the wall(s), are intended to create an upward flow of water moving past the units. See, for example, the Shaaf et al. patent. This upward flow of water contacts and helps dissipate the force of incoming waves before they reach a beach or other coastal area, thus reducing erosion. 
   In addition to the stability created by openings in the walls of the units described above, it is known in the prior art to form barriers or sea walls with a bottom wall or base having one or more legs extending downwardly to contact the ocean floor. See, for example, U.S. Pat. Nos. 4,978,247 to Lenson, U.S. Pat. No. 4,089,190 to Pey and Schaaf et al. Lips or other protrusions which extend from the base of prior art patents directed to coral reefs or sea walls are shown in U.S. Pat. Nos. 3,176,468 to Nagai et al and U.S. Pat. No. 3,368,357 to Takamori. All of these designs are intended to help resist movement of the units once they are positioned on the ocean floor, even under high current or tidal conditions. 
   Artificial reefs and sea walls taught in the prior art can be placed on the floor of an ocean, bay or other body of water either individually or in groups. The patents to Nagai et al and Pey, for example, disclose structures in which barrier units are arranged side-by-side and/or one on top of another. The height and length of the resulting structure can be varied, as desired. 
   Despite efforts in the prior art to avoid some of the problems encountered with the use of sunken vessels, tires or other objects as coral reefs and sea walls, many deficiencies remain. Many artificial reefs and sea walls are constructed of concrete reinforced with steel bars. Steel bars exposed to salt water over an extended period are subject to rusting, and this has a negative effect on the growth of delicate corals and other sea life. 
   Although one or more artificial reef and sea wall structures taught in the prior art include hollow interiors and tapered walls with one or more openings to promote growth of coral and other marine life, as well as protrusions extending from the bottom wall to enhance stability on the floor of the ocean or other body of water, such designs are lacking in several respects. None provide an effective construction for arranging a number of individual units in a combined structure which permits the passage of marine life and water throughout the structure. In locations where the floor of the body of water is sandy or covered with silt, protrusions extending from the bottom of one or more units tend to sink in, often to different depths, causing the units to be angled relative to one another if an attempt is made to orient multiple units side-by-side or end-to-end. Rocky ocean floor areas also present a problem of alignment of adjacent units. 
   Even when units of the type disclosed in the prior art are used individually to create an artificial reef or sea wall, the problem of choice of materials noted above is present and many are relatively unstable when exposed to moderate to high current or tidal forces. In many designs, the weight distribution, is unacceptable compared to the overall height of the unit and they tend to topple over even if provided with protrusions or other anchoring structure on the bottom wall. Although many units include openings in one or more walls as noted above, the small size of such openings relative to the surface area of the wall in which they are formed leads to instability of the unit when impacted by tide and current forces. Such small openings also prevent larger fish from entering the units to use them for shelter, as a spawning ground or an estuarial habitat. Still other designs employ one or more openings in the side or top of the unit, but no ingress or egress for animals thus effectively trapping crustaceans and other marine life in the interior of the unit. 
   SUMMARY OF THE INVENTION 
   The modular units of this invention are intended for use as an artificial reef, marine habitat and/or sea wall which can be placed along the floor of an ocean, bay, or other body of water. Each unit includes a top wall, bottom wall, opposed side walls and opposed end walls which are interconnected to form a hollow interior. In one embodiment, the bottom wall is formed with one or more angled openings, and in an alternative embodiment most of the surface area of the bottom wall is open to the hollow interior. The side walls are tapered or angled from the bottom wall to the top wall so that the top wall is much smaller in cross sectional dimension than the bottom wall. Each of the top wall, bottom wall, side walls and end walls is formed with an opening or hole. The size and location of these holes is designed to: (i) allow access of marine life into the interior of the units, (ii) permit-the passage of sunlight therein, (iii) direct the flow of sea water into and through the units in a way which increases stability of the units when placed on the ocean floor, and (iv) permit alignment of the holes of one unit with those of another when stacked together, as noted below. 
   The modular units of this invention are preferably formed of concrete which includes a mixture of bonding agents intended to reduce porosity and absorption of sea water. The concrete is dense and heavy, thus adding to the stability of the units when placed on the ocean floor. No steel bars or other reinforcing members are employed. 
   Either one or both embodiments of the modular units of this invention can be stacked one on top of the other and located side-by-side in columns and rows to form an artificial reef, sea wall or marine estuary/habitat. Preferably, two modular units are placed side-by-side and a third unit (of either embodiment) is inverted and placed atop the two other units. The holes in the side walls of the modular units are formed to align with those of adjacent units allowing marine life and ocean water to freely pass through the interior of the multiple units. Other units may be placed end-to-end to form columns with those units already located side-by-side in rows. The openings in the end walls of adjacent units within a column align with one another, in a manner similar to the openings in the side walls of units in a given row, to provide further access of marine life to the interior of the overall structure. Essentially, any number of modular units can be positioned in columns and rows to obtain the desired size, shape and height of the reef, sea wall, or marine habitat. When the units are utilized as a sea wall, it is contemplated that the sloped or tapered side walls of the units would be oriented on the ocean floor in the direction of the current or predominant tidal force. The side walls are effective to deflect the water flow vertically upwardly, which tends to cause waves moving toward shore to break at a location further from the beach, thus reducing beach erosion. 
   A number of alternative embodiments are provided to secure the modular units to the ocean floor to resist dislodgement by currents or other water forces (storms, hurricanes, etc). In one embodiment, the bottom wall of each modular unit is provided with a leg at each comer which fit into corresponding openings in an anchoring device such as a rail system as described below. Alternatively, the bottom wall of the units may be formed with a lip or other protrusion which sink into the sea floor to enhance stability. The units are assembled on land or in the water, and marine grade mortar can be used to connect adjacent units to one another and/or to the anchoring device for added stability. 

   
     DESCRIPTION OF THE DRAWING 
     The structure, operation and advantages of the presently preferred embodiment of this invention will become further apparent upon consideration of the following description, taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a perspective view of one embodiment of the modular unit of this invention; 
       FIG. 2  is a front view of the modular unit of  FIG. 1 ; 
       FIG. 3  is a side view of the modular unit of  FIG. 1 ; 
       FIG. 4  is a perspective view of an alternative embodiment of the modular unit of this invention; 
       FIG. 5  is a front view of the modular unit of  FIG. 4 ; 
       FIG. 6  is a side view of the modular unit of  FIG. 4 ; 
       FIG. 7  is a perspective view of two modular units of  FIG. 1  oriented side-by-side, with a modular unit of  FIG. 4  placed in an inverted position between them; 
       FIG. 8  is a cross sectional view taken generally along line  8 — 8  of  FIG. 7 ; 
       FIG. 9  is a view similar to  FIG. 7  except with a number of groups of modular units arranged in an array; 
       FIG. 10  is a perspective view of one embodiment of an anchoring device to mount the modular units of  FIG. 1  to the floor of a body of water; 
       FIG. 11  is a perspective view of an alternative embodiment of an anchoring device according to this invention; and 
       FIG. 12  is a partial perspective view of a still further embodiment of an anchoring device herein. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring initially to  FIGS. 1-3 , one embodiment of a modular unit  10  according to this invention is shown. The unit  10  comprises a top wall  12 , a bottom wall  14 , two side walls  16 ,  18  and two end walls  20 ,  22  which are interconnected to form a hollow interior  24 . Each of the walls  12 - 22  is preferably formed of a marine concrete with no steel reinforcing bars or the like which can corrode upon exposure to salt water. The top wall  12  is substantially horizontally oriented and has a small cross-sectional area compared to the other walls of unit  10 . As best seen in  FIG. 3 , the bottom wall  14  is formed with a generally horizontally disposed corner portion  26  at each of its four corners joined to an inwardly tapering transition portion  28 . A support or leg  30  extends downwardly from each corner portion  26  of the bottom wall  14 , for purposes described below. Each of the end walls  20  and  22  extends generally vertically from the bottom wall  14  and parallel to one another. As best seen in  FIG. 2 , each side wall  16  and  18  is formed with a lower section  32  tapering outwardly from the bottom wall  14 , a generally vertical intermediate section  34  and an upper section  36  which tapers inwardly from the intermediate section  34  to the top wall  12 . The angle  38  at which the upper section  36  tapers is preferably about 45°. For purposes of the present discussion, the terms “horizontal,” “vertical,” “upper,” “lower,” “top” and “bottom” refer to the orientation of the unit  10  as it is depicted in the Figs. 
   One important aspect of this invention is the provision of openings throughout the unit  10  to permit the flow of water through it, to provide a path for fish and other marine life to swim and take up residence within the interior  24  and to allow sunlight to shine on portions of the interior  24 . The top wall  12  is formed with an opening  40 , the bottom wall has an opening  42  formed at the juncture of the tapered transition portions  28 , each of the side walls  16 ,  18  is formed with an opening  44  and the end walls  20 ,  22  each have an opening  46 . See also FIG.  8 . All of the openings  40 - 44  intersect the hollow interior  24  of the unit  10 . 
   As discussed above, one disadvantage of many prior art designs of unit employed as artificial reefs, marine habitats and/or sea walls is an inherent instability when placed on the floor of a body of water, particularly during periods of high currents, storms and hurricanes. The unit  10  of this invention overcomes such deficiency in a number of respects. Initially, the angulation of the side walls  16 ,  18 , as well as the overall height of the unit  10 , enhance the stability of the unit  10 . Preferably, the unit  10  is placed on the ocean floor or other body of water such that one of the side walls  16 ,  18  faces in the anticipated direction of the current, tide. or wave movement created by storms or the like. The flow of water over the low profile, vertically compact unit  10 , and its angled side walls  16 ,  18 , tends to exert a downward force on the unit  10 , e.g. toward the floor of the body of water, adding to stability. Additionally, the opening  44  in each side wall  16 ,  18  has a rim  48  which is angled downwardly, toward the bottom wall  14 . The flow of water through the opening  44  engages the angled rim  48  and tends to exert a downward force on the unit  10  to further stabilize it. The legs  30  also provide stabilization of the unit  10 , as described below in connection with a discussion of  FIGS. 10-12 . 
   Referring now to  FIGS. 4-6 , an alternative embodiment of a modular unit  50  is shown which has a construction similar to that of unit  10 . Unit  50  includes a top wall  52 , a bottom wall  54 , opposed side walls  56 ,  58  and opposed end walls  60 ,  62  interconnected to form a hollow interior  63 . The top wall  52  and end walls  60 ,  62  of unit  50  are identical to the top wall  14  and end walls  20 ,  22  of unit  10 , and have respective openings  64 ,  66  which are of the same dimension and location as openings  40  and  46  depicted in  FIGS. 1-3 . 
   Each side wall  56  and  58  has the same shape as side walls  16 ,  18  of unit  10 , e.g. an outwardly extending lower section  68  connected to a vertical intermediate section  70 , and an inwardly tapering upper section  72  connected between the intermediate section  70  and top wall  52 . Preferably, the lower section  68  of each side wall  56 ,  58  is formed with an opening  74  and the upper section  72  is formed with an opening  76 , both of which intersect the hollow interior  63 . The opening  76  in the upper section  72  of each side wall  56 ,  58  is in the same position, and has the same dimension, as the opening  44  in side walls  16 ,  18  of unit  10 . Preferably, such opening  76  is formed with a rim  78  angled downwardly toward the bottom wall  54  in the same manner as the rim  48  of unit  10 . Further, the angle at which the upper section  72  is tapered is the same as the angle  38  of upper section  36  as shown in FIG.  2 . 
   The bottom wall  54  of unit  50  is closed but the opening  74  in each side wall  56 ,  58  is located near the bottom wall  54  to permit ingress and egress of marine animals. Unlike the unit  10 , no legs are formed along the bottom wall  54  of unit  50 , although a small lip  82  may protrude from the bottom wall  54  as best seen in  FIGS. 5 and 7 . 
   Stacking of Modular Units 
   Each of the modular units  10  and  50  may be placed on the floor of the ocean or other body of water individually for the purpose of forming an artificial reef, marine habitat and/or a sea wall. In many applications, however, it is desirable to provide a more substantial structure for such purposes. Referring now to  FIGS. 7-9 , illustrations are provided of modular units  10  and  50  which are arranged in columns and rows to form a stacked array or structure. 
   In the embodiment of  FIG. 7 , two units  10  are placed side-by-side in the upright orientation with their legs  30  in position to contact the ocean floor or an anchoring device described below. Preferably, the vertical intermediate section  34  of the side wall  18  of one unit  10  contacts the vertical, intermediate section  34  of the side wall  16  of an adjacent unit  10 . One unit  50  is then inverted and placed in between the two units  10  so that the bottom wall  54  of unit  50  faces upwardly and its top wall  52  faces downwardly. In this position, the opening  74  in the upper section  72  of each side wall  56  and  58  of unit  50  aligns with an opening  44  in the upper section  36  of a side wall  16  or  18  of one of the units  10 . As depicted by the arrows in  FIG. 8 , when the units  10  and  50  are stacked in this orientation a number of paths are created for the flow of water and the transit of marine life through the structure. Because the units  10  have an opening  42  in their bottom wall  14 , crustaceans and other marine life which might enter the structure will not become trapped inside. 
     FIG. 9  depicts one representation of a number of groups of units  10  and units  50  arranged in columns  84  and rows  86  in the same orientation shown in  FIGS. 7 and 8 . The openings  44  and  74  in the side walls  16 ,  18  and  56 ,  58 , respectively, align with one another within each row  86  as described above. Additionally, the opening  46  in the end wall  20  of one unit  10  aligns with the opening  46  in the end wall  22  of an abutting unit  10  in each column  84 . Essentially any of units  10  and  50  may be combined in this fashion to produce a marine habitat, artificial reef or barrier wall of desired dimension. It should also be understood that while  FIGS. 7-9  depict arrays of units  10  and  50  wherein two units  10  are placed side-by-side with an inverted unit  50  between them, other arrangements may also be used. For example, three units  10  may be employed with one unit inverted, two units  50  may be placed side-by-side in an upright position with one unit  10  inverted between them, or, three units  50  can form the array. 
   Regardless of what combination of units  10  and  50  are employed to form the structure, essentially the same flow paths shown by the arrows in  FIG. 8  are provided. Additionally, the structure retains a relatively low profile or short vertical height since the inverted unit  10  or  50  nestles in between the side-by-side units and extends only a short distance above them. This enhances the stability of the overall structure. 
   Mounting of Units to Ocean Floor 
   As described above, the units  10  are provided with a leg  30  extending from each corner portion  26  of the bottom wall  14 , and the bottom wall  54  of the units  50  is formed with a lip  82 . It is contemplated that either unit  10  or  50  may be placed directly on the floor of the ocean or other body of water, and the legs  30  or lip  82  will assist in stabilizing the units  10 ,  50  against movement which could be caused by currents, tides or wave action from storms and the like. 
   It is desirable for the units  10  and  50 , particularly when arranged in a structure such as shown in  FIGS. 7-9 , to be oriented generally horizontally and vertically relative to one another so that the openings in the side walls and end walls of abutting units  10  and  50  align with one another as described above. In some locations, the floor of the ocean or other body of water may be relatively soft or silty, and/or have rocks or other obstructions. Conditions of this type can prevent the units  10  and  50  from properly aligning with one another or cause them to sink into the ocean floor and thus block some of the openings in the walls. 
   With reference to  FIGS. 10-12 , alternative embodiments of an anchoring device are shown which address the problem noted above. The anchoring device  88 . of  FIG. 10  comprises two outer rail units  90  and a center rail unit  91 , each consisting of a first rail  92  having a number of spaced holes  94  and a second rail  96  formed with spaced holes  98 . The first and second rails  92 ,  96  of each rail unit  90  are spaced from one another and connected by cross braces  100 . The first and second rails  92  and  96  of the center rail unit  91  are formed with a number of bores  102  in their side walls which align with bores  104  formed in the side wall of the second rail  96  of one outer rail unit  90  and in the side wall of the first rail  92  of the other outer rail unit  90 . These aligning bores  102  and  104  receive a connector bar  106  which functions to secure the abutting rails units  90  and  91  together. 
   The holes  94  and  98  in the first and second rails  92 ,  96  are formed to receive the legs  30  of the modular units  10 . The units  10  straddle the first and second rails  92 ,  96  of each rail unit  90  and  91 , so that two legs  30  of a unit  10  are inserted within the openings  94  of a first rail  92 , and the other two legs  30  of the unit  10  seat within the openings  98  of a second rail  96 . When the entire anchoring device  88  is filled with units  10 , the units  10  located along the center rail unit  91  abut the units  10  on the two outer rail units  90 . 
   Two additional embodiments of an anchoring device according to this invention are depicted in  FIGS. 11 and 12 . The anchoring device  108  of  FIG. 11  consists of two inner rails  110  each formed with a number of longitudinally spaced pairs of holes  112 , and two outer rails  114  each formed with a single set of longitudinally spaced holes  116 . The inner rails  110  are connected to one another by cross braces  118 , and to one of the outer rails  114  by cross braces  120 . The modular units  10  are mounted to the anchoring device  108  by inserting the legs  30  into the holes  116  of an outer rail  114  and the holes  112  of an adjacent inner rail  110 . Other modular units  10  can be mounted in between the two inner rails  110  by straddling the area where the cross braces  118  extend and inserting the legs  30  into adjacent holes  112  in the inner rails  110 . 
   The anchoring device  122  of  FIG. 12  consists of two rails  124  each having a number of spaced recesses  126  formed to receive the legs  30  of a modular unit  10  which spans the two rails  124 . Preferably, the rails  124  are connected by cross braces  128 . 
   In each of the embodiments of  FIGS. 10-12 , the anchoring devices  88 ,  108  and  122  provide a platform for mounting the modular units  10  and  50  above the floor of the body of water and in the proper orientation relative to one another as described above. It is contemplated that the anchoring devices  88 ,  108  or  122  could be connected to the units  10  and  50  prior to placement on the floor of the body of water or by divers underwater. Further, marine concrete or other fastening materials can be employed to secure the units  10  and  50  to the anchoring devices  88 ,  108  or  122 , and to one another, before or after placement in the water. Although the anchoring devices  88 ,  108  and  122  depicted in  FIGS. 10-12  having openings to receive the legs  30  of units  10 , it is contemplated that a concrete slab could be employed with no openings as an alternative. 
   While the invention has been described with reference to a preferred embodiment, it should be understood by those skilled in the art that various changes may be made and equivalents substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.