To study Mechant Navy, you need to have Physics , Chemistry and Mathematics as your combination in 10+2 and you have to obtain atleast 50% or equivalent marks in 10+2. Now to get admission into different colleges you need to sit for entrance exams like

1. JEE Mains and Advanced

2. IMU- CET

3. HIMT- OET

4. TMI-BITS-EE

And the UG Courses that you can take up B.Tech / B.E in

1. Offshore Engineering

2. Naval Engineering

3. Marine Engineering

4. Naval Architecture and Ocean Engineering

And you can do M.Tech/ M.E after that to pursue your dream.

Hope it helps, all the best!!

Hi
Here is the eligibility criteria for admission in merchant navy -
The eligibility for joining merchant navy is finishing class 12 with physics , chemistry and mathematics.

Candidates have to be unmarried indian citizens (male or female).

Normal vision is required but glasses up to plus or minus 2.5 may be allowed.

Admission is through an entrance followed by a screening test and a main written examination.

After clearing the test, there is an interview and a medical test.

You also need to complete a ship training course prior to the employment. The course is generally short-term where the candidates are taught basic security concerns of voyaging.
Hope it helps.....