Hello Syed,

First of all Marine Engineering and Mechanical are two different streams of engineering.Either you can complete your B.tech in Mechanical or Marine Engineering.

To get into any of these streams you have to give entrance test such as JEE mains and your state board entrance tests and choose a college which provides these courses.

And it is possible to do your Masters in Marine engineering if you have done Mechanical engineering in B.tech and vice versa.For this you have to give GATE.

I hope this helped you.
All the best!

Sir plz give answers