DESC:FORM-2

THE PATENTS ACT, 1970
(39 OF 1970)
and
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
(See Section 10, Rule 13)

“TRAILING SUCTION DREDGER WITH HOPPERS BARGES”

Adani Ports and Special Economic Zone Limited
An Indian Company
Having address at
Adani Corporate House,
Shantigram, Near Vaishnodevi Circle,
S G Highway, Khodiyar,
Ahmedabad – 382421, Gujarat, India.

The following specification particularly describes the invention and the manner in which it is to be performed.
FIELD OF THE INVENTION

The present invention relates to the field of dredging activity. More particularly, the present invention pertains to a continuous dredging system that de-links dredging activity and transportation and disposal activities over separate vessels, thereby enabling uninterrupted dredging by the TSD while SPHBs (self-propelling hopper barges) independently transport and dispose of dredged material, resulting in a substantial increase in active productive time, up to 75%.

BACKGROUND OF THE INVENTION
Dredging is the process of removing soil, such as sand or gravel, from underwater and transporting it from one place to another. The trailing suction hopper dredgers (TSHD’s) are primarily used to dredge sand, silt and gravel. Compacted sand and other cohesive soils can also be dredged by the use of water jets, blades or rippers fitted in the drag head. The trailing suction hopper dredgers (TSHD’s) can easily handle soft and loose soils, such as sand, silt and gravel and are deployed in a wide range of dredging projects such as deepening and maintenance of waterways, land reclamation, port construction, mining and the supply of marine aggregates.
The conventional trailing suction hopper dredgers rips-off the soil from the seabed using one or two of its dragheads which are fitted at the free end of the dredge tubes. The dislodged dredged material is sucked up the suction tubes using dredge pumps. The dredged material is routed through pipelines in to the hopper (cargo hold) of the dredger till it filled to its maximum carrying capacity. Once the hopper of the TSHD is filled to its capacity, the TSHD lifts the Dredge tube(s) off the seabed and starts sailing towards the designated disposal area. The TSHD can dispose the dredged material from hopper in three (3) ways.
1. Rainbow discharge (Jetting the dredge material in slurry form in a rainbow arch. This method is used when the dredged material is suitable for land reclamation or beach nourishment purposes.)
2. Shore pumping (Pumping the material from TSHD’s hopper to land through floating & shore pipelines. This method is also used when the dredged material is suitable for land reclamation)
3. Bottom door dumping (By dumping the dredged materials on the designated seabed area (called as Dumping Ground) through bottom doors under the TSHD. This is generally the most used method of disposal when TSHD engages in maintenance dredging activities to maintain depths in a port area).
After disposing the dredged material, the TSHD sails with empty hopper to come back again to the identified dredging location and subsequently commences the next dredging cycle. This is the conventional process followed by TSHD’s and therefore results in low productivity.
The major drawback of such a dredging process is the high time spent by an extremely costly vessel fitted with some very costly equipment travelling up and down to the dumping ground thereby greatly reducing the time available to the dredger to carry out the actual dredging process. Hence, there persists a need for a continuous dredging system that de-links the dredging activity from the transportation and disposal activity of the dredged material and increases the productive stage of said activity to 75%.

PRIOR ART AND ITS DISADVANTAGES
In all large dredging projects, where a Cutter Suction Dredgers cannot be used due to operational, climatic or navigational constraints, TSHD are used. In order to complete large dredging projects on time, dredging contractors use multiple TSHD’s or very large TSHD’s (depths permitting) to complete the project on time.
Dredging companies have over the years kept building larger and larger hopper size TSHD’s to complete projects within a short time-frame. This has resulted in very costly TSHDs (trailing suction hopper dredger) being built which have large hopper volumes, large installed propulsion engines, large generators for powering the bow thrusters and massive dredge pumps so that the dredging cycle can be completed in the least possible time.
A US patent application No. US201815869118A relates to an invention which encompasses a moonpool for enhanced dredge head manoeuvrability and a carouseling mechanism to facilitate continuous dredging operations by interchangeably utilizing multiple barges. The barge is in fluidic communication with the drag arm. The movement of the drag arm and drag head is controlled by port control and starboard control. The system is designed to improve efficiency and productivity in underwater excavation and material transport
However, in the said prior art, the dredger requires coupling of the discharge pipeline with the barge’s loading pipe, and both the vessels are needed to align properly with each other during coupling and decoupling phases which consumes a lot of time, hence limiting its production capacity. Furthermore, the barges used are non-propelling and require separate tug boats to assist them in transportation, thereby increasing the need for skilled manpower and management. Moreover, the cited invention also fails to provide a dual loading arm mechanism that enables parallel loading of two barges attached to either side of the dredger. Additionally, the present invention is faced with large maintenance costs, statutory compliances and interface challenges due to integration of multiple and complex systems.
Another US patent application number US10167609 discloses a vessel and vessel/barge systems for dredging underwater surfaces. The vessel includes a hull with a bottom, bow portion, stern portion, port side, and starboard side. The vessel also includes a deck supported by the hull and a pump system mounted within the hull. A drag arm pivotably couples to the pump system. The vessel additionally includes a void defined by contiguous watertight walls or bulkheads joined to and extending upward from the bottom of the hull. The contiguous watertight walls or bulkheads are (i) vertically extensive of a perimeter of an aperture in the bottom of the hull, (ii) outboard, astern, and forward the aperture, or (iii) some combination thereof. The barge is releasably coupled to the vessel. Moreover, the barge is in fluidic communication with the drag arm.
However, in the above-mentioned prior art, the dredger and barge are connected physically through a carousel coupling mechanism. This makes the prior art rigid (not flexible) and thus it can only operate in calm weather without waves & swells. Thus, the prior art is restricted to working in rivers and calm waters only and is not suitable to operate in open sea and in all-weather conditions. Also, in the above-mentioned patent application, the barge is coupled in front of the Dredger and non-propelled. The Barge(s) thus require additional support flotilla such as separate tugs/ boats in assisting them during their positioning for dredging operations, coupling-decoupling, transiting to and from the dumping ground as well as during dumping operations. This process substantially increases the number of supporting vessels required for allowing continuous dredging operations besides increasing the number of activities which are required to be executed to complete one dredging cycle of the dredging operation. Since the barges are not self-propelled, a support tug is required for the entire duration of all the activities. The number of activities required to be undertaken for completing one dredging cycle are quite numerous, time consuming as well as highly labour intensive.
Another prior art document EP10000914A discloses a method that involves receiving dredged materials in form of sediments from a ground-water body by a suction pipe and a suction towing head using towed hopper dredges.
The drawbacks of above-mentioned prior art are that this dredged soil disposal method is depends on the flow of water. In calm water bodies where the water is not “flowing”, the prior art will not be effective in removing the sediments to a faraway deeper depth location.

DISADVANTAGES OF THE PRIOR ART:
Existing technologies used for dredging, suffers from all or at least any of the below mentioned disadvantages:
• Many of the prior arts require dredger and barge to be physically connected through carousel coupling, which limits the active productivity of the system.
• Many of the prior arts are restricted to working in rivers and cannot be operated in sea or in all weather conditions.
• Most of the prior arts require separate tug boats to assist them through coupling-decoupling activities as well as during the dumping of the dredged material. This increases the number of vessels required for the dredging operation, thereby increasing the statutory compliance requirements and operational costs.
• Most of the prior arts only cover the mechanism required for suction of dredged material from the seabed and fail to consider providing a mechanism for activities including but not limited to disposal of the dredged material.
• In many of the prior arts, the dredger performs all the activities involved in the dredging process as a single unit wherein majority of operating time is wasted in non-productive but necessary activities, thereby decreasing the productivity output. This also makes repairs and maintenance of conventional TSHD is more complex due to integration of multiple and complex systems.
• Most of the conventional TSHDs have bottom opening doors, which remain below the water surface, causing wear and tear of such parts. This requires the dredger to be dry-docked for repairs. Since there is a scarcity of dry-docking facilities for TSHDs in India, the TSHD owners have to consider dry-docking facilities outside India, thus incurring greater costs and forex outflows.
• Most of the prior arts require their loading pipelines of the loaded barge with water before disconnecting and has to connect and align with the next empty barge. If not flushed, the residual slurry in the loading can settle and choke the pipeline, thus leading to increased downtime before next operation.

OBJECTS OF THE INVENTION
The main object of the present invention is to provide a combined fleet system of trailing suction dredger with hopper barges.
Another object of the present invention is to provide a trailing suction dredger with hopper barges that is adapted with a dual loading arm mechanism that enables immediate loading of one hopper barge after another in real-time.
Yet another object of the present invention is to provide a trailing suction dredger with hopper barges that substantially increases the annual productivity by engaging in productive stage of dredging for as high as 75% time.
Yet another object of the present invention is to provide a trailing suction dredger with hopper barges that is equipped with two independent dredging pipe systems with 100% capacity.
Yet another object of the present invention is to provide a trailing suction dredger with hopper barges that maximises the production time.
Yet another object of the present invention is to provide a trailing suction dredger with hopper barges that allows continuous dredging activity with minimum downtime.
Yet another object of the present invention is to provide a trailing suction dredger with multiple hopper barges that eliminates the transportation and dredge disposal time during production cycle.
Yet another object of the present invention is to provide a trailing suction dredger that enables parallel attachment of two hopper barges onto each side of the dredger.
Yet another object of the present invention is to provide a trailing suction dredger with multiple self-propelling hopper barges that increases the number of independent dumb hopper barges required for completing the dredging operations.
Yet another object of the present invention is to provide a trailing suction dredger with hopper barges that eliminates the problem of choking of the loading pipeline or the draghead.
Yet another object of the present invention is to provide a trailing suction dredger with a dredging system that reduces the repair & maintenance complexities of TSD’s through simplified design and layout of the dredging equipment and pipelines.
Yet Another object of the present invention is to provide a trailing suction dredger with hopper barges that requires lower manning scales and number of personnel required to operate the TSD and Hopper barges.
Yet another object of the present invention is to provide a trailing suction dredger with hopper barges that can operate in shallow as well as deep waters.
Yet another object of the present invention is to provide a trailing suction dredger with hopper barges which does not involve coupling-decoupling of the hopper barges with the dredger.
Yet another object of the present invention is to provide a trailing suction dredger with hopper barges which is independent of water flow and can operate in waterbodies with or without currents.

BRIEF DESCRIPTION OF DRAWINGS
Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:
Figure 1 : Shows the top view of Trailing Suction Dredger (TSD) according to the present invention.
Figure 2 : Shows the side view of Trailing Suction Dredger (TSD) according to the present invention.
Figure 3 : Shows the front-back view of the arrangement of TSD+H fleet.
Figure 4 : Shows the elevation view of the arrangement of hopper barge with TSD.
Meaning of Reference numerals of Trailing Suction Dredger with Hopper Barges (TSD+H):
1 : Aperture (moonpool)
2 : Dredging pipe System
3 : Draghead
4 : Suction bend
5 : Suction inlet
6 : Dredge pump
7 : Loading arms
8 : Gantries
9 : Azimuth Stern drive
10 : Bow thrusters
11 : Pneumatic fenders
12 : Funnel Shaped drainage
13 : Water overflow system
14 : Drain channel
15 : TSD (trailing suction dredger)
16 : Hopper barges (H)

SUMMARY OF THE INVENTION
The present invention relates to a continuous dredging system comprising a trailing suction dredger (TSD) (15) and plurality of self-propelling hopper barges (SPHB) (16), wherein the fleet of the system is referred to as TSD+H. By enabling the TSD (15) to operate continuously while the SPHBs (16) handle the transportation and disposal of dredged material, the system achieves a significant increase in productive dredging time, potentially upto 75% of the total operational time. The system is suitable for dredging across various conditions, including shallow-deep waters, busy navigational channels and areas with cross currents.
Said TSD+H fleet includes two sets of vessels, a dredging vessel (TSD) (15) and multiple hopper barges (H) (16), engineered to carry out separate yet complementary activities.
The primary features of said TSD (15) are as stated below:
• an electrical propulsion system powered by generators present on board of TSD and includes two azimuth stern drives (9), and bow thrusters (10), to support TSD’s propulsion and the vessel’s other electrical power requirements;
• a longitudinal aperture called the moonpool (1), located centrally along the midship of the vessel (TSD) (15), symmetrically along the longitudinal and athwartship axis;
• a dredging system comprising of:
o two independent dredging pipes/tubes (2) each capable of operating at full capacity, out of which only one dredging pipe is deployed at any given time, into the sea through the moonpool (1),
o a suction draghead (3) installed on one end of the dredging pipe (2), equipped with jet water system, for seabed excavation,
o a suction bend (4) present on the opposite end of the dredging pipe (2), and
o an underwater or an inboard dredge pump (6) connected to the dredging pipe (2);
• gantries (8) driven by hydraulic or electric winches to deploy the dredging tube (2) into the sea Each of said dredging tube (2);
• dragheads (3) equipped with a high-pressure jet water system to dislodge the seabed material through the combined action of the cutting forces exerted by the draghead and the material loosening properties of said high pressure jet water system;
• an underwater dredge pump (6), or in another embodiment, an inboard dredge pump connected to the dredging pipe (2), facilitating a continuous positive suction and eliminating the requirement for a deeper draft and enabling the TSD to dredge even in shallow waters;
• barge loading system characterized by two retractable loading arms (7) which can be swung out and retracted inside the line of TSD hull using hydraulic cylinders.
From the loading arms (7), the dredged material is transferred into the self-propelled hopper barges (SPHB) (16) which sail parallel to the TSD, without being attached to it and maintains a 2 meters athwartship distance from the vessel (TSD).
Further, the primary features of the hopper barges (16) (H) are as follows:
• electrical propulsion system including two azimuth stern drives and bow thrusters to provide the barges with exceptional maneuverability,
• a funnel shaped drainage system (12) to direct the dredged material towards the centre of the hopper barge (H), ensuring uniform distribution of dredged material inside said SPHB,
• a water flow system (13) to maximize the loading capacity of the hopper and facilitates draining of water out from the hopper,
• a drain channel (14) running for almost the entire length of the hopper of the loading barge and featuring drop flaps which are controlled individually using pneumatic or hydraulic pistons to drop the dredged material from the channel into the barge hopper.
Furthermore, the decoupled and independent configuration of TSD (15) and H (16) as separate vessels allows for routine maintenance activities to be conducted independently without disrupting dredging operations. Additionally, the TSD (15) being lighter than conventional trailing suction hopper dredgers (TSHD) due to the de-linked hopper system, offers enhanced flexibility in terms of dry-docking and easy access to ship repair facilities in India.
Additionally, according to the test data demonstrated in this document, it is noted that TSD+H system consistently achieves peak monthly and annual production for both silt and coarse sand, demonstrating a substantial improvement in dredging productivity.

DETILED DESCRIPTION OF THE INVENTION
The following description is presented to enable any person skilled in the art to make and use the invention and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and features disclosed herein.
It is to be understood that the term “comprising” or “comprises” used in the specification and claims refers to the element of the invention which comprises X, Y, and Z, which means that the invention might have other elements in addition to X, Y, and Z. For example, their invention could include A, B, and/or C as long as it also has X, Y, and Z.
The present invention pertains to a continuous dredging system engineered to de-couple the dredging activity performed by the trailing suction dredger (TSD) (15) from the transportation and disposal activities carried out by one or more self-propelled hopper barges (H) (16). Said system, comprising a fleet of Trailing suction dredger (TSD) and multiple self-propelled hopper barges (H) (hereafter referred to as TSD+H), facilitates uninterrupted dredging operation by the TSD while multiple hopper barges (H) (16) independently handle the transportation and disposal of dredged material. Said arrangement of the system substantially enhances the productive dredging time of the TSD (15), potentially increasing operational time-duration up to 75% of the total operational time.
Said TSD+H fleet is capable of dredging in various water depths, including but not limited to shallow and deep waters, busy navigational channels and even during cross currents. The fleet features simplified equipment configuration and integrated systems, and is characterized by smaller vessel sizes, resulting in reduced repair and maintenance costs, lower skill requirements of labour, and reduced statutory compliance.
Furthermore, the decoupled and independent configuration of TSD+H as separate vessels allows for routine maintenance activities to be conducted independently without disrupting dredging operations. Additionally, the TSD (15) being lighter than conventional trailing suction hopper dredgers (TSHD) due to the de-linked hopper system, offers enhanced flexibility in terms of dry-docking and easy access to ship repair facilities in India.
Said system comprises a TSD+H fleet that includes two sets of vessels engineered to carry out separate yet complementary activities enlisted as below:
1. a Trailing Suction Dredger (TSD) (15) to perform dredging activity, having LOA (length overall) of 90 - 100m, beam of about 20m and draft of about 5m, normal sailing speed of about 10 knots and sailing speed of about 2 – 3 knots while dredging;

2. plurality of self-propelling hopper barges (SPHBs) (16) operating parallel to the TSD to execute transportation and disposal activity, having capacity of 4000 – 4500 m3, LOA (length overall) of 70 – 80m, beam of 20m and draft of about 5m, and loaded sailing speed of about 10 knots.
In the disclosed system, the TSD (15) does not constitute a hopper for material storage. Instead, the dredged material is directly discharged from the TSD to the hopper barges (H) (16) through a barge loading mechanism. Said hopper barges (H) (16) sail parallel to the TSD maintaining a 2 meters athwartship distance from the vessel, and subsequently transport the material to the designated dumping locations for disposal. This increases the productivity and achieves an efficiency increase of nearly 3 times compared to the conventional TSHDs systems as the TSD has the capability to engage in productive stage of dredging for as high as 75%.
Further, said TSD+H system eliminates the need for the hopper to physically link and de-link from the TSD (15) during the dredging operations, thereby eliminating downtime associated with such unproductive activities. In addition to this, the system’s simplified construction allows said TSD+H fleet (comprising 1 TSD and 5 barges) to be procured at a lower cost compared to a medium-sized conventional TSHD (8000-10000 m3 hopper capacity).
In accordance with the embodiments, one aspect of the invention relates to the trailing suction dredger (TSD) (15) which includes a hull comprising of several water-tight compartments. Said hull supports a deck, bottom, bow portion, stern portion, port side of the vessel and starboard side of the vessel. Furthermore, said TSD (15) also has a wheelhouse situated on top of the crew accommodation and positioned at front of the vessel.
Further, referring to the embodiments shown in Figure 1 and 2, the structural and functional components of the TSD vessel (15) primarily comprises of:
• an electrical propulsion system consisting of stern drives (9) and bow thrusters (10),

• a moonpool (1) centrally located along the midship section of the TSD vessel (TSD),

• a dredging pipe system (2), configured to the loading arms at the point of connection to the hull,

• two retractable loading arms (7) to transfer dredged material to the hopper barges (H),

• gantries (8) integrated with the dredging pipe system (2) and actuated by hydraulic or electric winches, and

• plurality of pneumatic fenders (11) on both sides of the vessel to eliminate the chances of accidental contact damage.
Said electrical propulsion system comprise of stern drives (9) and bow thrusters (10), operatively configured to the TSD to support its propulsion and the vessel’s other electrical power requirements. Said electrical propulsion system is powered by generators present on the TSD vessel.
As depicted in Figures 1 and 3, said moonpool (1) is a longitudinal aperture, centrally located along the midship section of the TSD vessel (TSD) (15) and is aligned along both the longitudinal and athwartship axes. Moreover, the moonpool (1) is closed at both ends and its length surpasses the length of the vessel's midship section (TSD). Additionally, its width exceeds the dimensions of the draghead (3) preferably by two meters. This particular configuration ensures the safe and efficient deployment of the dredging tubes (2) and the dragheads (3) into the seabed. To further enhance operational safety and the movement of the dredging tube (2), the vessel's hull (TSD) tapers towards its bottom on either side of the moonpool (1). This tapering configuration enables the lateral movement of the dredging tube (2) within the aperture (1), thereby significantly reducing the potential for damage to both, the vessel hull and the dredging tube (2).
Now, referring to the embodiments disclosed in Figures 1 – 3, said dredging system comprises of:
• two independent dredging pipes/tubes (2), of which only one dredging pipe is deployed at any given time,

• a suction draghead (3) affixed to one end of the dredging pipe, and equipped with jet water system for seabed excavation (2),

• a suction bend (4) present on the opposite end of the dredging pipe (2), and

• an underwater or an inboard dredge pump (6) connected to the dredging pipe (2).
Said present invention incorporates two independent dredging pipes system (2), each capable of operating at high capacity. This redundancy ensures that, in an event of failure or inoperability of one system (such as due to a clogged draghead (3)), the other system can continue to operate without any interruption. Thus, this configuration enables the TSD to maintain continuous dredging operation and achieve its maximum rated productivity.
Furthermore, said dredging pipe (2) is deployed into the water through the moonpool (1) by means of wires from the gantries (8), which are actuated by hydraulic or electric winches. Each dredging pipe (2) is composed of steel sections and features an independent gantry system (8). Moreover, the integration of universal joint couplings, rubber hoses and sliding joints in the dredging pipes (2) imparts the necessary flexibility for effective operation during the dredging activity.
Referring to the embodiments shown in Figure 3, one end of each dredging pipe (2) is equipped with a draghead (3) while the opposite end of the dredging pipe (2) curves upward in the TSD vessel, making a suction bend (4). Said suction bend (4) connects the draghead to the suction inlet (5) located in the TSD hull.
Said draghead (3), attached at the end of the dredging tube, is connected to an underwater dredge pump (6) and equipped with a high-pressure jet water system which helps in dislodging of the seabed material through the combined action involving the cutting forces applied by the draghead and the material loosening properties of said high pressure jet water system.
Said dredging system further incorporates an underwater dredge pump (6), or, in certain embodiments an inboard dredge pump (6), connected to the dredging pipe (2) and facilitates a continuous positive suction, eliminating the requirement for a deeper draft and enabling the TSD to dredge even in shallow waters. The dredged material is drawn in by the underwater dredge pump (6) and passed on to the suction inlet (5) in the TSD hull through the dredging pipe (2). The dredging pipe (2) and dredge pumps (6) are conveniently positioned on the TSD deck for ease of maintenance and repairs.
Again, referring to the embodiments is Figures 1 – 3, the dredging pipe (2) bifurcates into two parallel branches at the point of connection to the hull, ultimately leading to the formation of barrel-like structures called loading arms (7), at its terminal. Dredged material from the dredging pipe (2) is directed towards the respective loading arms (7) through a series of gate valves that regulate material flow. During operation, one branch of the loading arm (7) is closed using a valve, while the other remains open, allowing the utilization of only one loading arm (7) at a time for material transfer to the hopper barge (H).
It is important to note that since the TSD is equipped with two independent dredging pipe (2), the dredged material is directed from the dredging pipe to either of the loading arms (7).
Referring to Figure 1, 3 and 4, said dual loading arms (7) are capable of being swung out and retracted within the hull line of the TSD vessel using hydraulic cylinders. From the loading arms (7), the dredged material is transferred into the self-propelled hopper barges (SPHB) that sail parallel to the TSD, maintaining a two-meter athwartship distance from the vessel (TSD).
Furthermore, as shown in Figures 1,3, and 4, the TSD vessel is equipped with pneumatic fenders (11) on both sides of the vessel to eliminate the chances of accidental contact damage to the TSD or the hopper barges (H) (16).
According to another embodiment, the TSD may also comprises of auto heeling tanks to correct the list/tilting of the ship caused by the swinging out of the loading arms (7) on either side of the vessel, and ballast tanks to allow adjustment of the vessel’s draft depending upon the available depth of the water and prevailing weather conditions.
According to the above-mentioned embodiments of the trailing suction dredger (TSD) (15) and plurality of self-propelled hopper barges (H), said TSD (15) loads one of the hopper barges (16) (H1) sailing alongside the TSD maintaining a 2-meter athwartship distance, in real-time through loading arm no. 1 while another hopper barge (H2) positions itself on the opposite side of the TSD, such that it is in a ready-to-load condition at a pre-determined duration, before the completion of loading of the first hopper barge (H1).
Further, in accordance with the embodiments illustrated in Figures 3 and 4, another aspect of the invention pertains to the continuous dredging system involving TSD and multiple hopper barges (TSD+H). The primary embodiments of said hopper barge comprise of:
• electrical propulsion system, comprising two azimuth stern drives (9) and bow thrusters (10),

• a funnel shaped drainage system along the length of the hopper (12),

• adjustable water overflow system to minimize water turbidity (13),

• a drain channel (14), to release dredged material into the hopper (H).

Said electrical propulsion system comprises two azimuth stern drives (9) and bow thrusters (10). Said components provide the barges with exceptional maneuverability.
Said funnel shaped drainage system (12) directs the dredged material towards the centre of the hopper barge (H), ensuring uniform distribution of dredged material inside said SPHB.
Said water flow system (13) maximizes the hopper loading capacity and facilitates drainage of water.
Said drain channel (14) extends nearly the entire length of the hopper and features drop flaps controlled individually by pneumatic or hydraulic pistons to release dredged material into the hopper.
Referring to Figure 3, the TSD+H fleet is equipped with said electrically powered retractable azimuth stern drives and bow thrusters. Said components provide the TSD+H fleet with high manoeuvrability, enabling parallel sailing and efficient dredging even in cross current conditions. Furthermore, in order to maintain the visibility of the TSD (15) and hopper barge (16) is not impacted by the spray of the dredging material, the accommodation unit of TSD+H is positioned in the forward part of the vessel (15).
In few embodiments of the present invention, said TSD+H system may possess a swell compensator system to allow TSD+H to undertake dredging operations during adverse swell conditions and also when trailing the draghead over uneven seabed. Moreover, to prevent contact damage to the vessels, said draghead (3) and dredging pipe (2) are provided with rubber cushion pads. Further, the hull plates in the area susceptible to contact from the dredging tube (2) couplings and draghead (3) may be reinforced using heavier section structural components and hull plates.
In yet another embodiment, the TSD is also adequately powered to handle 2-barge hip-tow mechanism.
WORKING OF INVENTION
The present invention discloses a continuous dredging system which aims to de-link the dredging activity performed by the trailing suction dredger (TSD) (15) from the transportation and disposal activities carried out by the hopper barges (H). Said objective is achieved by utilizing a fleet comprising of Trailing suction dredger (TSD) and multiple self-propelled hopper barges (16) (H) (hereafter referred to as TSD+H).
Referring to Figures 1 – 4 of the present invention, the working of trailing suction dredger with hopper barges, is described as under:
The seabed is dislodged with the help of the draghead (3) equipped with a high-pressure jet water system, using the combined action of the cutting forces of the draghead (3) and said jet water system. Thereafter, the dredged material is sucked in by the dredge pump (6) and is directed towards one of the loading arms (7) situated on either side of the TSD with the help of the dredge pipe (2).
Said loading arms (7) are retractable and are swung out and placed over the empty hopper barges to transfer the dredged material. Said loading arms are retracted inside the line of TSD hull using hydraulic cylinders to keep the height of said loading arms (7) manageable.
From the loading arms (7), the dredged material is transferred into the self-propelled hopper barges (SPHB) secured alongside the TSD using mooring ropes.
The dredged material is emptied on to the hopper barge funnel (12) from the loading arms (7). The sloping shape of the funnel (12) directs the material to flow towards the centre of the hopper barge. Thereafter, the dredged material flows into the drain channel (14) which directs the dredged material along the entire length of the hopper by means of suitably placed openings which are opened or closed by means of drop flaps, to load the hopper hold evenly irrespective of the type of material being dredged.
Said drop flaps need to be operated carefully to ensure even loading of the hopper barge while receiving coarse dredge material such as sand as sand tends to settle very fast close to the area that they have been dropped at, unlike silt which tends to spread out evenly throughout the length and width of the hopper due to its slow settling time.
To ensure that the self-propelling hopper barges (SPHB) remain alongside safely during the loading process, they are secured alongside the TSD using mooring ropes. Further, suitably placed pneumatic fenders (11) of sufficient diameter and energy absorption capacity are secured on both side of the TSD to prevent any contact damage to the barge or the TSD. The placement of the mooring rope drums and bits are configured in such a way so as to facilitate quick and safe mooring and unmooring operations. The barges once fully loaded are casted off and loading will commence in the next empty barge which is already made fast alongside the TSD, through another loading arm (7) on the other side of the vessel.
Barge loading process:
For the process of loading of the hopper barges, barge no. 1 (H1) sails alongside the TSD, maintaining a 2 meters athwartship distance while the TSD dredges and loads said H1 in real-time, through loading arm no. 1. Just as the loading barge no. 1 is near completion, barge no. 2 (H2) proceeds to position itself on the other side of the TSD. The empty barge H2 is in ready-to-load condition atleast 5 minutes prior to completion of loading of the barge no.1.
The presence of draft-load sensors and flowmeter in the loading barges, send signals when the maximum capacity of the hopper is reached. Once H1 is fully loaded and the TSD operator receives the signals, he switches the discharge over to the loading arm no. 2 and commences loading of said H2. Simultaneously, H1 detaches from the TSD to proceed for disposal of dredged material. The loading process for the second hopper barge (H2) starts while simultaneously positioning a third hopper barge (H3) for subsequent loading.
TEST DATA OF THE INVENTION
A comparative analysis of the annual production of the proposed TSD+H with the conventional 8000 Beagle Trailing Suction Hopper Dredger using the same IHC supplied dredge pump has been demonstrated. For sake of simplification and comparison, the production figures have been compared assuming the same underwater pump, soil properties, dredging depths, dredging location and sailing distance to the dumping ground area.
The productivity calculation has been made for two types of soils, i.e. silt sand and coarse sand, the properties of which are as follows:
1. Silt, easily dredge-able:
- yield stress 20 N/m2
- dynamic viscosity 0.02 Ns/m2
- dredged density 1250 kg/m3
2. silt contains no gas Coarse sand (free running) with a grain size distribution of:
- d 10% on sieve 0.961 mm
- d 50% on sieve 0.372 mm
- d 90% on sieve 0.211 mm
- silt content 0 %
- density in situ 2000 kg/m3 (pores filled with water).
Dredging Parameters:
o Dredging Depth: 25 meters
o Dredging Location: Inner Channel Segment of Dhamra Port
o Dredging Equipment: TSHD (Trailing Suction Hopper Dredger) and TSD+H (Trailing Suction Dredger + Hopper Barge)
o Dredging Mode: Single and Double Pipe Operations for TSHD, Single Pipe for TSD+H
o Dredging Efficiency: 90% (accounting for human induced inefficiencies.)
Operational Parameters:
o Dumping Ground Distance: 13.2 Nautical Miles
o Sailing Speed: 10 knots for TSD+H, 9 knots for Hopper Barges
o Hopper Capacity of TSHD: 8000 cubic meters
o Hopper capacity of TSD+H: 4000 cubic meters
o Operational Days: 310 days per year (365 days - 55 days for repairs and maintenance and other activities such as fueling, survey and inspections.)
o Operational hours: 310*24 = 7440 hours
Production Calculation:
o Theoretical Production: Based on the dredging pump's output into the hopper.
o Actual Production: Adjusted for operational efficiency and cycle time.
o Cycle Time: Calculated based on sailing distance, speed, and loading/unloading time.
o Number of Trips: Determined by operational days and cycle time.
It is to be understood that the production of TSHD is based on the output of the dredging pump being discharged into the hopper.
Case 1: 8000 M3 TSHD single pipe operation
• Productivity in silt: At a depth of 25m, the productivity in silt was 8088 m3/hour. Overflow of the dredger was adjusted at maximum level since silt doesn’t settle easily.

Further, the loading time for 8000 m3 of silt was calculated as follows:
(hopper capacity/ productivity in silt) 8000/8088 = 0.99 hour.
The total cycle time for round trip including dredging and dumping of dredged material was calculated to be 3.76 hours.
Number of trips in 310 days = (310 x 24)/3.76 = 1,979 trips (total operational hours/total cycle time)
Productivity in silt in 310 days = 1979 x 8000 x 0.9 = 14,248,800 m3. (number of trips x hopper capacity x dredging efficiency)
• Productivity in coarse sand: Depth was of 25m, and hopper capacity was 8000 m3. Overflow of the barge was adjusted at 6200m3 level. Thus, for a hopper load of 12400 tons, this results in 6200 m3 of sand, considering that the density of coarse sand is 2000 Kg/m3.

Further, the loading time for 6200 m3 of coarse sand is calculated to be approximately 2.08 hours. Said loading time is based on mean mixture density of 1350 Kg/m3 and about 1% average overflow losses.
The total cycle time for round trip including dredging and dumping of dredged material was calculated to be 4.85 hours.
Number of trips in 310 days = (310 x 24)/4.85 = 1534 trips (total operational hours/total cycle time)
Productivity in coarse sand in 310 days = 1534 x 6200 x 0.9 = 8,559,720 m3. (number of trips x hopper capacity x dredging efficiency).
Case 2: 8000 M3 TSHD double pipe operation
• Productivity in silt: At a depth of 25m, the productivity in silt was 16176 m3/hour. Overflow of the dredger was adjusted at maximum level since silt doesn’t settle easily.

Further, the loading time for 8000 m3 of silt was calculated as follows:
(hopper capacity/ productivity in silt) 8000/16176 = 0.5 hour.
The total cycle time for round trip including dredging and dumping of dredged material was calculated to be 3.26 hours.
Number of trips in 310 days = (310 x 24)/3.26 = 2278 trips (total operational hours/total cycle time)
Productivity in silt in 310 days = 2278 x 8000 x 0.9 = 16,406,738m3. (number of trips x hopper capacity x dredging efficiency).
• Productivity in coarse sand: Depth was set at 25m, and hopper capacity was 8000 m3. Overflow of the barge was adjusted at 6526m3 level. Thus, for a hopper load of 12400 tons, this results in 6200 m3 of sand and 326 m3 of water, considering that the density of coarse sand is 2000 Kg/m3.

Further, the loading time for 6200 m3 of coarse sand is calculated to be approximately 1.04 hours. Said loading time is based on mean mixture density of 1350 Kg/m3 and about 1% average overflow losses.
The total cycle time for round trip including dredging and dumping of dredged material was calculated to be 3.81 hours.
Number of trips in 310 days = (310 x 24)/3.81 = 1952 trips (total operational hours/total cycle time)
Productivity in coarse sand in 310 days = 1952 x 6200 x 0.9 = 10,896,377 m3. (number of trips x hopper capacity x dredging efficiency).
Case 3: TSD+H single pipe operation (according to the embodiments of the present invention)
• Productivity in silt: At a depth of 25m, the productivity in silt was 8088 m3/hour. Overflow of the dredger was adjusted at maximum level since silt doesn’t settle easily.

Further, the loading time for 4000 m3 of silt was calculated as follows:
(hopper capacity/ productivity in silt) 4000/8088 = 30 minutes.
Additionally, change-over time from one barge to the other barge is 1 min, hence total processing time to load one barge is: 30 + 1 = 31 minutes = 0.517 hours.
The need for total cycle time for round trip is eliminated as dredging and dumping activity of dredged material has been de-linked by utilization of separate vessels.
Hence, here we calculate the total number of barges (16) loaded in 310 days, which is calculated as:
(310 x 24)/0.517 = 14.390 barges (total operational hours/total time taken to fill one barge)
Productivity in silt in 310 days = 14.390 x 4000 x 0.9 = 51,804,000 m3. (number of barges loaded x hopper capacity x dredging efficiency).
• Productivity in coarse sand: Depth was set at 25m, and hopper capacity was 4000 m3. Overflow of the barge (16) was adjusted at 3263m3 level. Thus, for a hopper load of 6200 tons, this results in 2937 m3 of sand and 326 m3 of water, considering that the density of coarse sand is 2000 Kg/m3.

Further, the loading time for 2937 m3 of coarse sand is calculated to be approximately 59 minutes. Said loading time is based on mean mixture density of 1350 Kg/m3 and about 1% average overflow losses.
Additionally, change-over time from one barge to the other barge is 1 min, hence total processing time to load one barge is: 59 + 1 = 60 minutes = 1 hour.
The need for total cycle time for round trip is eliminated as dredging and dumping activity of dredged material has been de-linked by utilization of separate vessels.
Hence, here we calculate the total number of barges loaded in 310 days, which is calculated as:
(310 x 24)/1 = 7440 barges (total operational hours/total time taken to fill one barge)
Productivity in silt in 310 days = 7440 x 2937 x 0.9 = 19,166,150 m3. (number of barges loaded x hopper capacity x dredging efficiency).

A comparative table showing the productivity in silt achieved by the dredgers in the afore-mentioned cases is as under:
Table 1: Comparison in productivity of silt achievable in different cases
Case 1 Case 2 Case 3
Activities 8000 M3 TSHD single pipe operation 8000 M3 TSHD double pipe operation TSD+H single pipe operation

Hopper capacity 8000 m3 8000 m3 4000 m3
Hopper loading time 0.99 hour 0.5 hour 0.517 hour
Cycle time/ barges loaded 3.76 hours 3.26 hours 14,390 barges loaded
Hourly production of 80 mm dia underwater pump 8088 m3 16176 m3 8088 m3
Monthly production 1,187,400 m3 1,367,228 m3 4,317,000 m3
Annual production (310 days) 14,248,800 m3 16406,738 m3 51,804,000 m3

A comparative table showing the productivity in coarse sand achieved by the dredgers in the afore-mentioned cases is as under:

Table 2: comparison in productivity of coarse silt achievable in different cases
Case 1 Case 2 Case 3
Activities 8000 M3 TSHD single pipe operation 8000 M3 TSHD double pipe operation TSD+H single pipe operation

Hopper capacity 8000 m3 8000 m3 4000 m3
Hopper loading time 2.08 hour 1.04 hours 1 hour
Cycle time/ barges loaded 4.85 hours 3.81 hours 7440 barges loaded
Hourly production of 80 mm dia underwater pump 4000 m3 8000 m3 8088 m3
Set barge overflow 6200 m3 6256 m3 (6200 m3 sand) 3263 m3 (2937 m3 sand)
Monthly production 713,310 m3 908,031 m3 1,597,179 m3
Annual production (310 days) 8,559,720 m3 10,896,377 m3 19,166, 150 m3

The afore-mentioned test data indicates that the TSD+H single-pipe operation excels in terms of barge loading time and annual loading capacity due to its minimized downtime. Additionally, this configuration consistently achieves peak monthly and annual production for both silt and coarse sand, demonstrating a substantial improvement in dredging productivity.
The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

ADVANTAGES OF THE PRESENT INVENTION
The present invention of trailing suction dredger with hoppers barges has the following advantages:
• increases annual productivity.
• with two independent dredging pipe systems with 100% capacity.
• maximizes the production time.
• allows continuous dredging activity with minimum downtime.
• eliminates the transportation and dredge disposal time during production cycle.
• enables parallel attachment of two hopper barges onto each side of the dredger.
• adapted with a dual loading arm mechanism that enables immediate loading of one hopper barge after another in real-time.
• increases the number of independent dumb hopper barges required for completing the dredging operations.
• eliminates the problem of choking of the draghead.
• reduces the repair & maintenance complexities of TSD’s through simplified design and layout of the dredging equipment and pipelines.
• requires lower manning scales and number of personnel required to operate the TSD and Hopper barges.
• can operate in shallow as well as deep waters.
• which does not involve coupling-decoupling of the hopper barges with the dredger.
• can operate in waterbodies with or without currents.
,CLAIMS:We Claim
1. A trailing suction dredger with hopper barges (TSD+H); wherein
- said TSD (15) vessel configured to dredge the seabed, comprises
an electrical propulsion system consisting of stern drives (9) and bow thrusters (10) to support the propulsion of the TSD vessel, a moonpool (1) centrally located along the midship section of the TSD vessel (15), a dredging pipe system (2) configured to the loading arms at the point of connection to the hull, two retractable loading arms (7) operably mounted at each side of the TSD vessel (15), gantries (8) integrated with the dredging pipe system (2) and actuated by hydraulic or electric winches, to deploy said dredging pipe (2) through said moonpool (1) into the water, and plurality of pneumatic fenders (11) on either sides of the TSD vessel (15) to eliminate the chances of accidental contact damage to the TSD (15) or the hopper barges (H);
characterized in that, said dredging pipe system (2) comprises two independent dredging pipes (2) each equipped with a suction draghead (3) on the bottom end, a suction bend (4) present on the opposite end of the dredging pipe (2) connecting the draghead (3) to the suction inlet (5) located in the TSD hull, and an underwater or an inboard dredge pump (6) connected to the dredging pipe;
wherein, the dredging pipe (2) bifurcates into two parallel branches at the point of connection to the hull, ultimately leading to the loading arms (7); and dual retractable loading arms (7) capable of being swung out and retracted within the TSD’s hull line using hydraulic cylinders, enabling sequential loading of plurality of hopper barges (16) in real-time by loading one of the hopper barge (H1) through loading arm no. 1 and simultaneously, positioning another hopper barge (H2) on the opposite side of the TSD in ready-to-load condition at a predetermined duration before the completion of loading of the one of the hopper barge (H1);
- said plurality of self-propelled hopper barges (H) (16) operating parallel to the TSD vessel (15), comprises
an electrical propulsion system, comprising azimuth stern drives and bow thrusters, a funnel-shaped drainage system (12) along the hopper's length to direct dredged material towards the centre of the hopper (16), an adjustable water overflow system (13) to maximize loading capacity, and facilitate water drainage, and a drain channel (14) with individually controlled drop flaps to release dredged material into the hopper and facilitate symmetric loading of the barge.

2. The trailing suction dredger as claimed in claim 1, wherein said suction draghead (3) is affixed to the bottom end of the dredging pipe (2) and is equipped with jet water system for seabed excavation.

3. The trailing suction dredger as claimed in claim 1, wherein one branch of the loading arm (7) is closed using a valve, and other remains open to allow utilization of only one loading arm (7) at a time for material transfer to the hopper barge (H) (16) for continuous dredging process during operation.

4. The trailing suction dredger as claimed in claim 1, wherein said moonpool (1) is closed at both ends and comprises a length that surpasses the length of the TSD (15) midship section and a width exceeding the dimensions of the draghead (3) by two for safe deployment of the dredging tubes (2) and the dragheads (3) into the water.

Dated this 15th day of March, 2025

_____________________
(Ms.) GOPI JATIN TRIVEDI
IN/PA- 993
Authorized agent of the applicant
To,
The Controller of Patent
The Patent Office,
At Mumbai.