Hello,
You are medically fit and you have completed BTech in Biomedical Engineering and MTech in Medical Instrumentation, but for becoming a marine engineer through IMU CET, your current degrees do not match the required stream. Marine engineering needs a background in mechanical, marine, or naval architecture. Biomedical or medical-related engineering is not considered equivalent.

You also cannot take lateral entry through IMU CET with your qualifications. If you still want to enter the marine field, the usual option is the Graduate Marine Engineering (GME) course, but that also accepts only mechanical or similar branches.
Kindly check the below link to explore about marine engineering course:
https://www.careers360.com/courses/marine-engineering-course