Teaching as a profession after B.E.

Your core subject is Marine Engineering. Now you are not interested in teaching in this line. It appears strange as you lose the great opportunity of getting lecturer post in any college or university where you can teach this subject after qualifying in the NET (National Eligibility Test). Anyway if you have no interest in teaching in this particular line then there are other options also which are there for other ordinary graduates and that is to go for B.Ed. course. You can apply for B.Ed. course either in the regular stream or by correspondence and then only you can think of applying for a teaching job in some school or college for the subjects that you choose in your B.Ed course.

B.Ed. is a 2 years course and one should have at least 50% marks in one's Bachelor's Degree exam for applying for it. The course can be pursued in regular or correspondence mode. The age eligibility is from 21 to 35 years.

The B.Ed. course is a comprehensive education training course comprising of theory and practical sessions. It covers subjects like Philosophical and Sociological Basis of Education, Nature and Development, Teaching–Learning Process, School Management, Computer Education, Guidance and Counselling and some optional papers. For correspondence mode, first theory is completed and then practical session of teaching are arranged at some centre.

You are a marine engineer. I think you prefer a teacher post but you don't want to teach marine engineering. If you are ready to teach a Marine engineering course you will be offered directly a teaching job in many private engineering colleges. While working there you can complete your M.Tech also. Once you complete your M Tech, you can try for Ph. D or by clearing NET you can be a lecturer in any government college with UGC scales.

If you are not ready to teach Marine engineering, you have to go for a B.Ed, This is a 2-year course. You can take mathematics and science as the subjects and you can complete that course and get into any school as a teacher.

Since you do have the Marine Engineering background and still you are on the job in the Marine - field but since you are no more interested in continuation of the job in this line, you are interested to clear GATE.
However, there are altogether 22 subjects / streams included with which you can clear the GATE examination and some of the options being Electrical Engineering, Chemical Engineering, Mechanical Engineering, Mathematics, Metallurgical Engineering etc which can be opted to clear the GATE.
You must take a note of this fact that Marine Engineering is not included in the existing GATE scheme and as such you will have to opt for one of the streams included for this test.
Mechanical Engineering is very close to Marine Engineering since some subjects of former stream were taught to you up to 3 rd semester. The next option could be Mathematics since you have had enough exposure in this subject while doing Marine Engineering.
Choice of subjects should not distract your mind while attempting for GATE. This is the only guiding principle.
Once you clear the GATE with the scoring of 99 percentiles and beyond, you will be inducted in the M.Tech programme in the stream for which you appeared.
Your next attempt should be to appear for NET test and clearing this test would pave the way for your Lecturership in the constituent college. While entering into the teaching line in a college, you can take up Ph. D for your better prospects in terms of emoluments and further promotions.