This invention generally relates to means for protecting beaches and shorelines from erosion by the ebb and flow of tides, seiches and waves. In particular, this invention relates to means for causing sand, suspended in a body of water, to gravitate to the seabed for the purpose of forming a shore-protecting sandbar. More particularly, the invention relates to means, adapted to float upon the surface, and further adapted to withstand the tremendous forces sometimes generated by a dynamic body of water.
For hundreds of years, mankind has been aware of the destructive force of tides, seiches and waves, and has conceived multifarious devices for reducing the adverse effects of these naturally-occurring phenomena. Though the prior art devices are far too numerous to individually specify, they can be generally categorized into several groups. One group relates to massive, bulk-fill breakwaters such as a dual-wall construct filled with concrete, rocks, earth, etc. These breakwaters tend to dissipate the energy of incoming waves by their sheer mass, thereby protecting nearby shores and beaches.
Another group of breakwater devices utilizes a frame, having a series of hinged baffles, secured to the seabed. The baffles are adapted to offer resistance to incoming waves, thereby reducing the destructive force of the water. The primary advantage of these devices is that they do not require the extraordinary mass used in more conventional breakwaters. As a result, they are easier to transport and erect, and are less costly to construct. On the other hand, these devices are more likely to be torn apart by large waves, or are more readily undermined at their foundations by the continuing ebb and flow of the water.
A third category of breakwaters provides means for depositing waterborne sand on the seabed for the purpose of creating an artificial sandbar. These structures generally consist of a water permeable barrier affixed to the bottom of the sea, adapted to block passage of much of the sand suspended in the water. This sand subsequently gravitates to the base of the barrier where it begins to form an artificial sandbar which itself serves as a breakwater. Like the second group of breakwaters described above, however, these devices do not readily maintain their structural integrity in rough water conditions, and are susceptible to subversion at their foundations. As a result, they often tear apart or become dislodged from the sea bottom long before an artificial sandbar can be created.
It is therefore a primary object of this invention to devise means for providing shores and beaches with the protective effect of massive, bulk-fill breakwaters without the concomitant expense, transportation and construction drawbacks. This is accomplished by depositing waterborne sand at predetermined points on the seabed to create an artificial sandbar. Such a sandbar can, of course, dissipate a substantial portion of the energy associated with an incoming wave which might otherwise erode or damage the shoreline.
It is another object of the invention to provide means for creating an artificial sandbar which do not readily tear apart or become dislodged from the seabed in rough water. As explained in more detail hereinafter, this is accomplished by providing flotation means which offer substantial resistance to incoming waves of moderate strength, thereby causing sand suspended in water to gravitate to the seabed. When waves of great strength appear, however, the flotation means remain on the surface of the water, providing little resistance but also sustaining minimal damage. Thereafter, when waves of moderate strength reappear, resistance is again provided causing more sand to drift to the bottom until an artificial sandbar is ultimately created.