Is Indian Navy B tech good?

It all depends upon your definition of good. You will be achieving two goals by pursuing a Bachelor's degree in Indian Navy. On one hand while you will be serving your nation (you will be proud beyond imagination) and on the other hand you will be learning to apply the science with your fellow mates in real life situations under a disciplined environment. So you can forget about a regular/average civilian life.

You will pursuing your degree under the Indian government. Now think about the quality of education that is offered by central government institutes like IITs and NITs. Rather make an amendment in this you will not be living with civilians. You will be training in the navy and studying according to their rules. Which means less liberty and strict and disciplined life. As far as the quality of education is concerned, you don't need to worry about it! You will be learning stuff from renowned professionals and teachers. You will learn to solve daily life problems of navy men like a professional. And lifestyle will be different. This is the 'good' different we are talking about. You will train with your first officers as an intern and by the end you will have handsome salary package. This is what people call the golden opportunity. After all it is the Indian Navy we are talking about here!