Naval architecture and ship building is the most demanding course in CUSAT,last year(2012-13) their placement package was about Rs 26 lac per annum and i think around 12 of them got placed ....Due to this brilliant placement opportunities,this course becomes most demanding......Now considering the marks u need to score,we just can't tell that exactly,it totally depends on the level of paper....but to get into ship department,u need to come within the rank of 300...that is u need to score maximum out of 750.....i think scoring around 650(just an assumption) would make ur deck clear...since u belong to OBC,it clearly increases ur chances with that marks.... :) god bless ....