Title:
Cutter suction dredge
Kind Code:
A1


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.



Inventors:
Heuvelman, Cornelis (MJ Rhenen, NL)
Application Number:
11/011576
Publication Date:
06/15/2006
Filing Date:
12/14/2004
Primary Class:
International Classes:
E02F9/06
View Patent Images:
Related US Applications:
20030097772Excavation cleanup deviceMay, 2003Christensen
20090229149Remote control for shifting the gears of a snowplow truck transmissionSeptember, 2009Tesinsky
20080073090Automated snow plowMarch, 2008Harris
20010037588BUCKET WITH QUICK ATTACH BLADENovember, 2001Royer
20070220783Auger For Use With Trenching AssemblySeptember, 2007Hamburger et al.
20040060209Tooth block attached to bucket for shovel machine and bucket for the sameApril, 2004Watanabe
20090282707Snow melting and removal machineNovember, 2009Shenouda
20040250454SnowplowDecember, 2004Jager
20050076547Backhoe safety teethApril, 2005Leblanc
20050229444Shore or river bank reclamation structureOctober, 2005Lin
20070044348Trenching jackhammer attachmentMarch, 2007Walker et al.



Primary Examiner:
BEACH, THOMAS A
Attorney, Agent or Firm:
Kenneth S. Weitzman (New York, NY, US)
Claims:
I claim:

1. A modular, adjustable length dredge assembly, comprising: a hull; an adjustable length dredge ladder, the ladder having a front section coupled to a rotatable cutter head for loosening material to be dredged and a rear section 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 including a plurality of releasably interconnected hollow pipe sections forming a first fluid tight channel therein, and the rear section of the ladder including a plurality of releasably interconnected hollow pipe sections that form at least one second fluid tight channel in the rear section of the ladder to increase the bouyancy of the ladder, wherein additional pipe sections may be added or removed from the rear section to adjust the length of the ladder, and wherein water is selectively introduced into at least the first fluid tight channel to increase the weight of the ladder to achieve a desired cutter pressure and control cutter torque.

2. The modular, adjustable length dredge assembly according to claim 1, wherein water is selectively drained from at least the first fluid tight channel to facilitate buoyancy of the ladder in the hoisted position.

3. The modular, adjustable length dredge assembly according to claim 1, wherein the plurality of interconnected hollow pipe sections in the front section of the ladder are sealed at each end to form a plurality of a first fluid tight channels.

4. The modular, adjustable length dredge assembly according to claim 3, wherein the plurality of interconnected hollow pipe sections in the front section of the ladder are sealed at each end by a blind flange.

5. The modular, adjustable length dredge assembly according to claim 1, wherein the rear section of the ladder comprises a second plurality of releasably interconnected hollow pipe sections that is substantially parallel to the first plurality of releasably interconnected hollow pipe sections.

6. The modular, adjustable length dredge assembly according to claim 1, wherein the hull comprises a fore section platform, an aft section platform, and a third plurality of releasably interconnected hollow pipe sections for longitudinally connecting the fore section platform to the aft section platform.

7. The modular, adjustable length dredge assembly according to claim 6, wherein the length of the hull is adjustable by adding or removing pipe sections from the third plurality of releasably interconnected hollow pipe sections.

8. The modular, adjustable length dredge assembly according to claim 6, further comprising a fourth plurality of releasably interconnected hollow pipe sections that is substantially parallel to the third plurality of releasably interconnected hollow pipe sections and which longitudinally connects the fore section platform to the aft section platform.

9. The modular, adjustable length dredge assembly according to claim 6, wherein the rear section of the ladder is pivotally coupled to the aft section platform.

10. The modular, adjustable length dredge assembly according to claim 1, wherein the ladder is substantially horizontal when in the hoisted position.

11. The modular, adjustable length dredge assembly according to claim 1, further comprising a suction pump positioned on the ladder in proximity to the cutter head.

12. The modular, adjustable length dredge assembly according to claim 6, wherein the fore section platform includes at least one pontoon.

13. The modular, adjustable length dredge assembly according to claim 6, wherein the aft section platform includes at least one pontoon.

14. A modular dredge assembly, comprising: a hull section; and a ladder section having a fore end supporting a cutter device and an aft end pivotally connected to the hull section, the ladder section having an initial floating position resulting from substantial zero buoyancy of the ladder section.

15. The dredge assembly according to claim 14, wherein the hull section is adjustable in length.

16. The dredge assembly according to claim 14, wherein the ladder section is adjustable in length.

17. The dredge assembly according to claim 14, wherein the hull section and ladder section are adjustable in length.

18. The dredge assembly according to claim 14, wherein the ladder section includes two parallel pipes of adjustable length, each of the pipes respectively formed from a series of removably interconnected hollow pipe sections.

19. The dredge assembly according to claim 14, wherein the hull section includes fore and aft platforms, and a pair of parallel pipes of adjustable length, each of the pair of parallel pipes of adjustable length respectively formed from a series of removably interconnected hollow pipe sections.

20. The dredge assembly according to claim 14, wherein the fore end of the ladder section includes weight adjusting pipes.

21. The dredge assembly according to claim 20, wherein the weight adjusting pipes permit the ingress and egress of water to selectively control the weight of the ladder to achieve a desired cutter pressure and resist cutter torque.

22. The dredge assembly according to claim 14, wherein the ladder is substantially horizontal when in the initial floating position.

23. The dredge assembly according to claim 14, further comprising a suction pump positioned on the ladder section in proximity to the cutter device.

24. The dredge assembly according to claim 14, wherein the hull section includes a plurality of pontoons.

25. The dredge assembly according to claim 19, wherein the fore and aft platforms include at least one pontoon.

26. The dredge assembly according to claim 25, wherein the fore and aft platforms include a plurality of pontoons.

27. The dredge assembly according to claim 26, wherein at least one of the plurality of pontoons is spaced apart from an adjacent pontoon.

28. The dredge assembly according to claim 26, wherein at least two of the plurality of pontoons abut one another.

29. A modular, adjustable length dredge assembly, comprising: a hull having a fore section platform, an aft section platform, and a first pair of a plurality of substantially parallel, releasably interconnected hollow pipe sections of adjustable length longitudinally connecting the fore section platform to the aft section platform; and a dredge ladder comprising a second pair of a plurality of substantially parallel, releasably interconnected hollow pipe sections of adjustable length having a rear section pivotally coupled to the hull and a front section coupled to a rotatable cutter head, wherein the adjustable lengths of the first pair of a plurality of substantially parallel, releasably interconnected hollow pipe sections and the second pair of a plurality of substantially parallel, releasably interconnected hollow pipe sections results from the removal or insertion of additional hollow pipe sections so that the first and second pair of interconnected pipe sections may be either shortened or lengthened.

30. The modular dredge assembly according to claim 29, wherein the second pair of a plurality of substantially parallel interconnected pipe sections are selectively movable from a hoisted position where the ladder floats to an operative position where the cutter head engages a surface to be dredged.

31. The modular dredge assembly according to claim 30, wherein the ladder is substantially horizontal when in the hoisted position.

32. The modular dredge assembly according to claim 30, wherein the front section of the ladder comprises a plurality of hollow pipe sections such that water is selectively permitted to enter at least one of the hollow pipe sections to increase the weight of the ladder to achieve a desired cutter pressure and resist cutter torque.

33. The modular dredge assembly according to claim 32, wherein water is selectively permitted to discharge from at least one of the hollow pipe sections to decrease the weight of the ladder to achieve the desired cutter pressure.

34. The modular dredge assembly according to claim 30, further comprising a suction pump positioned on the ladder in proximity to the cutter head.

35. The modular dredge assembly according to claim 29, wherein the rear section of the second pair of a plurality of substantially parallel interconnected pipe sections is pivotally coupled to the aft section platform.

36. The modular dredge assembly according to claim 29, wherein the fore section platform includes at least one pontoon.

37. The modular dredge assembly according to claim 29, wherein the aft section platform includes at least one pontoon.

38. A modular, size adjustable dredge assembly, comprising: first and second sets of pontoons capable of being assembled into fore and aft section platforms; first and second sets of releasably interconnected pipe sections, the pipe sections being hollow, water tight with flanged ends, interchangeable with one another and capable of being assembled together to provide substantially parallel pipes that cooperate with the pontoon sections to form adjustably spaced fore and aft section platforms; third and fourth sets of releasably interconnected pipe sections, the pipe sections being hollow, water tight with flanged ends, interchangeable with one another and capable of being assembled into a dredge ladder; a fifth set of pipe sections capable of forming a tapered or triangular suction pump and cutter support platform, including pipes for adjusting the weight of the suction pump and cutter support platform; and a cutter and a suction pump for assembly in close proximity to one another on the support platform.

39. A method of adjusting the linear dimension of a dredge assembly, comprising: providing a hull having a fore section platform, an aft section platform, and a first pair of a plurality of substantially parallel, releasably interconnected pipe sections longitudinally connecting the fore section platform to the aft section platform; providing a ladder having a second pair of a plurality of substantially parallel, releasably interconnected pipe sections having an aft section pivotally coupled to the aft section platform and a fore section coupled to a cutter head, and inserting or removing pipe sections from at least one of the hull and ladder to adjust hull length, ladder length or both.

40. A method of adjusting the weight of a dredge ladder to achieve a desired cutter pressure and resist cutter torque, comprising: releasably interconnecting a plurality of hollow pipe sections in at least a portion of the dredge ladder to form at least one fluid tight channel therein; and introducing water into the at least one fluid tight channel to increase the weight of the ladder to achieve the desired cutter pressure and resist cutter torque.

41. The method according to claim 40, further comprising draining water from the at least one fluid tight channel to decrease the weight of the ladder to achieve the desired cutter pressure.

Description:

FIELD OF THE INVENTION

This application relates generally to dredge assemblies and, more particularly, to a modular, size-adjustable cutter suction dredge (“CSD”) assembly.

BACKGROUND OF THE INVENTION

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.

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's weight (inertia), as well as the forces or cutter torque developed as a consequence of cutting the waterway bed or surface.

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.

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.

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

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.

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.

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

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.

FIG. 1 is a perspective view of the dredge assembly in accordance with a preferred embodiment of the present invention;

FIG. 2 is a perspective view of the fore section platform of the preferred dredge assembly illustrated in FIG. 1;

FIG. 3 is a perspective view of the aft section platform of the preferred dredge assembly illustrated in FIG. 1;

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;

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;

FIG. 5 is a perspective view of the preferred fore section platform illustrated in FIG. 2 with the dredge ladder in the hoisted position;

FIG. 6 is a perspective view of the preferred aft section platform illustrated in FIG. 3 with the dredge ladder in the hoisted position;

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;

FIG. 8B is a perspective view of the preferred dredge assembly illustrated in FIG. 8A;

FIG. 9A is a side elevation view of the preferred dredge assembly illustrated in FIG. 1 with the dredge ladder partially hoisted;

FIG. 9B is a perspective view of the preferred dredge assembly illustrated in FIG. 9A;

FIG. 10A is a side elevation view of the preferred dredge assembly illustrated in FIG. 1 with the dredge ladder substantially hoisted; and

FIG. 10B is a perspective view of the dredge assembly illustrated in FIG. 10B.

DETAILED DESCRIPTION OF THE INVENTION

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 31a and 31b. Each pipe 31a and 31b 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.

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.

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 16a, ladder-hoist pulleys 16b and ladder-hoist wires or cables 16c.

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.

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 31a and 31b, 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 31c and 31d of the interconnected pipe sections 31a and 31b 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 16a, pulleys 16b, and cables 16c, as shown in FIGS. 2, 5 &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.

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 31a and 31b, 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 25a and 25b, 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.

As shown in FIG. 1, the two substantially parallel pipe sections 31, respectively formed from the series of interconnected standard industrial pipes 31a and 31b, have opposing end portions that are used to form both the fore section platform 10 and the aft section platform 20. The pipes 31a and 31b 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 31a and 31b 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.

An example of two interconnected standard industrial pipe sections 31a or 31b is shown in FIG. 4B. The pipe sections 31a or 31b are preferably interconnected to each of their respective neighboring pipe sections 31a and 31b 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 31a and 31b.

As discussed above with respect to the pipe sections 31a and 31b used to form the fore and aft section platforms 10, 20, all of the interconnected pipes 31a and 31b are secured to their neighboring pipes 31a and 31b 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 31a and 31b, resulting from the water-tight seal trapping air within each pipe section 31a and 31b, the collective buoyancy of the interconnected series of pipe sections 31a and 31b 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 31a and 31b, one or more pontoons 11 may be positioned along the lengths thereof, as shown in FIG. 1.

The dredge ladder 40, as shown in FIG. 1, preferably comprises a ladder after part 40a and a ladder front part 40b. The ladder after part 40a, 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 42a and 42b preferably having “blind” (closed) flanges. The pipe sections 42a and 42b used to form the ladder after part 40a are similar to the pipe sections 31a and 31b. The pipes 42a and 42b may be made from any suitable material, preferably ship building steel. The pipe sections 42a and 42b are preferably either the same size or larger than the pipe sections 31a and 31b. Each pipe section 42a and 42b is preferably secured to its neighboring pipe section 42a and 42b 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.

An example of two interconnected standard industrial pipe sections 42a or 42b is shown in FIG. 4C. The pipe sections 42a, 42b are preferably interconnected to each of their respective neighboring pipe sections 42a, 42b 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 42a and 42b. The overall buoyancy of the sealed, interconnected pipe sections 40a and 40b counter the accumulated weight of the pipes 40a and 40b 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, 10A &10B, the entire dredge ladder 40 will float (i.e., have substantially zero net load). In this way, the network of ladder-hoist winches 16a, ladder-hoist pulleys 16b, and ladder-hoist wires or cables 16c 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.

The ladder after part 40a, as shown in FIGS. 1, 3 &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 40a.

In the preferred embodiment, the ladder front part 40b, as shown in FIGS. 1, 5 &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 46a and 46b for providing cutter head orientation. The ladder front part 40b includes a pump mounting section 47 and a pivotal cutter head mounting section 48.

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 31a, 31b, 42a, and 42b. The rear portion of the pump mounting section 47 preferably includes at its opposing lateral sides, angled pipe sections 47a and 47b with “blind” (closed) flanges, which interface with the respective adjacent closed flanges of pipe sections 42a and 42b of the front end of the ladder after part 40a. The standard industrial tubing forming the pump mounting section 47 and pipe sections 47a and 47b may be made from any suitable material, preferably ship building steel.

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 40b and are transferred to the pontoons 11 via the wire or cable system 16. As such, the forces acting on the ladder after part 40a and its pivoting connection to the aft section platform 20 remain low, thereby permitting use of a ladder after part 40a with reduced torque resistant properties.

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.

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.

As best shown in FIGS. 5 & 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 46a and 46b 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 40b 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.

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 26a, which, like the ladder after part 40a, may be made smaller or larger depending on the number of pipes 26a 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.

The pontoon sections 11 and pipes 31a, 31b, 42a, 42b 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.

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.

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.