Semi-submersible marine vehicle useful in bad weather, which operates remotely

Abstract

The present invention relates to semi-submersible vehicle useful in bad weather operation comprising: 1- Two buoyant tubes (2) with equipment for balancing ballast water and moving the vessel, including electronic equipment; 2 - Two solid ballast tubes (3), which are the heavy keel of the vehicle attached to each one of the hull (2), 3 - Horizontal and vertical interconnecting struts (5); 4 - Two payload capsules (1) which are detachable; 5 - Upper deck (6) including (A) navigation lights, (B) sensors, (C) floaters, (D) tanks vent heads and (E) engine intake and exhaust ports; and 6 - Small water plane area upper structure (4), linking the deck (6), buoyant tubes (2), transfer intake, exhaust (4A), and vent lines, as well as power and data lines.

Description

SEMI-SUBMERSIBLE MARINE VEHICLE USEFUL IN BAD WEATHER, WHICH OPERATES REMOTELYCross-Reference to Related Applications

[0001] This application claims priority to U.S. Provisional Application No.63 / 509,255, entitled ‘SEMI-SUBMERSIBLE VEHICLE FOR BAD WEATHER OPERATION,” filed on June 20, 2023.FIELD OF THE INVENTION

[0002] The present invention relates to a semi-submersible marine vehicle, and more particularly to the ROV (Remotely operated vehicle) and survey remote operations in severe weather conditions.BACKGROUND OF THE INVENTION

[0003] The invention relates to an improvement in the field of semi-submersible marine vehicles. In particular, it relates to remotely operated vehicle, which combines both SWATH and heavy keel configurations. This gives the vehicle the capability of superior stability during subsea vehicle deployment and recovery in relatively high sea states and besides the operability and survivability in bad weather conditions and in high waves even though its small size.

[0004] The current solutions for subsea operations require a survey vessel, which is usually a dynamically positioned vessel. The cost of such operations becomes even more expensive when considering the downtime due to bad weather. Vessels usually have conventional hulls or catamarans, for which the operating sea state is limited to their length. So, if the operation weather window is to be increased, larger vessels are needed. Another plausible solution would be to consider other types of vessels with special designs.

[0005] A heavy keel increases the righting lever arm of the vessel. When properly utilized, it makes the vessel immune for capsizing. Although they have a very high righting arm, heavy keel vessels are not suitable for rough seaoperations, because of the existence of the main buoyancy element (hull) above the waterline.

[0006] SWATH hulls have been developed for operation in high waves with superior stability. This is achieved by making the main buoyancy element always submerged (buoyant tubes), and connected to the superstructure via struts. The height of a strut is typically a trade-off between the height of the incident waves and the allowed draft. However, struts are usually made of heavy construction to withstand the induced loads from the superstructure, relative hull motion, and wave loads. For that reason, it cannot be too high, and the cross-sectional area of the strut would not be small enough to eliminate the effect of the induced displacement due to waves. In addition, the maximum height of the strut is related to the vessel length. It cannot be too tall, as it severely decreases stability in rough seas.

[0007] FR2565195 relates to a semi-submersible marine craft for operation on the surface or in a semi-submerged condition.

[0008] WO2014003595 relates to marine transport, more specifically, to rescue vehicles equipped with positioning devices as well as with deep-sea active search.

[0009] None of the above prior art documents disclosed the vehicle of the present invention with its distinctive features by combining the heavy keel configuration with an ultra-small water plane area design. This enhances the stability of too-long struts. In addition, by optimizing the induced loads in the superstructure, thinner struts are used.

[0010] In a specific embodiment, the invention provides a semi-submersible unmanned vehicle that is remotely or autonomously operated and utilizes dynamic positioning. The novel semi-submersible vehicle is capable of operating in very challenging weather conditions due to its size, by compromising the ultra-small water plane area of the struts and heavy keel concept with a precise ballast system for draft control. The maximum survivable wave height is governed by parametersrelated to the minimum GZ intact stability margins, the height, and Tons per Centimeter immersion (TPc) of the small water plane area struts, which have a direct effect on the cutoff frequency of the Response Amplitude Operator (RAO). The RAO relates the vehicle response amplitude to the wave height and frequency bands. In addition to the foregoing, the objectives of the present invention are addressed by the provision of systems such as dynamic positioning, automatic ballast, and vertical heave thrusters.SUMMARY OF THE INVENTION

[0011] The present invention relates to a vehicle intended to be used for offshore survey and operations involving launch and recovery of the ROV (Remotely operated vehicle) comprising:-Two buoyant tubes (2); two solid ballast tubes (3); interconnecting horizontal and vertical struts (5); two payload capsules (1); a small water plane area upper structure (4); and a light upper deck (6). Wherein the vehicle can be disassembled and transported in standard containers; wherein the two buoyant tubes (2) provide substantially all of the buoyancy in the vehicle and contain the majority of the components. The two solid ballast tubes (3) are the heavy keel of the vehicle, which are filled with the required solid ballast and may contain other heavy components such as batteries.

[0012] The interconnecting struts (5) are designed to replace the deck in common twin-hull vessels. The deck (6) is low in weight. It provides suitable reserved buoyancy by means of the lightweight buoyancy device. It is maintained above the waterline and connected to the buoyant tubes by an ultra-small water plane area structure. This structure links the deck (6) and buoyant tubes (2) and transfers intake, exhaust, and vent lines, as well as power and data lines. The two payload capsules (1) are detachable, so that a suitable capsule is installeddepending on the targeted mission. Each capsule (1) is balanced prior to installation on the vehicle to not affect the overall stability. Capsules (1) have one or more watertight compartments for payload components. Most of the capsule is flooded, where underwater equipment such as ROVs (Remotely operated vehicles) and LARS systems are installed.

[0013] The vehicle of the present invention has four azimuth thrusters (11), which fulfill dynamic position requirements. There are also four tunnel thrusters (18), with vectored thrust in the heave direction, used to stabilize the vehicle in high waves to smooth the ROV (Remotely operated vehicle) launch and recovery. Those thrusters (18) utilize hub-less propeller configuration, which is further extended to counter-rotating configuration for size compactness with higher thrust. The contrarotating propellers have radial gear and are driven using a conventional motor connected to a gearbox. This thruster configuration is better than rim-driven thrusters (18) in aspects such as thrust to diameter and thrust to weight ratio. In addition, there are four ballast tanks (7,8) with a dedicated pump and control valves for each.

[0014] The vehicle of the present invention uses a hybrid power feature to extend its endurance over a month. This is achieved by means of the hybrid operation between generators and battery banks as well as utilizing the return break power through the Active Front End on the DC bus. The vehicle of the present invention has full system redundancy for dynamic positioning functionality, including multiple signal channels and duplicated internal networks to ensure the availability of navigation and control data in any situation. The vehicle of the present invention is equipped with various wireless communication technologies, including satellite internet, that offer worldwide coverage. Advanced motion sensors are installed on the vehicle, such as two inertial navigation systems (INS), two gyrocompasses, two wind sensors, and speed sensors that provide STW andSOG data. In addition, position reference systems are installed, such as two DGPS, radar, a thermal PTZ camera, and LiDAR.

[0015] The vehicle of the present invention also has an emergency airbag system that automatically inflates and generates extra lift, preventing it from sinking and damaging subsea structures.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and related objects, features, and advantages of the present invention will be more fully understood by reference to the following, detailed description of the preferred, albeit illustrative, embodiment of the present invention when taken in conjunction with the accompanying figures, wherein:

[0017] FIG. 1 is an isometric view of the vehicle of the present invention;

[0018] FIG. 2 is a schematic showing the surface operating condition of the vehicle;

[0019] FIG. 3 is a schematic showing the submerged operating condition of the vehicle;

[0020] FIG. 4 is a side view of the vehicle;

[0021] FIG. 5 is a front view of the vehicle;

[0022] FIG. 6 is a side-section view of the buoyant tube;

[0023] FIG. 7 is a side-section view of the payload capsule;

[0024] FIG. 8a is a side-section view of the payload capsule with doors opened for ROV (Remotely operated vehicle) launching;

[0025] FIG. 8b is a side-section view of the payload capsule with the ROV (Remotely operated vehicle) deployed;

[0026] FIG. 9 is a schematic of the ballast system;

[0027] FIG. 10a is a schematic of the inflatable emergency buoyancy device;

[0028] FIG. 10b is a schematic showing the vehicle with an emergency buoyancy device inflated;

[0029] FIG. 11 a is a top view of the contrarotating hub-less propeller thruster;

[0030] FIG. 11b is a cross sectional view of the contrarotating hub-less propeller DETAILED DESCRIPTION

[0031] The present invention relates to semi-submersible vehicle for bad weather operation comprising:

[0032] 1 - Two buoyant tubes (2), wherein each of the buoyant tube comprising:

[0033] Two-ballast water tank (AFT (7), FWD (8)), two thrusters (11) and two thruster mounting and motor spaces (13);

[0034] -A first room compartment for Electrical equipment (15) includes (A) control panels; (B) Thrusters motors drives; (D) Power management system components; (E) Fixed firefighting system; (F) HVAC (Heating, ventilation and air conditioning system;

[0035] -A second room compartment for generator (16) includes (A) Generator;(B) Pumps & various piping system; (c) Water chiller; (d) Fixed firefighting system; (E) Air intake fan; (F) Engine exhaust system, wherein one fuel tank (17) located below the first and second compartment (15, 16);

[0036] - AFT Door (9); FWD Rubber fender ( 10); AFT compartment ( 14) for remotely operated vehicle (ROV) docking & doors mechanism including hydraulic system components space (12);

[0037] 2-Two solid ballast tubes (3), which are the heavy keel of the vehicle attached to each one of the buoyant tubes (2), and they are filled with the required solid ballast, and contain other heavy components such as batteries;

[0038] 3 -Horizontal and vertical interconnecting struts (5) which strengthen the vehicle structure and provide bypass and connections between the buoyant tubes (2) and ballast tubes (3);

[0039] 4-Two payload capsules (1) which are detachable so that suitable capsule is installed depending on the targeted mission;

[0040] 5 -Upper deck (6) includes (A) Navigation lights used to determine the direction and path during navigation; (B) Sensors; (C) Floaters (D) Tanks vent heads which are the ventilators of tanks for air entrance and emission during tanks filling and discharge (E) Engine intake and exhaust ports; and

[0041] 6 -Small water plane area upper structure (4), the said structure links the deck (6), buoyant tubes (2), transfer intake, exhaust (4A), and vent lines, as well as power and data lines.

[0042] -The below illustrated drawing shows all the components of the vehicle of the present invention:

[0043] The components of the upper deck shown as below:

[0044] (A) Navigation lights;

[0045] (B) Different sensors;

[0046] (C) Floaters;

[0047] (D) Tanks vent heads; and

[0048] (E) Engine intake and exhaust ports

[0049] There are many sensors (B) used in the system of the vehicle of the present invention as shown below:

[0050] 1-Wind station sensor to measure the wind current, wind speed, Air temperature and humidity;

[0051] 2-Gyro Compass sensor to measure the magnetic heading and absolute heading of the vehicle;

[0052] 3 -Differential GPS to measure the position, velocity and heading of the vehicle;

[0053] 4-Draft Sensor to measure the distance from water surface;

[0054] 5-INS which measures the position, velocity, attitude and heading of the vehicle of the present invention;

[0055] 6-Radar which scans the surrounding area and detect targets and vehicles in log range;

[0056] 7-Guidance Camera used for vehicle motion planning;

[0057] 8-Starlink used for satellite internet communication;

[0058] 9- WIFI used for communication with the onshore station;

[0059] 10-VHF used for communication with ports and stations;

[0060] 11 -Thermal Cameras used for target detection and area scanning;

[0061] 12-AIS used for communication with nearby vehicles and navigation;

[0062] 13 -Lidar which scans the surrounding area and detect targets and vehicles in short range; and

[0063] 14-Radar Reflector used for reflecting radar signals to represent vehicle position.

[0064] Referring to the figures of the present invention, FIG. 1 shows the invented vehicle. It is a twin hull semisubmersible with a heavy keel attached to each hull.

[0065] FIGS. 2 and 3 show the two main modes of operations. The surface mode at which the buoyant tubes (2) are partially submerged is for refueling or operating at low draft in shallow waters. The submerged mode in FIG.3 where the mean water line is usually at the middle of the struts height, is the optimum for operating in high waves. The induced displacement due to wave motion on the ultra-thin struts is very small.

[0066] FIGS. 4 and 5 illustrate the components of the vehicle, which are:

[0067] Two buoyant tubes (2) generating the required buoyancy of the vehicle. Each buoyant tube (1) has two compartments (15, 16) containing vehicle systems, one fuel tank (17), two ballast tanks (7, 8), and two azimuth thrusters (11).

[0068] Horizontal and vertical interconnecting struts (5), which strengthen the vehicle structure and provide bypass and connections between the buoyant tubes (2) and ballast tubes (3).

[0069] They replace the deck structure with conventional twin hulls. The two fuel tanks (17) are connected using a bypass fuel line that is routed through the struts (5), as well as communication and electrical connections.

[0070] However, fuel lines are kept away from electrical connections as per marine rule instructions.

[0071] Solid ballast tubes (3) comprising solid ballast that balances the vehicle and prevents it from capsizing, and the vertical hub-less contrarotating thrusters (18). The vertical heave thrusters are used to damp the vehicle response motion to the incident waves, which helps to smooth the underwater equipment launch and recovery in high waves.

[0072] Upper struts (4) that connect the deck (6) to the buoyant tubes (2). It has a veiy small water plane area (4) that guarantees minimal motion excitation due to waves. The struts (4) are long enough to allow for the vehicle’s operation in the designed high- wave conditions.

[0073] This strut configuration is possible due to the lightweight deck (6), which exerts smaller forces and moments compared to regular deck contractions. The struts (4) also provide routing for intake and exhaust lines (4A) required for the contained equipment and engines inside the buoyant tubes (2).

[0074] In addition, vent lines for fuel and ballast tanks (7, 8) are routed on the upper strut (4) as well. Communication and power cables are routed inside ballast tank vents, which are also selected of submersible grade for the case if vents are flooded.

[0075] The deck (6) is simplified to consist of only an equipment mast and a lightweight buoyancy device. The buoyancy device provides more restoring force for survivability when the vehicle operates in higher waves.

[0076] In addition, it prevents the deck equipment from flooding in case of severe damage, so that emergency devices keep working. The deck equipmentincludes wireless telemetry, position references, controllers, and any other necessary equipment for the vehicle to utilize dynamic positioning thrusters.

[0077] FIG. 6 shows a section side view of the buoyant tube (2) comprising two equipment compartments (15, 16) separated by a fire tolerant bulkhead, two ballast tanks (7, 8), and one fuel tank (17).

[0078] FIG. 7 shows the payload capsule (1), which has one compartment (14) used to contain the door control system and other survey equipment. The rest of it is flooded by water. In the presented case, the payload capsule (1) is equipped with a mini-ROV system comprising: a submersible tether system, ROV, and LARS.

[0079] FIG. 8a shows the ROV (Remotely operated vehicle) being launched from the vehicle with aft doors (9) opened. While FIG. 8b shows the ROV (Remotely operated vehicle) during operation, where the aft doors (9) are closed to maintain smooth vehicle operation.

[0080] These figures are schematics of the payload capsule (1) equipped with ROV system. When the vehicle arrives at the working site, the vehicle holds its position in the submerged condition. The aft doors (9) of the pay load capsule (1) open using hydraulic actuators. Then a bar is extended at the top door. The ROV then flies out of the capsule (1) while the tether system is automatically feeding the required tether. Once the ROV reaches a certain depth away from the vehicle, the doors close, as shown in fig.8b. The ROV latching system works as a clump weight to prevent the tether from being sucked by the thrusters (11).

[0081] FIG. 9 shows the diagram of the ballast system circuit. The high precision of the ballast system is achieved by utilizing proportional control valves in conjunction with a pump reversing valve set. All valves have a fast actuation time (in milliseconds). In addition, the pump has variable speed, which allows for a wider operating range with the large, varying water head due to the wave motion over the long strut and the varying conditions between surface and submerged. Theballast system also compromises sophisticated control and filtering algorithms that utilize draft measurements, ballast water line pressure, and tank levels to maintain the trimming and draft conditions at optimum points for the sea state. In addition to maintaining the trimming condition and varying the draft, the ballast system automatically compensates for fuel consumption.

[0082] FIG. 10a shows the inflatable emergency buoyancy device comprising an inflatable airbag system, which is fed from onboard standby air cylinders. The actuation element allows air to fill the airbags when severe damage in the hull is detected. The decision is taken via onboard computer, depending on the severity of the damage, which is indicated by the number of flooded compartments.

[0083] FIG- 10b shows a schematic of the damaged vehicle when the emergency buoyancy is activated. The buoyancy device is stored inside a streamlined sacrificial shell or inside a flooded recess in the hull.

[0084] FIG. 1 la shows a contrarotating hub-less propeller thruster (18) comprising a motor, contrarotating hub-less propellers, as shown in FIG. 11b, and a gearbox.

[0085] Furthermore, the vehicle of the present invention has distinctive features in bad weather, wherein the mode of operation for both normal weather and bad weather will reflect on the equipment behavior described as below:

[0086] The vehicle of the present invention has an advanced autopilot system that allows various autonomous control functionalities such as dynamic positioning, following underwater vehicles, automatic trim and draft control, and hovering, at which the sophisticated automatic ballast and heave thrusters dampen the vehicle’s heave, roll, and pitch motions to smooth ROV deployment and recovery.

[0087] The vehicle is also equipped with state-of-the-art sensors, navigation systems, and Al for automatic collision avoidance and optimum path planning.

[0088] It is worth mentioning that the vehicle of the present invention has three working modes (remote control, semi-autonomous, fully autonomous). All these modes are designed to be performed with no need for a mother vessel while being monitored by the onshore Remote Operation Center (ROC). ROC provides remote survey, inspection, and piloting from onshore, enabling real-time execution, monitoring, and data delivery.

[0089] Moreover, the vehicle of the present invention has full system redundancy for dynamic positioning functionality, including multiple signal channels and duplicated internal networks to ensure the availability of navigation and control data in any situation. The vehicle is equipped with various wireless communication technologies, including satellite internet, that offer worldwide coverage. Motion sensors include two or more inertial navigation systems (INS) that provide roll, pitch, heading, position, and velocity data; two or more gyro- compasses that provide heading; two or more wind sensors that provide wind speed and direction; and one or more speed sensors that provide STW and SOG data. The position reference system includes two or more DGPS for accurate positioning, radar, a thermal PTZ camera, and LiDAR, which increases the level of situational awareness even in difficult conditions such as night operations of fog.

[0090] The vehicle of the present invention has a distinctive feature to sense the normal and bad weather as described below:

[0091] The apparent weather condition is real-time monitored by the onboard wind sensors and draft sensors. Wind speed is measured using the wind sensors on board. While wave height is estimated using a sophisticated sensor fusion algorithm that utilizes the readings of the draft pressure sensors, ultrasonic sensors (installed on the deck), and motion reference units, the weather condition is then categorized accordingly.

[0092] - Moreover, the vehicle of the present invention has a monitoring team and the role of its monitoring team on shore is described as below:

[0093] The ROC team, which consists of a captain, surveyor, ROV pilot, inspection team, and report coordinators, has the capability to perform the following from the base:

[0094] - Monitor and control the vehicle of the present invention;

[0095] - Ensure that the vehicle is following the field regulations and safety roles;

[0096] - Communicate with the surrounding platforms and vessels;

[0097] - Launch and recover the subsea inspection vehicles; and

[0098] - Control the subsea vehicles to perform the required inspection mission.

[0099] It is worth mentioning that the vehicle of the present invention has solved the problem of those disclosed in the prior art because the vehicle solution of the present invention is unique as the current vehicle is a semi-submersible vehicle comprising both SWATH and heavy keel configurations. This gives it the capability of superior stability during subsea vehicle deployment and recovery in relatively high-sea states. In addition to its operability and survivability in adverse bad weather conditions (high waves), even though its small size.

[0100] The vehicle also has too long struts (4) that connect the deck (6) to the buoyant tubes (2) (hulls). The struts (4) also function as a snorkel, providing the required atmosphere for engines and tank vents and discharges the exhaust.

[0101] Furthermore, the vehicle has unique systems such as:

[0102] - An automatic precise ballast system that is capable of maintaining an accurate draft during operation.

[0103] - Vertical thrusters (18) which are used to maintain smooth subsea vehicle deployment and recovery in challenging weather conditions and thevertical thrusters (18) are hub-less and contrarotating propellers, which eliminate the risk of being tangled due to the suction of fishnets, robes, etc.

[0104] - An emergency inflatable device that automatically inflates in case of severe damage. It prevents the vehicle from sinking and causing damage to subsea structures and pipelines.

[0105] - Detachable payload capsule (1) that is custom-built depending on the pay load specifications. There are two capsules (1) that could be equipped with different payloads, i.e., 2x ROVs in the same mission. This extends the level of redundancy to the survey and inspection tasks; where another ROV is always standby in case of failure in the other.

[0106] The below is a summary of ROV operations when they are transported by vehicle to a location:

[0107] ROVs are commonly used for a variety of operations, such as underwater inspection, maintenance, repair, and scientific research. There are no limitations on the transported ROV capabilities. During ROV operations, the ROV is deployed from the payload capsule in the vehicle using a suitable mechanism. A tether provides power and communication to the ROV in case it is remotely operated. The operator controls various tools and sensors attached to the ROV, such as manipulator arms, sonars, and sampling devices.

[0108] The vehicle of the present invention has the following autonomous control functionalities:

[0109] 1- Autopilot and DP functions;This compromises any combination of the following:• Speed hold;• Heading hold;• Position hold;• Follow- way points;• Loiter (to move in an orbital path with a predefined center and radius);

[0110] 2- Follow underwater vehicles;

[0111] In this mode, the vehicle follows the deployed underwater vehicle using its position, and velocity reference from the USBL.

[0112] 3. Load case transition

[0113] In this mode, the vehicle changes its draft and trimming condition automatically• Auto trim• Draft control

[0114] 4. Hover functionIn this mode, and using sophisticated automatic ballast and heave thrusters, the vehicle damps heave, roll, and pitch motions to smooth vehicle deployment and recovery.

[0115] 5. Other autonomous functions• Collision avoidance• Optimum path planning

[0116] Numerical references of the invention:- Payload capsule ( 1 )- Buoyant tube (2)- Solid ballast tube (3)- Small water plane area upper structure (4)- Exhaust and intake (4A)- Struts (5)- Upper deck (6)- (AFT) Ballast water tank (7)- (FWD) Ballast water tank (8)- (AFT) Doors (9)- (FWD) Rubber fender (10)- Thruster (11)- Hydraulic system components space (12)- Thruster mounting & motor space (13)- AFT compartment (14)- Electrical Equipment (Room / compartment) (15)- Generator (Room / compartment) (16)- Fuel Tank (17)- Vertical thrusters (18)

Claims

CLAIMS:1- A semi-submersible vehicle, which is useful in bad weather operation comprising:- Two buoyant tubes (2);-Two solid ballast tubes (3), which are the heavy keel of the vehicle attached to each one of the buoyant tubes (2) which are filled with the required solid ballast and contain other heavy components such as batteries;-Horizontal and vertical interconnecting struts (5) which strengthen the vehicle structure and provide bypass and connections between the buoyant tubes (2) and ballast tubes (3);-Two pay load capsules (1) which are detachable so that suitable capsule is installed depending on the targeted mission;-Upper deck (6) includes (A) Navigation lights used to determine the direction and pass during navigation; (B) Sensors; (C) Floaters (D) Tanks vent heads which are the ventilators of tanks for air entrance and emission during tanks filling and discharge (E) Engine intake and exhaust ports; and-Ultra-Small water plane area upper structure (4), the said structure links the deck (6), buoyant tubes (2), transfer intake, exhaust (4A), and vent lines, as well as power and data lines;Characterized in that:-It senses the normal and bad weather with high efficiency, wherein the apparent weather condition is real-time monitored by the onboard wind sensors and draft sensors, wherein wind speed is measured using the wind sensors on board. While wave height is estimated using a sophisticated sensor fusion algorithm that utilizes the readings of the draft pressure sensors, ultrasonic sensors (installed on the deck), and motion reference units, the weather condition is then categorized accordingly;- It contains both SWATH and heavy keel configurations which gives it the capability of superior stability during subsea vehicle deployment and recovery in relatively high-sea states and its operability and survivability in adverse bad weather conditions (high waves), even though its small size;- It has an automatic precise ballast system that is capable of maintaining an accurate draft during operation.2- The semi-submersible vehicle according to claim 1, wherein each of the buoyant tubes comprising:- Two ballast water tanks (AFT (7), FWD (8)), two thrusters (11) and two thrusters mounting and motor spaces (13);-A first room compartment for Electrical equipment (15) includes (A) control panels; (B) Thrusters motor drives; (D) Power management system components;(E) Fixed firefighting system; (F) HVAC (Heating, ventilation and air conditioning system;-A second room compartment for generator (16) includes (A) Generator; (B) Pumps & various piping system; (c) Water chiller; (d) Fixed firefighting system;(E) Air intake fan; (F) Engine exhaust system, wherein one fuel tank (17) located below the first and second compartments (15, 16);- AFT Door (9); FWD Rubber fender (10); AFT compartment (14) for remotely operated vehicle (ROV) docking & doors mechanism including hydraulic system components space (12);3- The semi-submersible vehicle according to claim 1, wherein the vehicle has payload capsules (1), each capsule is balanced prior to installation on the vehicle to not affect the overall stability and the said capsules (1) have one or more watertight compartments for payload components.4- The semi-submersible vehicle according to claim 1 , wherein the vehicle has four azimuth thrusters (11), which fulfill dynamic positioning requirements5- The semi-submersible vehicle according to claim 1, wherein the vehicle has four tunnel thrusters (18) with vectored thrust in the heave direction used to stabilize the vehicle in high waves to smooth the ROV (Remotely operated vehicle) launch and recovery.6- The semi-submersible vehicle according to claim 5, wherein the vertical heave thrusters (18) utilize hub-less propeller configuration, which is further extended to contrarotating configuration for size compactness with higher thrust, wherein the contrarotating propellers have radial gear and are driven using a motor or engine connected to a gearbox.7- The semi-submersible vehicle according to claim 1, wherein the vehicle uses a hybrid power feature to extend its endurance over a month by means of the hybrid operation between generators and battery banks as well as utilizing the return break power through the Active Front End on the DC bus, wherein the said vehicle has full system redundancy for dynamic positioning functionality, including multiple signal channels and duplicated internal networks to ensure the availability of navigation and control data in any situation.8- The semi-submersible vehicle according to claim 1, wherein the said vehicle also has an inflatable emergency buoyancy device comprising an inflatable airbag system that automatically inflates and generates extra lift, preventing it from sinking and damaging subsea structures.9- The semi-submersible vehicle according to claim 1, wherein the said vehicle has two main modes of operations:(A) The surface mode at which the buoyant tubes (1) are partially submerged is for refueling or operating at low draft in shallow waters; and(B) The submerged mode where the mean water line is usually at the middle of the upper structure height, which is the optimum for operating in high waves and theinduced displacement due to wave motion on the ultra-thin upper structure is very small.10- The semi-submersible vehicle according to claim 1, wherein the payload capsule (8) has one or more compartments (12) used to contain the door control system and other survey equipment, wherein the rest of it is flooded by water and the said payload capsule (8) is equipped with a mini-ROV system comprising: a submersible tether system, ROV, and LARS.11- The semi-submersible vehicle according to claim 1, wherein the vehicle is useful in bad weather, as the mode of operation for both normal weather and bad weather will reflect on the equipment behavior as below:-The vehicle has an advanced autopilot system that allows various autonomous control functionalities such as dynamic positioning, following underwater vehicles, automatic trim and draft control, and hovering, at which the sophisticated automatic ballast and heave thrusters dampen the vehicle’s heave, roll, and pitch motions to smooth ROV deployment and recovery;- The vehicle is also equipped with state-of-the-art sensors, navigation systems, and Al for automatic collision avoidance and optimum path planning;- The vehicle has three working modes (remote control, semi-autonomous, fully autonomous). All these modes are designed to be performed with no need for a mother vessel while being monitored by the onshore Remote Operation Center (ROC), wherein ROC provides remote survey, inspection, and piloting from onshore, enabling real-time execution, monitoring, and data delivery;- The vehicle has full system redundancy for dynamic positioning functionality, including multiple signal channels and duplicated internal networks to ensure the availability of navigation and control data in any situation.12- The semi-submersible vehicle according to claim 1, wherein the vehicle has one or more autonomous control functionalities as below:A- Autopilot and DP functions;• Speed hold;• Heading hold;• Position hold;• Follow- way points;• Loiter (to move in an orbital path with a predefined center and radius);B- Follow underwater vehicles; wherein in this mode, the vehicle follows the deployed underwater vehicle using its position, and velocity reference from the USBL;C- Load case transition, wherein in this mode, the vehicle changes its draft and trimming condition automatically:• Auto trim• Draft controlD- Hover function, wherein in this mode, and using sophisticated automatic ballast and heave thrusters, the vehicle damps heave, roll, and pitch motions to smooth vehicle deployment and recovery.E- Other autonomous functions• Collision avoidance• Optimum path planning13 - Methods of operating the semi-submersible vehicle according to claim 1 comprising:-The pay load capsule (1) which is equipped with ROV system and when the vehicle arrives at the working site, the vehicle holds its position in the submerged condition;-The aft doors (9) of the pay load capsule (1) open using hydraulic actuators; and a bar is extended at the top door;- The ROV then flies out of the capsule (1) while the tether system is automatically feeding the required tether. Once the ROV reaches a certain depth away from the vehicle, the doors close. The ROV latching system works as a clump weight to prevent the tether from being sucked by the thrusters (11).

Images