G.A. Ramadass

National Institute of Ocean Technology | NIOT · Deep Sea Technologies

Spherical pressure hull for manned submersible may experience extreme environmental conditions. Damage assessment of the spherical pressure hull subjected to an underwater explosion of a mine or a depth charge or a gas explosion in offshore industries is very much required. This study focuses on elastic and inelastic numerical analysis on the spher...

Deep-sea mining involves the extraction of valuable minerals from the ocean floor. The transportation of deep-sea mineral deposits from the seafloor to the surface is crucial for the success of deep-sea mining operations. The slurry pumping system is responsible for conveying a mixture of minerals, sediments, and water over significant distances. D...

The oceans comprise valuable resources that can be effectively utilized by mankind. Ocean consists with the mineral deposits such as sulphides, cobalt, and polymetallic nodules, presenting niche opportunities for extraction. India and other contemporary countries are working to explore these minerals with their innovation techniques. The current pa...

Deep-sea mining has emerged as an industry with the goal of extracting minerals from the ocean floor. To explore and extract mineral resources from the profound ocean depths, specialized vehicles designed for deep-sea mining operations are required. This research focuses on investigating the hydrodynamic characteristics of these vehicles, aiming to...

The current research article presents the experimental investigation to comprehend the critical suction height and the region influenced by flow around particles during the hydraulic collection of polymetallic nodules (PMNs). The present investigation employed a water jet-eductor driven suction pipe to collect PMNs from the deep sea bed. Rectangula...

The Bengal Fan, the largest submarine fan in the world, spanning the whole Bay of Bengal resulted from the India-Asia collision event and subsequent Himalayan orogeny. It is a significant depositional feature formed by the major river systems: the Ganges and Brahmaputra. Previous studies revealed the occurrence of an extensive channel-levee system...

Spherical shell plays an important role in deep-water submersibles. This work reports the analysis and testing of spherical shells with an inner diameter of 150 mm and a wall thickness of 1 mm. Five spherical shell models are manufactured and subjected to hyperbaric pressure. By using a bridge gauge and ultrasonic thickness gauge, imperfection and...

Ocean Electronics Group of National Institute of Ocean Technology (NIOT), Ministry of Earth Sciences (MoES) has customized a hexacopter heavy lift small category drone and initiated adapting Drone technology for Marine applications. The UIN number of NIOT drone is UA006SZS1EX. The group has recently (19th - 20th July 2023) carried out a series of d...

Scientists are using human occupied vehicles to explore underwater environments. There are several mechanical features used in the design of human occupied vehicles. These mechanical features are primarily based on environmental factors such as high external pressure, low temperature, and corrosion resistance. In this paper, human occupied vehicles...

A numerical and experimental investigation has been done to understand the critical suction height (h) and flow influenced area around the Polymetallic nodules (PMNs) for hydraulic collection of the PMNs. The experimental investigation was carried out by using an educator driven suction pump for collecting polymetallic nodules. The studies were per...

Deep seabed polymetallic nodule mining machines have to operate in extremely soft ocean floor having soils of shear strength in the order of 1-3 kPa. The extent of sinkage and pullout force or breakout force required to lift the mining machine from the seafloor bottom needs to be evaluated for the successful operation and retrieval of the mining ma...

The current approach for mining of Poly-metallic nodules at a water depth of 6000m uses a tracked vehicle for locomotion on seabed. As the sea bed sediments are very soft clays, it is necessary to study the soil machine interaction characteristics. The extent of sinkage of mining machine in very soft clays is critical as the soil resistances acting...

Ocean technology developments in India commenced quite late compared to many developed countries. This has resulted in India struggling in the last two decades to make up for the time delay. The activities taken up in India in this area are enumerated in this article. The non-living resources and their method of utilization, along with the challeng...

With the land-based resources depleting faster, effective exploration and sustained harvesting of the Ocean resources, taking into account the economic growth, social needs and the health of the Ocean environment is essential. India with a 7600 km long coastline and an exclusive economic zone of 2.3 million km2 and spear heading the blue economic g...

Drone based water quality measurement system (WQMS) is an Unmanned Aerial Vehicle (UAV) instrumented with series of high resolution water quality measuring sensors such as fast responding micro thermistor probes (MTP) to measure the sea water temperature, conductivity, pH, Turbidity, Dissolved Oxygen, partial CO2 and Micro plastic sensors. Compared...

Drone based water quality measurement system (WQMS) includes an Unmanned Aerial Vehicle (UAV) instrumented with series of high resolution water quality measuring sensors such as fast responding micro thermistor probes (MTP) to measure the sea water temperature, conductivity, pH, Turbidity, Dissolved Oxygen, partial CO2 and Micro plastic sensors. Co...

Drone based water quality measurement system (WQMS) includes an Unmanned Aerial Vehicle (UAV) instrumented with series of high resolution water quality measuring sensors such as fast responding micro thermistor probes (MTP) to measure the sea water temperature, conductivity, pH, Turbidity, Dissolved Oxygen, partial CO2 and Micro plastic sensors. Co...

A manned submersible is an underwater vehicle that is capable of operating independently. During the design process, estimating resistance and power is key to choosing the right propeller. The shape improvement of the manned submersible has a significant impact on the submersible's energy utilization and endurance. Using computational fluid dynamic...

A spherical pressure hull is one of the most critical components of manned submersibles. Almost one-third of the submersible’s weight is occupied by it. This paper describes the process of the structural design of a shallow water steel spherical pressure hull. The classical design rule is used to arrive at a preliminary estimate of spherical pressu...

Measurement of in-situ properties of gas hydrates in the laboratory is essential before the extraction of gas from the hydrate reservoirs. We report the measurement of thermal conductivity of methane hydrates using the needle probe as 1.29 W/mK at 4°C at 59 bar and THF hydrate as 0.64 W/mK at 4°C in the silica sand with the initial liquid saturatio...

As a non-conventional promising energy resource, methane hydrates research is gaining momentum globally as alternate resource with low carbon foot print. Many challenges are to be addressed for gas hydrates extraction feasibility approach in deep water marine settings. The reaction of the reservoir soil during methane gas production from the Natura...

In heavy machineries the power to weight ratio of the drive train performs a major role in designing the mechanics of the movers. Hydraulic system were preferred for the highest power to weight ratio and compact in design for the work to be accomplished. It is even more critical in the design considerations of the underwater vehicle for the hyperba...

In order to cater to the scientific demand for deep ocean exploration with human presence, manned submersible capable of operating up to 6000 m depth is being designed and developed at National Institute of Ocean Technology. The submersible can accommodate three personnel inside the confined space volume of 4.8 m 3 human capsule (personnel sphere)...

The Tsunami Test Rig consists of a host computer, motion controller, motor, encoder, frame for equipment under test, water tank and power backup. Pre recorded Tsunami event data is fed to the computer. The computer has a Graphical User Interface for setting up various parameters for the test and data logging. The motion controller receives data inp...

As part of adapting a drone (Unmanned Aerial Vehicle) for ocean observation applications, Ocean Electronics Group-NIOT has conducted a field study on the drone stability (static & dynamic) with CTD sensor and instrumentation payload using a 10 kg lifting capacity drone with the support of external private industry (M/s. Fopple Technologies, Kankipa...

Marine biogrowth infestation of a seawater intake system was investigated. A digital camera fixed onto a skid was used to record the biogrowth at intervals of 5 m up to a depth of 55 m. Divers inspected the intake shaft and collected the biogrowth samples for biomass estimation. A biomass density of 7.5 kg m⁻² and 28.2 kg m⁻² was recorded at 5 and...

The Tsunami detection system consists of a sea-bed electronic system to detect Tsunami wave and a surface buoy to relay the information to data reception Centre. The power efficient systems works on Alkaline/Lithium primary battery pack. The sea bed electronic system and surface buoy system are communicates through a bidirectional acoustic telemetr...

This paper presents ${a}$ new, and efficient, wear debris detection sensor based on passive wireless LC sensing approach. This sensor enables online monitoring of metal debris in hydraulic flow tubes with large thickness, employed in high-pressure applications. In conventional inductive debris sensors, the coil is kept outside the tube. $(i)$ H...

Design and fabrication procedures used in spherical pressure hull construction have been described in this paper. An appropriate design standard has been applied to ensure the safety and reliability of the pressure hull. Considering the material and manufacturing facility available, steel has been chosen as the pressure hull material. Design and ma...

Human occupied vehicles (HOV) offer enhanced manoeuvering over the remotely operated vehicles and autonomous underwater vehicles. The presence of human increases the dexterity of the HOV operations, but at the same time, the man-rated vehicle design and operation requires significant attention to vehicle reliability , and in turn human safety. This...

In India, scientific investigations of ocean basins have been in progress for more than five decades using indirect and direct measurement devices. These studies were aimed at resource identification, ecological, palaeo-oceanographic and palaeo-climatic research. To cater to the need of the ocean community, Remotely Operated Vehicles (ROV) rated fo...

In India, effective use of hydrocarbon fuels are essential for achieving energy security, economic growth, climate goals and to bridge the implementation delays in the renewable energy sector. Based on the published data, the paper reviews the role of hydrocarbon resources in the Indian energy sector and the need for an innovation-centered ecosyste...

Gas hydrates are considered as a strategic unconventional clean hydrocarbon resource. This paper analyses the techno-economic viability of the methane gas production from the fracture-dominated gas hydrate reservoir in the Krishna-Godavari basin, east coast of India based on multi-well configurations. The analysis is done using the gas hydrate fiel...

Materials used for construction of ocean exploration vehicles require excellent resistance to corrosion in marine environment and higher strength to weight ratio. Acrylic is one of such material which has added benefit of having transparency to be used as material for construction of human occupied pressure hull for Manned Submersible. This paper d...

Autonomous underwater swarm robotic systems (AU-SRS) are vital for exploration of the vast marine resources, spatio-temporal monitoring of the oceans for understanding the changing climate patterns, marine pollution monitoring, defense, and identification of assets lost in the oceans. The paper summarizes the technological developments in the auton...

Viewport window in pressure hull is susceptible to high stress and can experience cracks at its corner. For studying the viewport behaviour at its corner a numerical analysis is carried out on the viewport window. The results show that the stresses are high at the corner. Furthermore, the corner of the viewport is smoothened using the fillet radius...

Remotely operated underwater vehicle (ROV)-based spectral irradiance measurements at South Andaman coral reef islands are used to derive water quality parameters (chlorophyll-a, total-suspended sediments, turbidity, salinity, Secchi disk depth, diffuse attenuation coefficient) at different depths of the water column. Different combination of standa...

India has been developing technology for deep-sea mining in the Central Indian Ocean Basin from 6000m water depth. The Central Indian Ocean Basin (CIOB) is abundant in nodules which are rich sources of minerals like manganese, copper, cobalt, and nickel. The intended mining machine has to collect the nodules from the seabed, crush them, and pump it...

India has been involved in developing the technology for deep-sea mining in the Central Indian Ocean Basin (CIOB) from approximately 6000m water depth. The Central Indian Ocean Basin is abundant in nodules which are rich sources of minerals like manganese, copper, cobalt, and nickel. The mining machine has to collect the nodules from the seabed, cr...

The quadcopter-based unmanned underwater and aerial vehicle has been designed. The vehicle electronics pressure casing has been designed and fabricated using acrylic material which can withstand an atmospheric pressure in aerial condition and external pressure of 10bar in underwater condition to fly in both aerial and underwater conditions up to 10...

The article presents the effectiveness of a subsea optical wireless communication (OWC) system comprising a light-emitting diode (LED) transmitter and a photodiode (PD) receiver when operated at various water depths in the Arabian Sea. An optical attenuation profile identified from solar hyperspectral irradiance measured in up to a 90-m water depth...

Understanding the influence of low temperature and high hydrostatic pressure in the starting performance of deep-sea pressure-compensated (PC) induction motors is essential for sizing of the motor and upstream power systems. This paper presents the observations from experiments carried out on industry-standard 3000-V rated deep-sea PC induction mot...

This current study reports on comparison of nonlinear buckling behaviour of composite material under external hydrostatic pressure using finite element concept. Triaxial failure analysis has been employed at micro level to predict the damage behaviour and failure envelopes of polymer carbon-fiber reinforced composite involving thickness stresses. I...

This paper presents a new and efficient sensor for monitoring the presence of wear debris received by the storage tank in hydraulic systems. The proposed sensor plug employs a magnetic approach to attract the ferrous debris in the storage tank. A capacitive sensing scheme is employed in the same sensor plug to sense the presence of the debris accum...

Understanding the variations in the energy discharge performance of pressurecompensated valve-regulated lead acid (PC VRLA) batteries under the influence of increased hydrostatic pressure is essential for the reliable design of deepocean battery-powered systems. The paper reviews developments in the field of pressure-tolerant electronics and presen...

With land-based resources depleting fast, sustained harvesting of ocean resources with an appropriate trade-off between economic growth, social needs, and the health of the ocean environment is essential. India, with an over 7600-km-long coastline, an exclusive economic zone of 2.3 million km ² , and seeking extension for additional 560 km, has ini...

India has been a Pioneer Investor for seabed exploration and exploitation of polymetallic nodules and has been allotted a mining area in the Central Indian Ocean Basin (CIOB) by the International Seabed Authority (ISA). National Institute of Ocean Technology (NIOT) has been responsible for developing technologies for deep sea mining system for harv...

Reliable power supply, precise position determination and effective communication are the key requirements for strategic autonomous underwater vehicles (AUV) involved in long duration scientific missions, search operations and when operated as a swarm. The paper presents the challenging range of AUV developed for deep water, Polar and intervention...

Manned submersibles are important platforms for exploration and research under the oceans. One of the most important components of the manned submersible is the viewport, which develops high stresses due to the nature of its design. The basic dimensions of the viewport window and its flange are determined using ASME PVHO-1. Analysis of the viewport...

Coral reef biodiversity in South Andaman Islands, India was studied using indigenously developed remotely operated underwater vehicle, PROVe. The vehicle was manoeuvred in coral reef habitats using underwater navigational aids to record faunal assemblages along with underwater spatio-temporal spectral irradiance characteristics coupled with surface...

Natural gas hydrates is considered as a strategic unconventional clean hydrocarbon resource in the energy sector. Understanding the behavior of the rising methane gas bubbles during production leaks from the deep marine gas hydrate reservoirs well head is essential for environmental impact studies and to design environmental monitoring systems. Num...

An ice corer was developed to collect continuous, undisturbed ice core from submerged ice shelves in polar region. Mounting systems were developed to use the corer in a ROV, based on position and force requirement of the coring operation. The first system was developed by fixing the ice corer in the vertical thruster of the ROV and using rotational...

Thin spherical pressure hulls are used as a human occupancy in deep water applications. DNV and other standards specify the imperfection allowed for pressure hulls. Numerical analyses are carried out to find the buckling pressure for both perfect and imperfect thin spherical pressure hulls, considering the geometric and material non-linearities. It...

Ice core samples from the polar ice shelves contain valuable paleo-climatic records and information for understanding the unique polar under-ice ecosystem. This paper describes the finite element analysis-aided design, development, and qualification of a 63-mm-inner diameter, 250-mm-long variable power underwater remotely operated vehicle-mountable...

This paper presents the finite element electrothermal analysis done on an industry standard Kevlar armored subsea power cable to determine the cable overload and short circuit ampacities up to 256 times the continuous current rating. It is identified that the subsea cable could withstand 1.5 times and 256 times the rated current for a period of 17...

The contents of this chapter are from published literature by the team working in the area of deep-sea mining at National Institute of Ocean Technology (NIOT). It starts with a brief introduction on deep-sea mining technologies. This is followed by the historical perspectives and the present-day work and execution in phases towards deep-sea mining...

The soft soil deformation due to central vertical and inclined loading on a plywood platform was simulated by finite element analysis to predict bearing capacity of the platform. The Mohr-Coulomb model was used to model very soft soil behavior. A set of experiments were carried out to observe the deformation behavior of soft soil in vertical loadin...

This paper presents the electro-thermal modelling and simulation, done on a standard Kevlar-armored subsea electrooptic cable based on the finite element analysis (FEA) approach, to determine the cable ampacity when operated in air, water and buried in the seabed under the relevant ambient environmental conditions. Compared to the ampacity in air a...

A reliable Dynamic Positioning (DP) system is the key requirement for critical offshore activities. This paper presents the quantitative reliability assessment for offshore multi-megawatt capacity electric DP systems based on the present technological maturity and the offshore industry-reported component failure rates. It is identified that the Int...

Coral bleaching reported in the North Bay, Andaman Islands during the April last week of 2016 due to thermal stress. The Coral Bleaching Alert System (CBAS) a service providing by Indian National Centre for Ocean Information Services (INCOIS) has reported the warning and the bleaching has been confirmed from the field survey conducted on April 26,...

Time transience-related nonreciprocal effect due to ambient temperature variations has significant influence in the bias stability performance of interference-type fiber optic gyroscopes (I-FOG). This paper presents the thermal finite element analysis (FEA) done on a 10-km-long I-FOG sensing coil wound with a diameter of 10 cm in a bipolar configur...

A deep water work class ROV (ROSUB 6000) rated for 6000 m subsea depth has been developed at National Institute of Ocean technology, Chennai, India. ROSUB 6000 system consists of a free swimming ROV, tether management system (TMS), power container, control console container, Launching and retrieval system (LARS) and electro optical umbilical cable....

This paper presents a dynamic simulation model development for a Brushless DC (BLDC) motor driven thruster system for submersibles. A model for the BLDC motor is attempted which includes the effect of inductance variation with rotor position. The modeling effort is validated by comparing the results with those of the physical thruster system by exp...

In this work authors reports simulation of tsunami detection algorithm in MATLAB software, validation of tsunami detection system in a tank, qualification of tsunami detection algorithm in an automated test rig in the laboratory. It also discuss the results from tsunami detection systems on a tsunami event (12 September 2007) deployed in the Bay of...

Deep sea mining is mineral retrieval process that takes place on the ocean floor wherein global industries are actively exploring and experimenting of different techniques in this relatively new concept of mining for extracting it economically from depths of 5000–5500 m below the ocean’s surface. National Institute of Ocean Technology (NIOT), India...

On-demand reliability is the key requirement for lithium-ion batteries (LIBs) used for powering time-critical remote-located offshore systems. Based on the reported lithium-ion (li-ion) cell failure model, failure rate and on-demand reliability of a li-ion cell are computed for a range of charge-discharge cycles and maintenance intervals. The resul...

Natural gas hydrates are considered to be a strategic unconventional hydrocarbon resource in the Indian energy sector, and thermal stimulation is considered as one of the methods for producing methane from gas hydrate-bearing sediments. This paper discusses the importance of this abundantly available blue economic resource and analyzes the efficien...

The kinetics of methane gas hydrate under confined environment in porous media have been studied for the understanding of formation and dissociation behavior under this condition. We have developed a replica of natural hydrate-bearing atmosphere in a laboratory scale experimental set-up and examined the silica sand size effect on the formation and...

National Institute of Ocean Technology (NIOT) under the aegis of Ministry of Earth Sciences, Government of India has developed a Mini work class Polar Remotely Operated Vehicle (PROVe) for polar studies. PROVe is an unmanned, free swimming underwater vehicle. As part of the 34thIndian scientific expedition to Antarctica (ISEA) a team of six members...

Inverters play a key role in realizing reliable multi-megawatt power electronic converters used in offshore applications, as their failure leads to production losses and impairs safety. The performance of high power handing semiconductor devices with high speed control capabilities and redundant configurations helps in realizing a fault-tolerant de...

The effectiveness of the electro-thermal and depressurisation based techniques applied to three marine gas hydrate reservoir settings of India is modeled and simulated using MATLAB and TOUGH + HYDRATE reservoir modeling software. The results indicate that the depressurisation technique (with an achievable ΔP of >90 bar) will be effective in dissoci...

This paper presents a quantitative approach to operational risk modeling and estimation of Safety Integrity Levels, required for the deep water electric work class remotely operated vehicle with reference to ROSUB6000 developed by the National Institute of Ocean Technology, India. ROSUB6000 is used for carrying out bathymetric surveys, gas hydrate...

A hyperbaric test system is developed for testing underwater components upto a maximum pressure of 50 bar. The system consists of an internal pressure chamber, a hydraulic pump, fluid tank and pressure relief valve. The design calculations of i) cylindrical shell of specified internal diameter, ii) integral flange, iii) blind flange with openings,...

Underwater position data is a key requirement for the navigation and control of unmanned underwater vehicles. The proposed navigation scheme can be used in any vessel or boat for any shallow water vehicle. This paper presents the position estimation algorithm developed for shallow water Remotely Operated Vehicles (ROVs) using attitude data and Dopp...

The hybrid robot, will be a battery operated four wheel drive vehicle with a rigid chassis for all terrain operation. The vehicle will be suited for various payloads based on applications with geological, atmospheric sensors such as oxygen measurement, glacier thickness measurement, CO2 measurement, thermal properties measurement, salinity, buried...