ELECTIVE SUBJECTSSEMESTER-VI (ELECTIVE -72 hrs)DOUBLE HULL TANKER VESSELSOrigin of double hull ships, their usefulness and superiority over conventional single skin ships, use of double hull tank ships- for transport of different types of commodities, prevention of oil-spill and pollution of sea, IMO requirements, schedule for phasing out single hull tank vessels of different sizes.Design considerations, main dimension, hull-weight estimate, double hull requirements, minimum depth of double bottom tank, wing tank width, clearance for inspection etc. maximum cargo tank size, capacity effect of free surface, damage stability, hydrostatically balanced loading, sloshing loads, its elimination or minimization.Structural design, non-uniform and uniform stress distribution, unidirectional longitudinal) structural members, elimination of transverse structural members (except transverse bulkheads), minimization of structural discontinuities and stress concentration zones, use of steel of higher strength, resistance to grounding and collision, classification society requirements, access to inside and bottom spaces.Cargo handling system, use of submerged pumps, ordinary pumps of new independent pumps, cargo transfer system, assurance of quality of cargo oil, complete elimination of risk of admixture of different grades of oil, concealed pipe-lines, easy maintenance, inspection and cleaning, elimination of explosion risks.Economic aspects, fast loading discharging of oil cargo, quicker cleaning, ballasting and deballasting, larger number of trips per year.