Journal Articles
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Item Need of natural biocides in antifouling paints for prevention of marine pollution(International Journal of Innovation Research & Development, 2015-07) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S."Antifouling paints were developed to prevent marine growth on ship hulls in the middle of the 19th century. As they were designed to continuously leach biocides at the paint/seawater interface which were the predominant means of controlling fouling for a vast majority of the vessels, over a period of years in the latter part of the last century there has been a marked improvement in the effective life of antifouling paints. Different types of antifouling paints came into being but after a particular breakthrough when self- polishing paints were developed in 1960s. Due to its controlled leaching rate, the self -polishing paints containing TBT was a huge success. However, due to serious environmental effects, these paints have been banned since 2008 and have been replaced by copper based antifouling paints with some success. It was observed that the extensive use of copper based antifouling paints has led to the accumulation of copper and its compounds in the marine environment particularly in the vicinity of ports and harbors and is beginning to pose a serious environmental problem. Foul release coatings are biocide-free –works on a foul release basis by providing a very smooth, low-friction surface which reduce the strength of adhesion of fouling. However, they are applicable only to high- speed, high-activity vessels, in addition to other issues such as high cost, difficult, application procedure and are easily prone to mechanical damage. Biocides from natural products appear to be the only viable alternative in the foreseeable future to protect ship hulls from fouling. This paper reviews the possible natural products that have the potential to be incorporated in to commercial antifouling paints and explores their range of activity"Item CFD analysis for a ballast free ship design(NISCAIR-CSIR, India, 2014-11) Godey, Avinash; Misra, S. C.; Sha, O. P.Shipping transfers approximately 3 to 5 billion tonnes of ballast water internationally each year. This ballast water transferred between different ports is a serious environmental problem. There are many marine species like bacteria, small invertebrates and the eggs, etc., that are carried in ship’s ballast water which are small enough to pass through a ship’s intake at ports and when discharged, lead to severe ecological problems. To overcome this, a concept of ballast free ship has been developed in which ballast water exchange and treatment is avoided by providing flow-through longitudinal pipes in the double bottom instead of conventional ballast tank. During the design of the ballast free ship, different hull forms have been generated with various hull shapes of the vessel which have been studied with regard to hydrodynamic behaviour. Finally one hull form has been selected for further study. The present work aims to estimate the penalty on resistance using CFD techniques using SHIPFLOW® software. These results are validated by model experiments for the conventional and the proposed ballast Free form at loaded and ballast drafts in the Hydrodynamics Laboratory of the Department of Ocean Engineering and Naval Architecture, IIT Kharagpur.Item Failure analysis of antifouling paints on ships hull(NISCAIR-CSIR, India, 2014-11) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.Fouling on ships hull occurs due to the attachment of barnacles, mollusks and other aquatic organisms on the underwater area of the hull. This leads to increased drag, fuel consumption, resulting in unscheduled dry-docking. Recent advances in antifouling (AF) paints, in general, offer protection against fouling in about 95 % of the vessels immersed surface. However, the remaining area which amounts to 5% or less of the total area does get fouled. Although this level of fouling has marginal impact on the routine performance of the vessel, it is a predominant vector for the transmigration of invasive species which is a serious environmental concern. Virtually all ocean going vessels are coated with antifouling paints, predominant among them are “Self polishing coatings”. These coatings depend on the shear forces on the hull surface caused by the motion of the vessel for the paint to “polish” away and release a biocide at a predetermined rate that results in the hull to be essentially fouling free. Currently hulls are coated with a uniform layer of antifouling paints. However, computational fluid dynamics (CFD) analysis conducted on various types of vessels have indicated that there are certain “hotspots” where shear stresses and therefore the polishing rates are exceedingly high which would polish the AF paints at a much faster rate and ultimately result in the failure of the AF coating. The analysis also indicates that these hotspots primarily depend on the profile of the vessels, its speed and its draft. The current practice of a uniform coat of AF paint does not take into account the fact that there are certain areas of the vessel where the polishing rates are excessive. A possible solution to this issue is to first identify these hotspots and suitable paint schemes/formulations are to be applied in these areas. Such painting schemes would prevent the premature failure of the AF coating in general and significantly reduce the risk of transmigration of invasive species.Item Development of a four-bladed surface piercing propeller series(Naval Engineers Journal, 2012) Misra, S. C.; Gokarn, R. P.; Sha, O. P.; Suryanarayana, Ch.; Suresh, R. V.The intent of this work was to develop a methodical series of four-bladed propellers of the surface piercing type so as to be able to design a surface piercing propeller for a given operating condition. A test rig along with instrumentation was developed at NSTL to determine the open water characteristics of surface piercing propellers experimentally. Initially, four model propellers were designed and manufactured with four different section shapes with the same pitch ratio and blade area ratio. The diameter of all the model propellers was fixed at 250mm. These propellers were of two basic section shapes: wedge and diamond back. To study the effect of trailing edge inclination (cup shape) three different wedge shapes were developed with the trailing edge making angles of 0°, 30°, and 60° to the horizontal respectively. These four propellers were tested extensively in the High Speed Towing Tank of NSTL. Weber number effects were found to be small in the model tests that were carried out at 20rps for the 250mm diameter propellers. The best performance at all immersions was obtained from SPP-3, the propeller having wedge shaped sections with the trailing edge inclined at 60° to the horizontal. The astern performance of this propeller was found to be satisfactory from the limited number of tests that were conducted.Item Sustainable development and ship life cycle(International Journal of Innovation Research & Development, 2012-12) Misra, S. C.Transportation of goods and people across water is a necessary engineering activity for economic growth of individuals and society. But does this growth affect sustainable development through environmental degradation? A ship's life cycle consists of concept exploration, design, production, operation and maintenance and dismantling. Stages in the life cycle of a ship in which large energy is consumed can be said to be (i) shipbuilding (ii) ship operation and maintenance and (iii) ship dismantling. The energy consumed in building a ship can be grouped under major heads as establishment energy, direct energy in materials and its transportation, direct energy consumed in construction of the particular ship, indirect or overhead energy consumed in the shipyard which cannot be billed to a ship. The green ship concept is evolved to reduce energy consumption in shipbuilding, ship operation and maintenance. This can be achieved by optimised structural design for steel weight reduction and use of alternative materials, possible use of alternative and renewable fuels, propulsion systems and auxiliary systems, Innovative design development such as Ballast Free Ship(BFS) and proper system integration. Ship Design plays a crucial role for ensuring ship construction, operation and dismantling. It is therefore necessary to increase the scope of concept design by incorporating use of numerical analysis procedures at early stages of design, consideration of alternative fuels and propulsion systems, use of design for production and design for maintenance techniques. Standardisation and modularisation should be incorporated in ship design for improved production.Item Environmentally friendly antifouling paints and painting schemes(International Journal of Innovation Research & Development, 2012-12) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.Since the 1970's Tributyl tin based antifouling paints were widely used to control fouling on ships hulls. These coatings offered up to 5 years of foul-free hulls and were the most effective antifouling paints ever produced. However, due to serious environmental effects, these paints have been banned since 2008 and have been replaced by copper based antifouling paints with some success. However, the extensive use of copper based antifouling paints has led to the accumulation of cooper and its compounds in the marine environment particularly in the vicinity of ports and harbors and is beginning to pose a serious environmental problem. This paper explores the possibility of incorporating environmentally friendly biocides in antifouling paints that exhibit a low persistence in the marine environment particularly those biocides that are available in the Indian context. Another serious problem facing the marine environment is the issue of Invasive species. In recent years the issue of invasive marine species has been receiving considerable attention due to the fact that introduction of non indegenous species or non-native species transmigrated from other areas to coastal waters often results in the reduction and even extinction of the native species and thereby severely disrupts the natural marine ecosystems. The predominant vector for the transport of nonindigenous species in marine environments has been shipping. While ballast water receives the most attention, hull fouling is now considered to be the most significant means for translocation of these organisms. Certain niche areas of the vessel such as bow thrusters, sea chest, stern tube, rudder etc. are the likely areas to be heavily fouled. Although this fouling does not affect the overall performance of the vessel, would however, be a vector for the transportation of Invasive species. In addition, the other areas that are likely to be fouled are on locations where antifouling paint has been worn of due to excessive shear and bending of the hull. This paper attempts to identify such areas using CFD simulations and suggest that special paint schemes must be incorporated in these niche areas.Item Development of a ballast free ship design(International Journal of Innovation Research & Development, 2012-12) Godey, Avinash; Misra, S. C.; Sha, O. P.Shipping transfers approximately 3 to 5 billion tonnes of ballast water internationally each year. Ballast water discharges non-native species leading to severe ecological problems. The present work aims at a design solution into the ballastless ship in which ballast water exchange and treatment is avoided by providing flow-through longitudinal pipes in the double bottom instead of conventional ballast tanks. During the design of the ballast less ship, different hull forms are generated with altering the hull shape in forward and aft out of which one was finalised. In addition to change in hull form the internal tank arrangement has been changed so that the propeller immersion and the minimum draft required in the ballast condition is achieved. Structural arrangement for the mid ship section was proposed for the modified hull form of ballast less ship as well as data on valves had been collected for the flow through condition. Finally, resistance tests were conducted on equivalent models of scale ratio 1:71 for the conventional and the proposed ballsatless form at the loaded and ballast drafts in the Hydrodynamic Towing Tank of the Department of Ocean Engineering and Naval Architecture, IIT Kharagpur. The model experiments on ballast less ship show an increase in resistance in ballast draft when compared to a conventional tanker due to the flow through pipes in double bottom.Item Antifouling paint schemes for green ships(Ocean Engineering, 2019) Mukherjee, A.; Madhu, Joshi; Misra, S. C.; Ramesh, U. S.Recent advances in antifouling (AF) paints in general prevent fouling in about 95% of the vessel's immersed surface. However the remaining area which amounts to 5% or less of the total area does get fouled. Although this level of fouling has marginal impact on the routine performance of the vessel it is a predominant vector for the transmigration of invasive species which is now a serious environmental concern. Virtually all ocean going vessels are coated with antifouling paints predominant among them are “Self polishing coatings”. CFD analysis conducted on various types of vessels have indicated that there are certain “hotspots” where the polishing rates are exceedingly high and would polish the AF paints at a much faster rate and ultimately result in the failure of the AF coating. A possible solution to this issue is to first identify these hotspots and suitable paint schemes/formulations are to be applied in such areas. An experimental procedure utilizing a “drum-test” apparatus can be used to compute the coating thicknesses based on wall shear stresses. Such painting schemes would prevent the premature failure of the AF coating in general and significantly reduce the risk of transmigration of invasive species in particular.Item Control of biocorrosion to prevent the propagation of invasive species(Indian Maritime University, Chennai, 2010-09) Joshi, Madhu; Mukherjee, A.; Ramesh, U. S.; Misra, S. C.Biocorrosion or biofouling on ships hull occursdue to the attachment of barnacles, mollusks and other aquatic organisms on the surface of ships which leads to increase in fuel consumption, reduction of the vessels speed, premature failure of the hull, etc. Recent developments in antifouling paints, in general, prevent fouling in about 95% percent of the vessels underwater surface, which ship operators find satisfactory as far as the routine vessel operation is concerned. However, this is not sufficient to prevent the transport or invasion of alien species. In recent years the issue of invasive marine species has been receiving considerable attention due to the fact that introduction of nonidegenous species or non-native species transmigrated from other areas to coastal waters often results in the reduction and even extinction of the native species and thereby severely disrupting the natural marine ecosystems. The predominant vector for the transport of nonindigenous species in marine environments has been shipping. While ballast water receives the most attention, hull fouling is now considered to be the most significant means for translocation of these organisms. For example, 90 percent of the 343 marine alien species in Hawaii are thought to have arrived through hull fouling Certain niche areas of the vessel such as bow thrusters, sea chest, stern tube, rudder etc. are the likely areas to be heavily fouled. In addition, the other areas that are likely to be fouled are on locations where antifouling paint has been worn of due to excessive shear and bending of the hull. This paper reviews the various antifouling strategies and aims identify areas on the hull surfaces of certain classes of vessels that are prone to fouling by excessive shear and bending and identify suitable antifouling treatments to further reduce the risk of transportation of alien species.null.listelement.badge A study on the seasonal variability of nearshore waves off Visakhapatnam, east coast of India(International Journal of Innovative Research and Development, 2012-12) Suresh, R. R. V.; Patnaik, K. V. K. R. K.; Ramesh, U. S.; Misra, S. C.Wave rider buoy data during the period June 2009 to May 2010 was analyzed to examine the seasonal trends in the nearshore waves off Visakhapatnam, east coast of India. During fair weather conditions, wave heights were observed to be higher in the southwest monsoon season with maximum significant wave height (Hs) of about 2.76m in the month of July and average Hs of about 1.6m. The higher values of spectral band width emphasize that the wave heights covered a wide range for major period of the year. A large standard deviation of swell period represents the occurrence of distant swell in a wide range to the study region. The seasonal cycle of wave heights off Visakhapatnam, East Coast of India is dominated by SW monsoon winds. The waves at study area are resultant of sea and large swells from south of Bay of Bengal