Abstract:
The wave break has an elongated shape and three wave-breaking surfaces mounted thereon and forming an elongated triangular configuration. The wave break has a lazy side on its forward edge, such that the force of the wave tilts it about the forward edge to increase a projection of its wave-breaking surfaces against the incoming wave. Because of the lazy forward side of the wave break, the leading stringer dive into each wave without deviating substantially from a horizontal plane. The trailing side of the wave break is subject to the lifting forces of each wave and therefore, the trailing side tilts upward and downward in use. The trailing side tilts upward and downward about the leading stringer to rotate the wave-breaking barriers into a more or less perpendicular alignment relative to the wave movement, for breaking the wave more effectively.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 61/193,930 filed Jan. 9, 2009. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention pertains to floating breakwaters or break walls installed along harbours to protect vessels moored in these harbours, and most particularly, it pertains to self-adjusting wave breaks that automatically expose a larger wave-breaking surface when floating in larger waves. These break walls are also installed to prevent soil erosion along shore lines. 
       BACKGROUND OF THE INVENTION 
       [0003]    The efficiency of a breakwater depends on its ability to break up and scatter waves without being lifted by these waves. This efficacy is difficult to achieve with a floating breakwater having a slack mooring line, in particular, because upward forces from the breakwater&#39;s buoyancy tend to push the breakwater at the surface of the wave. 
         [0004]    In the past, at least two attempts have been made to design a floating wave break that is intended to plunge through a wave to cut through and to disperse the crest of the wave. These prior art wave breaks have no similarities with the wave break according to the present invention, but the prior art documents describing these older breakwaters are nonetheless cited herein below simply to illustrate the environment in which the present invention will be described. 
         [0005]    U.S. Pat. No. 335,032 issued to L. W. Leeds on Jan. 26, 1886 discloses different wave breaks, each having a floating structure and a wedge-like horizontal plow-bar, referred to as a cut-water, projecting forward from the floating structure. The cut-water bar penetrates the waves along a horizontal plane to break the force of the waves before they reach the floating structure. 
         [0006]    U.S. Pat. No. 3,952,521 issued to J. M. Potter on Apr. 27, 1976 discloses an elongated triangular structure supported on two tubular floats. The floats have airfoil-like fins on their sides to cause the floats to dig into the forward side of a wave and to retain the wave break against the lifting forces of the wave so that the wave break can pass through the crest of the wave. 
         [0007]    Although the devices of the prior art deserve undeniable merits, there is a need for a more efficient floating wave break which can be easily moved and anchored with slack mooring lines. 
       SUMMARY OF THE INVENTION 
       [0008]    In the present invention, there is provided a wave break that has an elongated shape and three wave-breaking surfaces mounted thereon to form an elongated triangular configuration. The wave break has a lazy side on its forward edge, such that the force of the wave tilts it about the forward edge to increase a projection of its wave breaking surfaces against the incoming wave. 
         [0009]    More specifically, in one aspect of the present invention there is provided a wave break that has an elongated structure with a triangular cross-section. The triangular cross-section has the shape of a right-angle triangle with a right-angle side and an acute-angle side. The right angle shape is defined by three elongated stringers from which a leading stringer is at the acute-angle side. 
         [0010]    The elongated structure also has three wave barrier surfaces extending there along. Each of these wave barrier surfaces is made of a plurality of pipe members spaced apart from each other and extending at right angle between two of the afore-mentioned stringers. 
         [0011]    Each of the stringers on the right-angled side, and each pipe member has a sealed hollow configuration forming a floating vessel. The leading stringer has added weight therein or open ends such that a buoyancy thereof is substantially nil. The wave break also has a mooring line attached to the leading stringer. 
         [0012]    Because of the lazy forward side of the wave break, the leading stringer dive into each wave without deviating substantially from a horizontal plane. The trailing side of the wave break is subject to the lifting forces of each wave and therefore, the trailing side tilts upward and downward in use. The trailing side tilts upward and downward about the leading stringer to rotate the wave breaking barriers of the wave break into a more or less perpendicular alignment relative to the wave movement, for breaking the wave more effectively. 
         [0013]    Also, the wave break according to the present invention is relatively light and easy to transport and to install as compared to other breakwaters available commercially. 
         [0014]    This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiment thereof in connection with the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    A preferred embodiment of the present invention is illustrated in the accompanying drawings, in which like numerals denote like parts throughout the several views, and in which: 
           [0016]      FIG. 1  is a perspective view of a breakwater made with self-adjusting wave break segments according to a preferred embodiment of the present invention, joined end-to-end; 
           [0017]      FIG. 2  is an end view of a preferred wave break segment floating along the hollow of a wave or on calm waters; 
           [0018]      FIG. 3  is an end view of the preferred wave break segment floating through a wave; 
           [0019]      FIG. 4  is a reference illustration showing the period and amplitude of a wave; 
           [0020]      FIG. 5  is an enlarged end view of the preferred wave break segment illustrated in  FIGS. 2 and 3 ; 
           [0021]      FIG. 6  is a cross section view of one pipe member in the preferred wave break segment as seen along line  6 - 6  in  FIG. 5 ; 
           [0022]      FIG. 7  is a partial oblique view of the wave break segment as seen along line  7 - 7  in  FIG. 5 ; 
           [0023]      FIG. 8  is a cross-section plan view of the preferred wave break segment as seen along line  8 - 8  in  FIG. 5 ; 
           [0024]      FIG. 9  is an enlarged view of the end of a wave break showing optional structural variations that are within the scope of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0025]    The expression “wave break” is used by seamen to describe a wave breaking structure protecting a harbour, and therefore it is also used herein for convenience to describe the wave break structure according to the present invention. 
         [0026]    Referring firstly to  FIG. 1 , the preferred wave break  20  consists mainly of an elongated openwork structure having a triangular cross-section. The openwork structure is made of hollow pipes. The hollow pipes are preferably made of plastic, but can also be made of metal tubes having a relatively thin wall. The preferred wave break  20  has a transportable length and is referred to herein interchangeably as a wave break or a wave break segment. These segments are joined to each other, at joints  22 , to form breakwaters  24  having lengths of 20 feet or more, for example. 
         [0027]    These breakwaters  24  are anchored to the seabed by slack mooring cables  26  or chains. The expression “slack mooring cables or chains” is used here to describe a mooring system that allows the wave break  20  to rise and fall with the tides. It will be appreciated that the tension of the mooring lines can be adjusted to retain the leading stringer within a desired vertical displacement, according to wave heights and tides at the installation site. 
         [0028]    These breakwaters  24  are installed in straight lines, or most preferably, these breakwaters are installed to form an arc having a convex side facing the incoming waves, as illustrated in  FIG. 1 . 
         [0029]    Referring now to  FIGS. 2 and 3 , the preferred wave break  20  is made of three open planar frameworks connected to each other by three parallel longitudinal stringers, in a right-angle triangular configuration. In use, the acute-angle side of the wave break  20  faces against the movement  28  of the waves as illustrated. 
         [0030]    The stringer on the leading edge of the wave break  20  is referred to as the leading stringer  30 . In use, a mooring line  24  is attached to the leading stringer  30 . 
         [0031]    The-stringer on the trailing edge is referred to as the trailing stringer  32 , and the stringer on the upper edge is referred to as the upper stringer  34 . The open framework extending between the leading stringer  30  and the upper stringer  34  is referred to as the first barrier surface  40 . The open framework lying between the upper stringer  34  and the trailing stringer  32  is referred to as the second barrier surface  42 , and the open framework lying between the leading stringer  30  and the trailing stringer  32  is referred to as the third barrier surface  44 . 
         [0032]    The preferred wave break  20  is made of cylindrical pipe members that are sealed at ends and at all joints so that they constitute hollow floating structures. The leading stringer  30  is weighted down with concrete  46  or other heavy material so that the wave break  20  tilts forward in calm water. The leading stringer  30  is weighted down or its ends are left open, so that its buoyancy is substantially nil and so that it remains submerged below the water surface, as illustrated in  FIG. 2  in calm waters. Using seamen language, the preferred wave break  20  has a lazy forward side, which does not react or that is slow to react to buoyant forces. 
         [0033]    It should be understood that the weighing of the leading stringer  30  can also be done partially or entirely by using heavy mooring chains  24  instead of cables. 
         [0034]    Because of the structural features of the preferred wave break  20 , the leading stringer  30  plunges into the waves  60  in rough waters, as illustrated in  FIG. 3 . The buoyancy forces on the third barrier surface  44  and on the trailing stringer  32  causes the wave break  20  to tilt forward when traversing a wave  60 , thereby reducing the angle ‘A’ as illustrated in  FIGS. 2 and 3 . It will be appreciated that the reduction of the angle ‘A’ is in direct relationship with the height of the waves  60 , because it varies directly with the portion of the wave break  20  that is submerged when a wave pass through the wave break  20 . 
         [0035]    The variation in the angle ‘A’ is due to a rotation of the wave break  20  about the leading stringer  30  in a direction ‘B’. A rotation of the wave break  20  in the direction ‘B’ causes the leading stringer  30  to dive through an incoming wave  60  and causes the first barrier surface  40  to move toward a perpendicular alignment relative to the movement of the wave  60 . Similarly, the tilting of the wave break  20  in the direction ‘B’ causes the second and third barrier surfaces  42 ,  44  to form converging fence-like surfaces across the movement of the wave  60 , as illustrated in  FIG. 3 . 
         [0036]    As it can be understood, all three barrier surfaces  40 ,  42  and  44  cooperate together to break up the waves  60  in two cascading steps. A first step consists of passing the wave through a quasi-vertical barrier to change the direction of the flow a first time, and the second step consists of passing the waves through the converging fence-like surfaces, for changing the direction of the wave a second and third times. 
         [0037]    After the passage of a wave  60  through the wave break  20 , the wave break  20  returns back to its initial attitude as illustrated in  FIG. 2 . The buoyancy forces on the preferred wave break  20  cause the wave break  20  to tilt back and forth and to self-adjust to the height of the wave entering into its barrier surfaces  40 ,  42  and  44 . 
         [0038]    In high waves, the first barrier surface  40  rotates toward a vertical alignment, thereby presenting a maximum degree of resistance to the incoming wave  60 . Because of the triangular cross-section of the wave break  20 , the buoyancy forces on the second and third barrier surfaces  42 ,  44  generate a torque about the leading stringer  30 , to force the first barrier surface  40  to move toward a vertical alignment. This torque increases with the degree of immersion of the wave break  20 . Similarly, this torque causes the second and third barrier surfaces  42 ,  44  to move toward a funnel-like alignment where both surfaces converge together and contribute substantially equally to the breaking-up of the wave  60 . 
         [0039]    The expression “self-adjusting” in the description of the present invention comes from the fact that the wave break  20  tilts back and forth about the leading stringer  30 , to increase or to decrease the aggressiveness with which the wave-breaking surfaces thereof are oriented in response to the height of a wave being penetrated. 
         [0040]    Referring now to  FIGS. 4-9 , additional structural details of the preferred wave break  20  will be described. 
         [0041]    In a preferred embodiment, each barrier surfaces  40 ,  42 ,  44  is made of spaced-apart parallel pipe members each having a same diameter as the longitudinal stringers  30 ,  32 ,  34 . The pipe members forming the first surface barrier  40  are labelled as pipe members  70 . The pipe members labelled as  72  form the second surface barrier  42 , and the pipe members labelled as  74  form the third surface barrier  44 . 
         [0042]    The preferred length of the pipe members  74  forming the third surface barrier  44  or the base of the wave break  20  is preferably one quarter (¼) of the period ‘P’ of typical waves found at the location where the wave break  20  will be installed. The length of the pipe members  72  forming the second surface barrier  42  or the height of the wave break  20  is preferably the same dimension as a typical wave height ‘H’ found at the location where the wave break will be installed. 
         [0043]    Typical dimensions for the length of the pipe members  72 ,  74  and  70  are six, eight and ten feet respectively, and the diameter of each pipe member is about twelve to sixteen inches. The dimensions of the pipe members in the preferred wave break  20  are adjusted according to the severity of the conditions where the wave break will be installed. These dimensions are adjusted according to factors such a wave height, wave period, water current and the length of the breakwater  24  to be formed. 
         [0044]    Each of the barrier pipe members  70 ,  72  and  74  has fins  76  on its sides as illustrated in  FIG. 6 . The purpose of these fins in the first barrier surface  40  is to deflect water sideways and against one of the pipe members  72 ,  74  in the second and third barrier surfaces  42 ,  44 . The purpose of the fins  76  on the pipe members  72 ,  74  is to deflect water sideways and create turbulence behind the wave break  20  to further break up the waves  60  after these waves have passed through the wave break  20 . 
         [0045]    The preferred spacing ‘S’ of pipe members  70 ,  72  or  74  along a same barrier surface  40 ,  42  or  44  is about at least twice as much as the outside diameter of one pipe member. The preferred spacing of pipe members in one barrier surface from the pipe members in an adjacent barrier surface is about the same as the diameter of one pipe member, such that the pipe members in one surface barrier is offset the distance of one pipe member from the pipe members in an adjacent barrier surface. 
         [0046]    The width of the fins  76  on each of the pipe members  70 ,  72 , and  74 , is equal to or less than the radius on one pipe member, such that the effective width ‘W’ of each pipe member, as shown in  FIG. 6 , is about twice or slightly less than twice the diameter of one pipe member. The effective width ‘W’ of each pipe member is also determined taking into account the water current present at the location where the wave break  20  will be installed. The effective width ‘W’ is selected so that the drag created on the wave break  20  by the water current does not prevent an effective tilting of the wave break  20  as described herein. 
         [0047]    Similarly, the inclination ‘C’ of the fins  76  can vary from 0° to 60° and this angle is also determined according to the severity of the conditions at the installation site. 
         [0048]    Referring now to  FIG. 9 , this illustration will be used to explain two structural variations which should be considered to be withing the scope of the present invention. As mentioned before, the stringers  32  and  34  on the right-angle side of the wave break  20  have closed ends so that they act as floating vessels. In order to further increase the buoyancy of the wave break  20 , and to further promote a rotation of the wave break  20  about the leading stringer  30 , the trailing stringer may have a larger diameter than the other stringers, as illustrated by label  32 ′ in  FIG. 9 . Also, as mentioned before, the leading stringer  30  may have open ends as indicated by label  30 ′, so that its buoyancy is substantially nil. 
         [0049]    The dotted lines in  FIGS. 7 ,  8  and  9  indicate a repetition of the pipe member arrangements over the full length of a wave break segment  20 .