Hello Rakesh,

As you said you have done Marine Engineering why you're not joining directly by approaching any shipping company with your documents, CDC and passport. 

If you really want to do GME course from any college or Institute better to go for the college which has been opened by the shipping companies as they place you onboard their vessels so you don't have to wait for the placement the Institutes are Anglo Eastern Maritime Academy, Great Eastern Training Institute, Shipping corporation of India etc. Are among the good colleges to apply for GME course. 

Feel free to ask any query, will be happy to help you.

All the best!!