Abstract:
A modular, size-adjustable dredge assembly including a hull and an adjustable length dredge ladder pivotally connected to the hull. The dredge ladder includes a front section that is coupled to a rotatable cutter head for loosening material to be dredged and a rear section that is pivotally connected to the hull to permit the ladder to selectively move from a hoisted position where the ladder floats to an operative position where the cutter head engages a surface to be dredged. The front section of the ladder includes a first plurality of releasably interconnected hollow pipe sections that form a first fluid tight channel therein in which water is selectively permitted to enter to increase the weight of the ladder to achieve the desired cutter pressure and to control cutter torque. The rear section of the ladder includes a plurality of releasably interconnected hollow pipe sections that form a second fluid tight channel to increase the bouyancy of the ladder. The hull may include a fore section platform, an aft section platform, and a second plurality of releasably interconnected hollow pipe sections for longitudinally connecting the fore section platform to the aft section platform. The length of the hull and/or ladder is adjustable by adding or removing pipe sections from the first and second plurality of releasably interconnected hollow pipe sections.

Description:
FIELD OF THE INVENTION  
       [0001]     This application relates generally to dredge assemblies and, more particularly, to a modular, size-adjustable cutter suction dredge (“CSD”) assembly.  
       BACKGROUND OF THE INVENTION  
       [0002]     Dredges and, in particular, CSDs are used to remove material (e.g., rock, sand, clay, etc.) from the bottom, floor, bed or other surface of lakes, rivers, oceans, seas, harbors or other waterways. Existing CSDs typically include a floating barge that carries an elongated ladder, boom or similar structure. The ladder is typically pivotally connected to the barge such that it can be lowered from a hoisted position to an operative position where the ladder is in proximity to the waterway bed or surface to be dredged. A rotating cutter head is typically located near a free end of the ladder such that, in its operative position, teeth on the cutter head engage the waterway bed or surface to loosen material to be dredged. A mixture of loosened material and water collected at the cutter head is drawn into a suction pipe connected to the ladder and pumped to a desire location where the material is discharged.  
         [0003]     The ladder construction and its connection to the barge in existing CSDs, however, must be very strong and rigid to resist the torque created by the interaction of the cutter head on the surface to be dredged (“cutter torque”). Otherwise, the ladder will have a tendency to rotate or windup due to the cutter torque. Moreover, dredging with existing CSDs is difficult at depths over 45 meters (148 feet). The length of the conventional ladder, for dredging at depths of 45 meters or greater, is susceptible to bending. Such bending is caused by the ladder&#39;s weight (inertia), as well as the forces or cutter torque developed as a consequence of cutting the waterway bed or surface.  
         [0004]     To address these problems, strengthening components have been incorporated in the ladder and at its connection point at the hull of the barge to compensate for the increased operational depths and to resist cutter torque. Reinforcing a conventional ladder to operate at such depths, however, is expensive and a time-consuming process. This process requires extensive redesign of the ladder and its connection to the hull, a significant number of additional components, and a great deal of steelwork. In addition, the weight of the reinforced ladder is significant and expensive hoisting winches are often necessary to lift the ladder from its operating position.  
         [0005]     Furthermore, because the ladder structure has been reinforced to operate at a greater depth and to resist cutter torque, and its weight increased as a result, the suction pump that draws the dredged material cannot be located at the end of the ladder near the cutter head. Consequently, suction capability can become compromised due to the increased distance between the pump and the waterway bed or surface to be dredged.  
         [0006]     Also, reinforcing the ladder to operate at such depths leads to decreased flexibility with respect to assembling and disassembling the CSD. Moreover, transportation of the CSD becomes difficult.  
       SUMMARY OF THE INVENTION  
       [0007]     To overcome these and other deficiencies in conventional dredges, a modular, size-adjustable dredge assembly is provided that includes a hull and an adjustable length dredge ladder pivotally connected to the hull. The dredge ladder includes a front section that is coupled to a rotatable cutter head for loosening material to be dredged and a rear section that is pivotally connected to the hull to permit the ladder to selectively move from a hoisted position where the ladder floats to an operative position where the cutter head engages a surface to be dredged. The front section of the ladder includes a plurality of releasably interconnected hollow pipe sections that form a first fluid tight channel therein in which water is selectively permitted to enter to increase the weight of the ladder to achieve the desired cutter pressure and to withstand the cutter torque. The rear section of the ladder includes a plurality of releasably interconnected hollow pipe sections that form a second fluid tight channel to increase the bouyancy of the ladder. Additional pipe sections may be added or removed from the rear section to adjust the length of the ladder.  
         [0008]     Similarly, the hull may include a fore section platform, an aft section platform, and a second plurality of releasably interconnected hollow pipe sections for longitudinally connecting the fore section platform to the aft section platform. The length of the hull is adjustable by adding or removing pipe sections from the second plurality of releasably interconnected hollow pipe sections.  
         [0009]     The foregoing specific objects and advantages of the invention are illustrative of those that can be achieved by the present invention and are not intended to be exhaustive or limiting of the possible advantages which can be realized. Thus, these and other objects and advantages of this invention will be apparent from the description herein or can be learned from practicing this invention, both as embodied herein or as modified in view of any variations which may be apparent to those skilled in the art. Accordingly, the present invention resides in the novel parts, constructions, arrangements, combinations and improvements herein shown and described. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The accompanying figures best illustrate the details of the preferred apparatus, system and method of the present invention. Like reference numbers and designations in these figures refer to like elements.  
         [0011]      FIG. 1  is a perspective view of the dredge assembly in accordance with a preferred embodiment of the present invention;  
         [0012]      FIG. 2  is a perspective view of the fore section platform of the preferred dredge assembly illustrated in  FIG. 1 ;  
         [0013]      FIG. 3  is a perspective view of the aft section platform of the preferred dredge assembly illustrated in  FIG. 1 ;  
         [0014]      FIG. 4A  is a perspective view of a preferred pontoon utilized in fore and aft•section platforms illustrated in  FIGS. 2 and 3 ;  FIG. 4B  is a side view of two interconnected pipe sections utilized in the hull of the preferred dredge assembly illustrated in  FIG. 1 ;  
         [0015]      FIG. 4C  is a side view of two interconnected pipe sections utilized in the dredge ladder of the preferred dredge assembly illustrated in  FIG. 1 ;  
         [0016]      FIG. 5  is a perspective view of the preferred fore section platform illustrated in  FIG. 2  with the dredge ladder in the hoisted position;  
         [0017]      FIG. 6  is a perspective view of the preferred aft section platform illustrated in  FIG. 3  with the dredge ladder in the hoisted position;  
         [0018]      FIG. 7  is a perspective view of the preferred fore section platform illustrated in  FIG. 5  with the dredge ladder in a partially lowered position;  FIG. 8A  is a side elevation view of the preferred dredge assembly illustrated in  FIG. 1  with the dredge ladder fully lowered for dredging in deep water;  
         [0019]      FIG. 8B  is a perspective view of the preferred dredge assembly illustrated in  FIG. 8A ;  
         [0020]      FIG. 9A  is a side elevation view of the preferred dredge assembly illustrated in  FIG. 1  with the dredge ladder partially hoisted;  
         [0021]      FIG. 9B  is a perspective view of the preferred dredge assembly illustrated in  FIG. 9A ;  
         [0022]      FIG. 10A  is a side elevation view of the preferred dredge assembly illustrated in  FIG. 1  with the dredge ladder substantially hoisted; and  
         [0023]      FIG. 10B  is a perspective view of the dredge assembly illustrated in  FIG. 10B .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]     Referring now to the drawings and, in particular, to  FIG. 1 , a dredge assembly  1 , such as a CSD, has a hull  5  that preferably includes at least a fore section platform  10  and an aft section platform  20 . As discussed in greater detail below with respect to  FIG. 2 , the platforms  10 ,  20  are comprised of a plurality of interconnected pontoons  11 . The platforms  10 ,  20  are preferably connected to one another by at least two substantially parallel pipe sections  30 . Each pipe section  30  is preferably formed from a series of interconnected standard industrial pipes  31   a  and  31   b . Each pipe  31   a  and  31   b  preferably has sealed, “blind” (closed) flanges best seen in  FIG. 4B . The hull  5  is illustrated to include an additional pontoon  11  positioned between the aft and fore section platforms  10 ,  20 , but could be eliminated, or replaced by several pontoons sections  11 .  
         [0025]     The pontoons  11  may be made from any suitable material, preferably ship building steel. The size of the pontoons  11  are preferably the same dimensions as standard cargo containers or a high cube (“hicube”) containers (e.g., 20 ft. (L)×8 ft. (W)×4 ft. (H); 20 ft. (L)×6 ft. (W)×8 ft. (H); 20 ft. (L)×8 ft. (W)×8 ft. (H); 40 ft. (L)×8 ft. (W)×4 ft. (H); 40 ft. (L)×8 ft. (W)×6 ft. (H); 40 ft. (L)×8 ft. (W)×8 ft. (H)) to facilitate convenient transportation of the pontoons. In this manner, conventional container corners (lockings) may be mounted on the corners of the pontoons to allow them to be handled and transported in the same manner as standard containers.  
         [0026]     A dredge ladder  40  is pivotally secured at its rear most end (aft end) to the aft section platform  20 . The front most end (fore end) of dredge ladder  40  may be lowered to the bottom of the waterway for dredging and subsequently raised, or hoisted, for stowage using a network of ladder-hoist winches  16   a , ladder-hoist pulleys  16   b  and ladder-hoist wires or cables  16   c.    
         [0027]     As shown in  FIG. 2 , the fore section platform  10  comprises a plurality of pontoons  11 , preferably disposed in a relatively intimate, side-by-side manner. A control cabin  15 , for example, may be provided on a portion of the upper surface  12  of the fore section platform  10  from which dredge control and operation may be carried out. Although the fore section platform  10  is illustrated in  FIG. 2  as being comprised of five pontoons  11 , the actual number of pontoons  11  may be varied so as to either increase or decrease the overall length of the hull to accommodate differing dredging situations, fore section platform  10  surface area  12  requirements, or buoyancy requirements, etc.  
         [0028]     Each pontoon  11  is preferably positioned and secured to its neighboring pontoon(s)  11  by way of at least two substantially parallel series of interconnected standard industrial pipe sections  31   a  and  31   b , portions of which extend, in a water-tight matter, through pontoons  11  from the front side  13  to the rear side  14  of the fore section platform  10 . Extreme ends  31   c  and  31   d  of the interconnected pipe sections  31   a  and  31   b  securing pontoons  11  of the fore section platform  10 , for example, are shown in  FIG. 5 . A single pontoon  11  is shown in  FIG. 4A . Also included on the fore section platform  10 , are a number of winches  16   a , pulleys  16   b , and cables  16   c , as shown in  FIGS. 2, 5  &amp;  7 , which form a part of the network of ladder-hoist winches, ladder-hoist pulleys, and ladder-hoist wires that lower, raise, hoist, secure, stow, control the cutter torque, or otherwise operate the dredge ladder  40 .  
         [0029]     As shown in  FIG. 3 , the aft section platform  20  comprises a plurality of pontoons  11  preferably disposed in a spaced-apart, side-by-side manner. Although the aft section  20  is illustrated in  FIG. 3  as being comprised of five pontoons  11 , the actual number of pontoons  11  may be varied so as to either increase or decrease the overall length of the hull to accommodate differing dredging situations, aft section platform  20  surface area  22  requirements, or buoyancy requirements, etc. Each pontoon  11  is preferably secured, near its opposing lateral ends, to each of its neighboring pontoon(s)  11  by way of at least the two substantially parallel series of interconnected standard industrial pipes  31   a  and  31   b , portions of which extend, in a water-tight manner, through the pontoons  11  from the front side  23  to the rear side  24  of the aft section platform  20 . In the preferred embodiment, the pontoons  11  forming the aft section platform  20  are spaced apart from one another, as opposed to the close positioning of the pontoons  11  of the fore section  10 . The spacing of the pontoons  11  used with the aft section platform  20  is greater than the spacing used to form the fore section platform  10 . This greater spacing of the pontoons  11  distributes the greater overall weight of the aft section  20  over a larger surface area of the water contributing to greater buoyancy and stability to the dredge assembly  1 . Various enclosures  25   a  and  25   b , which, for example, house the engine, electrical controls or power plant, may be included on a portion of the upper surface  22  of the aft section platform  20 .  
         [0030]     As shown in  FIG. 1 , the two substantially parallel pipe sections  31 , respectively formed from the series of interconnected standard industrial pipes  31   a  and  31   b , have opposing end portions that are used to form both the fore section platform  10  and the aft section platform  20 . The pipes  31   a  and  31   b  may be made from any suitable material, preferably ship building steel. Pipe sections  31  are continuous and connect the fore section platform  10  with the aft section platform  20  to form the hull  5  of the dredge assembly  1 . The actual number of interconnected pipes  31   a  and  31   b  forming the hull  5  is not limited to the specific number illustrated in the figures, but may be varied to increase or decrease the overall length of the hull to accommodate differing dredge situations or to accommodate varying lengths of the dredge ladder  40  discussed further below.  
         [0031]     An example of two interconnected standard industrial pipe sections  31   a  or  31   b  is shown in  FIG. 4B . The pipe sections  31   a  or  31   b  are preferably interconnected to each of their respective neighboring pipe sections  31   a  and  31   b  by way of their respective sealed, “blind” (closed) flanges F. Any suitable known securing means, such as, for example, conventional nut and bolt combinations or couplings, may be used to interconnect the respective pipe sections  31   a  and  31   b.    
         [0032]     As discussed above with respect to the pipe sections  31   a  and  31   b  used to form the fore and aft section platforms  10 ,  20 , all of the interconnected pipes  31   a  and  31   b  are secured to their neighboring pipes  31   a  and  31   b  in a water-tight manner, including the interconnected pipes disposed intermediate of the fore and aft section platforms  10  and  20 . Due to the buoyancy of each pipe section  31   a  and  31   b , resulting from the water-tight seal trapping air within each pipe section  31   a  and  31   b , the collective buoyancy of the interconnected series of pipe sections  31   a  and  31   b  increases their overall buoyancy, stability and structural integrity due to their tendency to float. To further increase overall buoyancy and structural integrity of the two lengths of interconnected pipe sections  31   a  and  31   b , one or more pontoons  11  may be positioned along the lengths thereof, as shown in  FIG. 1 .  
         [0033]     The dredge ladder  40 , as shown in  FIG. 1 , preferably comprises a ladder after part  40   a  and a ladder front part  40   b . The ladder after part  40   a , as seen in  FIGS. 1-3  and  5 - 7 , is preferably constructed from two substantially parallel pipe sections  41 , respectively formed from a series of interconnected standard industrial pipes  42   a  and  42   b  preferably having “blind” (closed) flanges. The pipe sections  42   a  and  42   b  used to form the ladder after part  40   a  are similar to the pipe sections  31   a  and  31   b . The pipes  42   a  and  42   b  may be made from any suitable material, preferably ship building steel. The pipe sections  42   a  and  42   b  are preferably either the same size or larger than the pipe sections  31   a  and  31   b . Each pipe section  42   a  and  42   b  is preferably secured to its neighboring pipe section  42   a  and  42   b  using blind “closed” flanges to create a water-tight seal throughout their interconnected length to increase their overall buoyancy as a result of air being internally trapped therein.  
         [0034]     An example of two interconnected standard industrial pipe sections  42   a  or  42   b  is shown in  FIG. 4C . The pipe sections  42   a ,  42   b  are preferably interconnected to each of their respective neighboring pipe sections  42   a ,  42   b  by way of their respective sealed, “blind” (closed) flanges F. Any suitable known securing means, such as, for example, conventional nut and bolt combinations or couplings, may be used to interconnect pipe sections  42   a  and  42   b . The overall buoyancy of the sealed, interconnected pipe sections  40   a  and  40   b  counter the accumulated weight of the pipes  40   a  and  40   b  to provide a dredge ladder  40  exhibiting a substantially zero net load. On the basis of the substantially zero net load, the length limitations of the dredge ladder  40  become virtually non-existent, resulting in a dredge ladder  40  that may conceivably extend to any required length. When hoisted to the horizontal position under the hull  5 , as shown in  FIGS. 5, 7 ,  8 ,  10 A &amp;  10 B, the entire dredge ladder  40  will float (i.e., have substantially zero net load). In this way, the network of ladder-hoist winches  16   a , ladder-hoist pulleys  16   b , and ladder-hoist wires or cables  16   c  remain unloaded while the ladder  40  is in the hoisted position. Also, when hoisted to the horizontal position, components (e.g., cutter head  43 , cutter motor  44 , suction pump and motor  45 , suction pipe, and discharge conduit  26 ) located on the ladder  40  are preferably just above water level to facilitate maintenance, while the ladder pipe sections remain just below water level.  
         [0035]     The ladder after part  40   a , as shown in  FIGS. 1, 3  &amp;  6 , is pivotally attached to the aft section platform  20  by way of any sufficient conventional pivoting means (not shown), preferably disposed between the lateral ends of at least one pontoon  11  of the aft section platform  20  and the end portions of the ladder after part  40   a.    
         [0036]     In the preferred embodiment, the ladder front part  40   b , as shown in  FIGS. 1, 5  &amp;  7 , has a generally triangular shape and includes a cutter head  43 , cutter motor  44  for driving the cutter head  43 , an underwater suction pump and motor  45 , and hydraulic cylinders  46   a  and  46   b  for providing cutter head orientation. The ladder front part  40   b  includes a pump mounting section  47  and a pivotal cutter head mounting section  48 .  
         [0037]     Preferably, the pump mounting section  47  has a generally isosceles trapezoidal shape and is constructed from a plurality of standard industrial tubing or pipes having “blind” (closed) flanges, similar to pipes  31   a ,  31   b ,  42   a , and  42   b . The rear portion of the pump mounting section  47  preferably includes at its opposing lateral sides, angled pipe sections  47   a  and  47   b  with “blind” (closed) flanges, which interface with the respective adjacent closed flanges of pipe sections  42   a  and  42   b  of the front end of the ladder after part  40   a . The standard industrial tubing forming the pump mounting section  47  and pipe sections  47   a  and  47   b  may be made from any suitable material, preferably ship building steel.  
         [0038]     The tubing forming the pump mounting section  47  is preferably hollow and sealed at their respective ends using “blind” (closed) flanges. Each tube preferably includes a water intake opening or hole for allowing water to be introduced therein adding weight to the dredge ladder  40  when an increase of pressure is needed on the cutter head  43  depending on the properties of the soil being dredged. In addition, the ability to increase the weight of the dredge ladder  40  by adding water therein functions to control cutter torque on the ladder, such that the majority of forces are concentrated on the ladder front part  40   b  and are transferred to the pontoons  11  via the wire or cable system  16 . As such, the forces acting on the ladder after part  40   a  and its pivoting connection to the aft section platform  20  remain low, thereby permitting use of a ladder after part  40   a  with reduced torque resistant properties.  
         [0039]     In one embodiment, a closing plug (not shown) may be used to seal the water inlet openings when the tubing is filled with the desired volume of water. Each tube also preferably includes a conventional valve (not shown) to permit the water to be discharged or drained from the tubing forming the pump mounting section  47  using an air compressor. Draining of the tubing forming the pump mounting section  47  serves to reduce the weight of the dredge ladder and the associated pressure on the cutter head  43 , as well as to facilitate maintenance of the structure and to prevent the water from freezing during stoppages in the winter.  
         [0040]     It is understood that the tubing forming the pump mounting section  47  may be filled and/or drained “on-line” during the dredging operation to facilitate, among other things, increasing or decreasing the pressure on the cutter head. Alternatively, the tubing may be filled with water manually after the dredge is assembled prior to the dredging operation to achieve the desired cutter pressure and to resist cutter torque depending on the properties of the soil being dredged.  
         [0041]     As best shown in  FIGS. 5 &amp; 7 , the cutter head section  48  is pivotally attached to the extreme front portion of the pump mounting section  47  using any conventional mounting that will allow the desired pivotal motion. Movement of the cutter head  43 , via movement of the pivotal cutter head mounting section  48 , is preferably accomplished by way of hydraulic cylinders  46   a  and  46   b  disposed between the pump mounting section  47  and the cutter head section  48 . Regardless of the relative position of the cutter head mounting section  48  or the actual depth that the ladder front part  40   b  is submerged, the relative distance between the cutter head  43  and the suction pump  45 , which pumps dredged material loosened by the cutter head  43  away from the cutter head  43 , remains in close proximity thereto. Thus, the suction pump and cutting head are separated by a distance that is substantially independent of the ladder length.  
         [0042]     In operation, dredged material loosened by the rotating cutter head  43  is drawn into an inlet conduit connected to the inlet of pump  45 . Suction pump  45  then pumps the dredged material to the waterway surface through a suction or discharge conduit  26  connected to the outlet or discharge of the suction pump  45  and preferably mounted on the dredge ladder  40 . The conduit  26  is preferably a series of interconnected industrial pipe sections  26   a , which, like the ladder after part  40   a , may be made smaller or larger depending on the number of pipes  26   a  needed for the depth obtained. Preferably, the suction conduit  26  is connected at the surface to the inlet of a second pump  28 , located, for example, on the aft section platform  20 , which assists in pumping the dredged material through the conduit  26  to the surface. The second pump  28  then discharges the dredged material to a desired location through a conduit connected to the outlet of the pump. It is understood that more than one pump can be utilized for removing the dredged material and that the invention is not limited to the number of pumps illustrated in the figures.  
         [0043]     The pontoon sections  11  and pipes  31   a ,  31   b ,  42   a ,  42   b  may be selected from standard, commercially available and readily transportable elements, preferably having a size and shape facilitating shipment using standard cargo transport containers, such as 20 or 40 TEU (twenty-foot equivalent units). In this manner, the modular dredge assembly may be readily disassembled, transported by sea, air and/or rail, and then readily reassembled on-site prior to use.  
         [0044]     In addition, because of the modular design, the parts of the dredge assembly can be used to retrofit existing dredges. The tubular or support components that separate the fore and aft section platforms of the hull can be replaced with the interchangeable, discrete pipe sections, as can the ladder. Thus, an existing dredge device can be converted into a more flexible system.  
         [0045]     Although illustrative embodiments have been described herein in detail, it should be noted and understood that the descriptions and drawings have been provided for purposes of illustration only, and that other variations both in form and detail can be added thereupon without departing from the spirit and scope of the invention. The terms and expressions have been used as terms of description and not terms of limitation. There is no limitation to use the terms or expressions to exclude any equivalents of features shown and described or portions thereof.